WorldWideScience

Sample records for atmospheric line observations

  1. GARLIC - A general purpose atmospheric radiative transfer line-by-line infrared-microwave code: Implementation and evaluation

    Science.gov (United States)

    Schreier, Franz; Gimeno García, Sebastián; Hedelt, Pascal; Hess, Michael; Mendrok, Jana; Vasquez, Mayte; Xu, Jian

    2014-04-01

    A suite of programs for high resolution infrared-microwave atmospheric radiative transfer modeling has been developed with emphasis on efficient and reliable numerical algorithms and a modular approach appropriate for simulation and/or retrieval in a variety of applications. The Generic Atmospheric Radiation Line-by-line Infrared Code - GARLIC - is suitable for arbitrary observation geometry, instrumental field-of-view, and line shape. The core of GARLIC's subroutines constitutes the basis of forward models used to implement inversion codes to retrieve atmospheric state parameters from limb and nadir sounding instruments. This paper briefly introduces the physical and mathematical basics of GARLIC and its descendants and continues with an in-depth presentation of various implementation aspects: An optimized Voigt function algorithm combined with a two-grid approach is used to accelerate the line-by-line modeling of molecular cross sections; various quadrature methods are implemented to evaluate the Schwarzschild and Beer integrals; and Jacobians, i.e. derivatives with respect to the unknowns of the atmospheric inverse problem, are implemented by means of automatic differentiation. For an assessment of GARLIC's performance, a comparison of the quadrature methods for solution of the path integral is provided. Verification and validation are demonstrated using intercomparisons with other line-by-line codes and comparisons of synthetic spectra with spectra observed on Earth and from Venus.

  2. Atmospherical simulations of the OMEGA/MEX observations

    Science.gov (United States)

    Melchiorri, R.; Drossart, P.; Combes, M.; Encrenaz, T.; Fouchet, T.; Forget, F.; Bibring, J. P.; Ignatiev, N.; Moroz, V.; OMEGA Team

    The modelization of the atmospheric contribution in the martian spectrum is an important step for the OMEGA data analysis.A full line by line radiative transfer calculation is made for the gas absorption; the dust opacity component, in a first approximation, is calculated as an optically thin additive component.Due to the large number of parameters needed in the calculations, the building of a huge data base to be interpolated is not envisageable, for each observed OMEGA spectrum with calculation for all the involved parameters (atmospheric pressure, water abundance, CO abundance, dust opacity and geometric angles of observation). The simulation of the observations allows us to fix all the orbital parameters and leave the unknown parameters as the only variables.Starting from the predictions of the current meteorological models of Mars we build a smaller data base corresponding on each observation. We present here a first order simulation, which consists in retrieving atmospheric contribution from the solar reflected component as a multiplicative (for gas absorption) and an additive component (for suspended dust contribution); although a fully consistent approach will require to include surface and atmosphere contributions together in synthetic calculations, this approach is sufficient for retrieving mineralogic information cleaned from atmospheric absorption at first order.First comparison to OMEGA spectra will be presented, with first order retrieval of CO2 pressure, CO and H2O abundance, and dust opacity.

  3. A New Window into Escaping Exoplanet Atmospheres: 10830 Å Line of Helium

    Science.gov (United States)

    Oklopčić, Antonija; Hirata, Christopher M.

    2018-03-01

    Observational evidence for escaping exoplanet atmospheres has been obtained for a few exoplanets to date. It comes from strong transit signals detected in the ultraviolet, most notably in the wings of the hydrogen Lyα (Lyα) line. However, the core of the Lyα line is often heavily affected by interstellar absorption and geocoronal emission, limiting the information about the atmosphere that can be extracted from that part of the spectrum. Transit observations in atomic lines that are (a) sensitive enough to trace the rarefied gas in the planetary wind and (b) do not suffer from significant extinction by the interstellar medium could enable more detailed observations, and thus provide better constraints on theoretical models of escaping atmospheres. The absorption line of a metastable state of helium at 10830 Å could satisfy both of these conditions for some exoplanets. We develop a simple 1D model of escaping planetary atmospheres containing hydrogen and helium. We use it to calculate the density profile of helium in the 23S metastable excited state and the expected in-transit absorption at 10830 Å for two exoplanets known to have escaping atmospheres. Our results indicate that exoplanets similar to GJ 436b and HD 209458b should exhibit enhanced transit depths at 10830 Å, with ∼8% and ∼2% excess absorption in the line core, respectively.

  4. GARLIC — A general purpose atmospheric radiative transfer line-by-line infrared-microwave code: Implementation and evaluation

    International Nuclear Information System (INIS)

    Schreier, Franz; Gimeno García, Sebastián; Hedelt, Pascal; Hess, Michael; Mendrok, Jana; Vasquez, Mayte; Xu, Jian

    2014-01-01

    A suite of programs for high resolution infrared-microwave atmospheric radiative transfer modeling has been developed with emphasis on efficient and reliable numerical algorithms and a modular approach appropriate for simulation and/or retrieval in a variety of applications. The Generic Atmospheric Radiation Line-by-line Infrared Code — GARLIC — is suitable for arbitrary observation geometry, instrumental field-of-view, and line shape. The core of GARLIC's subroutines constitutes the basis of forward models used to implement inversion codes to retrieve atmospheric state parameters from limb and nadir sounding instruments. This paper briefly introduces the physical and mathematical basics of GARLIC and its descendants and continues with an in-depth presentation of various implementation aspects: An optimized Voigt function algorithm combined with a two-grid approach is used to accelerate the line-by-line modeling of molecular cross sections; various quadrature methods are implemented to evaluate the Schwarzschild and Beer integrals; and Jacobians, i.e. derivatives with respect to the unknowns of the atmospheric inverse problem, are implemented by means of automatic differentiation. For an assessment of GARLIC's performance, a comparison of the quadrature methods for solution of the path integral is provided. Verification and validation are demonstrated using intercomparisons with other line-by-line codes and comparisons of synthetic spectra with spectra observed on Earth and from Venus. - Highlights: • High resolution infrared-microwave radiative transfer model. • Discussion of algorithmic and computational aspects. • Jacobians by automatic/algorithmic differentiation. • Performance evaluation by intercomparisons, verification, validation

  5. ALMA Long Baseline Observations of the Dynamical Atmospheres of AGB Stars

    Science.gov (United States)

    Vlemmings, Wouter

    2018-04-01

    I will present the current status of ALMA long baseline observations of W Hya, R Leo, R Dor and Mira. We have recently obtained band 4, 6 and 7 observations of the line and continuum emission tracing the temperature and dynamics in their extended atmosphere. Our preliminary analysis confirms our previous detection of a hotspot on W Hya, and reveals unexpected lines in most of the sources, as well as possible fast rotation in the atmopshere of one of the stars. The observations show the unique power of ALMA in observing the extended stellar atmospheres.

  6. Observations of chromospheric lines from OSO-8

    Science.gov (United States)

    Grossmann-Doerth, U.; Kneer, F.; Uexkuell, M.; Artzner, G. E.; Vial, J. C.

    1980-01-01

    Results of OSO-8 measurements of the line profiles of the solar Lyman alpha, Ca II K and Mg II k lines are presented. Observations were obtained with the Laboratoire de Physique Stellaire et Planetaire spectrometer at spectral resolutions of 0.25 and 0.060 A for Lyman alpha and 0.025 A for the Mg II and Ca II lines. The Lyman alpha profiles are found to be highly variable according to spatial position with the intensities of the three lines well correlated, and confirm previous observations of the quiet solar chromosphere. Data suggest that the quiet chromosphere is a dynamical phenomenon whose description in terms of a static model atmosphere is only qualitatively valid at best.

  7. IUE observations of Si and C lines and comparison with non-LTE models

    Science.gov (United States)

    Kamp, L. W.

    1982-01-01

    Classical model atmosphere techniques are applied to analyze IUE spectra, and to determine abundances, effective temperatures and gravities. Measurements of the equivalent widths and other properties of the line profiles of 24 photospheric lines of Si II, Si III, Si IV, C II, C III and C IV are presented in the range of 1175-1725 A for seven B and two O stars. Observed line profiles are compared with theoretical profiles computed using non-LTE theory and models, and using line-blanketed model atmospheres. Agreement is reasonably good, although strong lines are calculated to be systematically stronger than those observed, while the reverse occurs for weak lines, and empirical profiles have smaller wings than theoretical profiles. It is concluded that the present theory of line formation when used with solar abundances, represents fairly well observed UV photospheric lines of silicon and carbon ions in the atmospheres of main sequence stars of types B5-O9.

  8. Observations of CO in Titan's Atmosphere Using ALMA

    Science.gov (United States)

    Serigano, Joseph; Nixon, Conor A.; Cordiner, Martin; Irwin, Patrick G. J.; Teanby, Nicholas; Charnley, Steven B.; Lindberg, Johan E.; Remijan, Anthony J.

    2015-11-01

    The advent of the Atacama Large Millimeter/submillimeter Array (ALMA) has provided a powerful facility for probing the atmospheres of solar system targets at long wavelengths (84-720 GHz) where the rotational lines of small, polar molecules are prominent. In the dense, nitrogen-dominated atmosphere of Titan, photodissociation of molecular nitrogen and methane leads to a wealth of complex hydrocarbons and nitriles in small abundances. Past millimeter/submillimeter observations, including ground-based observations as well as those by the Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft, have proven the significance of this wavelength region for the derivation of vertical mixing profiles, latitudinal and seasonal variations, and molecular detections. Previous ALMA studies of Titan have presented mapping and vertical column densities of hydrogen isocyanide (HNC) and cyanoacetylene (HC3N) (Cordiner et al. 2014) as well as the first spectroscopic detection of ethyl cyanide (C2H5CN) in Titan’s atmosphere (Cordiner et al. 2015).Here, we report several submillimetric observations of carbon monoxide (CO) and its isotopologues 13CO, C18O, and C17O in Titan’s atmosphere obtained with flux calibration data from the ALMA Science Archive. We employ NEMESIS, a line-by-line radiative transfer code, to determine the stratospheric abundances of these molecules. The abundance of CO in Titan's atmosphere is determined to be approximately 50±1 ppm, constant with altitude, and isotopic ratios are determined to be approximately 12C/13C = 90, 16O/18O = 470, and 16O/17O = 2800. This report presents the first spectroscopic detection of C17O in the outer solar system, detected at >11σ confidence. This talk will focus on isotopic ratios in CO in Titan's atmosphere and will compare our results to previously measured values for Titan and other bodies in the Solar System. General implications for the history of Titan from measurements of CO and its isotopologues will be

  9. Spectroscopy of carbonated chains: experimental investigation and observation of Titan's atmosphere

    International Nuclear Information System (INIS)

    Jolly, Antoine

    2012-01-01

    In this report for an Accreditation to Supervise Research (HDR), the author proposes an overview of his research works. These works first addressed quantitative spectroscopy and more particularly the measurement of absolute absorption coefficients which are necessary parameters for the quantification of molecules which are remotely sensed through their spectroscopic signature. Secondly, the author addresses the adjustment of line lists in the infrared for a better investigation of recent observations of Titan's atmosphere made by the Cassini mission. Thirdly, he reports the use of this line list for the processing of observations of Titan. The last part addresses an experimental atmospheric simulation which aims at reproducing Titan's atmosphere by submitting its main components (nitrogen and methane) to an energetic flow representative of what is present on Titan

  10. FIMS Wavelength Calibration via Airglow Line Observations

    Directory of Open Access Journals (Sweden)

    Dae-Hee Lee

    2004-12-01

    Full Text Available Far-ultraviolet Imaging Spectrograph (FIMS is the main payload of the Korea's first scientific micro satellite STSAT-1, which was launched at Sep. 27 2003 successfully. Major objective of FIMS is observing hot gas in the Galaxy in FUV bands to diagnose the energy flow models of the interstellar medium. Supernova remnants, molecular clouds, and Aurora emission in the geomagnetic pole regions are specific targets for pointing observation. Although the whole system was calibrated before launch, it is essential to perform on-orbit calibration for data analysis. For spectral calibration, we observed airglow lines in the atmosphere since they provide good spectral references. We identify and compare the observed airglow lines with model calculations, and correct the spectral distortion appeared in the detector system to improve the spectral resolution of the system.

  11. Instrumental and atmospheric background lines observed by the SMM gamma-ray spectrometer

    Science.gov (United States)

    Share, G. H.; Kinzer, R. L.; Strickman, M. S.; Letaw, J. R.; Chupp, E. L.

    1989-01-01

    Preliminary identifications of instrumental and atmospheric background lines detected by the gamma-ray spectrometer on NASA's Solar Maximum Mission satellite (SMM) are presented. The long-term and stable operation of this experiment has provided data of high quality for use in this analysis. Methods are described for identifying radioactive isotopes which use their different decay times. Temporal evolution of the features are revealed by spectral comparisons, subtractions, and fits. An understanding of these temporal variations has enabled the data to be used for detecting celestial gamma-ray sources.

  12. Non-LTE Calculations of the Fe I 6173 Å Line in a Flaring Atmosphere

    Science.gov (United States)

    Hong, Jie; Ding, M. D.; Li, Ying; Carlsson, Mats

    2018-04-01

    The Fe I 6173 Å line is widely used in the measurements of vector magnetic fields by instruments including the Helioseismic and Magnetic Imager (HMI). We perform non-local thermodynamic equilibrium calculations of this line based on radiative hydrodynamic simulations in a flaring atmosphere. We employ both a quiet-Sun atmosphere and a penumbral atmosphere as the initial one in our simulations. We find that, in the quiet-Sun atmosphere, the line center is obviously enhanced during an intermediate flare. The enhanced emission is contributed from both radiative backwarming in the photosphere and particle beam heating in the lower chromosphere. A blue asymmetry of the line profile also appears due to an upward mass motion in the lower chromosphere. If we take a penumbral atmosphere as the initial atmosphere, the line has a more significant response to the flare heating, showing a central emission and an obvious asymmetry. The low spectral resolution of HMI would indicate some loss of information, but the enhancement and line asymmetry are still kept. By calculating polarized line profiles, we find that the Stokes I and V profiles can be altered as a result of flare heating. Thus the distortion of this line has a crucial influence on the magnetic field measured from this line, and one should be cautious in interpreting the magnetic transients observed frequently in solar flares.

  13. PROBING THE SOLAR ATMOSPHERE USING OSCILLATIONS OF INFRARED CO SPECTRAL LINES

    International Nuclear Information System (INIS)

    Penn, M. J.; Schad, T.; Cox, E.

    2011-01-01

    Oscillations were observed across the whole solar disk using the Doppler shift and line center intensity of spectral lines from the CO molecule near 4666 nm with the National Solar Observatory's McMath/Pierce solar telescope. Power, coherence, and phase spectra were examined, and diagnostic diagrams reveal power ridges at the solar global mode frequencies to show that these oscillations are solar p-modes. The phase was used to determine the height of formation of the CO lines by comparison with the IR continuum intensity phase shifts as measured in Kopp et al.; we find that the CO line formation height varies from 425 km μ > 0.5. The velocity power spectra show that while the sum of the background and p-mode power increases with height in the solar atmosphere as seen in previous work, the power in the p-modes only (background subtracted) decreases with height. The CO line center intensity weakens in regions of stronger magnetic fields, as does the p-mode oscillation power. Across most of the solar surface the phase shift is larger than the expected value of 90 0 for an adiabatic atmosphere. We fit the phase spectra at different disk positions with a simple atmospheric model to determine that the acoustic cutoff frequency is about 4.5 mHz with only small variations, but that the thermal relaxation frequency drops significantly from 2.7 to 0 mHz at these heights in the solar atmosphere.

  14. Non-LTE profiles of the Al I autoionization lines. [for solar model atmospheres

    Science.gov (United States)

    Finn, G. D.; Jefferies, J. T.

    1974-01-01

    A non-LTE formulation is given for the transfer of radiation in the autoionizing lines of neutral aluminum at 1932 and 1936 A through both the Bilderberg and Harvard-Smithsonian model atmospheres. Numerical solutions for the common source function of these lines and their theoretical line profiles are calculated and compared with the corresponding LTE profiles. The results show that the non-LTE profiles provide a better match with the observations. They also indicate that the continuous opacity of the standard solar models should be increased in this wavelength region if the center-limb variations of observed and theoretical profiles of these lines are to be in reasonable agreement.

  15. PROBING THE FLARE ATMOSPHERES OF M DWARFS USING INFRARED EMISSION LINES

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Sarah J.; Kowalski, Adam F.; Hawley, Suzanne L.; Hilton, Eric J.; Wisniewski, John P.; Tofflemire, Benjamin M., E-mail: sjschmidt@astro.washington.edu [Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada (Canada)

    2012-01-20

    We present the results of a campaign to monitor active M dwarfs using infrared spectroscopy, supplemented with optical photometry and spectroscopy. We detected 16 flares during nearly 50 hr of observations on EV Lac, AD Leo, YZ CMi, and VB 8. The three most energetic flares also showed infrared emission, including the first reported detections of P{beta}, P{gamma}, He I {lambda}10830, and Br{gamma} during an M dwarf flare. The strongest flare ({Delta}u = 4.02 on EV Lac) showed emission from H{gamma}, H{delta}, He I {lambda}4471, and Ca II K in the UV/blue and P{beta}, P{gamma}, P{delta}, Br{gamma}, and He I {lambda}10830 in the infrared. The weaker flares ({Delta}u = 1.68 on EV Lac and {Delta}U = 1.38 on YZ CMi) were only observed with photometry and infrared spectroscopy; both showed emission from P{beta}, P{gamma}, and He I {lambda}10830. The strongest infrared emission line, P{beta}, occurred in the active mid-M dwarfs with a duty cycle of {approx}3%-4%. To examine the most energetic flare, we used the static NLTE radiative transfer code RH to produce model spectra based on a suite of one-dimensional model atmospheres. Using a hotter chromosphere than previous one-dimensional atmospheric models, we obtain line ratios that match most of the observed emission lines.

  16. Spectral observations of atmospheric #betta#-ray background

    International Nuclear Information System (INIS)

    Jayanthi, U.B.; Blanco, F.G.; Aguiar, O.D. de; Jardim, J.O.D.; Benson, J.L.; Martin, I.M.; Rao, K.R.

    1981-05-01

    Based on the results of two balloon flights, made at Sao Jose dos Campos and at Juazeiro do Norte in Brazil, using omnidirectional gamma ray detectors, the different aspects of atmospheric gamma rays at equatorial latitudes in the energy interval of 0.3 to 4.5 MeV are investigated. The energy loss spectrum in this energy band is found no consist of a continuum and a photo peak at 0.51 MeV in agreement with previous observations. A discussion of the spectral nature of this background and the observed lower intensities of both the continuum and the 0.51 MeV line with reference to observations at other latitudes is presented. (Author) [pt

  17. Polarisation of auroral emission lines in the Earth's upper atmosphere : first results and perspectives

    Science.gov (United States)

    Lamy, H.; Barthelemy, M.; Simon Wedlund, C.; Lilensten, J.; Bommier, V.

    2011-12-01

    Polarisation of light is a key observable to provide information about asymmetry or anisotropy within a radiative source. Following the pioneering and controversial work of Duncan in 1959, the polarisation of auroral emission lines in the Earth's upper atmosphere has been overlooked for a long time, even though the red intense auroral line (6300Å) produced by collisional impacts with electrons precipitating along magnetic field lines is a good candidate to search for polarisation. This problem was investigated again by Lilensten et al (2006) and observations were obtained by Lilensten et al (2008) confirming that the red auroral emission line is polarised. More recent measurements obtained by Barthélemy et al (2011) are presented and discussed. The results are compared to predictions of the theoretical work of Bommier et al (2011) and are in good agreement. Following these encouraging results, a new dedicated spectropolarimeter is currently under construction between BIRA-IASB and IPAG to provide simultaneously the polarisation of the red line and of other interesting auroral emission lines such as N2+ 1NG (4278Å), other N2 bands, etc... Perspectives regarding the theoretical polarisation of some of these lines will be presented. The importance of these polarisation measurements in the framework of atmospheric modeling and geomagnetic activity will be discussed.

  18. Some characteristics of atmospheric gravity waves observed by radio-interferometry

    Directory of Open Access Journals (Sweden)

    Claude Mercier

    Full Text Available Observations of atmospheric acoustic-gravity waves (AGWs are considered through their effect on the horizontal gradient G of the slant total electron content (slant TEC, which can be directly obtained from two-dimensional radio-interferometric observations of cosmic radio-sources with the Nançay radioheligraph (2.2°E, 47.3°N. Azimuths of propagation can be deduced (modulo 180°. The total database amounts to about 800 h of observations at various elevations, local time and seasons. The main results are:

    line-height: 20px;">a AGWs are partially directive, confirming our previous results.

    line-height: 20px;">b The propagation azimuths considered globally are widely scattered with a preference towards the south.

    line-height: 20px;">c They show a bimodal time distribution with preferential directions towards the SE during daytime and towards the SW during night-time (rather than a clockwise rotation as reported by previous authors.

    line-height: 20px;">d The periods are scattered but are larger during night-time than during daytime by about 60%.

    line-height: 20px;">e The effects observed with the solar radio-sources are significantly stronger than with other radio-sources (particularly at higher elevations, showing the role of the geometry in line of sight-integrated observations.

  19. Depths of formation of the CN molecule lines in the solar atmosphere

    International Nuclear Information System (INIS)

    Porfir'eva, G.A.

    1975-01-01

    The depths of production of lines of weak bands of the CN molecule violet (lambda=4216A) system are calculated by the weight function method. Two models of solar atmosphere are used. Lines with the different rotational vibrational quantum numbers are produced practically in the same layer (tau approximately equal to 0.05-0.06). The difference of depths of production of the line center and the wing is small (Δtau 0 =0.005). The contribution functions for the solar disk center differ little from those for the edge. The calculations carried out are in good agreement with the results obtained from earlier observations

  20. Non-LTE, line-blanketed model atmospheres for late O- and early B-type stars

    Science.gov (United States)

    Grigsby, James A.; Morrison, Nancy D.; Anderson, Lawrence S.

    1992-01-01

    The use of non-LTE line-blanketed model atmospheres to analyze the spectra of hot stars is reported. The stars analyzed are members of clusters and associations, have spectral types in the range O9-B2 and luminosity classes in the range III-IV, have slow to moderate rotation, and are photometrically constant. Sampled line opacities of iron-group elements were incorporated in the radiative transfer solution; solar abundances were assumed. Good to excellent agreement is obtained between the computed profiles and essentially all the line profiles used to fix the model, and reliable stellar parameters are derived. The synthetic M II 5581 equivalent widths agree well with the observed ones at the low end of the temperature range studied, but, above 25,000 K, the synthetic line is generally stronger than the observed line. The behavior of the observed equivalent widths of N II, N III, C II and C III lines as a function of Teff is studied. Most of the lines show much scatter, with no consistent trend that could indicate abundance differences from star to star.

  1. Molecular line parameters for the atmospheric trace molecule spectroscopy experiment

    Science.gov (United States)

    Brown, L. R.; Farmer, C. B.; Toth, R. A.; Rinsland, Curtis P.

    1987-01-01

    During its first mission in 1985 onboard Spacelab 3, the ATMOS (atmospheric trace molecule spectroscopy) instrument, a high speed Fourier transform spectrometer, produced a large number of high resolution infrared solar absorption spectra recorded in the occultation mode. The analysis and interpretation of these data in terms of composition, chemistry, and dynamics of the earth's upper atmosphere required good knowledge of the molecular line parameters for those species giving rise to the absorptions in the atmospheric spectra. This paper describes the spectroscopic line parameter database compiled for the ATMOS experiment and referenced in other papers describing ATMOS results. With over 400,000 entries, the linelist catalogs parameters of 46 minor and trace species in the 1-10,000/cm region.

  2. Characterizing Exoplanet Atmospheres : A Complete Line List for Phosphine

    Science.gov (United States)

    Sousa-Silva, C.; Yurchenko, S. N.; Tennyson, J.

    2013-09-01

    The ability to characterise the atmospheres of cool stars, brown dwarfs and exoplanets requires fundamental data for all species contributing significantly to their opacity. However, with notable exceptions such as water and ammonia, existing molecular line lists are not sufficiently accurate or complete to allow for a full spectroscopic analysis of these bodies. ExoMol (www.exomol.com [1]) is a project that aims to rectify this by generating comprehensive line lists for all molecules likely to be detected in the atmospheres of cool astrophysical objects in the foreseeable future. The spectral data is generated by employing ab initio quantum mechanical methods, performing empirical refinement based on experimental spectroscopic data and harnessing high performance computing. Here we present our work on phosphine, (PH3), an equilateral pyramidal molecule (the phosphorus analogue to ammonia). Phosphine is known to be important for the atmospheres of giant-planets, cool stars and many other astronomical bodies. Rotational transition features of phosphine have been found in the far- infrared spectra of Saturn and Jupiter [2, 3], where it is a marker for vertical convection zones. A computed room temperature line list of phosphine is presented here [4], illustrated in the accompanying figure 1. This line list is a precursor to a high temperature equivalent to be produced in the near future, necessary for the analysis of cool stars and brown dwarfs. All the transitions' energy levels and Einstein A-coefficients were computed using the program TROVE [5].

  3. Calculated Resonance Line Profiles of [Mg II], [C II], and [Si IV] in the Solar Atmosphere

    Science.gov (United States)

    Avrett, E.; Landi, E.; McKillop, S.

    2013-12-01

    NASA's Interface Region Imaging Spectrograph space mission, launched 2013 June 27, is intended to study the structure of the solar chromosphere and the transition region between the chromosphere and corona. The spectral lines to be observed include the Mg II k line at 2796.5 Å, the C II 1334.5 Å line, and the Si IV line at 1393.8 Å, which are formed in the middle chromosphere, the upper chromosphere, and the lower transition region, respectively. Here we calculate the profiles of these lines from four models of the solar atmosphere, intended to represent the faint and mean internetwork, a network lane, and bright network. We show how the profiles change from the center of the solar disk toward the limb of the Sun and in response to outflows and inflows. These results are intended to cover the range of expected quiet-Sun observations and assist in their interpretation. We expect that the observations will lead to improvements in the models, which can then be used to estimate the required non-radiative heating in the different regions.

  4. Calculated resonance line profiles of [Mg II], [C II], and [Si IV] in the solar atmosphere

    International Nuclear Information System (INIS)

    Avrett, E.; McKillop, S.; Landi, E.

    2013-01-01

    NASA's Interface Region Imaging Spectrograph space mission, launched 2013 June 27, is intended to study the structure of the solar chromosphere and the transition region between the chromosphere and corona. The spectral lines to be observed include the Mg II k line at 2796.5 Å, the C II 1334.5 Å line, and the Si IV line at 1393.8 Å, which are formed in the middle chromosphere, the upper chromosphere, and the lower transition region, respectively. Here we calculate the profiles of these lines from four models of the solar atmosphere, intended to represent the faint and mean internetwork, a network lane, and bright network. We show how the profiles change from the center of the solar disk toward the limb of the Sun and in response to outflows and inflows. These results are intended to cover the range of expected quiet-Sun observations and assist in their interpretation. We expect that the observations will lead to improvements in the models, which can then be used to estimate the required non-radiative heating in the different regions.

  5. A NLTE line formation for neutral and singly-ionised calcium in model atmospheres of B-F stars

    Science.gov (United States)

    Sitnova, T. M.; Mashonkina, L. I.; Ryabchikova, T. A.

    2018-03-01

    We present non-local thermodynamic equilibrium (NLTE) line formation calculations for Ca I and Ca II in B-F stars. The sign and the magnitude of NLTE abundance corrections depend on line and stellar parameters. We determine calcium abundances for nine stars with reliable stellar parameters. For all stars, where the lines of both species could be measured, the NLTE abundances are found to be consistent within the error bars. We obtain consistent NLTE abundances from Ca II lines in the visible and near infra-red (IR, 8912-27, 9890 Å) spectrum range, in contrast with LTE, where the discrepancy between the two groups of lines ranges from -0.5 dex to 0.6 dex for different stars. Our NLTE method reproduces the Ca II 8912-27, 9890 Å lines observed in emission in the late B-type star HD 160762 with the classical plane-parallel and LTE model atmosphere. NLTE abundance corrections for lines of Ca I and Ca II were calculated in a grid of model atmospheres with 7000 K ≤ Teff ≤ 13000 K, 3.2 ≤ log g ≤ 5.0, -0.5 ≤ [Fe/H] ≤0.5, ξt= 2.0 km s-1. Our NLTE results can be applied for calcium NLTE abundance determination from Gaia spectra, given that accurate continuum normalisation and proper treatment of the hydrogen Paschen lines are provided. The NLTE method can be useful to refine calcium underabundances in Am stars and to provide accurate observational constraints on the models of diffusion.

  6. A NLTE line formation for neutral and singly ionized calcium in model atmospheres of B-F stars

    Science.gov (United States)

    Sitnova, T. M.; Mashonkina, L. I.; Ryabchikova, T. A.

    2018-07-01

    We present non-local thermodynamic equilibrium (NLTE) line formation calculations for Ca I and Ca II in B-F stars. The sign and the magnitude of NLTE abundance corrections depend on line and stellar parameters. We determine calcium abundances for nine stars with reliable stellar parameters. For all stars, where the lines of both species could be measured, the NLTE abundances are found to be consistent within the error bars. We obtain consistent NLTE abundances from Ca II lines in the visible and near infra-red (IR, 8912-27, 9890 Å) spectrum range, in contrast with LTE, where the discrepancy between the two groups of lines ranges from -0.5 to 0.6 dex for different stars. Our NLTE method reproduces the Ca II 8912-27, 9890 Å lines observed in emission in the late B-type star HD 160762 with the classical plane-parallel and LTE model atmosphere. NLTE abundance corrections for lines of Ca I and Ca II were calculated in a grid of model atmospheres with 7000 ≤ Teff ≤ 13 000 K, 3.2 ≤ log g ≤ 5.0, -0.5 ≤ [Fe/H] ≤0.5, ξt = 2.0 km s-1. Our NLTE results can be applied for calcium NLTE abundance determination from Gaia spectra, given that accurate continuum normalization and proper treatment of the hydrogen Paschen lines are provided. The NLTE method can be useful to refine calcium underabundances in Am stars and to provide accurate observational constraints on the models of diffusion.

  7. Some problems in interpretation of the New Horizons observations of Pluto's atmosphere

    Science.gov (United States)

    Krasnopolsky, Vladimir A.

    2018-02-01

    Here I briefly discuss the following problems related to Pluto's atmosphere: (1) restrictions to LTE in the rotational lines of H2O and HCN above 700 km that affect thermal balance of the atmosphere; (2) contradictions in the estimates of H2O influx from ablation of the interplanetary dust; (3) great difference between the haze volume surface area in the LORRI and MVIC observations and that in the UV solar occultations and the models, including significant corrections to sticking coefficients of C2H2, C2H4, C2H6, and HCN in condensation, and (4) Triton's thermosphere during the Voyager 2 flyby.

  8. OBSERVATIONS AND SIMULATIONS OF THE Na i D{sub 1} LINE PROFILES IN AN M-CLASS SOLAR FLARE

    Energy Technology Data Exchange (ETDEWEB)

    Kuridze, D.; Mathioudakis, M.; Jess, D. B.; Grant, S. D. T.; Kawate, T.; Keenan, F. P. [Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN (United Kingdom); Christian, D. J. [Department of Physics and Astronomy, California State University, Northridge, CA 91330 (United States); Kowalski, A. F.; Allred, J. C. [NASA/Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States); Simões, P. J. A. [SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

    2016-12-01

    We study the temporal evolution of the Na i D{sub 1} line profiles in the M3.9 flare SOL2014-06-11T21:03 UT, using observations at high spectral resolution obtained with the Interferometric Bidimensional Spectrometer instrument on the Dunn Solar Telescope combined with radiative hydrodynamic simulations. Our results show a significant increase in the intensities of the line core and wings during the flare. The analysis of the line profiles from the flare ribbons reveals that the Na i D{sub 1} line has a central reversal with excess emission in the blue wing (blue asymmetry). We combine RADYN and RH simulations to synthesize Na i D{sub 1} line profiles of the flaring atmosphere and find good agreement with the observations. Heating with a beam of electrons modifies the radiation field in the flaring atmosphere and excites electrons from the ground state 3s {sup 2}S to the first excited state 3p {sup 2}P, which in turn modifies the relative population of the two states. The change in temperature and the population density of the energy states make the sodium line profile revert from absorption into emission. Furthermore, the rapid changes in temperature break the pressure balance between the different layers of the lower atmosphere, generating upflow/downflow patterns. Analysis of the simulated spectra reveals that the asymmetries of the Na i D{sub 1} flare profile are produced by the velocity gradients in the lower solar atmosphere.

  9. Nonthermal ice nucleation observed at distorted contact lines of supercooled water drops.

    Science.gov (United States)

    Yang, Fan; Cruikshank, Owen; He, Weilue; Kostinski, Alex; Shaw, Raymond A

    2018-02-01

    Ice nucleation is the crucial step for ice formation in atmospheric clouds and therefore underlies climatologically relevant precipitation and radiative properties. Progress has been made in understanding the roles of temperature, supersaturation, and material properties, but an explanation for the efficient ice nucleation occurring when a particle contacts a supercooled water drop has been elusive for over half a century. Here, we explore ice nucleation initiated at constant temperature and observe that mechanical agitation induces freezing of supercooled water drops at distorted contact lines. Results show that symmetric motion of supercooled water on a vertically oscillating substrate does not freeze, no matter how we agitate it. However, when the moving contact line is distorted with the help of trace amounts of oil or inhomogeneous pinning on the substrate, freezing can occur at temperatures much higher than in a static droplet, equivalent to ∼10^{10} increase in nucleation rate. Several possible mechanisms are proposed to explain the observations. One plausible explanation among them, decreased pressure due to interface curvature, is explored theoretically and compared with the observational results quasiquantitatively. Indeed, the observed freezing-temperature increase scales with contact line speed in a manner consistent with the pressure hypothesis. Whatever the mechanism, the experiments demonstrate a strong preference for ice nucleation at three-phase contact lines compared to the two-phase interface, and they also show that movement and distortion of the contact line are necessary contributions to stimulating the nucleation process.

  10. CONSTRAINING HIGH-SPEED WINDS IN EXOPLANET ATMOSPHERES THROUGH OBSERVATIONS OF ANOMALOUS DOPPLER SHIFTS DURING TRANSIT

    International Nuclear Information System (INIS)

    Miller-Ricci Kempton, Eliza; Rauscher, Emily

    2012-01-01

    Three-dimensional (3D) dynamical models of hot Jupiter atmospheres predict very strong wind speeds. For tidally locked hot Jupiters, winds at high altitude in the planet's atmosphere advect heat from the day side to the cooler night side of the planet. Net wind speeds on the order of 1-10 km s –1 directed towards the night side of the planet are predicted at mbar pressures, which is the approximate pressure level probed by transmission spectroscopy. These winds should result in an observed blueshift of spectral lines in transmission on the order of the wind speed. Indeed, Snellen et al. recently observed a 2 ± 1 km s –1 blueshift of CO transmission features for HD 209458b, which has been interpreted as a detection of the day-to-night (substellar to anti-stellar) winds that have been predicted by 3D atmospheric dynamics modeling. Here, we present the results of a coupled 3D atmospheric dynamics and transmission spectrum model, which predicts the Doppler-shifted spectrum of a hot Jupiter during transit resulting from winds in the planet's atmosphere. We explore four different models for the hot Jupiter atmosphere using different prescriptions for atmospheric drag via interaction with planetary magnetic fields. We find that models with no magnetic drag produce net Doppler blueshifts in the transmission spectrum of ∼2 km s –1 and that lower Doppler shifts of ∼1 km s –1 are found for the higher drag cases, results consistent with—but not yet strongly constrained by—the Snellen et al. measurement. We additionally explore the possibility of recovering the average terminator wind speed as a function of altitude by measuring Doppler shifts of individual spectral lines and spatially resolving wind speeds across the leading and trailing terminators during ingress and egress.

  11. Multiangle lidar observations of the Atmosphere

    Science.gov (United States)

    Lalitkumar Prakash, Pawar; Choukiker, Yogesh Kumar; Raghunath, K.

    2018-04-01

    Atmospheric Lidars are used extensively to get aerosol parameters like backscatter coefficient, backscatter ratio etc. National Atmospheric Research Laboratory, Gadanki (13°N, 79°E), India has a powerful lidar which has alt-azimuth capability. Inversion method is applied to data from observations of lidar system at different azimuth and elevation angles. Data Analysis is described and Observations in 2D and 3D format are discussed. Presence of Cloud and the variation of backscatter parameters are seen in an interesting manner.

  12. Atmospheric Retrievals from Exoplanet Observations and Simulations with BART

    Science.gov (United States)

    Harrington, Joseph

    This project will determine the observing plans needed to retrieve exoplanet atmospheric composition and thermal profiles over a broad range of planets, stars, instruments, and observing modes. Characterizing exoplanets is hard. The dim planets orbit bright stars, giving orders of magnitude more relative noise than for solar-system planets. Advanced statistical techniques are needed to determine what the data can - and more importantly cannot - say. We therefore developed Bayesian Atmospheric Radiative Transfer (BART). BART explores the parameter space of atmospheric chemical abundances and thermal profiles using Differential-Evolution Markov-Chain Monte Carlo. It generates thousands of candidate spectra, integrates over observational bandpasses, and compares to data, generating a statistical model for an atmosphere's composition and thermal structure. At best, it gives abundances and thermal profiles with uncertainties. At worst, it shows what kinds of planets the data allow. It also gives parameter correlations. BART is open-source, designed for community use and extension (http://github.com/exosports/BART). Three arXived PhD theses (papers in publication) provide technical documentation, tests, and application to Spitzer and HST data. There are detailed user and programmer manuals and community support forums. Exoplanet analysis techniques must be tested against synthetic data, where the answer is known, and vetted by statisticians. Unfortunately, this has rarely been done, and never sufficiently. Several recent papers question the entire body of Spitzer exoplanet observations, because different analyses of the same data give different results. The latest method, pixel-level decorrelation, produces results that diverge from an emerging consensus. We do not know the retrieval problem's strengths and weaknesses relative to low SNR, red noise, low resolution, instrument systematics, or incomplete spectral line lists. In observing eclipses and transits, we assume

  13. Multiangle lidar observations of the Atmosphere

    Directory of Open Access Journals (Sweden)

    Lalitkumar Prakash Pawar

    2018-01-01

    Full Text Available Atmospheric Lidars are used extensively to get aerosol parameters like backscatter coefficient, backscatter ratio etc. National Atmospheric Research Laboratory, Gadanki (13°N, 79°E, India has a powerful lidar which has alt-azimuth capability. Inversion method is applied to data from observations of lidar system at different azimuth and elevation angles. Data Analysis is described and Observations in 2D and 3D format are discussed. Presence of Cloud and the variation of backscatter parameters are seen in an interesting manner.

  14. Observations and Modeling of Atmospheric Radiance Structure

    National Research Council Canada - National Science Library

    Wintersteiner, Peter

    2001-01-01

    The overall purpose of the work that we have undertaken is to provide new capabilities for observing and modeling structured radiance in the atmosphere, particularly the non-LTE regions of the atmosphere...

  15. Global Observations of Inorganic Gases in the Remote Atmosphere - First Observations from the Atmospheric Tomography Mission (ATom)

    Science.gov (United States)

    Veres, P. R.; Neuman, J. A.

    2017-12-01

    The Atmospheric Tomography Mission (ATom) is a NASA field program that investigates the impact of human emissions on air quality and climate in remote regions of the atmosphere. NASA DC-8 flights during the ATom sampled the atmosphere over the Pacific and Atlantic Oceans, up to 12 km altitude and nearly from pole to pole. New observations of key species (e.g. N2O5, reactive halogens, nitrous acid) in these regions are provided during the third deployment of the NASA DC-8 research aircraft (October, 2017) by the NOAA iodide ion time-of-flight chemical ionization mass spectrometer (iCIMS). In this study, we will present the first observations of inorganic gas-phase species using iCIMS from the ATom 3 deployment. Laboratory results detailing the instrument performance including inlet response times, background characterization and sensitivity will be presented. We will show vertical profiles of newly measured trace gases derived from in-situ observations, and discuss the potential impact on the NOx, NOy and reactive halogen budgets.

  16. TIME DEPENDENT NONEQUILIBRIUM IONIZATION OF TRANSITION REGION LINES OBSERVED WITH IRIS

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Sykora, Juan; Pontieu, Bart De; Hansteen, Viggo H. [Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, CA 94304 (United States); Gudiksen, Boris, E-mail: j.m.sykora@astro.uio.no [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway)

    2016-01-20

    The properties of nonstatistical equilibrium ionization of silicon and oxygen ions are analyzed in this work. We focus on five solar targets (quiet Sun; coronal hole; plage; quiescent active region, AR; and flaring AR) as observed with the Interface Region Imaging Spectrograph (IRIS). IRIS is best suited for this work owing to the high cadence (up to 0.5 s), high spatial resolution (up to 0.″32), and high signal-to-noise ratios for O iv λ1401 and Si iv λ1402. We find that the observed intensity ratio between lines of three times ionized silicon and oxygen ions depends on their total intensity and that this correlation varies depending on the region observed (quiet Sun, coronal holes, plage, or active regions) and on the specific observational objects present (spicules, dynamic loops, jets, microflares, or umbra). In order to interpret the observations, we compare them with synthetic profiles taken from 2D self-consistent radiative MHD simulations of the solar atmosphere, where the statistical equilibrium or nonequilibrium treatment of silicon and oxygen is applied. These synthetic observations show vaguely similar correlations to those in the observations, i.e., between the intensity ratios and their intensities, but only in the nonequilibrium case do we find that (some of) the observations can be reproduced. We conclude that these lines are formed out of statistical equilibrium. We use our time-dependent nonequilibrium ionization simulations to describe the physical mechanisms behind these observed properties.

  17. Testing common classical LTE and NLTE model atmosphere and line-formation codes for quantitative spectroscopy of early-type stars

    International Nuclear Information System (INIS)

    Przybilla, Norbert; Nieva, Maria-Fernanda; Butler, Keith

    2011-01-01

    It is generally accepted that the atmospheres of cool/lukewarm stars of spectral types A and later are described well by LTE model atmospheres, while the O-type stars require a detailed treatment of NLTE effects. Here model atmosphere structures, spectral energy distributions and synthetic spectra computed with ATLAS9/SYNTHE and TLUSTY/SYNSPEC, and results from a hybrid method combining LTE atmospheres and NLTE line-formation with DETAIL/SURFACE are compared. Their ability to reproduce observations for effective temperatures between 15 000 and 35 000 K are verified. Strengths and weaknesses of the different approaches are identified. Recommendations are made as to how to improve the models in order to derive unbiased stellar parameters and chemical abundances in future applications, with special emphasis on Gaia science.

  18. Modeling and interpretation of line observations*

    Directory of Open Access Journals (Sweden)

    Kamp Inga

    2015-01-01

    Full Text Available Models for the interpretation of line observations from protoplanetary disks are summarized. The spectrum ranges from 1D LTE slab models to 2D thermo-chemical radiative transfer models and their use depends largely on the type/nature of observational data that is analyzed. I discuss the various types of observational data and their interpretation in the context of disk physical and chemical properties. The most simple spatially and spectral unresolved data are line fluxes, which can be interpreted using so-called Boltzmann diagrams. The interpretation is often tricky due to optical depth and non-LTE effects and requires care. Line profiles contain kinematic information and thus indirectly the spatial origin of the emission. Using series of line profiles, we can for example deduce radial temperature gradients in disks (CO pure rotational ladder. Spectro-astrometry of e.g. CO ro-vibrational line profiles probes the disk structure in the 1–30 AU region, where planet formation through core accretion should be most efficient. Spatially and spectrally resolved line images from (submm interferometers are the richest datasets we have to date and they enable us to unravel exciting details of the radial and vertical disk structure such as winds and asymmetries.

  19. Infrared observations of planetary atmospheres

    International Nuclear Information System (INIS)

    Orton, G.S.; Baines, K.H.; Bergstralh, J.T.

    1988-01-01

    The goal of this research in to obtain infrared data on planetary atmospheres which provide information on several aspects of structure and composition. Observations include direct mission real-time support as well as baseline monitoring preceding mission encounters. Besides providing a broader information context for spacecraft experiment data analysis, observations will provide the quantitative data base required for designing optimum remote sensing sequences and evaluating competing science priorities. In the past year, thermal images of Jupiter and Saturn were made near their oppositions in order to monitor long-term changes in their atmospheres. Infrared images of the Jovian polar stratospheric hot spots were made with IUE observations of auroral emissions. An exploratory 5-micrometer spectrum of Uranus was reduced and accepted for publication. An analysis of time-variability of temperature and cloud properties of the Jovian atomsphere was made. Development of geometric reduction programs for imaging data was initiated for the sun workstation. Near-infrared imaging observations of Jupiter were reduced and a preliminary analysis of cloud properties made. The first images of the full disk of Jupiter with a near-infrared array camera were acquired. Narrow-band (10/cm) images of Jupiter and Saturn were obtained with acousto-optical filters

  20. On the influence of density and temperature fluctuations on the formation of spectral lines in stellar atmospheres

    International Nuclear Information System (INIS)

    Stahlberg, J.

    1985-01-01

    A method taking into account the influence of temperature and density fluctuations generated by the velocity field in stellar atmospheres on the formation of spectral lines is presented. The influenced line profile is derived by exchanging the values in a static atmosphere by a mean value and a fluctuating one. The correlations are calculated with the help of the well-know hydrodynamic eqs. It results, that in normal stellar atmospheres the visual lines are only very weakly influenced by such fluctuations due to the small values of the gradients of the pressure and density and of the velocity dispersion. (author)

  1. Atmospheric gamma-ray observation with the BETS detectorfor calibrating atmospheric neutrino flux calculations

    CERN Document Server

    Kasahara, K.; Torii, S.; Tamura, T.; Tateyama, N.; Yoshida, K.; Yamagami, T.; Saito, Y.; Nishimura, J.; Murakami, H.; Kobayashi, T.; Komori, Y.; Honda, M.; Ohuchi, T.; Midorikawa, S.; Yuda, T.

    2002-01-01

    We observed atmospheric gamma-rays around 10 GeV at balloon altitudes (15~25 km) and at a mountain (2770 m a.s.l). The observed results were compared with Monte Carlo calculations to find that an interaction model (Lund Fritiof1.6) used in an old neutrino flux calculation was not good enough for describing the observed values. In stead, we found that two other nuclear interaction models, Lund Fritiof7.02 and dpmjet3.03, gave much better agreement with the observations. Our data will serve for examining nuclear interaction models and for deriving a reliable absolute atmospheric neutrino flux in the GeV region.

  2. MAVEN Observations of Atmospheric Loss at Mars

    Science.gov (United States)

    Curry, Shannon; Luhmann, Janet; Jakosky, Bruce M.; Brain, David; LeBlanc, Francis; Modolo, Ronan; Halekas, Jasper S.; Schneider, Nicholas M.; Deighan, Justin; McFadden, James; Espley, Jared R.; Mitchell, David L.; Connerney, J. E. P.; Dong, Yaxue; Dong, Chuanfei; Ma, Yingjuan; Cohen, Ofer; Fränz, Markus; Holmström, Mats; Ramstad, Robin; Hara, Takuya; Lillis, Robert J.

    2016-06-01

    The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has been making observations of the Martian upper atmosphere and its escape to space since November 2014. The subject of atmospheric loss at terrestrial planets is a subject of intense interest not only because of the implications for past and present water reservoirs, but also for its impacts on the habitability of a planet. Atmospheric escape may have been especially effective at Mars, relative to Earth or Venus, due to its smaller size as well as the lack of a global dynamo magnetic field. Not only is the atmosphere less gravitationally bound, but also the lack of global magnetic field allows the impinging solar wind to interact directly with the Martian atmosphere. When the upper atmosphere is exposed to the solar wind, planetary neutrals can be ionized and 'picked up' by the solar wind and swept away.Both neutral and ion escape have played significant roles the long term climate change of Mars, and the MAVEN mission was designed to directly measure both escaping planetary neutrals and ions with high energy, mass, and time resolution. We will present 1.5 years of observations of atmospheric loss at Mars over a variety of solar and solar wind conditions, including extreme space weather events. We will report the average ion escape rate and the spatial distribution of escaping ions as measured by MAVEN and place them in context both with previous measurements of ion loss by other spacecraft (e.g. Phobos 2 and Mars Express) and with estimates of neutral escape rates by MAVEN. We will then report on the measured variability in ion escape rates with different drivers (e.g. solar EUV, solar wind pressure, etc.) and the implications for the total ion escape from Mars over time. Additionally, we will also discuss the implications for atmospheric escape at exoplanets, particularly weakly magnetized planetary bodies orbiting M-dwarfs, and the dominant escape mechanisms that may drive atmospheric erosion in other

  3. HIFI observations of water in the atmosphere of comet C/2008 Q3 (Garradd)

    Science.gov (United States)

    Hartogh, P.; Crovisier, J.; de Val-Borro, M.; Bockelée-Morvan, D.; Biver, N.; Lis, D. C.; Moreno, R.; Jarchow, C.; Rengel, M.; Emprechtinger, M.; Szutowicz, S.; Banaszkiewicz, M.; Bensch, F.; Blecka, M. I.; Cavalié, T.; Encrenaz, T.; Jehin, E.; Küppers, M.; Lara, L.-M.; Lellouch, E.; Swinyard, B. M.; Vandenbussche, B.; Bergin, E. A.; Blake, G. A.; Blommaert, J. A. D. L.; Cernicharo, J.; Decin, L.; Encrenaz, P.; de Graauw, T.; Hutsemekers, D.; Kidger, M.; Manfroid, J.; Medvedev, A. S.; Naylor, D. A.; Schieder, R.; Thomas, N.; Waelkens, C.; Roelfsema, P. R.; Dieleman, P.; Güsten, R.; Klein, T.; Kasemann, C.; Caris, M.; Olberg, M.; Benz, A. O.

    2010-07-01

    High-resolution far-infrared and sub-millimetre spectroscopy of water lines is an important tool to understand the physical and chemical properties of cometary atmospheres. We present observations of several rotational ortho- and para-water transitions in comet C/2008 Q3 (Garradd) performed with HIFI on Herschel. These observations have provided the first detection of the 212-101 (1669 GHz) ortho and 111-000 (1113 GHz) para transitions of water in a cometary spectrum. In addition, the ground-state transition 110-101 at 557 GHz is detected and mapped. By detecting several water lines quasi-simultaneously and mapping their emission we can constrain the excitation parameters in the coma. Synthetic line profiles are computed using excitation models which include excitation by collisions, solar infrared radiation, and radiation trapping. We obtain the gas kinetic temperature, constrain the electron density profile, and estimate the coma expansion velocity by analyzing the map and line shapes. We derive water production rates of 1.7-2.8 × 1028 s-1 over the range rh = 1.83-1.85 AU. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Figure 5 is only available in electronic form at http://www.aanda.org

  4. Observation of The Top of The Atmosphere Outgoing Longwave Radiation Using The Geostationary Earth Radiation Budget Sensor

    Science.gov (United States)

    Spencer, G.; Llewellyn-Jones, D.

    In the summer of 2002 the Meteosat Second Generation (MSG) satellite is due to be launched. On board the MSG satellite is the Geostationary Earth Radiation Budget (GERB) sensor. This is a new radiometer that will be able to observe and measure the outgoing longwave radiation from the top of the atmosphere for the whole ob- served Earth disc, due to its unique position in geostationary orbit. Every 15 minutes the GERB sensor will make a full Earth disc observation, centred on the Greenwich meridian. Thus, the GERB sensor will provide unprecedented coupled temporal and spatial resolution of the outgoing longwave radiation (4.0 to 30.0 microns), by first measuring the broadband radiation (0.32 to 30.0 microns) and then subtracting the measured reflected shortwave solar radiation (0.32 to 4.0 microns), from the earth- atmosphere system. The GERB sensor is able to make measurements to within an accuracy of 1 W/sq. m. A forward model is being developed at Leicester to simulate the data from the GERB sensor for representative geophysical scenes and to investigate key parameters and processes that will affect the top of the atmosphere signal. At the heart of this model is a line-by-line radiative transfer model, the Oxford Reference Forward Model (RFM) that is to be used with model atmospheres generated from ECMWF analysis data. When MSG is launched, cloud data from the Spinning Enhanced Visible and Infrared Imager (SEVIRI), also on board, is to be used in conjunction with GERB data.

  5. 1D Atmosphere Models from Inversion of Fe i 630 nm Observations with an Application to Solar Irradiance Studies

    Energy Technology Data Exchange (ETDEWEB)

    Cristaldi, Alice; Ermolli, Ilaria, E-mail: alice.cristaldi@oaroma.inaf.it [INAF Osservatorio Astronomico di Roma, via Frascati 33, Monte Porzio Catone, I-00078 (Italy)

    2017-06-01

    Present-day semi-empirical models of solar irradiance (SI) variations reconstruct SI changes measured on timescales greater than a day by using spectra computed in one dimensional atmosphere models (1D models), which are representative of various solar surface features. Various recent studies have pointed out, however, that the spectra synthesized in 1D models do not reflect the radiative emission of the inhomogenous atmosphere revealed by high-resolution solar observations. We aimed to derive observation-based atmospheres from such observations and test their accuracy for SI estimates. We analyzed spectropolarimetric data of the Fe i 630 nm line pair in photospheric regions that are representative of the granular quiet-Sun pattern (QS) and of small- and large-scale magnetic features, both bright and dark with respect to the QS. The data were taken on 2011 August 6, with the CRisp Imaging Spectropolarimeter at the Swedish Solar Telescope, under excellent seeing conditions. We derived atmosphere models of the observed regions from data inversion with the SIR code. We studied the sensitivity of results to spatial resolution and temporal evolution, and discuss the obtained atmospheres with respect to several 1D models. The atmospheres derived from our study agree well with most of the 1D models we compare our results with, both qualitatively and quantitatively (within 10%), except for pore regions. Spectral synthesis computations of the atmosphere obtained from the QS observations return an SI between 400 and 2400 nm that agrees, on average, within 2.2% with standard reference measurements, and within −0.14% with the SI computed on the QS atmosphere employed by the most advanced semi-empirical model of SI variations.

  6. Atmospheric correction of Earth-observation remote sensing images

    Indian Academy of Sciences (India)

    In earth observation, the atmospheric particles contaminate severely, through absorption and scattering, the reflected electromagnetic signal from the earth surface. It will be greatly beneficial for land surface characterization if we can remove these atmospheric effects from imagery and retrieve surface reflectance that ...

  7. Observations of ionospheric electric fields above atmospheric weather systems

    Science.gov (United States)

    Farrell, W. M.; Aggson, T. L.; Rodgers, E. B.; Hanson, W. B.

    1994-01-01

    We report on the observations of a number of quasi-dc electric field events associated with large-scale atmospheric weather formations. The observations were made by the electric field experiment onboard the San Marco D satellite, operational in an equatorial orbit from May to December 1988. Several theoretical studies suggest that electric fields generated by thunderstorms are present at high altitudes in the ionosphere. In spite of such favorable predictions, weather-related events are not often observed since they are relatively weak. We shall report here on a set of likely E field candidates for atmospheric-ionospheric causality, these being observed over the Indonesian Basin, northern South America, and the west coast of Africa; all known sites of atmospheric activity. As we shall demonstrate, individual events often be traced to specific active weather features. For example, a number of events were associated with spacecraft passages near Hurricane Joan in mid-October 1988. As a statistical set, the events appear to coincide with the most active regions of atmospheric weather.

  8. Deviation from local thermodynamical equilibrium in the solar atmosphere. Metodology. The line source function

    International Nuclear Information System (INIS)

    Shchukina, N.G.

    1980-01-01

    The methodology of the problem of deviation from local thermodynamical equilibrium in the solar atmosphere is presented. The difficulties of solution and methods of realization are systematized. The processes of line formation are considered which take into account velocity fields, structural inhomogeneity, radiation non-coherence etc. as applied to a quiet solar atmosphere. The conclusion is made on the regularity of deviation of the local thermodynamic equilibrium in upper layers of the solar atmosphere

  9. Observations and NLTE modeling of Ellerman bombs

    Science.gov (United States)

    Berlicki, A.; Heinzel, P.

    2014-07-01

    Context. Ellerman bombs (EBs) are short-lived, compact, and spatially well localized emission structures that are observed well in the wings of the hydrogen Hα line. EBs are also observed in the chromospheric CaII lines and in UV continua as bright points located within active regions. Hα line profiles of EBs show a deep absorption at the line center and enhanced emission in the line wings with maxima around ±1 Å from the line center. Similar shapes of the line profiles are observed for the CaII IR line at 8542 Å. In CaII H and K lines the emission peaks are much stronger, and EBs emission is also enhanced in the line center. Aims: It is generally accepted that EBs may be considered as compact microflares located in lower solar atmosphere that contribute to the heating of these low-lying regions, close to the temperature minimum of the atmosphere. However, it is still not clear where exactly the emission of EBs is formed in the solar atmosphere. High-resolution spectrophotometric observations of EBs were used for determining of their physical parameters and construction of semi-empirical models. Obtained models allow us to determine the position of EBs in the solar atmosphere, as well as the vertical structure of the activated EB atmosphere Methods: In our analysis we used observations of EBs obtained in the Hα and CaII H lines with the Dutch Open Telescope (DOT). These one-hour long simultaneous sequences obtained with high temporal and spatial resolution were used to determine the line emissions. To analyze them, we used NLTE numerical codes for the construction of grids of 243 semi-empirical models simulating EBs structures. In this way, the observed emission could be compared with the synthetic line spectra calculated for all such models. Results: For a specific model we found reasonable agreement between the observed and theoretical emission and thus we consider such model as a good approximation to EBs atmospheres. This model is characterized by an

  10. THE FORMATION OF IRIS DIAGNOSTICS. II. THE FORMATION OF THE Mg II h and k LINES IN THE SOLAR ATMOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Leenaarts, J.; Pereira, T. M. D.; Carlsson, M.; De Pontieu, B. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Uitenbroek, H., E-mail: jorritl@astro.uio.no, E-mail: tiago.pereira@astro.uio.no, E-mail: mats.carlsson@astro.uio.no, E-mail: bdp@lmsal.com, E-mail: huitenbroek@nso.edu [NSO/Sacramento Peak P.O. Box 62 Sunspot, NM 88349-0062 (United States)

    2013-08-01

    NASA's Interface Region Imaging Spectrograph (IRIS) small explorer mission will study how the solar atmosphere is energized. IRIS contains an imaging spectrograph that covers the Mg II h and k lines as well as a slit-jaw imager centered at Mg II k. Understanding the observations requires forward modeling of Mg II h and k line formation from three-dimensional (3D) radiation-magnetohydrodynamic (RMHD) models. This paper is the second in a series where we undertake this modeling. We compute the vertically emergent h and k intensity from a snapshot of a dynamic 3D RMHD model of the solar atmosphere, and investigate which diagnostic information about the atmosphere is contained in the synthetic line profiles. We find that the Doppler shift of the central line depression correlates strongly with the vertical velocity at optical depth unity, which is typically located less than 200 km below the transition region (TR). By combining the Doppler shifts of the h and k lines we can retrieve the sign of the velocity gradient just below the TR. The intensity in the central line depression is anti-correlated with the formation height, especially in subfields of a few square Mm. This intensity could thus be used to measure the spatial variation of the height of the TR. The intensity in the line-core emission peaks correlates with the temperature at its formation height, especially for strong emission peaks. The peaks can thus be exploited as a temperature diagnostic. The wavelength difference between the blue and red peaks provides a diagnostic of the velocity gradients in the upper chromosphere. The intensity ratio of the blue and red peaks correlates strongly with the average velocity in the upper chromosphere. We conclude that the Mg II h and k lines are excellent probes of the very upper chromosphere just below the TR, a height regime that is impossible to probe with other spectral lines. They also provide decent temperature and velocity diagnostics of the middle

  11. Simulation of submillimetre atmospheric spectra for characterising potential ground-based remote sensing observations

    Directory of Open Access Journals (Sweden)

    E. C. Turner

    2016-11-01

    Full Text Available The submillimetre is an understudied region of the Earth's atmospheric electromagnetic spectrum. Prior technological gaps and relatively high opacity due to the prevalence of rotational water vapour lines at these wavelengths have slowed progress from a ground-based remote sensing perspective; however, emerging superconducting detector technologies in the fields of astronomy offer the potential to address key atmospheric science challenges with new instrumental methods. A site study, with a focus on the polar regions, is performed to assess theoretical feasibility by simulating the downwelling (zenith angle = 0° clear-sky submillimetre spectrum from 30 mm (10 GHz to 150 µm (2000 GHz at six locations under annual mean, summer, winter, daytime, night-time and low-humidity conditions. Vertical profiles of temperature, pressure and 28 atmospheric gases are constructed by combining radiosonde, meteorological reanalysis and atmospheric chemistry model data. The sensitivity of the simulated spectra to the choice of water vapour continuum model and spectroscopic line database is explored. For the atmospheric trace species hypobromous acid (HOBr, hydrogen bromide (HBr, perhydroxyl radical (HO2 and nitrous oxide (N2O the emission lines producing the largest change in brightness temperature are identified. Signal strengths, centre frequencies, bandwidths, estimated minimum integration times and maximum receiver noise temperatures are determined for all cases. HOBr, HBr and HO2 produce brightness temperature peaks in the mK to µK range, whereas the N2O peaks are in the K range. The optimal submillimetre remote sensing lines for the four species are shown to vary significantly between location and scenario, strengthening the case for future hyperspectral instruments that measure over a broad wavelength range. The techniques presented here provide a framework that can be applied to additional species of interest and taken forward to simulate

  12. Atmospheric structure deduced from disturbed line profiles application to Ca II lines

    International Nuclear Information System (INIS)

    Mein, N.; Mein, P.; Malherbe, J.-M.; Dame, L.; Dumont, S.; CNRS, Laboratoire de Physique Stellaire et Planetaire, Verrieres-le-Buisson, France; College de France, Paris)

    1985-01-01

    A new method is described in order to derive physical quantities (temperature, pressure, radial velocities) from the observation of disturbed line profiles. A method of Fourier analysis is suggested with double profiles and a nonlinear expansion of the coefficient of the Fourier terms. An application to a sequence of H-Ca II lines is attempted. The method is a powerful tool allowing for the simultaneous determination of at least four physical quantities. 9 references

  13. Ground-based observations of exoplanet atmospheres

    NARCIS (Netherlands)

    Mooij, Ernst Johan Walter de

    2011-01-01

    This thesis focuses on the properties of exoplanet atmospheres. The results for ground-based near-infrared secondary eclipse observations of three different exoplanets, TrES-3b, HAT-P-1b and WASP-33b, are presented which have been obtained with ground-based telescopes as part of the GROUSE project.

  14. Characterization of extra-solar planets and their atmospheres (Spectroscopy of transits and atmospheric escape)

    International Nuclear Information System (INIS)

    Bourrier, Vincent

    2014-01-01

    Hot Jupiters are exo-planets so close to their star that their atmosphere can lose gas because of hydrodynamic escape. Transiting gaseous giants are an excellent way to understand this mechanism, but it is necessary to study other types of planets to determine its impact on the exo-planetary population. This thesis aims at using transit spectroscopy to observe the atmosphere of several exo-planets, to study their properties and to contribute to the characterization of hydrodynamic escape. UV lines observed with the Hubble telescope are analyzed with the numerical model of upper atmospheres we developed. Using the Ly-α line we identify energetic and dynamical interactions between the atmospheres of the hot Jupiters HD209458b and HD189733b and their stars. We study the dependence of the escape on the environment of a planet and on its physical properties, through the observation of a super-Earth and a warm Jupiter in the 55 Cnc system. Using observations of HD209458b, we show that magnesium lines are a window on the region of formation of hydrodynamic escape. We study the potential of transit spectroscopy in the near-UV to detect new cases of atmospheric escape. This mechanism is fostered by the proximity of a planet to its star, which makes it even more important to understand the formation and migration processes that can be traced in the alignment of a planetary system. Using measures from the spectrographs HARPS-N and SOPHIE we study the alignments of 55 Cnc e and the Kepler candidate KOI 12.01, whose planetary nature we also seek to validate. (author)

  15. X-Ray, UV and Optical Observations of Classical Cepheids: New Insights into Cepheid Evolution, and the Heating and Dynamics of Their Atmospheres

    Directory of Open Access Journals (Sweden)

    Scott G. Engle

    2012-06-01

    Full Text Available To broaden the understanding of classical Cepheid structure, evolution and atmospheres, we have extended our continuing secret lives of Cepheids program by obtaining XMM/Chandra X-ray observations, and Hubble space telescope (HST / cosmic origins spectrograph (COS FUV-UV spectra of the bright, nearby Cepheids Polaris, δ Cep and β Dor. Previous studies made with the international ultraviolet explorer (IUE showed a limited number of UV emission lines in Cepheids. The wellknown problem presented by scattered light contamination in IUE spectra for bright stars, along with the excellent sensitivity & resolution combination offered by HST/COS, motivated this study, and the spectra obtained were much more rich and complex than we had ever anticipated. Numerous emission lines, indicating 104 K up to ~3 × 105 K plasmas, have been observed, showing Cepheids to have complex, dynamic outer atmospheres that also vary with the photospheric pulsation period. The FUV line emissions peak in the phase range φ ≈ 0.8-1.0 and vary by factors as large as 10×. A more complete picture of Cepheid outer atmospheres is accomplished when the HST/COS results are combined with X-ray observations that we have obtained of the same stars with XMM-Newton & Chandra. The Cepheids detected to date have X-ray luminosities of log LX ≈ 28.5-29.1 ergs/sec, and plasma temperatures in the 2–8 × 106 K range. Given the phase-timing of the enhanced emissions, the most plausible explanation is the formation of a pulsation-induced shocks that excite (and heat the atmospheric plasmas surrounding the photosphere. A pulsation-driven α2 equivalent dynamo mechanism is also a viable and interesting alternative. However, the tight phase-space of enhanced emission (peaking near 0.8-1.0 φ favor the shock heating mechanism hypothesis.

  16. X-Ray, UV and Optical Observations of Classical Cepheids: New Insights into Cepheid Evolution, and the Heating and Dynamics of Their Atmospheres

    Science.gov (United States)

    Engle, Scott G.; Guinan, Edward F.

    2012-06-01

    To broaden the understanding of classical Cepheid structure, evolution and atmospheres, we have extended our continuing secret lives of Cepheids program by obtaining XMM/Chandra X-ray observations, and Hubble space telescope (HST) / cosmic origins spectrograph (COS) FUV-UV spectra of the bright, nearby Cepheids Polaris, δ Cep and β Dor. Previous studies made with the international ultraviolet explorer (IUE) showed a limited number of UV emission lines in Cepheids. The well-known problem presented by scattered light contamination in IUE spectra for bright stars, along with the excellent sensitivity & resolution combination offered by HST/COS, motivated this study, and the spectra obtained were much more rich and complex than we had ever anticipated. Numerous emission lines, indicating 10^4 K up to ~3 x 10^5 K plasmas, have been observed, showing Cepheids to have complex, dynamic outer atmospheres that also vary with the photospheric pulsation period. The FUV line emissions peak in the phase range φ ∼ 0.8-1.0 and vary by factors as large as 10x. A more complete picture of Cepheid outer atmospheres is accomplished when the HST/COS results are combined with X-ray observations that we have obtained of the same stars with XMM-Newton & Chandra. The Cepheids detected to date have X-ray luminosities of log Lx ~ 28.5-29.1 ergs/sec, and plasma temperatures in the 2-8 x 10^6 K range. Given the phase-timing of the enhanced emissions, the most plausible explanation is the formation of a pulsation-induced shocks that excite (and heat) the atmospheric plasmas surrounding the photosphere. A pulsation-driven α^2 equivalent dynamo mechanism is also a viable and interesting alternative. However, the tight phase-space of enhanced emission (peaking near 0.8-1.0 φ) favor the shock heating mechanism hypothesis.

  17. Initial analyses of surface spectral radiance between observations and Line-By-Line calculations

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P.D.; Clough, S.A. [Atmospheric and Environmental Research, Inc., Cambridge, MA (United States); Miller, N.E.; Shippert, T.R.; Turner, D.D. [Pacific Northwest Lab., Richland, WA (United States)] [and others

    1996-04-01

    The evaluation an improvement of radiative transfer calculations are essential to attain improved performance of general circulation models (GCMs) for climate change applications. A Quality Measurement Experiment (QME) is being conducted to analyze the spectral residuals between the downwelling longwave radiance measured by the University of Wisconsin Atmospheric Emitted Radiance Interferometer (AERI) and spectral radiance calculated by the Line-By-Line Radiative Transfer Model (LBLRTM). The three critical components of this study are (1) the assessment of the quality of the high resolution AERI measurements, (2) the assessment of the ability to define the atmospheric state in the radiating column, and (3) the evaluation of the capability of LBLRTM. Validations have been performed on spectral radiance data, obtained from April 1994 through July 1994, through the analysis of the spectral interval and physical process. The results are archived as a function of time, enabling the retrieval of specific data and facilitating investigations and diurnal effects, seasonal effects, and longer-term trends. While the initial focus is restricted to clear-sky analyses, efforts are under way to include the effects of clouds and aerosols. Plans are well formulated for the extension of the current approach to the shortwave. An overview of the concept of the QME is described by Miller et al. (1994), and a detailed description of this study is provided by Clough et al. (1994).

  18. Atmospheric interaction with nanosatellites from observed orbital decay

    Science.gov (United States)

    Macario-Rojas, A.; Smith, K. L.; Crisp, N. H.; Roberts, P. C. E.

    2018-06-01

    Nanosatellites have gained considerable presence in low Earth orbits wherein the atmospheric interaction with exposed surfaces plays a fundamental role in the evolution of motion. These aspects become relevant with the increasing applicability of nanosatellites to a broader range of missions objectives. This investigation sets out to determine distinctive drag coefficient development and attributes of atmospheric gas-surface interactions in nanosatellites in the common form of standard 3U CubeSats from observed orbital decay. As orbital decay can be measured with relative accuracy, and its mechanism broken down into its constituent sources, the value of drag-related coefficients can be inferred by fitting modelled orbit predictions to observed data wherein the coefficient of interest is the adjusted parameter. The analysis uses the data of ten historical missions with documented passive attitude stabilisation strategies to reduce uncertainties. Findings indicate that it is possible to estimate fitted drag coefficients in CubeSats with physical representativeness. Assessment of atomic oxygen surface coverage derived from the fitted drag coefficients is broadly consistent with theoretical trends. The proposed methodology opens the possibility to assess atmospheric interaction characteristics by using the unprecedented opportunity arising from the numerous observed orbital decay of nanosatellites.

  19. Results from Joint Observations of Jupiter's Atmosphere by Juno and a Network of Earth-Based Observing Stations

    Science.gov (United States)

    Orton, G. S.; Bolton, S. J.; Levin, S.; Hansen, C. J.; Janssen, M. A.; Adriani, A.; Gladstone, R.; Bagenal, F.; Ingersoll, A. P.; Momary, T.; Payne, A.

    2016-12-01

    The Juno mission has promoted and coordinated a network of Earth-based observations, including both space- and ground-based facilities, to extend and enhance observations made by the Juno mission. The spectral region and timeline of all of these observations are summarized in the web site: https://www.missionjuno.swri.edu/planned-observations. Among the earliest of these were observation of Jovian auroral phenomena at X-ray, ultraviolet and infrared wavelengths and measurements of Jovian synchrotron radiation from the Earth simultaneously with the measurement of properties of the upstream solar wind described elsewhere in this meeting. Other observations of significance to the magnetosphere measured the mass loading from Io by tracking its observed volcanic activity and the opacity of its torus. Observations of Jupiter's neutral atmosphere included observations of reflected sunlight from the near-ultraviolet through the near-infrared and thermal emission from 5 microns through the radio region. The point of these measurements is to relate properties of the deep atmosphere that are the focus of Juno's mission to the state of the "weather layer" at much higher atmospheric levels. These observations cover spectral regions not included in Juno's instrumentation, provide spatial context for Juno's often spatially limited coverage of Jupiter, and they describe the evolution of atmospheric features in time that are measured only once by Juno. We will summarize the results of measurements during the approach phase of the mission that characterized the state of the atmosphere, as well as observations made by Juno and the supporting campaign during Juno's perijoves 1 (August 27), 2 (October 19), 3 (November 2), 4 (November 15), and 5 (November 30). The Juno mission also benefited from the enlistment of a network of dedicated amateur astronomers who, besides providing input needed for public operation of the JunoCam visible camera, tracked the evolution of features in Jupiter

  20. Program of telluric lines monitoring

    Directory of Open Access Journals (Sweden)

    Vince I.

    2006-01-01

    Full Text Available A new observational program of telluric lines monitoring was introduced at Belgrade Astronomical Observatory. The ultimate goal of this program is to investigate the properties of Earth’s atmosphere through modeling the observed profiles of telluric lines. The program is intend to observe infrared molecular oxygen lines that were selected according to spectral sensitivity of the available CCD camera. In this paper we give the initial and the final selection criteria for spectral lines included in the program the description of equipment and procedures used for observations and reduction, a review of preliminary observational results with the estimated precision, and a short discussion on the comparison of the theoretical predictions and the measurements.

  1. Atmospheric CO2 Variability Observed From ASCENDS Flight Campaigns

    Science.gov (United States)

    Lin, Bing; Browell, Edward; Campbell, Joel; Choi, Yonghoon; Dobler, Jeremy; Fan, Tai-Fang; Harrison, F. Wallace; Kooi, Susan; Liu, Zhaoyan; Meadows, Byron; hide

    2015-01-01

    Significant atmospheric CO2 variations on various spatiotemporal scales were observed during ASCENDS flight campaigns. For example, around 10-ppm CO2 changes were found within free troposphere in a region of about 200x300 sq km over Iowa during a summer 2014 flight. Even over extended forests, about 2-ppm CO2 column variability was measured within about 500-km distance. For winter times, especially over snow covered ground, relatively less horizontal CO2 variability was observed, likely owing to minimal interactions between the atmosphere and land surface. Inter-annual variations of CO2 drawdown over cornfields in the Mid-West were found to be larger than 5 ppm due to slight differences in the corn growing phase and meteorological conditions even in the same time period of a year. Furthermore, considerable differences in atmospheric CO2 profiles were found during winter and summer campaigns. In the winter CO2 was found to decrease from about 400 ppm in the atmospheric boundary layer (ABL) to about 392 ppm above 10 km, while in the summer CO2 increased from 386 ppm in the ABL to about 396 ppm in free troposphere. These and other CO2 observations are discussed in this presentation.

  2. Isotope ratio in stellar atmospheres and nucleosynthesis

    International Nuclear Information System (INIS)

    Barbuy, B.L.S.

    1987-01-01

    The determination of isotopic ratios in stellar atmospheres is studied. The isotopic shift of atomic and molecular lines of different species of a certain element is examined. CH and MgH lines are observed in order to obtain the 12 C: 13 C and 24 Mg: 25 Mg: 26 Mg isotpic ratios. The formation of lines in stellar atmospheres is computed and the resulting synthetic spectra are employed to determine the isotopic abundances. The results obtained for the isotopic ratios are compared to predictions of nucleosynthesis theories. Finally, the concept of primary and secondary element is discussed, and these definitions are applied to the observed variations in the abundance of elements as a function of metallicity. (author) [pt

  3. The atmosphere of Pluto as observed by New Horizons.

    Science.gov (United States)

    Gladstone, G Randall; Stern, S Alan; Ennico, Kimberly; Olkin, Catherine B; Weaver, Harold A; Young, Leslie A; Summers, Michael E; Strobel, Darrell F; Hinson, David P; Kammer, Joshua A; Parker, Alex H; Steffl, Andrew J; Linscott, Ivan R; Parker, Joel Wm; Cheng, Andrew F; Slater, David C; Versteeg, Maarten H; Greathouse, Thomas K; Retherford, Kurt D; Throop, Henry; Cunningham, Nathaniel J; Woods, William W; Singer, Kelsi N; Tsang, Constantine C C; Schindhelm, Eric; Lisse, Carey M; Wong, Michael L; Yung, Yuk L; Zhu, Xun; Curdt, Werner; Lavvas, Panayotis; Young, Eliot F; Tyler, G Leonard

    2016-03-18

    Observations made during the New Horizons flyby provide a detailed snapshot of the current state of Pluto's atmosphere. Whereas the lower atmosphere (at altitudes of less than 200 kilometers) is consistent with ground-based stellar occultations, the upper atmosphere is much colder and more compact than indicated by pre-encounter models. Molecular nitrogen (N2) dominates the atmosphere (at altitudes of less than 1800 kilometers or so), whereas methane (CH4), acetylene (C2H2), ethylene (C2H4), and ethane (C2H6) are abundant minor species and likely feed the production of an extensive haze that encompasses Pluto. The cold upper atmosphere shuts off the anticipated enhanced-Jeans, hydrodynamic-like escape of Pluto's atmosphere to space. It is unclear whether the current state of Pluto's atmosphere is representative of its average state--over seasonal or geologic time scales. Copyright © 2016, American Association for the Advancement of Science.

  4. Results of Joint Observations of Jupiter's Atmosphere by Juno and a Network of Earth-Based Observing Stations

    Science.gov (United States)

    Orton, Glenn; Momary, Thomas; Bolton, Scott; Levin, Steven; Hansen, Candice; Janssen, Michael; Adriani, Alberto; Gladstone, G. Randall; Bagenal, Fran; Ingersoll, Andrew

    2017-04-01

    The Juno mission has promoted and coordinated a network of Earth-based observations, including both Earth-proximal and ground-based facilities, to extend and enhance observations made by the Juno mission. The spectral region and timeline of all of these observations are summarized in the web site: https://www.missionjuno.swri.edu/planned-observations. Among the earliest of these were observation of Jovian auroral phenomena at X-ray, ultraviolet and infrared wavelengths and measurements of Jovian synchrotron radiation from the Earth simultaneously with the measurement of properties of the upstream solar wind. Other observations of significance to the magnetosphere measured the mass loading from Io by tracking its observed volcanic activity and the opacity of its torus. Observations of Jupiter's neutral atmosphere included observations of reflected sunlight from the near-ultraviolet through the near-infrared and thermal emission from 5 μm through the radio region. The point of these measurements is to relate properties of the deep atmosphere that are the focus of Juno's mission to the state of the "weather layer" at much higher atmospheric levels. These observations cover spectral regions not included in Juno's instrumentation, provide spatial context for Juno's often spatially limited coverage of Jupiter, and they describe the evolution of atmospheric features in time that are measured only once by Juno. We will summarize the results of measurements during the approach phase of the mission that characterized the state of the atmosphere, as well as observations made by Juno and the supporting campaign during Juno's perijoves 1 (2016 August 27), 3 (2016 December 11), 4 (2017 February 2) and possibly "early" results from 5 (2017 March 27). Besides a global network of professional astronomers, the Juno mission also benefited from the enlistment of a network of dedicated amateur astronomers who provided a quasi-continuous picture of the evolution of features observed by

  5. W-band spaceborne radar observations of atmospheric river events

    Science.gov (United States)

    Matrosov, S. Y.

    2010-12-01

    While the main objective of the world first W-band radar aboard the CloudSat satellite is to provide vertically resolved information on clouds, it proved to be a valuable tool for observing precipitation. The CloudSat radar is generally able to resolve precipitating cloud systems in their vertical entirety. Although measurements from the liquid hydrometer layer containing rainfall are strongly attenuated, special retrieval approaches can be used to estimate rainfall parameters. These approaches are based on vertical gradients of observed radar reflectivity factor rather than on absolute estimates of reflectivity. Concurrent independent estimations of ice cloud parameters in the same vertical column allow characterization of precipitating systems and provide information on coupling between clouds and rainfall they produce. The potential of CloudSat for observations atmospheric river events affecting the West Coast of North America is evaluated. It is shown that spaceborne radar measurements can provide high resolution information on the height of the freezing level thus separating areas of rainfall and snowfall. CloudSat precipitation rate estimates complement information from the surface-based radars. Observations of atmospheric rivers at different locations above the ocean and during landfall help to understand evolutions of atmospheric rivers and their structures.

  6. ALMA observations of Titan's atmospheric chemistry and seasonal variation

    Science.gov (United States)

    Cordiner, Martin

    2017-04-01

    Titan is the largest moon of Saturn, with a thick (1.45 bar) atmosphere composed primarily of molecular nitrogen and methane. Photochemistry in Titan's upper atmosphere results in the production of a wide range of organic molecules, including hydrocarbons, nitriles and aromatics, some of which could be of pre-biotic relevance. Thus, we obtain insights into the possible molecular inventories of primitive (reducing) planetary atmospheres. Titan's atmosphere also provides a unique laboratory for testing our understanding of fundamental processes involving the chemistry and spectroscopy of complex organic molecules. In this talk, results will be presented from our studies using the Atacama Large Millimeter/submillimeter Array (ALMA) during the period 2012-2015, focussing in particular on the detection and mapping of emission from various nitrile species. By combining data from multiple ALMA observations, our spectra have reached an unprecedented sensitivity level, enabling the first spectroscopic detection and mapping of C2H3CN (vinyl cyanide) on Titan. Liquid-phase simulations of Titan's seas indicate that vinyl cyanide molecules could combine to form vesicle membranes (similar to the cells of terrestrial biology), and the astrobiological implications of this discovery will be discussed. Furthermore, ALMA observations provide instantaneous snapshot mapping of Titan's entire Earth-facing hemisphere, for gases inaccessible to previous instruments. Combined with complementary data obtained from the Cassini Saturn orbiter, as well as theoretical models and laboratory studies, our observed, seasonally variable, spatially resolved abundance patterns are capable of providing new insights into photochemical production and transport in primitive planetary atmospheres in the Solar System and beyond.

  7. He II lines in the spectrum of zeta Puppis

    International Nuclear Information System (INIS)

    Snijders, M.A.J.; Underhill, A.B.

    1975-01-01

    Equivalents widths of He II lines in the series n=2,3,4 and 5 are compiled and compared with predictions from plane-parallel, static model atmospheres using a non-LTE theory of line formation. The agreement between observation and prediction for a (50,000,4.0) model atmosphere is good for the upper members of the n=3 and the n=5 series, but the two lines of the n=2 series which are observed and the upper members of the n=4 series (4→15,4→17, etc.) are stronger than predicted. Well-determined profiles of lines from the n=3 series indicate v sin i=200 km s -1 . Profiles of the higher members of the n=4 series, however, do not match the predictions, the observed line cores being deeper than predicted. The n=4 level appears to be more overpopulated at moderate depths in the atmosphere than the non-LTE calculations with plane-parallel layers indicate. This may be due to an overlap of the H and He II lines in the even-even series caused by macroturbulent velocities of the hydrogen atoms and helium atoms

  8. Observations of atmospheric ammonia from TANSO-FTS/GOSAT

    Science.gov (United States)

    Someya, Yu; Imasu, Ryoichi; Saitoh, Naoko; Shiomi, Kei

    2017-04-01

    Atmospheric ammonia has large impacts on the nitrogen cycles or atmospheric environment such as nucleation of PM2.5 particles. It is reported that ammonia in the atmosphere has been increasing rapidly with the growth of population globally and this trend must continue in the future. Satellite observation is an effective approach to get to know the global perspectives of the gas. Atmospheric ammonia is observable using the thermal infrared (TIR) spectra, and IASI, TES and CrIS had been revealed those distributions. GOSAT also has TIR band including the ammonia absorption bands. GOSAT has the shorter revisit cycle than that of the other hyper-spectral TIR sounders mentioned above, therefore, the shorter time-scale events can be represented. In addition to the importance of the impacts of ammonia itself, the concentration ratio between ammonia and the other trace gases such as CO which is one of the main targets of the GOSAT-2 project is useful as the indicator of their emission sources. In this study, we introduce an algorithm to retrieve the column amount of atmospheric ammonia based on non-linear optimal estimation (Rogers, 2000) from GOSAT spectra in the ammonia absorption band between 960 - 970 cm-1. Temperature and water vapor profiles are estimated in advance of the ammonia retrieval. The preliminary results showed significant high concentrations of ammonia in the Northern India and the Eastern China as pointed out in the previous researches. We will discuss the global distribution of ammonia in the presentation.

  9. Southeast Atmosphere Studies: learning from model-observation syntheses

    Directory of Open Access Journals (Sweden)

    J. Mao

    2018-02-01

    Full Text Available Concentrations of atmospheric trace species in the United States have changed dramatically over the past several decades in response to pollution control strategies, shifts in domestic energy policy and economics, and economic development (and resulting emission changes elsewhere in the world. Reliable projections of the future atmosphere require models to not only accurately describe current atmospheric concentrations, but to do so by representing chemical, physical and biological processes with conceptual and quantitative fidelity. Only through incorporation of the processes controlling emissions and chemical mechanisms that represent the key transformations among reactive molecules can models reliably project the impacts of future policy, energy and climate scenarios. Efforts to properly identify and implement the fundamental and controlling mechanisms in atmospheric models benefit from intensive observation periods, during which collocated measurements of diverse, speciated chemicals in both the gas and condensed phases are obtained. The Southeast Atmosphere Studies (SAS, including SENEX, SOAS, NOMADSS and SEAC4RS conducted during the summer of 2013 provided an unprecedented opportunity for the atmospheric modeling community to come together to evaluate, diagnose and improve the representation of fundamental climate and air quality processes in models of varying temporal and spatial scales.This paper is aimed at discussing progress in evaluating, diagnosing and improving air quality and climate modeling using comparisons to SAS observations as a guide to thinking about improvements to mechanisms and parameterizations in models. The effort focused primarily on model representation of fundamental atmospheric processes that are essential to the formation of ozone, secondary organic aerosol (SOA and other trace species in the troposphere, with the ultimate goal of understanding the radiative impacts of these species in the southeast and

  10. Southeast Atmosphere Studies: learning from model-observation syntheses

    Science.gov (United States)

    Mao, Jingqiu; Carlton, Annmarie; Cohen, Ronald C.; Brune, William H.; Brown, Steven S.; Wolfe, Glenn M.; Jimenez, Jose L.; Pye, Havala O. T.; Ng, Nga Lee; Xu, Lu; McNeill, V. Faye; Tsigaridis, Kostas; McDonald, Brian C.; Warneke, Carsten; Guenther, Alex; Alvarado, Matthew J.; de Gouw, Joost; Mickley, Loretta J.; Leibensperger, Eric M.; Mathur, Rohit; Nolte, Christopher G.; Portmann, Robert W.; Unger, Nadine; Tosca, Mika; Horowitz, Larry W.

    2018-02-01

    Concentrations of atmospheric trace species in the United States have changed dramatically over the past several decades in response to pollution control strategies, shifts in domestic energy policy and economics, and economic development (and resulting emission changes) elsewhere in the world. Reliable projections of the future atmosphere require models to not only accurately describe current atmospheric concentrations, but to do so by representing chemical, physical and biological processes with conceptual and quantitative fidelity. Only through incorporation of the processes controlling emissions and chemical mechanisms that represent the key transformations among reactive molecules can models reliably project the impacts of future policy, energy and climate scenarios. Efforts to properly identify and implement the fundamental and controlling mechanisms in atmospheric models benefit from intensive observation periods, during which collocated measurements of diverse, speciated chemicals in both the gas and condensed phases are obtained. The Southeast Atmosphere Studies (SAS, including SENEX, SOAS, NOMADSS and SEAC4RS) conducted during the summer of 2013 provided an unprecedented opportunity for the atmospheric modeling community to come together to evaluate, diagnose and improve the representation of fundamental climate and air quality processes in models of varying temporal and spatial scales.This paper is aimed at discussing progress in evaluating, diagnosing and improving air quality and climate modeling using comparisons to SAS observations as a guide to thinking about improvements to mechanisms and parameterizations in models. The effort focused primarily on model representation of fundamental atmospheric processes that are essential to the formation of ozone, secondary organic aerosol (SOA) and other trace species in the troposphere, with the ultimate goal of understanding the radiative impacts of these species in the southeast and elsewhere. Here we

  11. Plasma line observations in the auroral oval

    International Nuclear Information System (INIS)

    Valladares, C.E.; Kelley, M.C.; Vickrey, J.F.

    1988-01-01

    We report here a series of experiments conducted at the Sondre Stromfjord incoherent scatter radar, aimed at detected enhanced plasma lines associated with midnight sector auroral arcs. Using different receivers, we detected both ion and plasma lines simultaneously. The plasma line signal was recorded with the use of a filter bank of eight frequencies. Plasma lines were found to originate mainly from the topside of the particle-produced E layer. The enhanced plasma lines are sometimes a factor of 100 times larger than the thermal level. Our data show a rapid decay of the plasma lines, however. In some cases, only a 30-s integration time was needed in order to unambiguously detect both upshifted and downshifted lines. The level of the plasma lines reaches values of, for the larger cases, up to 40 0 K above the noise temperature. These are considerably higher than results from prior auroral zone plasma line experiments. In situ observations of enhanced plasma waves in this same region are reported in a companion paper. copyright American Geophysical Union 1988

  12. Kosovo’s Ground Flash Density and Protection of Transmission Lines of the Kosovo Power System from Atmospheric Discharges

    Directory of Open Access Journals (Sweden)

    Bahri Prebreza

    2018-03-01

    Full Text Available In this paper is presented the protection of transmission power lines of the Kosovo Power System from atmospheric discharges, with the use of surge arresters. Atmospheric discharges represent one of the main causes of interruptions for the Kosovo Power System. In addition, the ground flash density for Kosovo is given. The transmission lines with the worst performance regarding atmospheric discharges are discussed in more detail and are presented recommendations about the surge arresters used to protect the system from these overvoltages. The data provided by the localized lightning system in Kosovo enable us to provide a detailed correlation of the reported outages of the Kosovo Power System and corresponding atmospheric discharges. Recommendations for protection in terms of surge arresters are given followed by subsequent dynamic simulations using MATLAB software.

  13. Robust Detection and Visualization of Jet-Stream Core Lines in Atmospheric Flow.

    Science.gov (United States)

    Kern, Michael; Hewson, Tim; Sadlo, Filip; Westermann, Rudiger; Rautenhaus, Marc

    2018-01-01

    Jet-streams, their core lines and their role in atmospheric dynamics have been subject to considerable meteorological research since the first half of the twentieth century. Yet, until today no consistent automated feature detection approach has been proposed to identify jet-stream core lines from 3D wind fields. Such 3D core lines can facilitate meteorological analyses previously not possible. Although jet-stream cores can be manually analyzed by meteorologists in 2D as height ridges in the wind speed field, to the best of our knowledge no automated ridge detection approach has been applied to jet-stream core detection. In this work, we -a team of visualization scientists and meteorologists-propose a method that exploits directional information in the wind field to extract core lines in a robust and numerically less involved manner than traditional 3D ridge detection. For the first time, we apply the extracted 3D core lines to meteorological analysis, considering real-world case studies and demonstrating our method's benefits for weather forecasting and meteorological research.

  14. Emergence of granular-sized magnetic bubbles through the solar atmosphere. I. Spectropolarimetric observations and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, Ada; Hansteen, Viggo H.; Van der Voort, Luc Rouppe [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, N-0315 Oslo (Norway); Bellot Rubio, Luis R. [Instituto de Astrofísica de Andalucía (CSIC), Apdo. 3040, E-18080 Granada (Spain); De la Cruz Rodríguez, Jaime, E-mail: ada@astro.uio.no [Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden)

    2014-02-01

    We study a granular-sized magnetic flux emergence event that occurred in NOAA 11024 in 2009 July. The observations were made with the CRISP spectropolarimeter at the Swedish 1 m Solar Telescope achieving a spatial resolution of 0.''14. Simultaneous full Stokes observations of the two photospheric Fe I lines at 630.2 nm and the chromospheric Ca II 854.2 nm line allow us to describe in detail the emergence process across the solar atmosphere. We report here on three-dimensional (3D) semi-spherical bubble events, where instead of simple magnetic footpoints, we observe complex semi-circular feet straddling a few granules. Several phenomena occur simultaneously, namely, abnormal granulation, separation of opposite-polarity legs, and brightenings at chromospheric heights. However, the most characteristic signature in these events is the observation of a dark bubble in filtergrams taken in the wings of the Ca II 854.2 nm line. There is a clear coincidence between the emergence of horizontal magnetic field patches and the formation of the dark bubble. We can infer how the bubble rises through the solar atmosphere as we see it progressing from the wings to the core of Ca II 854.2 nm. In the photosphere, the magnetic bubble shows mean upward Doppler velocities of 2 km s{sup –1} and expands at a horizontal speed of 4 km s{sup –1}. In about 3.5 minutes it travels some 1100 km to reach the mid chromosphere, implying an average ascent speed of 5.2 km s{sup –1}. The maximum separation attained by the magnetic legs is 6.''6. From an inversion of the observed Stokes spectra with the SIR code, we find maximum photospheric field strengths of 480 G and inclinations of nearly 90° in the magnetic bubble interior, along with temperature deficits of up to 250 K at log τ = –2 and above. To aid the interpretation of the observations, we carry out 3D numerical simulations of the evolution of a horizontal, untwisted magnetic flux sheet injected in the convection

  15. RAMAN SCATTERING BY MOLECULAR HYDROGEN AND NITROGEN IN EXOPLANETARY ATMOSPHERES

    Energy Technology Data Exchange (ETDEWEB)

    Oklopčić, Antonija [California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, California 91125 (United States); Hirata, Christopher M. [Center for Cosmology and Astroparticle Physics, Ohio State University, 191 West Woodruff Avenue, Columbus, Ohio 43210 (United States); Heng, Kevin, E-mail: oklopcic@astro.caltech.edu [Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012, Bern (Switzerland)

    2016-11-20

    An important source of opacity in exoplanet atmospheres at short visible and near-UV wavelengths is Rayleigh scattering of light on molecules. It is accompanied by a related, albeit weaker process—Raman scattering. We analyze the signatures of Raman scattering imprinted in the reflected light and the geometric albedo of exoplanets, which could provide information about atmospheric properties. Raman scattering affects the geometric albedo spectra of planets in the following ways. First, it causes filling-in of strong absorption lines in the incident radiation, thus producing sharp peaks in the albedo. Second, it shifts the wavelengths of spectral features in the reflected light causing the so-called Raman ghost lines. Raman scattering can also cause a broadband reduction of the albedo due to wavelength shifting of a stellar spectrum with red spectral index. Observing the Raman peaks in the albedo could be used to measure the column density of gas, thus providing constraints on the presence of clouds in the atmosphere. Observing the Raman ghost lines could be used to spectroscopically identify the main scatterer in the atmosphere, even molecules like H{sub 2} or N{sub 2}, which do not have prominent spectral signatures in the optical wavelength range. If detected, ghost lines could also provide information about the temperature of the atmosphere. In this paper, we investigate the effects of Raman scattering in hydrogen- and nitrogen-dominated atmospheres. We analyze the feasibility of detecting the signatures of Raman scattering with the existing and future observational facilities, and of using these signatures as probes of exoplanetary atmospheres.

  16. Retrieval and analysis of atmospheric XCO2 using ground-based spectral observation.

    Science.gov (United States)

    Qin, Xiu-Chun; Lei, Li-Ping; Kawasaki, Masahiro; Masafumi, Ohashi; Takahiro, Kuroki; Zeng, Zhao-Cheng; Zhang, Bing

    2014-07-01

    Atmospheric CO2 column concentration (column-averaged dry air mole fractions of atmospheric carbon dioxide) data obtained by ground-based hyperspectral observation is an important source of data for the verification and improvement of the results of CO2 retrieval based on satellite hyperspectral observation. However, few studies have been conducted on atmospheric CO2 column concentration retrieval based on ground-based spectral hyperspectral observation in China. In the present study, we carried out the ground-based hyperspectral observation in Xilingol Grassland, Inner Mongolia of China by using an observation system which is consisted of an optical spectral analyzer, a sun tracker, and some other elements. The atmospheric CO2 column concentration was retrieved using the observed hyperspectral data. The effect of a wavelength shift of the observation spectra and the meteorological parameters on the retrieval precision of the atmospheric CO2 concentration was evaluated and analyzed. The results show that the mean value of atmospheric CO2 concentration was 390.9 microg x mL(-1) in the study area during the observing period from July to September. The shift of wavelength in the range between -0.012 and 0.042 nm will generally lead to 1 microg x mL(-1) deviation in the CO2 retrievals. This study also revealed that the spectral transmittance was sensitive to meteorological parameters in the wavelength range of 6 357-6 358, 6 360-6 361, and 6 363-6 364 cm(-1). By comparing the CO2 retrievals derived from the meteorological parameters observed in synchronous and non-synchronous time, respectively, with the spectral observation, it was showed that the concentration deviation caused by using the non-synchronously observed meteorological parameters is ranged from 0.11 to 4 microg x mL(-1). These results can be used as references for the further improvement of retrieving CO2 column concentration based on spectral observation.

  17. MODELING ATMOSPHERIC EMISSION FOR CMB GROUND-BASED OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Errard, J.; Borrill, J. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Ade, P. A. R. [School of Physics and Astronomy, Cardiff University, Cardiff CF10 3XQ (United Kingdom); Akiba, Y.; Chinone, Y. [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801 (Japan); Arnold, K.; Atlas, M.; Barron, D.; Elleflot, T. [Department of Physics, University of California, San Diego, CA 92093-0424 (United States); Baccigalupi, C.; Fabbian, G. [International School for Advanced Studies (SISSA), Trieste I-34014 (Italy); Boettger, D. [Department of Astronomy, Pontifica Universidad Catolica de Chile (Chile); Chapman, S. [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, B3H 4R2 (Canada); Cukierman, A. [Department of Physics, University of California, Berkeley, CA 94720 (United States); Delabrouille, J. [AstroParticule et Cosmologie, Univ Paris Diderot, CNRS/IN2P3, CEA/Irfu, Obs de Paris, Sorbonne Paris Cité (France); Dobbs, M.; Gilbert, A. [Physics Department, McGill University, Montreal, QC H3A 0G4 (Canada); Ducout, A.; Feeney, S. [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom); Feng, C. [Department of Physics and Astronomy, University of California, Irvine (United States); and others

    2015-08-10

    Atmosphere is one of the most important noise sources for ground-based cosmic microwave background (CMB) experiments. By increasing optical loading on the detectors, it amplifies their effective noise, while its fluctuations introduce spatial and temporal correlations between detected signals. We present a physically motivated 3D-model of the atmosphere total intensity emission in the millimeter and sub-millimeter wavelengths. We derive a new analytical estimate for the correlation between detectors time-ordered data as a function of the instrument and survey design, as well as several atmospheric parameters such as wind, relative humidity, temperature and turbulence characteristics. Using an original numerical computation, we examine the effect of each physical parameter on the correlations in the time series of a given experiment. We then use a parametric-likelihood approach to validate the modeling and estimate atmosphere parameters from the polarbear-i project first season data set. We derive a new 1.0% upper limit on the linear polarization fraction of atmospheric emission. We also compare our results to previous studies and weather station measurements. The proposed model can be used for realistic simulations of future ground-based CMB observations.

  18. CAOS: the nested catchment soil-vegetation-atmosphere observation platform

    Science.gov (United States)

    Weiler, Markus; Blume, Theresa

    2016-04-01

    Most catchment based observations linking hydrometeorology, ecohydrology, soil hydrology and hydrogeology are typically not integrated with each other and lack a consistent and appropriate spatial-temporal resolution. Within the research network CAOS (Catchments As Organized Systems), we have initiated and developed a novel and integrated observation platform in several catchments in Luxembourg. In 20 nested catchments covering three distinct geologies the subscale processes at the bedrock-soil-vegetation-atmosphere interface are being monitored at 46 sensor cluster locations. Each sensor cluster is designed to observe a variety of different fluxes and state variables above and below ground, in the saturated and unsaturated zone. The numbers of sensors are chosen to capture the spatial variability as well the average dynamics. At each of these sensor clusters three soil moisture profiles with sensors at different depths, four soil temperature profiles as well as matric potential, air temperature, relative humidity, global radiation, rainfall/throughfall, sapflow and shallow groundwater and stream water levels are measured continuously. In addition, most sensors also measure temperature (water, soil, atmosphere) and electrical conductivity. This setup allows us to determine the local water and energy balance at each of these sites. The discharge gauging sites in the nested catchments are also equipped with automatic water samplers to monitor water quality and water stable isotopes continuously. Furthermore, water temperature and electrical conductivity observations are extended to over 120 locations distributed across the entire stream network to capture the energy exchange between the groundwater, stream water and atmosphere. The measurements at the sensor clusters are complemented by hydrometeorological observations (rain radar, network of distrometers and dense network of precipitation gauges) and linked with high resolution meteorological models. In this

  19. Atmospheric pressure photoionization for enhanced compatibility in on-line micellar electrokinetic chromatography-mass spectrometry

    NARCIS (Netherlands)

    Mol, Roelof; De Jong, Gerhardus J.; Somsen, Govert W.

    2005-01-01

    Atmospheric pressure photoionization (APPI) is presented as a novel means for the combination of micellar electrokinetic chromatography (MEKC) and mass spectrometry (MS). The on-line coupling is achieved using an adapted sheath flow interface installed on an orthogonal APPI source. Acetone or

  20. Outer atmospheres of cool stars. XII - A survey of IUE ultraviolet emission line spectra of cool dwarf stars

    Science.gov (United States)

    Linsky, J. L.; Bornmann, P. L.; Carpenter, K. G.; Hege, E. K.; Wing, R. F.; Giampapa, M. S.; Worden, S. P.

    1982-01-01

    Quantitative information is obtained on the chromospheres and transition regions of M dwarf stars, in order to determine how the outer atmospheres of dMe stars differ from dM stars and how they compare with the outer atmospheres of quiet and active G and K type dwarfs. IUE spectra of six dMe and four dM stars, together with ground-based photometry and spectroscopy of the Balmer and Ca II H and K lines, show no evidence of flares. It is concluded, regarding the quiescent behavior of these stars, that emission-line spectra resemble that of the sun and contain emission lines formed in regions with 4000-20,000 K temperatures that are presumably analogous to the solar chromosphere, as well as regions with temperatures of 20,000-200,000 K that are presumably analogous to the solar transition region. Emission-line surface fluxes are proportional to the emission measure over the range of temperatures at which the lines are formed.

  1. Atmospheric studies of C2 white dwarfs

    Science.gov (United States)

    Swanson, Steven Roger

    Model atmosphere and line formation calculations for the delta nu = + 1 Swan bands of the C2 molecule are presented for seven white dwarfs and are compared to high resolution optical spectra. Limits on the C-12 to C-13 ratio are computed for highly pressure broadened lines and are used to analyze the observed spectra for any sign of absorption by the (C-12)(C-13) molecule. The metal abundances in cool white dwarf atmospheres and the usefulness of the determination of the C-12 to C-13 ratio are discussed. The line center shift and the pressure broadening are used to determine a value for the van der Waals interaction constant, C6. This is done using a detailed line modelling program which explicitly includes approximately 2000 rotational transition lines within the vibrational bands, in conjunction with atmospheric models calculated by the LUCIFER atmosphere modelling program. The isotopic shift of the vibrational and rotational lines is also included in the model to compare the detectability of various C-12 to C-13 ratios. The line models fit the observed spectra with varying degrees of accuracy. One star, WD0548-001, shows an unusually small pressure shift and broadening for the high pressures that the atmospheric model predicts. The results show that only in the hottest stars with the least pressure broadened lines in this study can the isotopic effect be seen. With the data available, the best limit on the C-12 to C-13 ratio is a minimum of 40 for WD0856 + 331. The models show that even for very high signal to noise data, the isotopic shift in the Swan bands in very cool white dwarfs would be difficult to separate from the pressure broadening effects. It is shown that the isotopic ratio is high enough to rule out the possibility that the carbon is a relic from previous CNO burning.

  2. Atmospheric studies of C2 white dwarfs

    International Nuclear Information System (INIS)

    Swanson, S.R.

    1989-01-01

    Model atmosphere and line formation calculations for the delta nu = + 1 Swan bands of the C2 molecule are presented for seven white dwarfs and are compared to high resolution optical spectra. Limits on the C-12 to C-13 ratio are computed for highly pressure broadened lines and are used to analyze the observed spectra for any sign of absorption by the (C-12)(C-13) molecule. The metal abundances in cool white dwarf atmospheres and the usefulness of the determination of the C-12 to C-13 ratio are discussed. The line center shift and the pressure broadening are used to determine a value for the van der Waals interaction constant, C6. This is done using a detailed line modelling program which explicitly includes approximately 2000 rotational transition lines within the vibrational bands, in conjunction with atmospheric models calculated by the LUCIFER atmosphere modelling program. The isotopic shift of the vibrational and rotational lines is also included in the model to compare the detectability of various C-12 to C-13 ratios. The line models fit the observed spectra with varying degrees of accuracy. One star, WD0548-001, shows an unusually small pressure shift and broadening for the high pressures that the atmospheric model predicts. The results show that only in the hottest stars with the least pressure broadened lines in this study can the isotopic effect be seen. With the data available, the best limit on the C-12 to C-13 ratio is a minimum of 40 for WD0856 + 331. The models show that even for very high signal to noise data, the isotopic shift in the Swan bands in very cool white dwarfs would be difficult to separate from the pressure broadening effects. It is shown that the isotopic ratio is high enough to rule out the possibility that the carbon is a relic from previous CNO burning

  3. Atmospheric Responses from Radiosonde Observations of the 2017 Total Solar Eclipse

    Science.gov (United States)

    Fowler, J.

    2017-12-01

    The Atmospheric Responses from Radiosonde Observations project during the August 21st, 2017 Total Solar Eclipse was to observe the atmospheric response under the shadow of the Moon using both research and operational earth science instruments run primarily by undergraduate students not formally trained in atmospheric science. During the eclipse, approximately 15 teams across the path of totality launched radiosonde balloon platforms in very rapid, serial sonde deployment. Our strategy was to combine a dense ground observation network with multiple radiosonde sites, located within and along the margins of the path of totality. This can demonstrate how dense observation networks leveraged among various programs can "fill the gaps" in data sparse regions allowing research ideas and questions that previously could not be approached with courser resolution data and improving the scientific understanding and prediction of geophysical and hazardous phenomenon. The core scientific objectives are (1) to make high-resolution surface and upper air observations in several sites along the eclipse path (2) to quantitatively study atmospheric responses to the rapid disappearance of the Sun across the United States, and (3) to assess the performance of high-resolution weather forecasting models in simulating the observed response. Such a scientific campaign, especially unique during a total solar eclipse, provides a rare but life-altering opportunity to attract and enable next-generation of observational scientists. It was an ideal "laboratory" for graduate, undergraduate, citizen scientists and k-12 students and staff to learn, explore and research in STEM.

  4. Satellite observations of middle atmosphere-thermosphere vertical coupling by gravity waves

    Science.gov (United States)

    Trinh, Quang Thai; Ern, Manfred; Doornbos, Eelco; Preusse, Peter; Riese, Martin

    2018-03-01

    Atmospheric gravity waves (GWs) are essential for the dynamics of the middle atmosphere. Recent studies have shown that these waves are also important for the thermosphere/ionosphere (T/I) system. Via vertical coupling, GWs can significantly influence the mean state of the T/I system. However, the penetration of GWs into the T/I system is not fully understood in modeling as well as observations. In the current study, we analyze the correlation between GW momentum fluxes observed in the middle atmosphere (30-90 km) and GW-induced perturbations in the T/I. In the middle atmosphere, GW momentum fluxes are derived from temperature observations of the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite instrument. In the T/I, GW-induced perturbations are derived from neutral density measured by instruments on the Gravity field and Ocean Circulation Explorer (GOCE) and CHAllenging Minisatellite Payload (CHAMP) satellites. We find generally positive correlations between horizontal distributions at low altitudes (i.e., below 90 km) and horizontal distributions of GW-induced density fluctuations in the T/I (at 200 km and above). Two coupling mechanisms are likely responsible for these positive correlations: (1) fast GWs generated in the troposphere and lower stratosphere can propagate directly to the T/I and (2) primary GWs with their origins in the lower atmosphere dissipate while propagating upwards and generate secondary GWs, which then penetrate up to the T/I and maintain the spatial patterns of GW distributions in the lower atmosphere. The mountain-wave related hotspot over the Andes and Antarctic Peninsula is found clearly in observations of all instruments used in our analysis. Latitude-longitude variations in the summer midlatitudes are also found in observations of all instruments. These variations and strong positive correlations in the summer midlatitudes suggest that GWs with origins related to convection also propagate up to the T

  5. Non-LTE model atmospheres for supersoft X-ray sources

    Science.gov (United States)

    Rauch, T.; Werner, K.

    2010-02-01

    In the last decade, X-ray observations of hot stellar objects became available with unprecedented resolution and S/N ratio. For an adequate interpretation, fully metal-line blanketed Non-LTE model-atmospheres are necessary. The Tübingen Non-LTE Model Atmosphere Package (TMAP) can calculate such model atmospheres at a high level of sophistication. Although TMAP is not especially designed for the calculation of spectral energy distributions (SEDs) at extreme photospheric parameters, it can be employed for the spectral analysis of burst spectra of novae like V4743 Sgr or line identifications in observations of neutron stars with low magnetic fields in low-mass X-ray binaries (LMXBs) like EXO 0748-676.

  6. DISC ATMOSPHERES AND WINDS IN X-RAY BINARIES

    Directory of Open Access Journals (Sweden)

    Maria Díaz Trigo

    2013-12-01

    Full Text Available We review the current status of studies of disc atmospheres and winds in low mass X-ray binaries. We discuss the possible wind launching mechanisms and compare the predictions of the models with the existent observations. We conclude that a combination of thermal and radiative pressure (the latter being relevant at high luminosities can explain the current observations of atmospheres and winds in both neutron star and black hole binaries. Moreover, these winds and atmospheres could contribute significantly to the broad iron emission line observed in these systems.

  7. Lightning Performance on Overhead Distribution Lines : After Improvement Field Observation

    Directory of Open Access Journals (Sweden)

    Reynaldo Zoro

    2009-11-01

    Full Text Available Two feeders of 20 kV overhead distribution lines which are located in a high lightning density area are chosen to be observed as a field study due to their good lightning performance after improvement of lightning protection system. These two feeders used the new overhead ground wire and new line arrester equipped with lightning counter on the main lines. The significant reduced of lines outages are reported. Study was carried out to observe these improvements by comparing to the other two feeders line which are not improved and not equipped yet with the ground wire and line arrester. These two feeders located in the nearby area. Two cameras were installed to record the trajectory of the lightning strikes on the improved lines. Lightning peak currents are measured using magnetic tape measurement system installed on the grounding lead of lightning arrester. Lightning overvoltage calculations are carried out by using several scenarios based on observation results and historical lightning data derived from lightning detection network. Lightning overvoltages caused by indirect or direct strikes are analyzed to get the lightning performance of the lines. The best scenario was chosen and performance of the lines were improved significantly by installing overhead ground wire and improvement of lightning arrester installation.

  8. Lithium in the active sub-giant HD123351. A quantitative analysis with 3D and 1D model atmospheres using different observed spectra

    Science.gov (United States)

    Mott, A.; Steffen, M.; Caffau, E.; Strassmeier, K. G.

    Current 3D hydrodynamical model atmosphere simulations together with non-LTE spectrum synthesis calculations permit to determine reliable atomic and in particular isotopic chemical abundances. Although this approach is computationally time demanding, it became feasible in studying lithium in stellar spectra. In the literature not much is known about the presence of the more fragile {6Li} isotope in evolved metal-rich objects. In this case the analysis is complicated by the lack of a suitable list of atomic and molecular lines in the spectral region of the lithium resonance line at 670.8 nm. Here we present a spectroscopic comparative analysis of the Li doublet region of HD 123351, an active sub-giant star of solar metallicity. We fit the Li profile in three observed spectra characterized by different qualities: two very-high resolution spectra (Gecko@CFHT, R=120 000, SNR=400 and PEPSI@LBT, R=150 000, SNR=663) and a high-resolution SOPHIE@OHP spectrum (R=40 000, SNR=300). We adopt a set of model atmospheres, both 3D and 1D, having different stellar parameters (T_{eff} and log g). The 3D models are taken from the CIFIST grid of COBOLD model atmospheres and departures from LTE are considered for the lithium components. For the blends other than the lithium in this wavelength region we adopt the linelist of \\citet{melendez12}. We find consistent results for all three observations and an overall good fit with the selected list of atomic and molecular lines, indicating a high {6Li} content. The presence of {6Li} is not expected in cool stellar atmospheres. Its detection is of crucial importance for understanding mixing processes in stars and external lithium production mechanisms, possibly related to stellar activity or planetray accretion of {6Li}-rich material.

  9. Observed decrease in atmospheric mercury explained by global decline in anthropogenic emissions

    Science.gov (United States)

    Yanxu Zhang,; Daniel J. Jacob,; Hannah M. Horowitz,; Long Chen,; Helen M. Amos,; Krabbenhoft, David P.; Franz Slemr,; Vincent L. St. Louis,; Elsie M. Sunderland,

    2015-01-01

    Observations of elemental mercury (Hg0) at sites in North America and Europe show large decreases (∼1–2% y−1) from 1990 to present. Observations in background northern hemisphere air, including Mauna Loa Observatory (Hawaii) and CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) aircraft flights, show weaker decreases (Asia. Implementation of our inventory in a global 3D atmospheric Hg simulation [GEOS-Chem (Goddard Earth Observing System-Chemistry)] coupled to land and ocean reservoirs reproduces the observed large-scale trends in atmospheric Hg0 concentrations and in HgII wet deposition. The large trends observed in North America and Europe reflect the phase-out of Hg from commercial products as well as the cobenefit from SO2 and NOx emission controls on coal-fired utilities.

  10. Analysis of a Kalman filter based method for on-line estimation of atmospheric dispersion parameters using radiation monitoring data

    DEFF Research Database (Denmark)

    Drews, Martin; Lauritzen, Bent; Madsen, Henrik

    2005-01-01

    A Kalman filter method is discussed for on-line estimation of radioactive release and atmospheric dispersion from a time series of off-site radiation monitoring data. The method is based on a state space approach, where a stochastic system equation describes the dynamics of the plume model...... parameters, and the observables are linked to the state variables through a static measurement equation. The method is analysed for three simple state space models using experimental data obtained at a nuclear research reactor. Compared to direct measurements of the atmospheric dispersion, the Kalman filter...... estimates are found to agree well with the measured parameters, provided that the radiation measurements are spread out in the cross-wind direction. For less optimal detector placement it proves difficult to distinguish variations in the source term and plume height; yet the Kalman filter yields consistent...

  11. The NRPI multi-purpose on-line monitoring station for measurement of natural radioactivity in the ambient atmosphere and in the soil

    International Nuclear Information System (INIS)

    Jilek, K.; Slezakova, M.; Fronka, A.; Prokop, T.; Neubauer, L.

    2017-01-01

    During years 2010 12 an automated, on-line and wireless outdoor measurement station of atmospheric radon, gamma dose rate and meteorological parameters was realised at the National Radiation Protection Institute (NRPI) in Prague. At the turn of the year 2013 an expansion of the existing station was completed. Under the project funded by the Czech Technological Agency a new updated station was established, additionally equipped with modules for measurement of atmospheric radon/thoron short-lived decay products, radon in water and soil and radon exhalation rate from soil. After the introduction of the station updated key detection parameters and benefits, its use for atmospheric modelling and monitoring is demonstrated. There are summarised results from the 3-year measurement period in the NRPI outdoor area in Prague and from simultaneous annual measurement performed by another similar station located near uranium mud fields in DIAMO, state enterprise, Straz pod Ralskem. Observed seasonal and diurnal variations of atmospheric radon concentrations and variability of the equilibrium factor, F, are illustrated and compared. (authors)

  12. BARTTest: Community-Standard Atmospheric Radiative-Transfer and Retrieval Tests

    Science.gov (United States)

    Harrington, Joseph; Himes, Michael D.; Cubillos, Patricio E.; Blecic, Jasmina; Challener, Ryan C.

    2018-01-01

    Atmospheric radiative transfer (RT) codes are used both to predict planetary and brown-dwarf spectra and in retrieval algorithms to infer atmospheric chemistry, clouds, and thermal structure from observations. Observational plans, theoretical models, and scientific results depend on the correctness of these calculations. Yet, the calculations are complex and the codes implementing them are often written without modern software-verification techniques. The community needs a suite of test calculations with analytically, numerically, or at least community-verified results. We therefore present the Bayesian Atmospheric Radiative Transfer Test Suite, or BARTTest. BARTTest has four categories of tests: analytically verified RT tests of simple atmospheres (single line in single layer, line blends, saturation, isothermal, multiple line-list combination, etc.), community-verified RT tests of complex atmospheres, synthetic retrieval tests on simulated data with known answers, and community-verified real-data retrieval tests.BARTTest is open-source software intended for community use and further development. It is available at https://github.com/ExOSPORTS/BARTTest. We propose this test suite as a standard for verifying atmospheric RT and retrieval codes, analogous to the Held-Suarez test for general circulation models. This work was supported by NASA Planetary Atmospheres grant NX12AI69G, NASA Astrophysics Data Analysis Program grant NNX13AF38G, and NASA Exoplanets Research Program grant NNX17AB62G.

  13. Evaluating Land-Atmosphere Moisture Feedbacks in Earth System Models With Spaceborne Observations

    Science.gov (United States)

    Levine, P. A.; Randerson, J. T.; Lawrence, D. M.; Swenson, S. C.

    2016-12-01

    We have developed a set of metrics for measuring the feedback loop between the land surface moisture state and the atmosphere globally on an interannual time scale. These metrics consider both the forcing of terrestrial water storage (TWS) on subsequent atmospheric conditions as well as the response of TWS to antecedent atmospheric conditions. We designed our metrics to take advantage of more than one decade's worth of satellite observations of TWS from the Gravity Recovery and Climate Experiment (GRACE) along with atmospheric variables from the Atmospheric Infrared Sounder (AIRS), the Global Precipitation Climatology Project (GPCP), and Clouds and the Earths Radiant Energy System (CERES). Metrics derived from spaceborne observations were used to evaluate the strength of the feedback loop in the Community Earth System Model (CESM) Large Ensemble (LENS) and in several models that contributed simulations to Phase 5 of the Coupled Model Intercomparison Project (CMIP5). We found that both forcing and response limbs of the feedback loop were generally stronger in tropical and temperate regions in CMIP5 models and even more so in LENS compared to satellite observations. Our analysis suggests that models may overestimate the strength of the feedbacks between the land surface and the atmosphere, which is consistent with previous studies conducted across different spatial and temporal scales.

  14. Atmospheric ions and nucleation: a review of observations

    Directory of Open Access Journals (Sweden)

    A. Hirsikko

    2011-01-01

    Full Text Available This review is based on ca. 260 publications, 93 of which included data on the temporal and spatial variation of the concentration of small ions (<1.6 nm in diameter especially in the lower troposphere, chemical composition, or formation and growth rates of sub-3 nm ions. This information was collected on tables and figures. The small ions exist all the time in the atmosphere, and the average concentrations of positive and negative small ions are typically 200–2500 cm−3. However, concentrations up to 5000 cm−3 have been observed. The results are in agreement with observations of ion production rates in the atmosphere. We also summarised observations on the conversion of small ions to intermediate ions, which can act as embryos for new atmospheric aerosol particles. Those observations include the formation rates (J2[ion] of 2-nm intermediate ions, growth rates (GR[ion] of sub-3 nm ions, and information on the chemical composition of the ions. Unfortunately, there were only a few studies which presented J2[ion] and GR[ion]. Based on the publications, the formation rates of 2-nm ions were 0–1.1 cm−3 s−1, while the total 2-nm particle formation rates varied between 0.001 and 60 cm−3 s−1. Due to small changes in J2[ion], the relative importance of ions in 2-nm particle formation was determined by the large changes in J2[tot], and, accordingly the contribution of ions increased with decreasing J2[tot]. Furthermore, small ions were observed to activate for growth earlier than neutral nanometer-sized particles and at lower saturation ratio of condensing vapours.

  15. Non-LTE profiles of strong solar lines

    Science.gov (United States)

    Schneeberger, T. J.; Beebe, H. A.

    1976-01-01

    The complete linearization method is applied to the formation of strong lines in the solar atmosphere. Transitions in Na(I), Mg(I), Ca(I), Mg(II), and Ca(II) are computed with a standard atmosphere and microturbulent velocity model. The computed profiles are compared to observations at disk center.

  16. IRIS Observations of Magnetic Interactions in the Solar Atmosphere between Preexisting and Emerging Magnetic Fields. I. Overall Evolution

    Science.gov (United States)

    Guglielmino, Salvo L.; Zuccarello, Francesca; Young, Peter R.; Murabito, Mariarita; Romano, Paolo

    2018-04-01

    We report multiwavelength ultraviolet observations taken with the IRIS satellite, concerning the emergence phase in the upper chromosphere and transition region of an emerging flux region (EFR) embedded in the preexisting field of active region NOAA 12529 in the Sun. IRIS data are complemented by full-disk observations of the Solar Dynamics Observatory satellite, relevant to the photosphere and the corona. The photospheric configuration of the EFR is also analyzed by measurements taken with the spectropolarimeter on board the Hinode satellite, when the EFR was fully developed. Recurrent intense brightenings that resemble UV bursts, with counterparts in all coronal passbands, are identified at the edges of the EFR. Jet activity is also observed at chromospheric and coronal levels, near the observed brightenings. The analysis of the IRIS line profiles reveals the heating of dense plasma in the low solar atmosphere and the driving of bidirectional high-velocity flows with speed up to 100 km s‑1 at the same locations. Compared with previous observations and numerical models, these signatures suggest evidence of several long-lasting, small-scale magnetic reconnection episodes between the emerging bipole and the ambient field. This process leads to the cancellation of a preexisting photospheric flux concentration and appears to occur higher in the atmosphere than usually found in UV bursts, explaining the observed coronal counterparts.

  17. Non-LTE line-blanketed model atmospheres of hot stars. 2: Hot, metal-rich white dwarfs

    Science.gov (United States)

    Lanz, T.; Hubeny, I.

    1995-01-01

    We present several model atmospheres for a typical hot metal-rich DA white dwarf, T(sub eff) = 60,000 K, log g = 7.5. We consider pure hydrogen models, as well as models with various abundances of two typical 'trace' elements-carbon and iron. We calculte a number of Local Thermodynamic Equilibrium (LTE) and non-LTE models, taking into account the effect of numerous lines of these elements on the atmospheric structure. We demostrate that while the non-LTE effects are notvery significant for pure hydrogen models, except for describing correctly the central emission in H-alpha they are essential for predicting correctly the ionization balance of metals, such as carbon and iron. Previously reported discrepancies in LTE abundances determinations using C III and C IV lines are easily explained by non-LTE effects. We show that if the iron abundance is larger than 10(exp -5), the iron line opacity has to be considered not only for the spectrum synthesis, but also in the model construction itself. For such metal abundances, non-LTE metal line-blanketed models are needed for detailed abundance studies of hot, metal-rich white dwarfs. We also discuss the predicted Extreme Ultraviolet (EUV) spectrum and show that it is very sensitive to metal abundances, as well as to non-LTE effects.

  18. Observing atmospheric tides in Earth rotation parameters with VLBI

    Science.gov (United States)

    Girdiuk, Anastasiia; Böhm, Johannes; Schindelegger, Michael

    2015-04-01

    In this study, we assess the contribution of diurnal (S1) and semi-diurnal (S2) atmospheric tides to variations in Earth rotation by analyzing Very Long Baseline Interferometry (VLBI) observations. Particular emphasis is placed on the dependency of S1 and S2 estimates on varying settings in the a priori delay model. We use hourly Earth rotation parameters (ERP) of polar motion and UT1 as determined with the Vienna VLBI Software (VieVS) from 25 years of VLBI observations and we adjust diurnal and semi-diurnal amplitudes to the hourly ERP estimates after disregarding the effect of high-frequency ocean tides. Prograde and retrograde polar motion coefficients are obtained for several solutions differing in processing strategies (with/without thermal deformation, time span of observations, choice of a priori ERP model and celestial pole offsets) and we compare the corresponding harmonics with those derived from atmospheric and non-tidal oceanic angular momentum estimates.

  19. The radio recombination line spectrum of Orion A: Observations and analysis

    International Nuclear Information System (INIS)

    Lockman, F.J.; Brown, R.L.

    1975-01-01

    The entire body of radio observations of Orion A has been considered, and the means by which the temperature and density can be derived from the ratio T/subL//T/subC/ and the line width Δv of the hydrogen radio recombination lines is examined. Since it is critical to determine the extent to which low-frequency line measurements are contaminated by ''baseline-subtraction'' problems, new observations are presented which, together with general considerations of the line shape and data reduction processes, support the following conclusions: T/subL//T/subC/ and Δv can be accurately determined in the low-frequency observations even when erroneous baselines are removed; in accord with other studies, a density gradient must exist in the nebula; isothermal models cannot reproduce the observed line strenghts; the most dense parts of the nebula must be somewhat cooler than the surrounding gas. A model of Orion A has been constructed that is derived directly from the radio continuum observations. These observations demand that the simplest possible model of the nebula be comprised of three regions whose gross properties: the electrons density and the size: are defined by the continuum measurements. This model has been used for an analysis of the radio recombination line data, and virtually all known radio data on the Orion Nebula including Δv and T/subL//T/subC/ of the H nα lines from 610 MHz to 85 GHz Δv and T/subL//T/subC/ of all the observed H nβ lines; the shape and magnitude of the radio continuum spectrum can be reproduced. The application of this model to the problem of the abundance and distribution of ionized helium with the nebula is also considered

  20. NO TIMING VARIATIONS OBSERVED IN THIRD TRANSIT OF SNOW-LINE EXOPLANET KEPLER-421b

    International Nuclear Information System (INIS)

    Dalba, Paul A.; Muirhead, Philip S.

    2016-01-01

    We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler spacecraft only observed two transits of Kepler-421b, leaving the planet’s transit ephemeris unconstrained. Our visible light, time-series observations from the 4.3 m Discovery Channel Telescope were designed to capture pre-transit baseline and the partial transit of Kepler-421b, barring significant TTVs. We use the light curves to assess the probabilities of various transit models using both the posterior odds ratio and the Bayesian Information Criterion, and find that a transit model with no TTVs is favored to 3.6 σ confidence. These observations suggest that Kepler-421b is either alone in its system or is only experiencing minor dynamic interactions with an unseen companion. With the Kepler-421b ephemeris constrained, we calculate future transit times and discuss the opportunity to characterize the atmosphere of this cold, long-period exoplanet via transmission spectroscopy. Our investigation emphasizes the difficulties associated with observing long-period exoplanet transits and the consequences that arise from failing to refine transit ephemerides.

  1. NARROW-LINE-WIDTH UV BURSTS IN THE TRANSITION REGION ABOVE SUNSPOTS OBSERVED BY IRIS

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Zhenyong; Huang, Zhenghua; Xia, Lidong; Li, Bo; Madjarska, Maria S.; Fu, Hui; Mou, Chaozhou; Xie, Haixia, E-mail: z.huang@sdu.edu.cn, E-mail: xld@sdu.edu.cn [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, 264209 Shandong (China)

    2016-10-01

    Various small-scale structures abound in the solar atmosphere above active regions, playing an important role in the dynamics and evolution therein. We report on a new class of small-scale transition region structures in active regions, characterized by strong emissions but extremely narrow Si iv line profiles as found in observations taken with the Interface Region Imaging Spectrograph (IRIS). Tentatively named as narrow-line-width UV bursts (NUBs), these structures are located above sunspots and comprise one or multiple compact bright cores at sub-arcsecond scales. We found six NUBs in two data sets (a raster and a sit-and-stare data set). Among these, four events are short-lived with a duration of ∼10 minutes, while two last for more than 36 minutes. All NUBs have Doppler shifts of 15–18 km s{sup −1}, while the NUB found in sit-and-stare data possesses an additional component at ∼50 km s{sup −1} found only in the C ii and Mg ii lines. Given that these events are found to play a role in the local dynamics, it is important to further investigate the physical mechanisms that generate these phenomena and their role in the mass transport in sunspots.

  2. Observations of linear dependence between sulfate and nitrate in atmospheric particles

    Science.gov (United States)

    Kong, Lingdong; Yang, Yiwei; Zhang, Shuanqin; Zhao, Xi; Du, Huanhuan; Fu, Hongbo; Zhang, Shicheng; Cheng, Tiantao; Yang, Xin; Chen, Jianmin; Wu, Dui; Shen, Jiandong; Hong, Shengmao; Jiao, Li

    2014-01-01

    Hourly measurements of water-soluble inorganic ionic species in ambient atmospheric particles were conducted at Shanghai, Hangzhou, and Guangzhou sampling sites in China during the period of 2009-2011. The relation between sulfate and nitrate in particulate matter (PM10 and PM2.5) was examined based on these measurements. Results showed that the mass fraction of sulfate was strongly negatively correlated with that of nitrate in atmospheric particles on most of the sampling days, especially when sulfate and nitrate made up the vast majority of the total soluble anions and cations (Na+, K+, Ca2+, and Mg2+) made a small contribution to the total water-soluble ions, revealing that the formation mechanisms of sulfate and nitrate in the atmosphere are highly correlated, and there exists a significant negative correlation trend between sulfate and nitrate mass fractions in the atmospheric particles. We found that local meteorological conditions presented opposite influences on the mass fractions of sulfate and nitrate. Further analysis indicated that the two mass fractions were modulated by the neutralizing level of atmospheric aerosols, and the negative correlation could be found in acidic atmospheric particles. Strong negative correlation was usually observed on clear days, hazy days, foggy days, and respirable particulate air pollution days, whereas poor negative correlation was often observed during cloud, rain, snow, dust storm, and suspended dust events. The results can help to better understand the formation mechanisms of atmospheric sulfate and nitrate during air pollution episodes and to better explain field results of atmospheric chemistry concerning sulfate and nitrate.

  3. Characteristics of atmospheric gravity waves observed using the MU (Middle and Upper atmosphere) radar and GPS (Global Positioning System) radio occultation.

    Science.gov (United States)

    Tsuda, Toshitaka

    2014-01-01

    The wind velocity and temperature profiles observed in the middle atmosphere (altitude: 10-100 km) show perturbations resulting from superposition of various atmospheric waves, including atmospheric gravity waves. Atmospheric gravity waves are known to play an important role in determining the general circulation in the middle atmosphere by dynamical stresses caused by gravity wave breaking. In this paper, we summarize the characteristics of atmospheric gravity waves observed using the middle and upper atmosphere (MU) radar in Japan, as well as novel satellite data obtained from global positioning system radio occultation (GPS RO) measurements. In particular, we focus on the behavior of gravity waves in the mesosphere (50-90 km), where considerable gravity wave attenuation occurs. We also report on the global distribution of gravity wave activity in the stratosphere (10-50 km), highlighting various excitation mechanisms such as orographic effects, convection in the tropics, meteorological disturbances, the subtropical jet and the polar night jet.

  4. Documentation of Atmospheric Conditions During Observed Rising Aircraft Wakes

    Science.gov (United States)

    Zak, J. Allen; Rodgers, William G., Jr.

    1997-01-01

    Flight tests were conducted in the fall of 1995 off the coast of Wallops Island, Virginia in order to determine characteristics of wake vortices at flight altitudes. A NASA Wallops Flight Facility C130 aircraft equipped with smoke generators produced visible wakes at altitudes ranging from 775 to 2225 m in a variety of atmospheric conditions, orientations (head wind, cross wind), and airspeeds. Meteorological and aircraft parameters were collected continuously from a Langley Research Center OV-10A aircraft as it flew alongside and through the wake vortices at varying distances behind the C130. Meteorological data were also obtained from special balloon observations made at Wallops. Differential GPS capabilities were on each aircraft from which accurate altitude profiles were obtained. Vortices were observed to rise at distances beyond a mile behind the C130. The maximum altitude was 150 m above the C130 in a near neutral atmosphere with significant turbulence. This occurred from large vertical oscillations in the wakes. There were several cases when vortices did not descend after a very short initial period and remained near generation altitude in a variety of moderately stable atmospheres and wind shears.

  5. A simulation of the OMEGA/Mars Express observations: Analysis of the atmospheric contribution

    Science.gov (United States)

    Melchiorri, R.; Drossart, P.; Fouchet, T.; Bézard, B.; Forget, F.; Gendrin, A.; Bibring, J. P.; Manaud, N.; OMEGA Team; Berthé, M.; Bibring, J.-P.; Langevin, Y.; Forni, O.; Gendrin, A.; Gondet, B.; Manaud, N.; Poulet, F.; Poulleau, G.; Soufflot, A.; Mangold, N.; Bonello, G.; Forget, F.; Bezard, B.; Combes, M.; Drossart, P.; Encrenaz, T.; Fouchet, T.; Melchiorri, R.; Erard, S.; Bellucci, G.; Altieri, F.; Formisano, V.; Fonti, S.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Kottsov, V.; Ignatiev, N.; Moroz, V.; Titov, D.; Zasova, L.; Pinet, P.; Schmitt, B.; Sotin, C.; Hauber, E.; Hoffmann, H.; Jaumann, R.; Keller, U.; Arvidson, R.; Mustard, J.; Duxbary, T.

    2006-08-01

    Spectral images of Mars obtained by the Mars Express/OMEGA experiment in the near infrared are the result of a complex combination of atmospheric, aerosol and ground features. Retrieving the atmospheric information from the data is important, not only to decorrelate mineralogical against atmospheric features, but also to retrieve the atmospheric variability. Once the illumination conditions have been taken into account, the main source of variation on the CO2 absorption is due to the altitude of the surface, which governs atmospheric pressure variation by more than an order of magnitude between the summit of Olympus Mons down to the bottom of Valles Marineris. In this article we present a simplified atmospheric spectral model without scattering, specially developed for the OMEGA observations, which is used to retrieve the local topography through the analysis of the 2.0μmCO2 band. OMEGA atmospheric observations increase the horizontal resolution compared to MOLA altimetry measurements, and therefore complement the mineralogical studies from the same instrument. Finally, residual variations of the pressure can be related to atmospheric structure variation.

  6. Observation and modelling of the Fe XXI line profile observed by IRIS during the impulsive phase of flares

    Science.gov (United States)

    Polito, V.; Testa, P.; De Pontieu, B.; Allred, J. C.

    2017-12-01

    The observation of the high temperature (above 10 MK) Fe XXI 1354.1 A line with the Interface Region Imaging Spectrograph (IRIS) has provided significant insights into the chromospheric evaporation process in flares. In particular, the line is often observed to be completely blueshifted, in contrast to previous observations at lower spatial and spectral resolution, and in agreement with predictions from theoretical models. Interestingly, the line is also observed to be mostly symmetric and with a large excess above the thermal width. One popular interpretation for the excess broadening is given by assuming a superposition of flows from different loop strands. In this work, we perform a statistical analysis of Fe XXI line profiles observed by IRIS during the impulsive phase of flares and compare our results with hydrodynamic simulations of multi-thread flare loops performed with the 1D RADYN code. Our results indicate that the multi-thread models cannot easily reproduce the symmetry of the line and that some other physical process might need to be invoked in order to explain the observed profiles.

  7. Exploring atmospheric blocking with GPS radio occultation observations

    Directory of Open Access Journals (Sweden)

    L. Brunner

    2016-04-01

    Full Text Available Atmospheric blocking has been closely investigated in recent years due to its impact on weather and climate, such as heat waves, droughts, and flooding. We use, for the first time, satellite-based observations from Global Positioning System (GPS radio occultation (RO and explore their ability to resolve blocking in order to potentially open up new avenues complementing models and reanalyses. RO delivers globally available and vertically highly resolved profiles of atmospheric variables such as temperature and geopotential height (GPH. Applying a standard blocking detection algorithm, we find that RO data robustly capture blocking as demonstrated for two well-known blocking events over Russia in summer 2010 and over Greenland in late winter 2013. During blocking episodes, vertically resolved GPH gradients show a distinct anomalous behavior compared to climatological conditions up to 300 hPa and sometimes even further up into the tropopause. The accompanying increase in GPH of up to 300 m in the upper troposphere yields a pronounced tropopause height increase. Corresponding temperatures rise up to 10 K in the middle and lower troposphere. These results demonstrate the feasibility and potential of RO to detect and resolve blocking and in particular to explore the vertical structure of the atmosphere during blocking episodes. This new observation-based view is available globally at the same quality so that blocking in the Southern Hemisphere can also be studied with the same reliability as in the Northern Hemisphere.

  8. Observation of Atmospheric Constituents From Space

    Science.gov (United States)

    Burrows, J. P.

    Remote sensing of the atmosphere from space is a growing research field. Surprisingly but for good physical reasons, the mesosphere and stratosphere are easier to probe from space than the troposphere. GOME (Global Ozone Monitoring Experiment) and SCIAMACHY (Scanning Imaging absorption spectroMeter for Atmospheric CHartographY) are related European instruments, which were proposed and been designed to measure atmospheric constituents (gases, aerosols and clouds) by passive remote sensing of the up-welling solar radiation leaving atmosphere. GOME is a smaller version of SCIAMACHY and was launched as part of the core payload of the second European research satellite (ERS-2) on the 20th April 1995. GOME comprises four spectral channels and measures simultaneously the earthshine radiance or solar extra terrestrial irradiance between 240 and 790 nm. Inversion of GOME measurements using the DOAS (Differential Optical Absorption Spectroscopy) yields the total column of trace gases (e.g. O3, NO2, HCHO, BrO and OClO). Application of the FURM (Full Retrieval Method) enables the profiles of O3 to be retrieved. One of the important achievements of GOME has been the separation of tropopsheirc columns of trace gases using TEM (Tropospheric Excess Method). SCIAMACHY has been developed as Germa n, Dutch and Belgian contribution to ENVISAT. It has significantly enhanced capability compared to GOME, measuring a larger spectral range, 220-2380 nm, and observing in alternate nadir and limb modes as well as solar and lunar occultation. ENVISAT is to be launched into a sun synchronous polar orbit, having an equator crossing time of 10.00 a.m. at the beginning of March 2002. SCIAMACHY is thereby able to measure many more species and vertical profiles than GOME. This facilitates improved tropospheric retrievals. Finally GeoTROPE (Geostationary TROPospheric Explorer) is a new mission, which is proposed for launch within the ESA Earth Explorer Opportunity Mission. It comprises two national

  9. Sideband characterization and atmospheric observations with various 340 GHz heterodyne receivers

    Energy Technology Data Exchange (ETDEWEB)

    Renker, Matthias, E-mail: renker@iap.unibe.ch; Murk, Axel [Institute of Applied Physics, University of Bern, Bern (Switzerland); Rea, Simon P. [STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire (United Kingdom); Emrich, A.; Frisk, U. [OMNISYS Instruments, Västra Frölunda (Sweden)

    2014-08-15

    This paper describes sideband response measurements and atmospheric observations with a double sideband and two Single Sideband (SSB) receiver prototypes developed for the multi-beam limb sounder instrument stratosphere-troposphere exchange and climate monitor radiometer. We first show an advanced Fourier-Transform Spectroscopy (FTS) method for sideband response and spurious signal characterization. We then present sideband response measurements of the different prototype receivers and we compare the results of the SSB receivers with sideband measurements by injecting a continuous wave signal into the upper and lower sidebands. The receivers were integrated into a total-power radiometer and atmospheric observations were carried out. The observed spectra were compared to forward model spectra to conclude on the sideband characteristics of the different receivers. The two sideband characterization methods show a high degree of agreement for both SSB receivers with various local oscillator settings. The measured sideband response was used to correct the forward model simulations. This improves the agreement with the atmospheric observations and explains spectral features caused by an unbalanced sideband response. The FTS method also allows to quantify the influence of spurious harmonic responses of the receiver.

  10. LINE FORMATION IN SPECTRA OF X-RAY NOVAE

    OpenAIRE

    Suleimanov, V. F.; Shimansky, V. V.

    2017-01-01

    Results of X-ray Novae (XN) optical spectra computation are presented. The continuum and Balmer line are calculated. The model of XN as a self-irradiated accretion disk is used. Local (for given radius) disk atmospheres as model stellar atmospheres, heated due to external X-ray radiation are treated. Changes of spectra shape and equivalent widths of the Balmer lines depending from the luminosity and some others accretion disk parameters are investigated. The comparison of GRO JO422+32 observe...

  11. Atmospheric multidecadal variations in the North Atlantic realm: proxy data, observations, and atmospheric circulation model studies

    Directory of Open Access Journals (Sweden)

    K. Grosfeld

    2007-01-01

    Full Text Available We investigate the spatial and temporal characteristics of multidecadal climate variability in the North Atlantic realm, using observational data, proxy data and model results. The dominant pattern of multidecadal variability of SST depicts a monopolar structure in the North Atlantic during the instrumental period with cold (warm phases during 1900–1925 and 1970–1990 (1870–1890 and 1940–1960. Two atmospheric general circulation models of different complexity forced with global SST over the last century show SLP anomaly patterns from the warm and cold phases of the North Atlantic similar to the corresponding observed patterns. The analysis of a sediment core from Cariaco Basin, a coral record from the northern Red Sea, and a long-term sea level pressure (SLP reconstruction reveals that the multidecadal mode of the atmospheric circulation characterizes climate variability also in the pre-industrial era. The analyses of SLP reconstruction and proxy data depict a persistent atmospheric mode at least over the last 300 years, where SLP shows a dipolar structure in response to monopolar North Atlantic SST, in a similar way as the models' responses do. The combined analysis of observational and proxy data with model experiments provides an understanding of multidecadal climate modes during the late Holocene. The related patterns are useful for the interpretation of proxy data in the North Atlantic realm.

  12. The influence of electron collisions on non-LTE Li line formation in stellar atmospheres

    International Nuclear Information System (INIS)

    Osorio, Yeisson; Barklem, Paul; Lind, Karin; Asplund, Martin

    2012-01-01

    The influence of the uncertainties in the rate coefficient data for electron-impact excitation and ionization on non-LTE Li line formation in cool stellar atmospheres is investigated. We examine the electron collision data used in previous non-LTE calculations and compare them to our own calculations using the R-matrix with pseudostates (RMPS) method and to other calculations found in the literature.

  13. NSF Lower Atmospheric Observing Facilities (LAOF) in support of science and education

    Science.gov (United States)

    Baeuerle, B.; Rockwell, A.

    2012-12-01

    Researchers, students and teachers who want to understand and describe the Earth System require high quality observations of the atmosphere, ocean, and biosphere. Making these observations requires state-of-the-art instruments and systems, often carried on highly capable research platforms. To support this need of the geosciences community, the National Science Foundation's (NSF) Division of Atmospheric and Geospace Sciences (AGS) provides multi-user national facilities through its Lower Atmospheric Observing Facilities (LAOF) Program at no cost to the investigator. These facilities, which include research aircraft, radars, lidars, and surface and sounding systems, receive NSF financial support and are eligible for deployment funding. The facilities are managed and operated by five LAOF partner organizations: the National Center for Atmospheric Research (NCAR); Colorado State University (CSU); the University of Wyoming (UWY); the Center for Severe Weather Research (CSWR); and the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS). These observational facilities are available on a competitive basis to all qualified researchers from US universities, requiring the platforms and associated services to carry out various research objectives. The deployment of all facilities is driven by scientific merit, capabilities of a specific facility to carry out the proposed observations, and scheduling for the requested time. The process for considering requests and setting priorities is determined on the basis of the complexity of a field campaign. The poster will describe available observing facilities and associated services, and explain the request process researchers have to follow to secure access to these platforms for scientific as well as educational deployments. NSF/NCAR GV Aircraft

  14. NLTE Model Atmospheres for Super-Soft X-ray Sources

    Science.gov (United States)

    Rauch, Thomas; Werner, Klaus

    2009-09-01

    Spectral analysis by means of fully line-blanketed Non-LTE model atmospheres has arrived at a high level of sophistication. The Tübingen NLTE Model Atmosphere Package (TMAP) is used to calculate plane-parallel NLTE model atmospheres which are in radiative and hydrostatic equilibrium. Although TMAP is not especially designed for the calculation of burst spectra of novae, spectral energy distributions (SEDs) calculated from TMAP models are well suited e.g. for abundance determinations of Super Soft X-ray Sources like nova V4743 Sgr or line identifications in observations of neutron stars with low magnetic fields in low-mass X-ray binaries (LMXBs) like EXO 0748-676.

  15. A unique airborne observation. [Martian atmospheric temperature and abundances from occultation of Epsilon Geminorum

    Science.gov (United States)

    Elliot, J. L.; Dunham, E.; Church, C.

    1976-01-01

    The occultation of 3rd magnitude Epsilon Geminorum by Mars was observed using a 36-inch telescope equipped with a photoelectric photometer at the bent Cassegrain focus, carried aboard the Kuiper Airborne Observatory at altitudes up to 45,000 feet. Scintillation from the earth's atmosphere was greatly reduced in comparison with ground observations. The observations clearly show the central flash, caused by the symmetrical refraction of light by the atmosphere of Mars. The data are being analyzed to obtain temperature profiles and to assess the relative abundance of argon and carbon dioxide in the atmosphere of the planet.

  16. Atmospheric Radionuclides from the Fukushima Nuclear Accident-Two years observations in Tsukuba, Japan

    Science.gov (United States)

    Igarashi, Yasuhito; Kajino, Mizuo; Zaizen, Yuji; Adachi, Koji; Mikami, Masao; Kita, Kazuyuki; Hatano, Yuko

    2013-04-01

    The accident of Fukushima Dai-Ichi Nuclear Power Plant of the Tokyo Electric Power Corporation arisen by the hit of great earthquake and tsunami in March 11, 2011, emitted abundant fresh radioactive material to the atmospheric environment. The amount has been estimated to be at least a few-tenth of those from the Chernobyl accident (by NISA, etc.). By this large-scale contamination, atmospheric environments over Japan, especially the eastern part, were seriously impacted with such a massive amount of the anthropogenic radionuclides (e.g. typical hotspots). So the persisting aftermath is one of the concerns. Although the heavy primary emission seems to be terminated until April of 2011, 2ndary emissions from contaminated ground surface, coppices, fields, roads, any burnings of the contaminated materials generated the resuspension of radionuclides into the atmosphere. With 2-years observation for the Fukushima radioactivity at the Meteorological Research Institute, Japan (MRI) such persisting resuspension is considered in this presentation. The resuspension seems still in difficulty to give forecast by computer modeling; the observations are indispensable bodies of the research even in the future. The MRI has carried out observations of the atmospheric radionuclides, which are long-lived with potentials of environmental and health impacts, for more than 50 years. Aiming at to clarify temporal change in concentration of anthropogenic radionuclides in the atmosphere and its control factors, the observations have continued over the long period. The long-lasting impacts of the Fukushima accident are addressed with our long-term time series of the atmospheric radioactivity as a reference.

  17. POLARIZED LINE FORMATION IN NON-MONOTONIC VELOCITY FIELDS

    Energy Technology Data Exchange (ETDEWEB)

    Sampoorna, M.; Nagendra, K. N., E-mail: sampoorna@iiap.res.in, E-mail: knn@iiap.res.in [Indian Institute of Astrophysics, Koramangala, Bengaluru 560034 (India)

    2016-12-10

    For a correct interpretation of the observed spectro-polarimetric data from astrophysical objects such as the Sun, it is necessary to solve the polarized line transfer problems taking into account a realistic temperature structure, the dynamical state of the atmosphere, a realistic scattering mechanism (namely, the partial frequency redistribution—PRD), and the magnetic fields. In a recent paper, we studied the effects of monotonic vertical velocity fields on linearly polarized line profiles formed in isothermal atmospheres with and without magnetic fields. However, in general the velocity fields that prevail in dynamical atmospheres of astrophysical objects are non-monotonic. Stellar atmospheres with shocks, multi-component supernova atmospheres, and various kinds of wave motions in solar and stellar atmospheres are examples of non-monotonic velocity fields. Here we present studies on the effect of non-relativistic non-monotonic vertical velocity fields on the linearly polarized line profiles formed in semi-empirical atmospheres. We consider a two-level atom model and PRD scattering mechanism. We solve the polarized transfer equation in the comoving frame (CMF) of the fluid using a polarized accelerated lambda iteration method that has been appropriately modified for the problem at hand. We present numerical tests to validate the CMF method and also discuss the accuracy and numerical instabilities associated with it.

  18. Resonance-line transfer with partial redistribution. VIII. Solution in the comoving frame for moving atmospheres

    International Nuclear Information System (INIS)

    Mihalas, D.; Shine, R.A.; Kunasz, P.B.; Hummer, D.G.

    1976-01-01

    An analysis of the effects of partial frequency redistribution in the scattering process for lines formed in moving atmospheres has been performed using a flexible and general method which allows solutions of the transfer equation in the comoving frame of the gas. As a specific example, we consider the same chromospheric and atomic model, with the same velocity field, that was studied by Cannon and Vardavas. We find that the large changes in the profiles obtained by those authors, between the cases of complete and partial redistribution are spurious effects of angle averaging in the observer's frame instead of the comoving frame. Our results support fully the conclusion by Magnan that these changes are, in fact, unreal, at least for this particular model and redistribution function. Future work with other redistribution functions and with nonmonotone velocity fields will be possible using the techniques developed in this paper

  19. STS-39 Earth observation of Earth's limb at sunset shows atmospheric layers

    Science.gov (United States)

    1991-01-01

    STS-39 Earth observation taken aboard Discovery, Orbiter Vehicle (OV) 103, shows the Earth's limb at sunset with numerous atmospheric scattering layers highlighted. The layers consist of fine particles suspended in very stable layers of the atmosphere. The layers act as a prism for the sunlight.

  20. NonLTE ANALYSIS OF THE NaI LINES IN THE SOLAR SPECTRUM

    OpenAIRE

    Ivanova, D. V.; Shimansky, V. V.

    2017-01-01

    Solar spectrum of Nal lines by method of the nonLTE analysis is investigated. It shown, that in atmosphere of the Sun the Nal is in moderate ”overrecombination”. The analysis of influence of atomic data, models of atmospheres and damping constants for nonLTE deviation and sodium abundances is made. Observational solar spectrum of strong lines Nal has been synthesized in good approximation. On summary data of 15 lines the sodium abundance is determined:-5.78dex.

  1. Upper atmospheric planetary-wave and gravity-wave observations

    Science.gov (United States)

    Justus, C. G.; Woodrum, A.

    1973-01-01

    Previously collected data on atmospheric pressure, density, temperature and winds between 25 and 200 km from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others were analyzed by a daily-difference method, and results on the magnitude of atmospheric perturbations interpreted as gravity waves and planetary waves are presented. Traveling planetary-wave contributions in the 25-85 km range were found to have significant height and latitudinal variation. It was found that observed gravity-wave density perturbations and wind are related to one another in the manner predicted by gravity-wave theory. It was determined that, on the average, gravity-wave energy deposition or reflection occurs at all altitudes except the 55-75 km region of the mesosphere.

  2. X-Ray, UV and Optical Observations of Classical Cepheids: New Insights into Cepheid Evolution, and the Heating and Dynamics of Their Atmospheres

    OpenAIRE

    Engle, Scott G.; Guinan, Edward F.

    2012-01-01

    To broaden the understanding of classical Cepheid structure, evolution and atmospheres, we have extended our continuing secret lives of Cepheids program by obtaining XMM/Chandra X-ray observations, and Hubble space telescope (HST) / cosmic origins spectrograph (COS) FUV-UV spectra of the bright, nearby Cepheids Polaris, {\\delta} Cep and {\\beta} Dor. Previous studies made with the international ultraviolet explorer (IUE) showed a limited number of UV emission lines in Cepheids. The well-known ...

  3. Cine: Line excitation by infrared fluorescence in cometary atmospheres

    Science.gov (United States)

    de Val-Borro, Miguel; Cordiner, Martin A.; Milam, Stefanie N.; Charnley, Steven B.

    2017-03-01

    CINE is a Python module for calculating infrared pumping efficiencies that can be applied to the most common molecules found in cometary comae such as water, hydrogen cyanide or methanol. Excitation by solar radiation of vibrational bands followed by radiative decay to the ground vibrational state is one of the main mechanisms for molecular excitation in comets. This code calculates the effective pumping rates for rotational levels in the ground vibrational state scaled by the heliocentric distance of the comet. Line transitions are queried from the latest version of the HITRAN spectroscopic repository using the astroquery affiliated package of astropy. Molecular data are obtained from the LAMDA database. These coefficients are useful for modeling rotational emission lines observed in cometary spectra at sub-millimeter wavelengths. Combined with computational methods to solve the radiative transfer equations based, e.g., on the Monte Carlo algorithm, this model can retrieve production rates and rotational temperatures from the observed emission spectrum.

  4. Non-LTE line-blanketed model atmospheres of hot stars. 1: Hybrid complete linearization/accelerated lambda iteration method

    Science.gov (United States)

    Hubeny, I.; Lanz, T.

    1995-01-01

    A new munerical method for computing non-Local Thermodynamic Equilibrium (non-LTE) model stellar atmospheres is presented. The method, called the hybird complete linearization/accelerated lambda iretation (CL/ALI) method, combines advantages of both its constituents. Its rate of convergence is virtually as high as for the standard CL method, while the computer time per iteration is almost as low as for the standard ALI method. The method is formulated as the standard complete lineariation, the only difference being that the radiation intensity at selected frequency points is not explicity linearized; instead, it is treated by means of the ALI approach. The scheme offers a wide spectrum of options, ranging from the full CL to the full ALI method. We deonstrate that the method works optimally if the majority of frequency points are treated in the ALI mode, while the radiation intensity at a few (typically two to 30) frequency points is explicity linearized. We show how this method can be applied to calculate metal line-blanketed non-LTE model atmospheres, by using the idea of 'superlevels' and 'superlines' introduced originally by Anderson (1989). We calculate several illustrative models taking into accont several tens of thosands of lines of Fe III to Fe IV and show that the hybrid CL/ALI method provides a robust method for calculating non-LTE line-blanketed model atmospheres for a wide range of stellar parameters. The results for individual stellar types will be presented in subsequent papers in this series.

  5. Ground-based Observations for the Upper Atmosphere at King Sejong Station, Antarctica

    Science.gov (United States)

    Jee, Geonhwa; Kim, Jeong-Han; Lee, Changsup; Kim, Yong Ha

    2014-06-01

    Since the operation of the King Sejong Station (KSS) started in Antarctic Peninsula in 1989, there have been continuous efforts to perform the observation for the upper atmosphere. The observations during the initial period of the station include Fabry-Perot Interferometer (FPI) and Michelson Interferometer for the mesosphere and thermosphere, which are no longer in operation. In 2002, in collaboration with York University, Canada, the Spectral Airglow Temperature Imager (SATI) was installed to observe the temperature in the mesosphere and lower thermosphere (MLT) region and it has still been producing the mesopause temperature data until present. The observation was extended by installing the meteor radar in 2007 to observe the neutral winds and temperature in the MLT region during the day and night in collaboration with Chungnam National University. We also installed the all sky camera in 2008 to observe the wave structures in the MLT region. All these observations are utilized to study on the physical characteristics of the MLT region and also on the wave phenomena such as the tide and gravity wave in the upper atmosphere over KSS that is well known for the strong gravity wave activity. In this article, brief introductions for the currently operating instruments at KSS will be presented with their applications for the study of the upper atmosphere

  6. Ground-based Observations for the Upper Atmosphere at King Sejong Station, Antarctica

    Directory of Open Access Journals (Sweden)

    Geonhwa Jee

    2014-06-01

    Full Text Available Since the operation of the King Sejong Station (KSS started in Antarctic Peninsula in 1989, there have been continuous efforts to perform the observation for the upper atmosphere. The observations during the initial period of the station include Fabry-Perot Interferometer (FPI and Michelson Interferometer for the mesosphere and thermosphere, which are no longer in operation. In 2002, in collaboration with York University, Canada, the Spectral Airglow Temperature Imager (SATI was installed to observe the temperature in the mesosphere and lower thermosphere (MLT region and it has still been producing the mesopause temperature data until present. The observation was extended by installing the meteor radar in 2007 to observe the neutral winds and temperature in the MLT region during the day and night in collaboration with Chungnam National University. We also installed the all sky camera in 2008 to observe the wave structures in the MLT region. All these observations are utilized to study on the physical characteristics of the MLT region and also on the wave phenomena such as the tide and gravity wave in the upper atmosphere over KSS that is well known for the strong gravity wave activity. In this article, brief introductions for the currently operating instruments at KSS will be presented with their applications for the study of the upper atmosphere.

  7. Development of a Ground-Based Atmospheric Monitoring Network for the Global Mercury Observation System (GMOS

    Directory of Open Access Journals (Sweden)

    Sprovieri F.

    2013-04-01

    Full Text Available Consistent, high-quality measurements of atmospheric mercury (Hg are necessary in order to better understand Hg emissions, transport, and deposition on a global scale. Although the number of atmospheric Hg monitoring stations has increased in recent years, the available measurement database is limited and there are many regions of the world where measurements have not been extensively performed. Long-term atmospheric Hg monitoring and additional ground-based monitoring sites are needed in order to generate datasets that will offer new insight and information about the global scale trends of atmospheric Hg emissions and deposition. In the framework of the Global Mercury Observation System (GMOS project, a coordinated global observational network for atmospheric Hg is being established. The overall research strategy of GMOS is to develop a state-of-the-art observation system able to provide information on the concentration of Hg species in ambient air and precipitation on the global scale. This network is being developed by integrating previously established ground-based atmospheric Hg monitoring stations with newly established GMOS sites that are located both at high altitude and sea level locations, as well as in climatically diverse regions. Through the collection of consistent, high-quality atmospheric Hg measurement data, we seek to create a comprehensive assessment of atmospheric Hg concentrations and their dependence on meteorology, long-range atmospheric transport and atmospheric emissions.

  8. IUE observations of interstellar Si IV and C IV lines observed in the spectra of Wolf-Rayet stars

    International Nuclear Information System (INIS)

    Smith, L.J.; Willis, A.J.; Wilson, R.

    1980-01-01

    Recent IUE observations of Wolf-Rayet stars show narrow absorption lines in the highly ionized species of Si IV and C IV. The strengths of these 'interstellar' Si IV and C IV lines observed in the spectra of 10 WR stars and two other early-type stars are compared. Of the WR sample, six stars exhibit very strong Si IV and C IV lines (Wsub(lambda) approximately 0.3 to 0.5 A) whilst the other four stars show much weaker lines (Wsub(lambda) approximately 0.1 A). There is no correlation between the strengths of these lines with either stellar distance or colour excess. The weaker absorptions may arise in the individual stellar H II regions, the observed strengths being consistent with those expected for stars with Tsub(eff) = 30 000 K. Five of the other stars which exhibit very strong absorptions lie in the line of sight to active interstellar regions (Cygnus and Carina nebulae) and it is considered probable that, in addition to their H II region components, the bulk of the strong Si IV and C IV absorptions originate in hot gas associated with these active regions. In the case of the WN5 star HD 50896 violet-displaced components are observed in the interstellar lines of low ionization species. These are thought to be produced in the ring nebula S308 surrounding HD 50896. (author)

  9. EUV lines observed with EIS/Hinode in a solar prominence

    Science.gov (United States)

    Labrosse, N.; Schmieder, B.; Heinzel, P.; Watanabe, T.

    2011-07-01

    Context. During a multi-wavelength observation campaign with Hinode and ground-based instruments, a solar prominence was observed for three consecutive days as it crossed the western limb of the Sun in April 2007. Aims: We report on observations obtained on 26 April 2007 using EIS (Extreme ultraviolet Imaging Spectrometer) on Hinode. They are analysed to provide a qualitative diagnostic of the plasma in different parts of the prominence. Methods: After correcting for instrumental effects, the rasters at different wavelengths are presented. Several regions within the same prominence are identified for further analysis. Selected profiles for lines with formation temperatures between log (T) = 4.7 and log (T) = 6.3, as well as their integrated intensities, are given. The profiles of coronal, transition region, and He ii lines are discussed. We pay special attention to the He ii line, which is blended with coronal lines. Results: Some quantitative results are obtained by analysing the line profiles. They confirm that depression in EUV lines can be interpreted in terms of two mechanisms: absorption of coronal radiation by the hydrogen and neutral helium resonance continua, and emissivity blocking. We present estimates of the He ii line integrated intensity in different parts of the prominence according to different scenarios for the relative contribution of absorption and emissivity blocking to the coronal lines blended with the He ii line. We estimate the contribution of the He ii 256.32 Å line to the He ii raster image to vary between ~44% and 70% of the raster's total intensity in the prominence according to the different models used to take into account the blending coronal lines. The inferred integrated intensities of the He ii 256 Å line are consistent with the theoretical intensities obtained with previous 1D non-LTE radiative transfer calculations, yielding a preliminary estimate of the central temperature of 8700 K, a central pressure of 0.33 dyn cm-2, and a

  10. A tentative detection of the 183-GHz water vapor line in the martian atmosphere: Constraints upon the H2O abundance and vertical distribution

    Science.gov (United States)

    Encrenaz, TH.; Lellouch, E.; Cernicharo, J.; Paubert, G.; Gulkis, S.

    1995-01-01

    The 183-GHz water vapor line was tentatively detected on Mars in January 1991, with the IRAM 30-m millimeter antenna, under extremely dry atmospheric conditions. The measurement refers to the whole disk. The spectral line, although marginally detected, can be fit with a constant H2O mixing ratio of 1.0 x 10(exp -5), which corresponds to a water abundance of 1 pr-microns; in any case, an upper limit of 3 pr-microns is inferred. This value is comparable to the very small abundances measured by Clancy (1992) 5 weeks before our observation and seems to imply both seasonal and long-term variations in the martian water cycle.

  11. Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST

    Science.gov (United States)

    Morley, Caroline V.; Kreidberg, Laura; Rustamkulov, Zafar; Robinson, Tyler; Fortney, Jonathan J.

    2017-12-01

    Nine transiting Earth-sized planets have recently been discovered around nearby late-M dwarfs, including the TRAPPIST-1 planets and two planets discovered by the MEarth survey, GJ 1132b and LHS 1140b. These planets are the smallest known planets that may have atmospheres amenable to detection with the James Webb Space Telescope (JWST). We present model thermal emission and transmission spectra for each planet, varying composition and surface pressure of the atmosphere. We base elemental compositions on those of Earth, Titan, and Venus and calculate the molecular compositions assuming chemical equilibrium, which can strongly depend on temperature. Both thermal emission and transmission spectra are sensitive to the atmospheric composition; thermal emission spectra are sensitive to surface pressure and temperature. We predict the observability of each planet’s atmosphere with JWST. GJ 1132b and TRAPPIST-1b are excellent targets for emission spectroscopy with JWST/MIRI, requiring fewer than 10 eclipse observations. Emission photometry for TRAPPIST-1c requires 5-15 eclipses; LHS 1140b and TRAPPIST-1d, TRAPPIST-1e, and TRAPPIST-1f, which could possibly have surface liquid water, may be accessible with photometry. Seven of the nine planets are strong candidates for transmission spectroscopy measurements with JWST, although the number of transits required depends strongly on the planets’ actual masses. Using the measured masses, fewer than 20 transits are required for a 5σ detection of spectral features for GJ 1132b and six of the TRAPPIST-1 planets. Dedicated campaigns to measure the atmospheres of these nine planets will allow us, for the first time, to probe formation and evolution processes of terrestrial planetary atmospheres beyond our solar system.

  12. Dynamics of the middle atmosphere as observed by the ARISE project

    Science.gov (United States)

    Blanc, E.

    2015-12-01

    It has been strongly demonstrated that variations in the circulation of the middle atmosphere influence weather and climate all the way to the Earth's surface. A key part of this coupling occurs through the propagation and breaking of planetary and gravity waves. However, limited observations prevent to faithfully reproduce the dynamics of the middle atmosphere in numerical weather prediction and climate models. The main challenge of the ARISE (Atmospheric dynamics InfraStructure in Europe) project is to combine existing national and international observation networks including: the International infrasound monitoring system developed for the CTBT (Comprehensive nuclear-Test-Ban Treaty) verification, the NDACC (Network for the Detection of Atmospheric Composition Changes) lidar network, European observation infrastructures at mid latitudes (OHP observatory), tropics (Maïdo observatory), high latitudes (ALOMAR and EISCAT), infrasound stations which form a dense European network and satellites. The ARISE network is unique by its coverage (polar to equatorial regions in the European longitude sector), its altitude range (from troposphere to mesosphere and ionosphere) and the involved scales both in time (from seconds to tens of years) and space (from tens of meters to thousands of kilometers). Advanced data products are produced with the scope to assimilate data in the Weather Prediction models to improve future forecasts over weeks and seasonal time scales. ARISE observations are especially relevant for the monitoring of extreme events such as thunderstorms, volcanoes, meteors and at larger scales, deep convection and stratospheric warming events for physical processes description and study of long term evolution with climate change. Among the applications, ARISE fosters integration of innovative methods for remote detection of non-instrumented volcanoes including distant eruption characterization to provide notifications with reliable confidence indices to the

  13. Observed decrease in atmospheric mercury explained by global decline in anthropogenic emissions

    Science.gov (United States)

    Yanxu Zhang,; Daniel J. Jacob,; Hannah M. Horowitz,; Long Chen,; Helen M. Amos,; Krabbenhoft, David P.; Franz Slemr,; Vincent L. St. Louis,; Elsie M. Sunderland,

    2015-01-01

    Observations of elemental mercury (Hg0) at sites in North America and Europe show large decreases (∼1–2% y−1) from 1990 to present. Observations in background northern hemisphere air, including Mauna Loa Observatory (Hawaii) and CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) aircraft flights, show weaker decreases (inventories indicating flat or increasing emissions over that period. However, the inventories have three major flaws: (i) they do not account for the decline in atmospheric release of Hg from commercial products; (ii) they are biased in their estimate of artisanal and small-scale gold mining emissions; and (iii) they do not properly account for the change in Hg0/HgII speciation of emissions from coal-fired utilities after implementation of emission controls targeted at SO2 and NOx. We construct an improved global emission inventory for the period 1990 to 2010 accounting for the above factors and find a 20% decrease in total Hg emissions and a 30% decrease in anthropogenic Hg0 emissions, with much larger decreases in North America and Europe offsetting the effect of increasing emissions in Asia. Implementation of our inventory in a global 3D atmospheric Hg simulation [GEOS-Chem (Goddard Earth Observing System-Chemistry)] coupled to land and ocean reservoirs reproduces the observed large-scale trends in atmospheric Hg0 concentrations and in HgII wet deposition. The large trends observed in North America and Europe reflect the phase-out of Hg from commercial products as well as the cobenefit from SO2 and NOx emission controls on coal-fired utilities.

  14. Fine structure of charge exchange lines observed in laboratory plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ida, K.; Nishimura, S. [National Inst. for Fusion Science, Nagoya (Japan); Kondo, K.

    1997-01-01

    The influence of the fine structure of charge exchange lines appears only at the plasma edge or in the recombining phase where the ion temperature is low enough. The observed spectra in Li III and C VI are consistent with the sum of fine-structure components populated by statistical weights (assuming complete l-mixing) not by direct charge exchange cross sections. Some discrepancy was observed in the intensity ratio of fine-structure components between the observation and calculation for C VI in the recombining phase. The fine-structure of charge exchange lines gives an apparent Doppler shift in plasma rotation velocity measurement using charge exchange spectroscopy. (author)

  15. Observational Evidence of Magnetic Waves in the Solar Atmosphere

    Science.gov (United States)

    McIntosh, Scott W.

    2012-03-01

    The observational evidence in supporting the presence of magnetic waves in the outer solar atmosphere is growing rapidly - we will discuss recent observations and place them in context with salient observations made in the past. While the clear delineation of these magnetic wave "modes" is unclear, much can be learned about the environment in which they originated and possibly how they are removed from the system from the observations. Their diagnostic power is, as yet, untapped and their energy content (both as a mechanical source for the heating of coronal material and acceleration of the solar wind) remains in question, but can be probed observationally - raising challenges for modeling efforts. We look forward to the IRIS mission by proposing some sample observing sequences to help resolve some of the zoological issues present in the literature.

  16. Observations. Surface and Atmospheric Climate Change. Chapter 3

    Energy Technology Data Exchange (ETDEWEB)

    Trenberth, K.E.; Jones, P.D.; Ambenje, P.; Bojariu, R.; Easterling, D.; Klein Tank, A.; Parker, D.; Rahimzadeh, F.; Renwick, J.A.; Rusticucci, M.; Soden, B.; Zhai, P.

    2007-09-15

    This chapter assesses the observed changes in surface and atmospheric climate, placing new observations and new analyses made during the past six years (since the Third Assessment Report TAR) in the context of the previous instrumental record. In previous IPCC reports, palaeo-observations from proxy data for the pre-instrumental past and observations from the ocean and ice domains were included within the same chapter. This helped the overall assessment of the consistency among the various variables and their synthesis into a coherent picture of change. A short synthesis and scrutiny of the consistency of all the observations is included here (see Section 3.9). In the TAR, surface temperature trends were examined from 1860 to 2000 globally, for 1901 to 2000 as maps and for three sub-periods (1910-1945, 1946-1975 and 1976-2000). The first and third sub-periods had rising temperatures, while the second sub-period had relatively stable global mean temperatures. The 1976 divide is the date of a widely acknowledged 'climate shift' and seems to mark a time when global mean temperatures began a discernible upward trend that has been at least partly attributed to increases in greenhouse gas concentrations in the atmosphere. The picture prior to 1976 has essentially not changed and is therefore not repeated in detail here. However, it is more convenient to document the sub-period after 1979, rather than 1976, owing to the availability of increased and improved satellite data since then (in particular Television InfraRed Observation Satellite (TIROS) Operational Vertical Sounder (TOVS) data) in association with the Global Weather Experiment (GWE) of 1979. The post-1979 period allows, for the first time, a global perspective on many fields of variables, such as precipitation, that was not previously available. The availability of high-quality data has led to a focus on the post-1978 period, although physically this new regime seems to have begun in 1976

  17. A non-LTE study of silicon line formation in early-type main-sequence atmospheres.

    Science.gov (United States)

    Kamp, L. W.

    1973-01-01

    We have computed populations of 16 levels of Si III-V and radiation fields in all connecting transitions; in particular the first six Si III triplet levels, including the 4553 line, and the first six Si IV levels including 4089. The computations were done for four non-LTE H-He model atmospheres, provided by Auer and Mihalas. Estimates of corresponding MK types are B1.5 V, B0.5 V, O9 V, and O6. Solutions were obtained by iterating the linearized equations of radiative transfer and statistical equilibrium, except that for less important lines an approximate equivalent two-level atom treatment was used. Continuous opacities of C, N, O, and Ne were included. All abundances were solar values.

  18. Aperture synthesis observations of recombination lines from compact HII regions

    International Nuclear Information System (INIS)

    Gorkom, J.H. van.

    1980-01-01

    This thesis describes a continuation of early attempts to attain a high spectral dynamic range in general and to study recombination lines from compact HII regions in particular. These observations are made with the WSRT, until recently, the only instrument with sufficient angular resolution and sensitivity to provide at 6 cm detailed line maps of compact HII regions. An investigation into the spectral stability of the WSRT is described. Chromatic errors were found and their effects on maps are shown. These errors were found in the 80 channel filter spectrometer which was still in use at that time. The advent of the digital line backend (DLB) improved the dynamic range by an order of magnitude. An experiment is described which was partially aimed at testing the spectral stability of the DLB. It concerns a search for HI emission from the high velocity system of NGC 1275. Recombination line observations of the compact components in five giant HII regions are presented. The author discusses the radiative transfer problem in recombination lines and shows that non-LTE effects and pressure broadening can be of importance in compact HII regions. Observations obtained with the DLB are also presented. Because of the much better instrumental quality and improved insight into calibration procedures, mapping the H110α emission of DR21 and both the H110α and H166α emission of W3 was succeeded. (Auth.)

  19. Disturbance observer based model predictive control for accurate atmospheric entry of spacecraft

    Science.gov (United States)

    Wu, Chao; Yang, Jun; Li, Shihua; Li, Qi; Guo, Lei

    2018-05-01

    Facing the complex aerodynamic environment of Mars atmosphere, a composite atmospheric entry trajectory tracking strategy is investigated in this paper. External disturbances, initial states uncertainties and aerodynamic parameters uncertainties are the main problems. The composite strategy is designed to solve these problems and improve the accuracy of Mars atmospheric entry. This strategy includes a model predictive control for optimized trajectory tracking performance, as well as a disturbance observer based feedforward compensation for external disturbances and uncertainties attenuation. 500-run Monte Carlo simulations show that the proposed composite control scheme achieves more precise Mars atmospheric entry (3.8 km parachute deployment point distribution error) than the baseline control scheme (8.4 km) and integral control scheme (5.8 km).

  20. Panchromatic Calibration of Astronomical Observations with State-of-the-Art White Dwarf Model Atmospheres

    Science.gov (United States)

    Rauch, T.

    2016-05-01

    Theoretical spectral energy distributions (SEDs) of white dwarfs provide a powerful tool for cross-calibration and sensitivity control of instruments from the far infrared to the X-ray energy range. Such SEDs can be calculated from fully metal-line blanketed NLTE model-atmospheres that are e.g. computed by the Tübingen NLTE Model-Atmosphere Package (TMAP) that has arrived at a high level of sophistication. TMAP was successfully employed for the reliable spectral analysis of many hot, compact post-AGB stars. High-quality stellar spectra obtained over a wide energy range establish a data base with a large number of spectral lines of many successive ions of different species. Their analysis allows to determine effective temperatures, surface gravities, and element abundances of individual (pre-)white dwarfs with very small error ranges. We present applications of TMAP SEDs for spectral analyses of hot, compact stars in the parameter range from (pre-) white dwarfs to neutron stars and demonstrate the improvement of flux calibration using white-dwarf SEDs that are e.g. available via registered services in the Virtual Observatory.

  1. Observational Investigation of Solar Interior and Atmosphere

    Science.gov (United States)

    Kuhn, Jeffrey R.

    2003-01-01

    The Imaging Vector Magnetograph (IVM) has been modified to make it easier to observe at more than one spectral line. The cell holding the blocking filter has been replaced by a four-position filter wheel, so that changing to a different line is a matter of a few minutes rather than the several hours it used to take to disassemble the cell and install a new filter. Three new filters have been obtained, for Na 1589.6 nm, Fe 1630.25 nm, and H 1656.3 nm. The new filters have better bandpass profiles than the ones they replaced: somewhat wider, with flatter tops and steeper wings. This results in a reduction of parasitic light coming from adjacent Fabry-Perot orders, from seven percent to about two percent, and flattens the apparent continuum. The Mees CCD Imaging Spectrograph (MCCD) was upgraded under this grant, with a new control computer and data system. The camera was replaced with a faster, larger-format frame-transfer camera. Final integration of the upgrades is not yet complete, but tests indicate that the system cadence will be improved by a factor of five to ten, while increasing the spatial coverage by a factor of two (depending on observation options). Synoptic observations with the IVM and MCCD continue to be conducted daily, to the extent permitted by the fact that we have a single observer responsible for the observations. The older Haleakala Stokes Polarimeter is also used to make a daily vector magnetogram, normally of the region selected by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) duty scientists. This instrument, however, is showing its age to the extent that its maintenance is becoming something of a challenge. We also run a white light full-disk imager and a video H alpha prominence camera, continuously during times of observations. Of particular interest, we obtained rapid-cadence observations of the 2003 July 15 white light flare with both the IVM and MCCD. The vector magnetograms show no obvious difference between the

  2. Solar polarimetry: observations and theories

    Energy Technology Data Exchange (ETDEWEB)

    Rees, D E [Sydney Univ. (Australia). Dept. of Applied Mathematics

    1982-01-01

    This review surveys some recent observations of polarization in solar spectral lines with emphasis on their theoretical interpretation. Observations of non-magnetic resonance line polarization offer a new approach to temperature and density modelling of the atmosphere. They also provide a basis for comparison in Hanle effect studies of weak magnetic fields on the solar disk. Measurements of the Hanle effect are being used to deduce vector magnetic fields in prominences. It is now feasible to try to infer the vector field distribution in an active region such as a sunspot from analysis of the stokes parameter profiles of a Zeeman split line.

  3. Observational study of atmospheric surface layer and coastal weather in northern Qatar

    Science.gov (United States)

    Samanta, Dhrubajyoti; Sadr, Reza

    2016-04-01

    Atmospheric surface layer is the interaction medium between atmosphere and Earth's surface. Better understanding of its turbulence nature is essential in characterizing the local weather, climate variability and modeling of turbulent exchange processes. The importance of Middle East region, with its unique geographical, economical and weather condition is well recognized. However, high quality micrometeorological observational studies are rare in this region. Here we show experimental results from micrometeorological observations from an experimental site in the coastal region of Qatar during August-December 2015. Measurements of winds are obtained from three sonic anemometers installed on a 9 m tower placed at Al Ghariyah beach in northern Qatar (26.08 °N, 51.36 °E). Different surface layer characteristics is analyzed and compared with earlier studies in equivalent weather conditions. Monthly statistics of wind speed, wind direction, temperature, humidity and heat index are made from concurrent observations from sonic anemometer and weather station to explore variations with surface layer characteristics. The results also highlights potential impact of sea breeze circulation on local weather and atmospheric turbulence. The observed daily maximum temperature and heat index during morning period may be related to sea breeze circulations. Along with the operational micrometeorological observation system, a camera system and ultrasonic wave measurement system are installed recently in the site to study coastline development and nearshore wave dynamics. Overall, the complete observational set up is going to provide new insights about nearshore wind dynamics and wind-wave interaction in Qatar.

  4. USING THE ROSSITER–McLAUGHLIN EFFECT TO OBSERVE THE TRANSMISSION SPECTRUM OF EARTH’S ATMOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Yan, F.; Zhao, G. [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, 100012 Beijing (China); Fosbury, R. A. E.; Petr-Gotzens, M. G. [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München (Germany); Pallé, E., E-mail: feiy@nao.cas.cn, E-mail: gzhao@nao.cas.cn [Instituto de Astrofísica de Canarias, C/vía Láctea, s/n, E-38205 La Laguna, Tenerife (Spain)

    2015-06-20

    Due to stellar rotation, the observed radial velocity of a star varies during the transit of a planet across its surface, a phenomenon known as the Rossiter–McLaughlin (RM) effect. The amplitude of the RM effect is related to the radius of the planet which, because of differential absorption in the planetary atmosphere, depends on wavelength. Therefore, the wavelength-dependent RM effect can be used to probe the planetary atmosphere. We measure for the first time the RM effect of the Earth transiting the Sun using a lunar eclipse observed with the ESO High Accuracy Radial velocity Planet Searcher spectrograph. We analyze the observed RM effect at different wavelengths to obtain the transmission spectrum of the Earth’s atmosphere after the correction of the solar limb-darkening and the convective blueshift. The ozone Chappuis band absorption as well as the Rayleigh scattering features are clearly detectable with this technique. Our observation demonstrates that the RM effect can be an effective technique for exoplanet atmosphere characterization. Its particular asset is that photometric reference stars are not required, circumventing the principal challenge for transmission spectroscopy studies of exoplanet atmospheres using large ground-based telescopes.

  5. Surface-atmospheric water cycle at Gale crater through multi-year MSL/REMS observations

    Science.gov (United States)

    Harri, A. M.; Genzer, M.; McConnochie, T. H.; Savijarvi, H. I.; Smith, M. D.; Martinez, G.; de la Torre Juarez, M.; Haberle, R. M.; Polkko, J.; Gomez-Elvira, J.; Renno, N. O.; Kemppinen, O.; Paton, M.; Richardson, M. I.; Newman, C. E.; Siili, T. T.; Mäkinen, T.

    2017-12-01

    The Mars Science laboratory (MSL) has been successfully operating for almost three Martian years. That includes an unprecedented long time series of atmospheric observations by the REMS instrument performing measurements of atmospheric pressure, relative humidity (REMS-H), temperature of the air, ground temperature, UV and wind speed and direction. The REMS-H relative humidity device is based on polymeric capacitive humidity sensors developed by Vaisala Inc. and it makes use of three (3) humidity sensor heads. The humidity device is mounted on the REMS boom providing ventilation with the ambient atmosphere through a filter protecting the device from airborne dust. The REMS-H humidity instrument has created an unprecedented data record of more than two full Martian. REMS-H measured the relative humidity and temperature at 1.6 m height for a period of 5 minutes every hour as part of the MSL/REMS instrument package. We focus on describing the annual in situ water cycle with the REMS-H instrument data for the period of almost three Martian years. The results will be constrained through comparison with independent indirect observations and through modeling efforts. We inferred the hourly atmospheric VMR from the REMS-H observations and compared these VMR measurements with predictions of VMR from our 1D column Martian atmospheric model and regolith to investigate the local water cycle, exchange processes and the local climate in Gale Crater. The strong diurnal variation suggests there are surface-atmosphere exchange processes at Gale Crater during all seasons, which depletes moisture to the ground in the evening and nighttime and release the moisture back to the atmosphere during the daytime. On the other hand, these processes do not seem to result in significant water deposition on the ground. Hence, our modelling results presumably indicate that adsorption processes take place during the nighttime and desorption during the daytime. Other processes, e.g. convective

  6. Hydrogen Atom Collision Processes in Cool Stellar Atmospheres: Effects on Spectral Line Strengths and Measured Chemical Abundances in Old Stars

    International Nuclear Information System (INIS)

    Barklem, Paul S

    2012-01-01

    The precise measurement of the chemical composition of stars is a fundamental problem relevant to many areas of astrophysics. State-of-the-art approaches attempt to unite accurate descriptions of microphysics, non-local thermodynamic equilibrium (non-LTE) line formation and 3D hydrodynamical model atmospheres. In this paper I review progress in understanding inelastic collisions of hydrogen atoms with other species and their influence on spectral line formation and derived abundances in stellar atmospheres. These collisions are a major source of uncertainty in non-LTE modelling of spectral lines and abundance determinations, especially for old, metal-poor stars, which are unique tracers of the early evolution of our galaxy. Full quantum scattering calculations of direct excitation processes X(nl) + H ↔ X(n'l') + H and charge transfer processes X(nl) + H ↔ X + + H − have been done for Li, Na and Mg [1,2,3] based on detailed quantum chemical data, e.g. [4]. Rate coefficients have been calculated and applied to non-LTE modelling of spectral lines in stellar atmospheres [5,6,7,8,9]. In all cases we find that charge transfer processes from the first excited S-state are very important, and the processes affect measured abundances for Li, Na and Mg in some stars by as much as 60%. Effects vary with stellar parameters (e.g. temperature, luminosity, metal content) and so these processes are important not only for accurate absolute abundances, but also for relative abundances among dissimilar stars.

  7. Satellite- and ground-based observations of atmospheric water vapor absorption in the 940 nm region

    International Nuclear Information System (INIS)

    Albert, P.; Smith, K.M.; Bennartz, R.; Newnham, D.A.; Fischer, J.

    2004-01-01

    Ground-based measurements of direct absorption of solar radiation between 9000 and 13,000 cm -1 (770-1100 nm) with a spectral resolution of 0.05 cm -1 are compared with line-by-line simulations of atmospheric absorption based on different molecular databases (HITRAN 2000, HITRAN 99, HITRAN 96 and ESA-WVR). Differences between measurements and simulations can be reduced to a great amount by scaling the individual line intensities with spectral and database dependent scaling factors. Scaling factors are calculated for the selected databases using a Marquardt non-linear least-squares fit together with a forward model for 100 cm -1 wide intervals between 10,150 and 11,250 cm -1 as well as for the water vapor absorption channels of the Medium Resolution Imaging Spectrometer (MERIS) onboard the European Space Agency's (ESA) ENVISAT platform and the Modular Optoelectronic Scanner (MOS) on the Indian IRSP-3 platform, developed by the German Aerospace Centre (DLR). For the latter, the scaling coefficients are converted into correction factors for retrieved total columnar water vapor content and used for a comparison of MOS-based retrievals of total columnar atmospheric water vapor above cloud-free land surfaces with radio soundings. The scaling factors determined for 100 cm -1 wide intervals range from 0.85 for the ESA-WVR molecular database to 1.15 for HITRAN 96. The best agreement between measurements and simulations is achieved with HITRAN 99 and HITRAN 2000, respectively, using scaling factors between 0.9 and 1. The effects on the satellite-based retrievals of columnar atmospheric water vapor range from 2% (HITRAN 2000) to 12% (ESA-WVR)

  8. Mars atmosphere studies with the SPICAM IR emission phase function observations

    Science.gov (United States)

    Trokhimovskiy, Alexander; Fedorova, Anna; Montmessin, Franck; Korablev, Oleg; Bertaux, Jean-Loup

    Emission Phase Function (EPF) observations is a powerful tool for characterization of atmosphere and surface. EPF sequence provides the extensive coverage of scattering angles above the targeted surface location which allow to separate the surface and aerosol scattering, study a vertical distribution of minor species and aerosol properties. SPICAM IR instrument on Mars Express mission provides continuous atmospheric observations in near IR (1-1.7 mu) in nadir and limb starting from 2004. For the first years of SPICAM operation only a very limited number of EPFs was performed. But from the mid 2013 (Ls=225, MY31) SPICAM EPF observations become rather regular. Based on the multiple-scattering radiative transfer model SHDOM, we analyze equivalent depths of carbon dioxide (1,43 mu) and water vapour (1,38 mu) absorption bands and their dependence on airmass during observation sequence to get aerosol optical depths and properties. The derived seasonal dust opacities from near IR can be used to retrieve the size distribution from comparison with simultaneous results of other instruments in different spectral ranges. Moreover, the EPF observations of water vapour band allow to access poorly known H2O vertical distribution for different season and locations.

  9. Multi-Sensor Observations of Earthquake Related Atmospheric Signals over Major Geohazard Validation Sites

    Science.gov (United States)

    Ouzounov, D.; Pulinets, S.; Davindenko, D.; Hattori, K.; Kafatos, M.; Taylor, P.

    2012-01-01

    We are conducting a scientific validation study involving multi-sensor observations in our investigation of phenomena preceding major earthquakes. Our approach is based on a systematic analysis of several atmospheric and environmental parameters, which we found, are associated with the earthquakes, namely: thermal infrared radiation, outgoing long-wavelength radiation, ionospheric electron density, and atmospheric temperature and humidity. For first time we applied this approach to selected GEOSS sites prone to earthquakes or volcanoes. This provides a new opportunity to cross validate our results with the dense networks of in-situ and space measurements. We investigated two different seismic aspects, first the sites with recent large earthquakes, viz.- Tohoku-oki (M9, 2011, Japan) and Emilia region (M5.9, 2012,N. Italy). Our retrospective analysis of satellite data has shown the presence of anomalies in the atmosphere. Second, we did a retrospective analysis to check the re-occurrence of similar anomalous behavior in atmosphere/ionosphere over three regions with distinct geological settings and high seismicity: Taiwan, Japan and Kamchatka, which include 40 major earthquakes (M>5.9) for the period of 2005-2009. We found anomalous behavior before all of these events with no false negatives; false positives were less then 10%. Our initial results suggest that multi-instrument space-borne and ground observations show a systematic appearance of atmospheric anomalies near the epicentral area that could be explained by a coupling between the observed physical parameters and earthquake preparation processes.

  10. Observational constraints on the global atmospheric budget of ethanol

    Directory of Open Access Journals (Sweden)

    V. Naik

    2010-06-01

    Full Text Available Energy security and climate change concerns have led to the promotion of biomass-derived ethanol, an oxygenated volatile organic compound (OVOC, as a substitute for fossil fuels. Although ethanol is ubiquitous in the troposphere, our knowledge of its current atmospheric budget and distribution is limited. Here, for the first time we use a global chemical transport model in conjunction with atmospheric observations to place constraints on the ethanol budget, noting that additional measurements of ethanol (and its precursors are still needed to enhance confidence in our estimated budget. Global sources of ethanol in the model include 5.0 Tg yr−1 from industrial sources and biofuels, 9.2 Tg yr−1 from terrestrial plants, ~0.5 Tg yr−1 from biomass burning, and 0.05 Tg yr−1 from atmospheric reactions of the ethyl peroxy radical (C2H5O2 with itself and with the methyl peroxy radical (CH3O2. The resulting atmospheric lifetime of ethanol in the model is 2.8 days. Gas-phase oxidation by the hydroxyl radical (OH is the primary global sink of ethanol in the model (65%, followed by dry deposition (25%, and wet deposition (10%. Over continental areas, ethanol concentrations predominantly reflect direct anthropogenic and biogenic emission sources. Uncertainty in the biogenic ethanol emissions, estimated at a factor of three, may contribute to the 50% model underestimate of observations in the North American boundary layer. Current levels of ethanol measured in remote regions are an order of magnitude larger than those in the model, suggesting a major gap in understanding. Stronger constraints on the budget and distribution of ethanol and OVOCs are a critical step towards assessing the impacts of increasing the use of ethanol as a fuel.

  11. Tracking atmospheric boundary layer dynamics with water vapor D-excess observations

    KAUST Repository

    Parkes, Stephen

    2015-04-01

    Stable isotope water vapor observations present a history of hydrological processes that have impacted on an air mass. Consequently, there is scope to improve our knowledge of how different processes impact on humidity budgets by determining the isotopic end members of these processes and combining them with in-situ water vapor measurements. These in-situ datasets are still rare and cover a limited geographical expanse, so expanding the available data can improve our ability to define isotopic end members and knowledge about atmospheric humidity dynamics. Using data collected from an intensive field campaign across a semi-arid grassland site in eastern Australia, we combine multiple methods including in-situ stable isotope observations to study humidity dynamics associated with the growth and decay of the atmospheric boundary layer and the stable nocturnal boundary layer. The deuterium-excess (D-excess) in water vapor is traditionally thought to reflect the sea surface temperature and relative humidity at the point of evaporation over the oceans. However, a number of recent studies suggest that land-atmosphere interactions are also important in setting the D-excess of water vapor. These studies have shown a highly robust diurnal cycle for the D-excess over a range of sites that could be exploited to better understand variations in atmospheric humidity associated with boundary layer dynamics. In this study we use surface radon concentrations as a tracer of surface layer dynamics and combine these with the D-excess observations. The radon concentrations showed an overall trend that was inversely proportional to the D-excess, with early morning entrainment of air from the residual layer of the previous day both diluting the radon concentration and increasing the D-excess, followed by accumulation of radon at the surface and a decrease in the D-excess as the stable nocturnal layer developed in the late afternoon and early evening. The stable nocturnal boundary layer

  12. Polarization of Coronal Forbidden Lines

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hao; Qu, Zhongquan [Yunnan Observatories, Chinese Academy of Sciences, Kunming, Yunnan 650011 (China); Landi Degl’Innocenti, Egidio, E-mail: sayahoro@ynao.ac.cn [Dipartimento di Astronomia e Scienza dello Spazio, Università di Firenze, Largo E. Fermi 2, I-50125 Firenze (Italy)

    2017-03-20

    Since the magnetic field is responsible for most manifestations of solar activity, one of the most challenging problems in solar physics is the diagnostics of solar magnetic fields, particularly in the outer atmosphere. To this end, it is important to develop rigorous diagnostic tools to interpret polarimetric observations in suitable spectral lines. This paper is devoted to analyzing the diagnostic content of linear polarization imaging observations in coronal forbidden lines. Although this technique is restricted to off-limb observations, it represents a significant tool to diagnose the magnetic field structure in the solar corona, where the magnetic field is intrinsically weak and still poorly known. We adopt the quantum theory of polarized line formation developed in the framework of the density matrix formalism, and synthesize images of the emergent linear polarization signal in coronal forbidden lines using potential-field source-surface magnetic field models. The influence of electronic collisions, active regions, and Thomson scattering on the linear polarization of coronal forbidden lines is also examined. It is found that active regions and Thomson scattering are capable of conspicuously influencing the orientation of the linear polarization. These effects have to be carefully taken into account to increase the accuracy of the field diagnostics. We also found that linear polarization observation in suitable lines can give valuable information on the long-term evolution of the magnetic field in the solar corona.

  13. Music as atmosphere. Lines of becoming in congregational worship

    Directory of Open Access Journals (Sweden)

    Friedlind Riedel

    2015-06-01

    Full Text Available In this paper I offer critical attention to the notion of atmosphere in relation to music. By exploring the concept through the case study of the Closed Brethren worship services, I argue that atmosphere may provide analytical tools to explore the ineffable in ecclesial practices. Music, just as atmosphere, commonly occupies a realm of ineffability and undermines notions such as inside and outside, subject and object. For this reason I present music as a means of knowing the atmosphere. The first part of this paper points to the limits of an understanding of atmosphere as a constellation of things, as proposed by Gernot Böhme. In contrast to this, Hermann Schmitz conceptualises atmosphere as half-thing which suggests movement. Drawing on this, I propose to methodologically approach atmospheres as movements. Consequently, in the second part of this paper I closely analyse two motions as they cohere in Closed Brethren worship services: first, becoming (Deleuze and Guattari, a movement on the level of the individual worshiper; secondly, territorialisation (Deleuze and Guattari, a movement of the atmosphere towards its solidification. Here music as atmosphere is not a system of moral signification but a generative power affording intimate processes of divine encounter, whilst producing affective denominational difference.

  14. Vertical profiles of atmospheric fluorescent aerosols observed by a mutil-channel lidar spectrometer system

    Science.gov (United States)

    Huang, Z.; Huang, J.; Zhou, T.; Sugimoto, N.; Bi, J.

    2015-12-01

    Zhongwei Huang1*, Jianping Huang1, Tian Zhou1, Nobuo Sugimoto2, Jianrong Bi1 and Jinsen Shi11Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, China. 2Atmospheric Environment Division, National Institutes for Environmental Studies, Tsukuba, Japan Email: huangzhongwei@lzu.edu.cn Abstract Atmospheric aerosols have a significant impact on regional and globe climate. The challenge in quantifying aerosol direct radiative forcing and aerosol-cloud interactions arises from large spatial and temporal heterogeneity of aerosol concentrations, compositions, sizes, shape and optical properties (IPCC, 2007). Lidar offers some remarkable advantages for determining the vertical structure of atmospheric aerosols and their related optical properties. To investigate the characterization of atmospheric aerosols (especially bioaerosols) with high spatial and temporal resolution, we developed a Raman/fluorescence/polarization lidar system employed a multi-channel spectrometer, with capabilities of providing measurements of Raman scattering and laser-induced fluorescence excitation at 355 nm from atmospheric aerosols. Meanwhile, the lidar system operated polarization measurements both at 355nm and 532nm wavelengths, aiming to obtain more information of aerosols. It employs a high power pulsed laser and a received telescope with 350mm diameter. The receiver could simultaneously detect a wide fluorescent spectrum about 178 nm with spectral resolution 5.7 nm, mainly including an F/3.7 Crossed Czerny-Turner spectrograph, a grating (1200 gr/mm) and a PMT array with 32 photocathode elements. Vertical structure of fluorescent aerosols in the atmosphere was observed by the developed lidar system at four sites across northwest China, during 2014 spring field observation that conducted by Lanzhou University. It has been proved that the developed lidar could detect the fluorescent aerosols with high temporal and

  15. A Pilot Study to Evaluate California's Fossil Fuel CO2 Emissions Using Atmospheric Observations

    Science.gov (United States)

    Graven, H. D.; Fischer, M. L.; Lueker, T.; Guilderson, T.; Brophy, K. J.; Keeling, R. F.; Arnold, T.; Bambha, R.; Callahan, W.; Campbell, J. E.; Cui, X.; Frankenberg, C.; Hsu, Y.; Iraci, L. T.; Jeong, S.; Kim, J.; LaFranchi, B. W.; Lehman, S.; Manning, A.; Michelsen, H. A.; Miller, J. B.; Newman, S.; Paplawsky, B.; Parazoo, N.; Sloop, C.; Walker, S.; Whelan, M.; Wunch, D.

    2016-12-01

    Atmospheric CO2 concentration is influenced by human activities and by natural exchanges. Studies of CO2 fluxes using atmospheric CO2 measurements typically focus on natural exchanges and assume that CO2 emissions by fossil fuel combustion and cement production are well-known from inventory estimates. However, atmospheric observation-based or "top-down" studies could potentially provide independent methods for evaluating fossil fuel CO2 emissions, in support of policies to reduce greenhouse gas emissions and mitigate climate change. Observation-based estimates of fossil fuel-derived CO2 may also improve estimates of biospheric CO2 exchange, which could help to characterize carbon storage and climate change mitigation by terrestrial ecosystems. We have been developing a top-down framework for estimating fossil fuel CO2 emissions in California that uses atmospheric observations and modeling. California is implementing the "Global Warming Solutions Act of 2006" to reduce total greenhouse gas emissions to 1990 levels by 2020, and it has a diverse array of ecosystems that may serve as CO2 sources or sinks. We performed three month-long field campaigns in different seasons in 2014-15 to collect flask samples from a state-wide network of 10 towers. Using measurements of radiocarbon in CO2, we estimate the fossil fuel-derived CO2 present in the flask samples, relative to marine background air observed at coastal sites. Radiocarbon (14C) is not present in fossil fuel-derived CO2 because of radioactive decay over millions of years, so fossil fuel emissions cause a measurable decrease in the 14C/C ratio in atmospheric CO2. We compare the observations of fossil fuel-derived CO2 to simulations based on atmospheric modeling and published fossil fuel flux estimates, and adjust the fossil fuel flux estimates in a statistical inversion that takes account of several uncertainties. We will present the results of the top-down technique to estimate fossil fuel emissions for our field

  16. MIRO Observation of Comet C/2002 T7 (LINEAR) Water Line Spectrum

    Science.gov (United States)

    Lee, Seungwon; Frerking, Margaret; Hofstadter, Mark; Gulkis, Samuel; von Allmen, Paul; Crovisier, Jaques; Biver, Nicholas; Bockelee-Morvan, Dominique

    2011-01-01

    Comet C/2002 T7 (LINEAR) was observed with the Microwave Instrument for Rosetta Orbiter (MIRO) on April 30, 2004, between 5 hr and 16 hr UT. The comet was 0.63AU distance from the Sun and 0.68AU distance from the MIRO telescope at the time of the observations. The water line involving the two lowest rotational levels at 556.936 GHz is observed at 557.070 GHz due to a large Doppler frequency shift. The detected water line spectrum is interpreted using a non local thermal equilibrium (Non-LTE) molecular excitation and radiative transfer model. Several synthetic spectra are calculated with various coma profiles that are plausible for the comet at the time of observations. The coma profile is modeled with three characteristic parameters: outgassing rate, a constant expansion velocity, and a constant gas temperature. The model calculation result shows that for the distant line observation where contributions from a large coma space is averaged, the combination of the outgassing rate and the gas expansion velocity determines the line shape while the gas temperature has a negligible effect. The comparison between the calculated spectra and the MIRO measured spectrum suggests that the outgassing rate of the comet is about 2.0x1029 molecules/second and its gas expansion velocity about 1.2 km/s at the time of the observations.

  17. Simulating the Mg II NUV Spectra & C II Resonance Lines During Solar Flares

    Science.gov (United States)

    Kerr, Graham Stewart; Allred, Joel C.; Leenaarts, Jorrit; Butler, Elizabeth; Kowalski, Adam

    2017-08-01

    The solar chromosphere is the origin of the bulk of the enhanced radiative output during solar flares, and so comprehensive understanding of this region is important if we wish to understand energy transport in solar flares. It is only relatively recently, however, with the launch of IRIS that we have routine spectroscopic flarea observations of the chromsphere and transition region. Since several of the spectral lines observed by IRIS are optically thick, it is necessary to use forward modelling to extract the useful information that these lines carry about the flaring chromosphere and transition region. We present the results of modelling the formation properties Mg II resonance lines & subordinate lines, and the C II resonance lines during solar flares. We focus on understanding their relation to the physical strucutre of the flaring atmosphere, exploiting formation height differences to determine if we can extract information about gradients in the atmosphere. We show the effect of degrading the profiles to the resolution of the IRIS, and that the usual observational techniques used to identify the line centroid do a poor job in the early stages of the flare (partly due to multiple optically thick line components). Finally, we will tentatively comment on the effects that 3D radiation transfer may have on these lines.

  18. Asymmetries of the solar Ca II lines

    International Nuclear Information System (INIS)

    Heasley, J.N.

    1975-01-01

    A theoretical study of the influence of propagating acoustic pulses in the solar chromosphere upon the line profiles of the Ca II resonance and infrared triplet lines has been made. The major objective has been to explain the observed asymmetries seen in the cores of the H and K lines and to predict the temporal behavior of the infrared lines caused by passing acoustic or shock pulses. The velocities in the pulses, calculated from weak shock theory, have been included consistently in the non-LTE calculations. The results of the calculations show that these lines are very sensitive to perturbations in the background atmosphere caused by the pulses. Only minor changes in the line shapes result from including the velocities consistently in the line source function calculations. The qualitative changes in the line profiles vary markedly with the strength of the shock pulses. The observed differences in the K line profiles seen on the quiet Sun can be explained in terms of a spectrum of pulses with different wavelengths and initial amplitudes in the photosphere. (Auth.)

  19. Observation of solar hydrogen Ly-αline with the K-10-12 rocket

    International Nuclear Information System (INIS)

    Koshio, Takafumi; Masuoka, Toshio; Tono, Ichiro; Watanabe, Norihiko.

    1976-01-01

    The purpose of the observation is to perform the absolute irradiance measurement of the solar hydrogen Ly-α line (1216 A 0 ) in the exosphere. The solar hydrogen Ly-α line is emitted from the chromosphere, and contributes to the ionization in the lower ionosphere. The ionization chamber was used for the detection of the solar hydrogen Ly-α line. The K-10-9 rocket was launched on Jan. 18, 1976. The irradiance of the solar hydrogen Ly-α line was measured in the exosphere, and the height distribution of O 2 density was studied on the basis of the absorbancy of the HLy-α line. The result was in good agreement with the previously observed results. (Yoshimori, M.)

  20. The Heating of the Solar Atmosphere: from the Bottom Up?

    Science.gov (United States)

    Winebarger, Amy

    2014-01-01

    The heating of the solar atmosphere remains a mystery. Over the past several decades, scientists have examined the observational properties of structures in the solar atmosphere, notably their temperature, density, lifetime, and geometry, to determine the location, frequency, and duration of heating. In this talk, I will review these observational results, focusing on the wealth of information stored in the light curve of structures in different spectral lines or channels available in the Solar Dynamic Observatory's Atmospheric Imaging Assembly, Hinode's X-ray Telescope and Extreme-ultraviolet Imaging Spectrometer, and the Interface Region Imaging Spectrograph. I will discuss some recent results from combined data sets that support the heating of the solar atmosphere may be dominated by low, near-constant heating events.

  1. Observations of Orion in all four 18 cm OH Thermal Absoprtion Lines

    Science.gov (United States)

    Moore, Amber M.; Momjian, Emmanuel; Troland, Thomas; Sarma, Anuj; Greisen, Eric

    2018-01-01

    We present results obtained with Karl G. Jansky Very Large Array (VLA) D-configuration observations of the 18 cm OH absorption lines in the Orion Veil; a sheet of material 2-4 pc in front of the Trapezium stars. The goals of these observations were to (a) measure the magnetic field through the Zeeman effect using the 18 cm OH mainlines at 1665 and 1667 MHz and compare the results with those obtained with the pre upgrade VLA, (b) observe all four 18 cm OH lines (the two mainlines and the two satellite lines at 1612 and 1720 MHz) to infer physical conditions in the absorbing regions. For the first goal, we found that the more recent measurements are comparable to the earlier published results. To achieve the second goal, we plan to use the Cloudy spectral synthesis code to model physical conditions based upon observations of all four 18 cm OH lines. We also anticipate using Cloudy to assess the viability of a model previously applied to the M17 PDR in which the magnetic field of the Veil is in hydrostatic equilibrium with radiation pressure of stellar uv from the Trapezium.

  2. Explanation of the Inverse Doppler Effect Observed in Nonlinear Transmission Lines

    International Nuclear Information System (INIS)

    Kozyrev, Alexander B.; Weide, Daniel W. van der

    2005-01-01

    The theory of the inverse Doppler effect recently observed in magnetic nonlinear transmission lines is developed. We explain the crucial role of the backward spatial harmonic in the occurrence of an inverse Doppler effect and draw analogies of the magnetic nonlinear transmission line to the backward wave oscillator

  3. Impact of atmospheric refraction: how deeply can we probe exo-earth's atmospheres during primary eclipse observations?

    Energy Technology Data Exchange (ETDEWEB)

    Bétrémieux, Yan [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Kaltenegger, Lisa, E-mail: betremieux@mpia.de [Also at Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA. (United States)

    2014-08-10

    Most models used to predict or fit exoplanet transmission spectra do not include all the effects of atmospheric refraction. Namely, the angular size of the star with respect to the planet can limit the lowest altitude, or highest density and pressure, probed during primary eclipses as no rays passing below this critical altitude can reach the observer. We discuss this geometrical effect of refraction for all exoplanets and tabulate the critical altitude, density, and pressure for an exoplanet identical to Earth with a 1 bar N{sub 2}/O{sub 2} atmosphere as a function of both the incident stellar flux (Venus, Earth, and Mars-like) at the top of the atmosphere and the spectral type (O5-M9) of the host star. We show that such a habitable exo-Earth can be probed to a surface pressure of 1 bar only around the coolest stars. We present 0.4-5.0 μm model transmission spectra of Earth's atmosphere viewed as a transiting exoplanet, and show how atmospheric refraction modifies the transmission spectrum depending on the spectral type of the host star. We demonstrate that refraction is another phenomenon that can potentially explain flat transmission spectra over some spectral regions.

  4. Observed atmospheric total column ozone distribution from SCIAMACHY over Peninsular Malaysia

    International Nuclear Information System (INIS)

    Chooi, T K; San, L H; Jafri, M Z M

    2014-01-01

    The increase in atmospheric ozone has received great attention because it degrades air quality and brings hazard to human health and ecosystems. The aim of this study was to assess the seasonal variations of ozone concentrations in Peninsular Malaysia from January 2003 to December 2009 using Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY). Level-2 data of total column ozone WFMD version 1.0 with spatial resolution 1° × 1.25° were acquired through SCIAMACHY. Analysis for trend of five selected sites exhibit strong seasonal variation in atmospheric ozone concentrations, where there is a significant difference between northeast monsoon and southwest monsoon. The highest ozone values occurred over industrial and congested urban zones (280.97 DU) on August at Bayan Lepas. The lowest ozone values were observed during northeast monsoon on December at Subang (233.08 DU). In addition, the local meteorological factors also bring an impact on the atmospheric ozone. During northeast monsoon, with the higher rate of precipitation, higher relative humidity, low temperature, and less sunlight hours let to the lowest ozone concentrations. Inversely, the highest ozone concentrations observed during southwest monsoon, with the low precipitation rate, lower relative humidity, higher temperature, and more sunlight hours. Back trajectories analysis is carried out, in order to trace the path of the air parcels with high ozone concentration event, suggesting cluster of trajectory (from southwest of the study area) caused by the anthropogenic sources associated with biogenic emissions from large tropical forests, which can make important contribution to regional and global pollution

  5. A SURVEY OF ALKALI LINE ABSORPTION IN EXOPLANETARY ATMOSPHERES

    International Nuclear Information System (INIS)

    Jensen, Adam G.; Redfield, Seth; Endl, Michael; Cochran, William D.; Koesterke, Lars; Barman, Travis S.

    2011-01-01

    We obtained over 90 hr of spectroscopic observations of four exoplanetary systems with the Hobby-Eberly Telescope. Observations were taken in transit and out of transit, and we analyzed the differenced spectra—i.e., the transmission spectra—to inspect it for absorption at the wavelengths of the neutral sodium (Na I) doublet at λλ5889, 5895 and neutral potassium (K I) at λ7698. We used the transmission spectrum at Ca I λ6122—which shows strong stellar absorption but is not an alkali metal resonance line that we expect to show significant absorption in these atmospheres—as a control line to examine our measurements for systematic errors. We use an empirical Monte Carlo method to quantify these systematic errors. In a reanalysis of the same data set using a reduction and analysis pipeline that was derived independently, we confirm the previously seen Na I absorption in HD 189733b at a level of (– 5.26 ± 1.69) × 10 –4 (the average value over a 12 Å integration band to be consistent with previous authors). Additionally, we tentatively confirm the Na I absorption seen in HD 209458b (independently by multiple authors) at a level of (– 2.63 ± 0.81) × 10 –4 , though the interpretation is less clear. Furthermore, we find Na I absorption of (– 3.16 ± 2.06) × 10 –4 at <3σ in HD 149026b; features apparent in the transmission spectrum are consistent with real absorption and indicate this may be a good target for future observations to confirm. No other results (Na I in HD 147506b and Ca I and K I in all four targets) are significant to ≥3σ, although we observe some features that we argue are primarily artifacts.

  6. Soft X-rays from the sunlit earth's atmosphere

    International Nuclear Information System (INIS)

    McKenzie, D.L.; Rugge, H.R.; Charles, P.A.

    1982-01-01

    The HEAO-1 A-2 experiment low energy proportional counters have been used to measure the X-ray spectrum of the sunlit earth in the energy range 0.2 to 0.8 keV. The X-rays arise by coherent scattering of, or fluorescence of atmospheric constituents by, solar coronal X-rays incident on the atmosphere. Although the relative spectral contributions of the two processes depend upon the sun-earth-satellite geometry, fluorescent oxygen and nitrogen K X-ray emission is always important. The observed spectra were compared with calculations in order to derive the coronal temperature and emission measure, parameters that characterize the incident solar spectrum. These derived parameters agree well with the expected values for the nonflaring sun, and good agreement was obtained between measurements closely spaced in time but having a wide range of geometries and counting rates. Thus X-ray observations of the sunlit earth's atmosphere can be a useful monitor of solar activity for satellite-borne instrumentation unable to view the sun directly. The total measured fluorescent line flux agreed well with calculations, but the N:O line ratio did not. This disagreement is attributed to several causes which are discussed. (author)

  7. Atmospheric monitoring in the millimetre and submillimetre bands for cosmological observations: CASPER2

    Science.gov (United States)

    De Petris, M.; De Gregori, S.; Decina, B.; Lamagna, L.; Pardo, J. R.

    2013-02-01

    Cosmological observations from ground at millimetre and submillimetre wavelengths are affected by atmospheric absorption and consequent emission. The low- and high-frequency (sky-noise) fluctuations of atmospheric performance necessitate careful observational strategies and/or instrumental technical solutions. Measurements of atmospheric emission spectra are necessary for accurate calibration procedures as well as for site-testing statistics. CASPER2, an instrument designed to explore the 90-450 GHz (3-15 cm-1) spectral region, was developed and had its operation verified in the Alps. A Martin-Puplett interferometer (MPI) operates by comparing sky radiation, coming from a field of view (FOV) of 28 arcmin (full width at half-maximum) and collected by a 62-cm-diameter Pressman-Camichel telescope, with a reference source. The signals at the two output ports of the interferometer are detected by two bolometers cooled to 300 mK inside a wet cryostat. Three different but complementary interferometric techniques can be performed with CASPER2: amplitude modulation (AM), fast-scan (FS) and phase modulation (PM). An altazimuthal mount allows sky pointing, possibly co-aligned with the optical axis of the 2.6-m-diameter telescope of MITO (Millimetre and Infrared Testagrigia Observatory, Italy). The optimal time-scale to average acquired spectra is inferred by Allan variance analysis at five fiducial frequencies. We present the motivation for and design of the atmospheric spectrometer CASPER2. The procedure adopted to calibrate the instrument and the preliminary performance of it are described. Instrument capabilities were checked during the summer observational campaign at MITO in 2010 July by measuring atmospheric emission spectra with the three procedures.

  8. NON-LTE INVERSIONS OF THE Mg ii h and k AND UV TRIPLET LINES

    Energy Technology Data Exchange (ETDEWEB)

    De la Cruz Rodríguez, Jaime; Leenaarts, Jorrit [Institute for Solar Physics, Dept. of Astronomy, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm Sweden (Sweden); Ramos, Andrés Asensio [Instituto de Astrofísica de Canarias, E-38205, La Laguna, Tenerife (Spain)

    2016-10-20

    The Mg ii h and k lines are powerful diagnostics for studying the solar chromosphere. They have become particularly popular with the launch of the Interface Region Imaging Spectrograph ( IRIS ) satellite, and a number of studies that include these lines have lead to great progress in understanding chromospheric heating, in many cases thanks to the support from 3D MHD simulations. In this study, we utilize another approach to analyze observations: non-LTE inversions of the Mg ii h and k and UV triplet lines including the effects of partial redistribution. Our inversion code attempts to construct a model atmosphere that is compatible with the observed spectra. We have assessed the capabilities and limitations of the inversions using the FALC atmosphere and a snapshot from a 3D radiation-MHD simulation. We find that Mg ii h and k allow reconstructing a model atmosphere from the middle photosphere to the transition region. We have also explored the capabilities of a multi-line/multi-atom setup, including the Mg ii h and k, the Ca ii 854.2 nm, and the Fe i 630.25 lines to recover the full stratification of physical parameters, including the magnetic field vector, from the photosphere to the chromosphere. Finally, we present the first inversions of observed IRIS spectra from quiet-Sun, plage, and sunspot, with very promising results.

  9. New method of interpretation of the solar spectrum lines

    International Nuclear Information System (INIS)

    Sitnik, G.F.

    1975-01-01

    Close triplet lines, which appear from a common low level or from low sublevels with small energy difference are used. It is supposed that for such lines both the function of the source in line and the frequency dependence of the selective coefficient of absorption are the same over any depth of the region of line production in the atmosphere and change with the depth equally. The residual intensities of some lines of the triplet, which are measured for every line at a number of profile points (at the same distance from its center and at different distances from the solar limb center), serve as initial material. The intensities are expressed in terms of the intensity of the continuous spectrum in the center of the solar limb for the average wave length of the triplet interval. Such observations avoid the usual assumption about the source function constancy in line inside the line. On the contrary, the frequency dependence of this function is clarified by the use of this method. Calculations make it possible to determine the source function in line and its long-wave dependence inside the line; to derive a solar atmosphere model and to determine the source function in the continuous spectrum in accordance with observations at profile points in its middle part and in the wing; to find the relation between the selective and continuous absorption coefficients in the dependence on the optical depth in the continuous spectrum; and to find the long-wave dependences of coefficients for both the selective absorption and the selective emission at different optical depths

  10. Dark matter line emission constraints from NuSTAR observations of the Bullet Cluster

    DEFF Research Database (Denmark)

    Riemer-Sørensen, S.; Wik, D.; Madejski, G.

    2015-01-01

    Some dark matter candidates, e.g., sterile neutrinos, provide observable signatures in the form of mono-energetic line emission. We present the first search for dark matter line emission in the range in a pointed observation of the Bullet Cluster with NuSTAR. We do not detect any significant line...... emission and instead we derive upper limits (95% CL) on the flux, and interpret these constraints in the context of sterile neutrinos and more generic dark matter candidates. NuSTAR does not have the sensitivity to constrain the recently claimed line detection at , but improves on the constraints...... for energies of 10–25 keV....

  11. Geocoronal Balmer α line profile observations and forward-model analysis

    Science.gov (United States)

    Mierkiewicz, E. J.; Bishop, J.; Roesler, F. L.; Nossal, S. M.

    2006-05-01

    High spectral resolution geocoronal Balmer α line profile observations from Pine Bluff Observatory (PBO) are presented in the context of forward-model analysis. Because Balmer series column emissions depend significantly on multiple scattering, retrieval of hydrogen parameters of general aeronomic interest from these observations (e.g., the hydrogen column abundance) currently requires a forward modeling approach. This capability is provided by the resonance radiative transfer code LYAO_RT. We have recently developed a parametric data-model comparison search procedure employing an extensive grid of radiative transport model input parameters (defining a 6-dimensional parameter space) to map-out bounds for feasible forward model retrieved atomic hydrogen density distributions. We applied this technique to same-night (March, 2000) ground-based Balmer α data from PBO and geocoronal Lyman β measurements from the Espectrógrafo Ultravioleta extremo para la Radiación Difusa (EURD) instrument on the Spanish satellite MINISAT-1 (provided by J.F. Gómez and C. Morales of the Laboratorio de Astrofisica Espacial y Física Fundamental, INTA, Madrid, Spain) in order to investigate the modeling constraints imposed by two sets of independent geocoronal intensity measurements, both of which rely on astronomical calibration methods. In this poster we explore extending this analysis to the line profile information also contained in the March 2000 PBO Balmer α data set. In general, a decrease in the Doppler width of the Balmer α emission with shadow altitude is a persistent feature in every night of PBO observations in which a wide range of shadow altitudes are observed. Preliminary applications of the LYAO_RT code, which includes the ability to output Doppler line profiles for both the singly and multiply scattered contributions to the Balmer α emission line, displays good qualitative agreement with regard to geocoronal Doppler width trends observed from PBO. Model-data Balmer

  12. Detection of CS in Neptune's atmosphere from ALMA observations

    Science.gov (United States)

    Moreno, R.; Lellouch, E.; Cavalié, T.; Moullet, A.

    2017-12-01

    Context. The large and vertically non-uniform abundance of CO in Neptune's atmosphere has been interpreted as the result of past cometary impact(s), either single or distributed in size and time, which could also be at the origin of Neptune's HCN. Aims: We aim to provide observational support for this scenario by searching for other comet-induced species, in particular carbon sulfide (CS) which has been observed continuously in Jupiter since the 1994 Shoemaker-Levy 9 impacts. Methods: In April 2016 we used the ALMA interferometer to search for CS(7-6) at 342.883 GHz in Neptune. Results: We report on the detection of CS in Neptune's atmosphere, the first unambiguous observation of a sulfur-bearing species in a giant planet beyond Jupiter. Carbon sulfide appears to be present only at submillibar levels, with a column density of (2.0-3.1) × 1012 cm-2, and a typical mixing ratio of (2-20) × 10-11 that depends on its precise vertical location. The favoured origin of CS is deposition by a putative large comet impact several centuries ago, and the strong depletion of CS with respect to CO - compared to the Jupiter case - is likely due to the CS sticking to aerosols or clustering to form polymers in Neptune's lower stratosphere. Conclusions: The CS detection, along with recent analyses of the CO profile, reinforces the presumption of a large comet impact into Neptune 1000 yr ago, that delivered CO, CS, and HCN at the same time.

  13. Temporal characteristics of atmospheric ammonia and nitrogen dioxide over China based on emission data, satellite observations and atmospheric transport modeling since 1980

    Science.gov (United States)

    Liu, Lei; Zhang, Xiuying; Xu, Wen; Liu, Xuejun; Li, Yi; Lu, Xuehe; Zhang, Yuehan; Zhang, Wuting

    2017-08-01

    China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen (Nr). Atmospheric ammonia (NH3) and nitrogen dioxide (NO2) are the most important precursors for Nr compounds (including N2O5, HNO3, HONO and particulate NO3- and NH4+) in the atmosphere. Understanding the changes in NH3 and NO2 has important implications for the regulation of anthropogenic Nr emissions and is a requirement for assessing the consequence of environmental impacts. We conducted the temporal trend analysis of atmospheric NH3 and NO2 on a national scale since 1980 based on emission data (during 1980-2010), satellite observation (for NH3 since 2008 and for NO2 since 2005) and atmospheric chemistry transport modeling (during 2008-2015).Based on the emission data, during 1980-2010, significant continuous increasing trends in both NH3 and NOx were observed in REAS (Regional Emission inventory in Asia, for NH3 0.17 and for NOx 0.16 kg N ha-1 yr-2) and EDGAR (Emissions Database for Global Atmospheric Research, for NH3 0.24 and for NOx 0.17 kg N ha-1 yr-2) over China. Based on the satellite data and atmospheric chemistry transport model (CTM) MOZART-4 (Model for Ozone and Related chemical Tracers, version 4), the NO2 columns over China increased significantly from 2005 to 2011 and then decreased significantly from 2011 to 2015; the satellite-retrieved NH3 columns from 2008 to 2014 increased at a rate of 2.37 % yr-1. The decrease in NO2 columns since 2011 may result from more stringent strategies taken to control NOx emissions during the 12th Five Year Plan, while no control policy has focused on NH3 emissions. Our findings provided an overall insight into the temporal trends of both NO2 and NH3 since 1980 based on emission data, satellite observations and atmospheric transport modeling. These findings can provide a scientific background for policy makers that are attempting to control atmospheric pollution in China. Moreover, the multiple datasets

  14. A Ground-based validation of GOSAT-observed atmospheric CO2 in Inner-Mongolian grasslands

    International Nuclear Information System (INIS)

    Qin, X; Lei, L; Zeng, Z; Kawasaki, M; Oohasi, M

    2014-01-01

    Atmospheric carbon dioxide (CO 2 ) is a long-lived greenhouse gas that significantly contributes to global warming. Long-term and continuous measurements of atmospheric CO 2 to investigate its global distribution and concentration variations are important for accurately understanding its potential climatic effects. Satellite measurements from space can offer atmospheric CO 2 data for climate change research. For that, ground-based measurements are required for validation and improving the precision of satellite-measured CO 2 . We implemented observation experiment of CO 2 column densities in the Xilinguole grasslands in Inner Mongolia, China, using a ground-based measurement system, which mainly consists of an optical spectrum analyzer (OSA), a sun tracker and a notebook controller. Measurements from our ground-based system were analyzed and compared with those from the Greenhouse gas Observation SATellite (GOSAT). The ground-based measurements had an average value of 389.46 ppm, which was 2.4 ppm larger than from GOSAT, with a standard deviation of 3.4 ppm. This result is slightly larger than the difference between GOSAT and the Total Carbon Column Observing Network (TCCON). This study highlights the usefulness of the ground-based OSA measurement system for analyzing atmospheric CO 2 column densities, which is expected to supplement the current TCCON network

  15. Filling-in of Near-infrared Solar Lines by Terrestrial Fluorescence and Other Geophysical Effects: Simulations and Space-based Observations from SCIAMACHY and GOSAT

    Science.gov (United States)

    Joiner, Joanna (Editor); Yoshida, Yasuko; Vasilkov, A. P.; Middleton, E. M. (Editor); Campbell, P. K. E.; Yoshida, Y.; Huze, A.; Corp, L. A.

    2012-01-01

    Global mapping of terrestrial vegetation fluorescence from space has recently been accomplished with high spectral resolution (nu/nu greater than 35 000) measurements from the Japanese Greenhouse gases Observing SAellite (GOSAT). These data are of interest because they can potentially provide global information on the functional status of vegetation including light-use efficiency and global primary productivity that can be used for global carbon cycle modeling. Quantifying the impact of fluorescence on the O2-A band is important as this band is used for photon pathlength characterization in cloud- and aerosol-contaminated pixels for trace-gas retrievals including CO2. Here, we examine whether fluorescence information can be derived from space using potentially lower-cost hyperspectral instrumentation, i.e., more than an order of magnitude less spectral resolution (nu/nu approximately 1600) than GOSAT, with a relatively simple algorithm. We discuss laboratory measurements of fluorescence near one of the few wide and deep solar Fraunhofer lines in the long-wave tail of the fluorescence emission region, the calcium (Ca) II line at 866 nm that is observable with a spectral resolution of approximately 0.5 nm. The filling-in of the Ca II line due to additive signals from various atmospheric and terrestrial effects, including fluorescence, is simulated. We then examine filling-in of this line using the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) satellite instrument. In order to interpret the satellite measurements, we developed a general approach to correct for various instrumental artifacts that produce false filling-in of solar lines in satellite measurements. The approach is applied to SCIAMACHY at the 866 nm Ca II line and to GOSAT at 758 and 770 nm on the shoulders of the O2-A feature where there are several strong solar Fraunhofer lines that are filled in primarily by vegetation fluorescence. Finally, we compare temporal and

  16. Coordinated observation of field line resonance in the mid-tail

    Directory of Open Access Journals (Sweden)

    Y. Zheng

    2006-03-01

    Full Text Available Standing Alfvén waves of 1.1 mHz (~15 min in period were observed by the Cluster satellites in the mid-tail during 06:00-07:00 UT on 8 August 2003. Pulsations with the same frequency were also observed at several ground stations near Cluster's footpoint. The standing wave properties were determined from the electric and magnetic field measurements of Cluster. Data from the ground magnetometers indicated a latitudinal amplitude and phase structure consistent with the driven field line resonance (FLR at 1.1 mHz. Simultaneously, quasi-periodic oscillations at different frequencies were observed in the post-midnight/early morning sector by GOES 12 (l0≈8.7, Polar (l0≈11-14 and Geotail (l0≈9.8. The 8 August 2003 event yields rare and interesting datasets. It provides, for the first time, coordinated in situ and ground-based observations of a very low frequency FLR in the mid-tail on stretched field lines.

  17. Estimating Terrestrial Wood Biomass from Observed Concentrations of Atmospheric Carbon Dioxide

    NARCIS (Netherlands)

    Schaefer, K. M.; Peters, W.; Carvalhais, N.; van der Werf, G.; Miller, J.

    2008-01-01

    We estimate terrestrial disequilibrium state and wood biomass from observed concentrations of atmospheric CO2 using the CarbonTracker system coupled to the SiBCASA biophysical model. Starting with a priori estimates of carbon flux from the land, ocean, and fossil fuels, CarbonTracker estimates net

  18. A non-local thermodynamic equilibrium, line-blanketed synthetic spectrum of Iota Herculis - C, Al, and Si lines

    Science.gov (United States)

    Grigsby, James A.

    1991-01-01

    A non-LTE line-blanketed model stellar atmosphere is used to compute a model of I Herculis (B3 IV) with a Teff of 17,500 K and a log g of 3.75, following the conclusions of Peters and Polidan (1985). Detailed profiles of a number of lines of C, Al, and Si in the 1200-2000-A region are computed, including the resonance lines of C II, Al II, and Al III. These profiles are compared to observations obtained from the coaddition of eight IUE SWP images, using a technique developed by Leckrone and Adelman (1989). Comparison of carbon lines with a model that is underabundant in carbon by a factor of 2 relative to the sun indicates that the C abundance of Iota Her is at most one-half solar. Non-LTE effects are examined by comparing an LTE model possessing identical atmospheric parameters with the non-LTE model. Substantial differences in the populations of the model atomic states are found, but differences in the temperature structure of the two models often mask the non-LTE effects in the synthetic spectra.

  19. OT2_smalhotr_3: Herschel Extreme Lensing Line Observations (HELLO)

    Science.gov (United States)

    Malhotra, S.

    2011-09-01

    We request 59.8 hours of Herschel time to observe 20 normal star-forming galaxies in the [CII] 158 micron and [OI] 63 micron lines. These galaxies lie at high redshift (1observations of [CII], [OI], or both. Herschel offers the unique opportunity to study both lines with high sensitivity throughout this epoch (using HIFI for [CII] and PACS for [OI]). These two lines are the main cooling lines of the atomic medium. By measuring their fluxes, we will measure (1) the cooling efficiency of gas, (2) gas densities and temperatures near starforming regions, and (3) gas pressures, which are important to drive the winds that provide feedback to starformation processes. By combining the proposed observations with existing multiwavelength data on these objects, we will obtain as complete a picture of galaxy-scale star formation and ISM physical conditions at high redshifts as we have at z=0. Then perhaps we can understand why star formation and AGN activity peaked at this epoch. In Herschel cycle OT1, 49 high redshift IR luminous galaxies were approved for spectroscopy, but only two so-called normal galaxies were included. This is an imbalance that should be corrected, to balance Herschel's legacy.

  20. Characterization of the gamma radiation in space and in the atmosphere

    International Nuclear Information System (INIS)

    Lee, M.A.

    1986-05-01

    A characterization of the gamma-ray fields found in space and in the atmosphere is given. Included are values for the energies and intensities of gamma rays as observed in several experiments and reported in the open literature. Characteristics of the diffuse gamma-ray continuum are presented along with a brief discussion of the sources of this radiation. Also given are discrete gamma-ray line energies and intensities which have been observed in space and in the atmosphere. 37 refs., 7 figs., 12 tabs

  1. Atmospheric structure and helium abundance on Saturn from Cassini/UVIS and CIRS observations

    Science.gov (United States)

    Koskinen, T. T.; Guerlet, S.

    2018-06-01

    We combine measurements from stellar occultations observed by the Cassini Ultraviolet Imaging Spectrograph (UVIS) and limb scans observed by the Composite Infrared Spectrometer (CIRS) to create empirical atmospheric structure models for Saturn corresponding to the locations probed by the occultations. The results cover multiple locations at low to mid-latitudes between the spring of 2005 and the fall of 2015. We connect the temperature-pressure (T-P) profiles retrieved from the CIRS limb scans in the stratosphere to the T-P profiles in the thermosphere retrieved from the UVIS occultations. We calculate the altitudes corresponding to the pressure levels in each case based on our best fit composition model that includes H2, He, CH4 and upper limits on H. We match the altitude structure to the density profile in the thermosphere that is retrieved from the occultations. Our models depend on the abundance of helium and we derive a volume mixing ratio of 11 ± 2% for helium in the lower atmosphere based on a statistical analysis of the values derived for 32 different occultation locations. We also derive the mean temperature and methane profiles in the upper atmosphere and constrain their variability. Our results are consistent with enhanced heating at the polar auroral region and a dynamically active upper atmosphere.

  2. Simultaneous Observations of Atmospheric Tides from Combined in Situ and Remote Observations at Mars from the MAVEN Spacecraft

    Science.gov (United States)

    England, Scott L.; Liu, Guiping; Withers, Paul; Yigit, Erdal; Lo, Daniel; Jain, Sonal; Schneider, Nicholas M. (Inventor); Deighan, Justin; McClintock, William E.; Mahaffy, Paul R.; hide

    2016-01-01

    We report the observations of longitudinal variations in the Martian thermosphere associated with nonmigrating tides. Using the Neutral Gas Ion Mass Spectrometer (NGIMS) and the Imaging Ultraviolet Spectrograph (IUVS) on NASA's Mars Atmosphere and Volatile EvolutioN Mission (MAVEN) spacecraft, this study presents the first combined analysis of in situ and remote observations of atmospheric tides at Mars for overlapping volumes, local times, and overlapping date ranges. From the IUVS observations, we determine the altitude and latitudinal variation of the amplitude of the nonmigrating tidal signatures, which is combined with the NGIMS, providing information on the compositional impact of these waves. Both the observations of airglow from IUVS and the CO2 density observations from NGIMS reveal a strong wave number 2 signature in a fixed local time frame. The IUVS observations reveal a strong latitudinal dependence in the amplitude of the wave number 2 signature. Combining this with the accurate CO2 density observations from NGIMS, this would suggest that the CO2 density variation is as high as 27% at 0-10 deg latitude. The IUVS observations reveal little altitudinal dependence in the amplitude of the wave number 2 signature, varying by only 20% from 160 to 200 km. Observations of five different species with NGIMS show that the amplitude of the wave number 2 signature varies in proportion to the inverse of the species scale height, giving rise to variation in composition as a function of longitude. The analysis and discussion here provide a roadmap for further analysis as additional coincident data from these two instruments become available.

  3. A non-local thermodynamical equilibrium line formation for neutral and singly ionized titanium in model atmospheres of reference A-K stars

    Science.gov (United States)

    Sitnova, T. M.; Mashonkina, L. I.; Ryabchikova, T. A.

    2016-09-01

    We construct a model atom for Ti I-II using more than 3600 measured and predicted energy levels of Ti I and 1800 energy levels of Ti II, and quantum mechanical photoionization cross-sections. Non-local thermodynamical equilibrium (NLTE) line formation for Ti I and Ti II is treated through a wide range of spectral types from A to K, including metal-poor stars with [Fe/H] down to -2.6 dex. NLTE leads to weakened Ti I lines and positive abundance corrections. The magnitude of NLTE corrections is smaller compared to the literature data for FGK atmospheres. NLTE leads to strengthened Ti II lines and negative NLTE abundance corrections. For the first time, we have performed NLTE calculations for Ti I-II in the 6500 ≤ Teff ≤ 13 000 K range. For four A-type stars, we derived in LTE an abundance discrepancy of up to 0.22 dex between Ti I and Ti II, which vanishes in NLTE. For four other A-B stars, with only Ti II lines observed, NLTE leads to a decrease of line-to-line scatter. An efficiency of inelastic Ti I + H I collisions was estimated from an analysis of Ti I and Ti II lines in 17 cool stars with -2.6 ≤ [Fe/H] ≤ 0.0. Consistent NLTE abundances from Ti I and Ti II were obtained by applying classical Drawinian rates for the stars with log g ≥ 4.1, and neglecting inelastic collisions with H I for the very metal-poor (VMP) giant HD 122563. For the VMP turn-off stars ([Fe/H] ≤ -2 and log g ≤ 4.1), we obtained the positive abundance difference Ti I-II already in LTE, which increases in NLTE. Accurate collisional data for Ti I and Ti II are necessary to help solve this problem.

  4. First observation of the fourth neutral polarization point in the atmosphere

    Science.gov (United States)

    Horvath, Gabor; Bernath, Balazs; Suhai, Bence; Barta, Andras; Wehner, Rudiger

    2002-10-01

    In the clear sky there are three commonly known loci, the Arago, Babinet, and Brewster neutral points, where the skylight is unpolarized. These peculiar celestial points, bearing the names of their discoverers, have been the subject of many ground-based investigations, because their positions are sensitive indicators of the amount and type of atmospheric turbidity. According to theoretical considerations and computer simulations, there should exist an additional neutral point approximately opposite to the Babinet point, which can be observed only at higher altitudes in the air or space. Until now, this anonymous fourth neutral point has not been observed during air- or space-borne polarimetric experiments and has been forgotten, in spite of the fact that the neutral points were a basic tool in atmospheric research for a century. Here, we report on the first observation of this fourth neutral point from a hot air balloon. Using 180-field-of-view imaging polarimetry, we could observe the fourth neutral point at 450, 550, and 650 nm from different altitudes between 900 and 3500 m during and after sunrise at approximately 2240 below the anti-solar point along the anti-solar meridian, depending on the wavelength and solar elevation. We show that the fourth neutral point exists at the expected location and has characteristics similar to those of the Arago, Babinet, and Brewster points. We discuss why the fourth neutral point has not been observed in previous air- or space-borne polarimetric experiments. 2002 Optical Society of America

  5. Statistical simulation of information transfer through non-line-of-sight atmospheric optical communication channels

    Science.gov (United States)

    Tarasenkov, M. V.; Belov, V. V.; Poznakharev, E. S.

    2017-11-01

    Impulse response of non-line-of-sight atmospheric communication channels at wavelengths of 0.3, 0.5, and 0.9 μm are compared for the case in which the optical axes of the receiver and laser radiation lie in the plane perpendicular to the Earth's surface. The most efficient communication channel depending on the base distance is determined. For a wavelength of 0.5 μm and a concrete variant of the transceiving part of the communication system, the limiting communication range and the limiting repetition frequency of pulses that can be transmitted through the communication channel are estimated.

  6. Evaluation and Improvement of Polar WRF simulations using the observed atmospheric profiles in the Arctic seasonal ice zone

    Science.gov (United States)

    Liu, Z.; Schweiger, A. J. B.

    2016-12-01

    We use the Polar Weather Research and Forecasting (WRF) model to simulate atmospheric conditions during the Seasonal Ice Zone Reconnaissance Survey (SIZRS) over the Beaufort Sea in the summer since 2013. With the 119 SIZRS dropsondes in the18 cross sections along the 150W and 140W longitude lines, we evaluate the performance of WRF simulations and two forcing data sets, the ERA-Interim reanalysis and the Global Forecast System (GFS) analysis, and explore the improvement of the Polar WRF performance when the dropsonde data are assimilated using observation nudging. Polar WRF, ERA-Interim, and GFS can reproduce the general features of the observed mean atmospheric profiles, such as low-level temperature inversion, low-level jet (LLJ) and specific humidity inversion. The Polar WRF significantly improves the mean LLJ, with a lower and stronger jet and a larger turning angle than the forcing, which is likely related to the lower values of the boundary layer diffusion in WRF than in the global models such as ECMWF and GFS. The Polar WRF simulated relative humidity closely resembles the forcing datasets while having large biases compared to observations. This suggests that the performance of Polar WRF and its forecasts in this region are limited by the quality of the forcing dataset and that the assimilation of more and better-calibrated observations, such as humidity data, is critical for their improvement. We investigate the potential of assimilating the SIZRS dropsonde dataset in improving the weather forecast over the Beaufort Sea. A simple local nudging approach is adopted. Along SIZRS flight cross sections, a set of Polar WRF simulations are performed with varying number of variables and dropsonde profiles assimilated. Different model physics are tested to examine the sensitivity of different aspects of model physics, such as boundary layer schemes, cloud microphysics, and radiation parameterization, to data assimilation. The comparison of the Polar WRF runs with

  7. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. V. ALFVÉN IONIZATION

    International Nuclear Information System (INIS)

    Stark, C. R.; Helling, Ch.; Rimmer, P. B.; Diver, D. A.

    2013-01-01

    Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient to qualify the ionized component as a plasma, posing the question: what ionization processes can efficiently produce the required plasma that is the source of the radiation? We propose Alfvén ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization (≥10 –7 ) that they constitute plasmas. We outline the criteria required for Alfvén ionization and demonstrate its applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs, and M dwarfs with both solar and sub-solar metallicities. We find that Alfvén ionization is most efficient at mid to low atmospheric pressures where a seed plasma is easier to magnetize and the pressure gradients needed to drive the required neutral flows are the smallest. For the model atmospheres considered, our results show that degrees of ionization of 10 –6 -1 can be obtained as a result of Alfvén ionization. Observable consequences include continuum bremsstrahlung emission, superimposed with spectral lines from the plasma ion species (e.g., He, Mg, H 2 , or CO lines). Forbidden lines are also expected from the metastable population. The presence of an atmospheric plasma opens the door to a multitude of plasma and chemical processes not yet considered in current atmospheric models. The occurrence of Alfvén ionization may also be applicable to other astrophysical environments such as protoplanetary disks

  8. Temporal characteristics of atmospheric ammonia and nitrogen dioxide over China based on emission data, satellite observations and atmospheric transport modeling since 1980

    Directory of Open Access Journals (Sweden)

    L. Liu

    2017-08-01

    Full Text Available China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen (Nr. Atmospheric ammonia (NH3 and nitrogen dioxide (NO2 are the most important precursors for Nr compounds (including N2O5, HNO3, HONO and particulate NO3− and NH4+ in the atmosphere. Understanding the changes in NH3 and NO2 has important implications for the regulation of anthropogenic Nr emissions and is a requirement for assessing the consequence of environmental impacts. We conducted the temporal trend analysis of atmospheric NH3 and NO2 on a national scale since 1980 based on emission data (during 1980–2010, satellite observation (for NH3 since 2008 and for NO2 since 2005 and atmospheric chemistry transport modeling (during 2008–2015.Based on the emission data, during 1980–2010, significant continuous increasing trends in both NH3 and NOx were observed in REAS (Regional Emission inventory in Asia, for NH3 0.17 and for NOx 0.16 kg N ha−1 yr−2 and EDGAR (Emissions Database for Global Atmospheric Research, for NH3 0.24 and for NOx 0.17 kg N ha−1 yr−2 over China. Based on the satellite data and atmospheric chemistry transport model (CTM MOZART-4 (Model for Ozone and Related chemical Tracers, version 4, the NO2 columns over China increased significantly from 2005 to 2011 and then decreased significantly from 2011 to 2015; the satellite-retrieved NH3 columns from 2008 to 2014 increased at a rate of 2.37 % yr−1. The decrease in NO2 columns since 2011 may result from more stringent strategies taken to control NOx emissions during the 12th Five Year Plan, while no control policy has focused on NH3 emissions. Our findings provided an overall insight into the temporal trends of both NO2 and NH3 since 1980 based on emission data, satellite observations and atmospheric transport modeling. These findings can provide a scientific background for policy makers that are attempting to control atmospheric

  9. [Observation on atmospheric pollution in Xianghe during Beijing 2008 Olympic Games].

    Science.gov (United States)

    Pan, Yue-Peng; Wang, Yue-Si; Hu, Bo; Liu, Quan; Wang, Ying-Hong; Nan, Wei-Dong

    2010-01-01

    There is a concern that much of the atmospheric pollution experienced in Beijing is regional in nature and not attributable to local sources. The objective of this study is to examine the contribution of sources outside Beijing to atmospheric pollution levels during Beijing 2008 Olympic Games. The observations of SO2, NO(x), O3, PM2.5 and PM10 were conducted from June 1 to September 30, 2008 in Xianghe, a rural site about 70 km southeast of Beijing. Sources and transportation of atmospheric pollution during the experiment were discussed with surface meteorology data and backward trajectories calculated using HYSPLIT model. The results showed that the daily average maximum (mean +/- standard deviation) concentrations of SO2, NO(x), O3, PM2.5, and PM10 during observation reached 84.4(13.4 +/- 15.2), 43.3 (15.9 +/- 9.1), 230 (82 +/- 38), 184 (76 +/- 42) and 248 (113 +/- 52) microg x m(-3), respectively. In particular, during the pollution episodes from July 20 to August 12, the hourly average concentration of O3 exceeded the National Ambient Air Quality Standard II for 46 h (9%), and the daily average concentration of PM10 exceeded the Standard for 11 d (46%); PM2.5 exceeded the US EPA Standard for 18 d (75%). The daily average concentrations of SO2, NO(x), O3, PM2.5 and PM10 decreased from 27.7, 18.6, 96, 90, 127 microg x m(-3) in June-July to 5.8, 13.2, 80, 60, 106 microg x m(-3) during Olympic Games (August-September), respectively. The typical diurnal variations of NO(x), PM2.5 and PM10 were similar, peaking at 07:00 and 20:00, while the maximum of O3 occurred between 14:00 to 16:00 local time. The findings also suggested that the atmospheric pollution in Xianghe is related to local emission, regional transport as well as the meteorological conditions. Northerly wind and precipitation are favorable for diffusion and wet deposition of pollutants, while sustained south flows make the atmospheric pollution more serious. The lead-lag correlation analysis during the

  10. High Voltage Overhead Power Line Routing under an Objective Observability Criterion

    Directory of Open Access Journals (Sweden)

    L. Alfredo Fernandez-Jimenez

    2017-10-01

    Full Text Available The construction of new high voltage overhead power lines (HVOPLs has become a controversial issue for electricity companies due to social opposition. Citizens are concerned about how these power lines may have an impact on their lives, basically caused by their effects on health and safety. Visual impact is one of the most easily perceived. Although there are several published works that deal with the assessment of the visual impact produced by HVOPLs, no methodology has been proposed to assess this impact from an objective perspective. This work presents an original methodology which helps to identify the optimal routes for a new HVOPL under an objective observability criterion, enabling the selection of those with the lowest visibility in a zone. The application of the proposed methodology achieves a set of routes that links new HVOPL origin and destination points creating a corridor which includes all possible routes with an observability of its towers under a threshold limit. This methodology is illustrated by a real-life use corresponding to the selection of the route with least observability for a new power line in La Rioja (Spain. The results obtained may help to achieve a consensus between key stakeholders since it is focused on the specific issues of the planned HVOPL and its observability from an objective perspective.

  11. Modeling Exoplanetary Atmospheres using BART, TEA, and Drift-RHD; Theoretical studies and Observational Implications

    Science.gov (United States)

    Dobbs-Dixon, Ian

    The explosion in the number of exoplanets detected to date has revealed a surprising diversity. When attempting to model this diversity, it is crucial to account for the uncertainties resulting from our limited knowledge of chemical, dynamical, and cloud formation processes in their atmospheres. Combining a retrieval technique with theorydriven models is a particularly promising way to address these processes and constrain a physically plausible atmospheric structure. In particular, a detailed micro-physical treatment of clouds and the longitudinal and latitudinal assessments of temperature and chemical profiles, have yet to be addressed in the field. Our team members are experts in radiative-hydrodynamic modeling (Dr. Ian DobbsDixon), cloud kinetics (Dr. Christiana Helling), retrievals and thermo-equilibrium chemistry (Dr. Jasmina Blecic), and observational diagnostics and predictions (Dr. Thomas Greene). The key goals of this proposal are to extend our understanding of the 3D atmospheric structure of gas-giant exoplanets by coupling state-of-the-art selfconsistent models together with a retrieval framework to 1) address cloud kinetics in retrievals, 2) assess 3D temperature and chemical structures in retrievals, 3) model a suite of well-observed planets within the framework of our models, and 4) make observational predictions for current and future NASA missions. To address these goals we have developed a number of tools: Drift-RHD, TEA, BART, and OBS. Drift-RHD solves both the 3D radiative-hydrodynamic equations and a time dependent kinetic cloud model. TEA, Thermochemical Equilibrium Abundances, calculates abundances of chemical species present in the atmosphere. BART, a Bayesian Atmospheric Radiative Transfer code, is a statistical retrieval framework to explore the parameter space of atmospheric chemical abundances and thermal profiles. OBS is a suite of tools developed to simulate observations. Though these tools exist and have been utilized independently in

  12. SUMO: A small unmanned meteorological observer for atmospheric boundary layer research

    International Nuclear Information System (INIS)

    Reuder, J; Jonassen, M; Mayer, S; Brisset, P; Mueller, M

    2008-01-01

    A new system for atmospheric measurements in the lower troposphere has been developed and successfully tested. The presented Small Unmanned Meteorological Observer (SUMO) is based on a light-weighted commercially available model airplane, equipped with an autopilot and meteorological sensors for temperature, humidity and pressure. During the 5 week field campaign FLOHOF (Flow over and around HofsjoUkull) in Central Iceland the system has been successfully tested in July/August 2007. Atmospheric profiles of temperature, humidity, wind speed and wind direction have been determined up to 3500 m above ground. In addition the applicability of SUMO for horizontal surveys up to 4 km away from the launch site has been approved. During a 3 week campaign on and around Spitsbergen in February/March 2008 the SUMO system also proved its functionality under harsh polar conditions, reaching altitudes above 1500 m at ground temperatures of -20 deg. C and wind speeds up to 15 m s -1 . With its wingspan of 80 cm, its length of 75 cm and its weight of below 600 g, SUMO is easy to transport and operate even in remote areas. The direct material costs for one SUMO unit, including airplane, autopilot and sensors are below 1200 Euro. Assuming at least several tenths of flights for each airframe, SUMO provides a cost-efficient measurement system with a large potential to close the existing observational gap of reasonable atmospheric measurement systems in between meteorological masts/towers and radiosondes

  13. SUMO: A small unmanned meteorological observer for atmospheric boundary layer research

    Energy Technology Data Exchange (ETDEWEB)

    Reuder, J; Jonassen, M; Mayer, S [Geophysical Institute, University of Bergen, Allegaten 70, 5009 Bergen (Norway); Brisset, P [Ecole Nationale de l' Aviation Civile (ENAC), 7 avenue Edouard Belin, 31055 Toulouse (France); Mueller, M [Orleansstrasse 26a, 31135 Hildesheim (Germany)], E-mail: joachim.reuder@gfi.uib.no, E-mail: pascal.brisset@enac.fr, E-mail: marius.jonassen@gfi.uib.no, E-mail: martin@pfump.org, E-mail: stephanie.mayer@gfi.uib.no

    2008-05-01

    A new system for atmospheric measurements in the lower troposphere has been developed and successfully tested. The presented Small Unmanned Meteorological Observer (SUMO) is based on a light-weighted commercially available model airplane, equipped with an autopilot and meteorological sensors for temperature, humidity and pressure. During the 5 week field campaign FLOHOF (Flow over and around HofsjoUkull) in Central Iceland the system has been successfully tested in July/August 2007. Atmospheric profiles of temperature, humidity, wind speed and wind direction have been determined up to 3500 m above ground. In addition the applicability of SUMO for horizontal surveys up to 4 km away from the launch site has been approved. During a 3 week campaign on and around Spitsbergen in February/March 2008 the SUMO system also proved its functionality under harsh polar conditions, reaching altitudes above 1500 m at ground temperatures of -20 deg. C and wind speeds up to 15 m s{sup -1}. With its wingspan of 80 cm, its length of 75 cm and its weight of below 600 g, SUMO is easy to transport and operate even in remote areas. The direct material costs for one SUMO unit, including airplane, autopilot and sensors are below 1200 Euro. Assuming at least several tenths of flights for each airframe, SUMO provides a cost-efficient measurement system with a large potential to close the existing observational gap of reasonable atmospheric measurement systems in between meteorological masts/towers and radiosondes.

  14. Coupled atmosphere and land-surface assimilation of surface observations with a single column model and ensemble data assimilation

    Science.gov (United States)

    Rostkier-Edelstein, Dorita; Hacker, Joshua P.; Snyder, Chris

    2014-05-01

    Numerical weather prediction and data assimilation models are composed of coupled atmosphere and land-surface (LS) components. If possible, the assimilation procedure should be coupled so that observed information in one module is used to correct fields in the coupled module. There have been some attempts in this direction using optimal interpolation, nudging and 2/3DVAR data assimilation techniques. Aside from satellite remote sensed observations, reference height in-situ observations of temperature and moisture have been used in these studies. Among other problems, difficulties in coupled atmosphere and LS assimilation arise as a result of the different time scales characteristic of each component and the unsteady correlation between these components under varying flow conditions. Ensemble data-assimilation techniques rely on flow dependent observations-model covariances. Provided that correlations and covariances between land and atmosphere can be adequately simulated and sampled, ensemble data assimilation should enable appropriate assimilation of observations simultaneously into the atmospheric and LS states. Our aim is to explore assimilation of reference height in-situ temperature and moisture observations into the coupled atmosphere-LS modules(simultaneously) in NCAR's WRF-ARW model using the NCAR's DART ensemble data-assimilation system. Observing system simulation experiments (OSSEs) are performed using the single column model (SCM) version of WRF. Numerical experiments during a warm season are centered on an atmospheric and soil column in the South Great Plains. Synthetic observations are derived from "truth" WRF-SCM runs for a given date,initialized and forced using North American Regional Reanalyses (NARR). WRF-SCM atmospheric and LS ensembles are created by mixing the atmospheric and soil NARR profile centered on a given date with that from another day (randomly chosen from the same season) with weights drawn from a logit-normal distribution. Three

  15. Observations of atmospheric Hg species and depositions in remote areas of China

    Directory of Open Access Journals (Sweden)

    Feng X.

    2013-04-01

    Full Text Available From September 2007, we conducted continuous measurements of speciated atmospheric mercury (Hg and atmospheric mercury depositions at five remote sites in China. Four of these sites were involved in the Global Mercury Observation System (GMOS as ground-based stations. These stations were located in the northwest, southwest, northeast, and east part of China, respectively, which represent the regional atmospheric Hg budgets in different areas of China. The preliminary results showed that mean TGM concentrations were in the range of 1.60 – 2.88 ng m-3, with relatively higher levels observed at sites in Eastern China and Southwestern China and lower levels at sites in Northeastern and Northwestern China. TGM concentrations at remote sites of China were also higher than those reported from background sites in North America and Europe, and this is corresponding very well with the Chinese great anthropogenic Hg emissions. Gaseous oxidized mercury (GOM and particulate bounded mercury (PBM were in the ranges of 3.2 – 7.4 pg m−3 and 19.4 – 43.5 pg m-3, respectively. The preliminary result on precipitation showed mean precipitation THg concentrations were in the range of 2.7 – 18.0 ng L-1.

  16. Global Hawk dropsonde observations of the Arctic atmosphere obtained during the Winter Storms and Pacific Atmospheric Rivers (WISPAR field campaign

    Directory of Open Access Journals (Sweden)

    J. M. Intrieri

    2014-11-01

    Full Text Available In February and March of 2011, the Global Hawk unmanned aircraft system (UAS was deployed over the Pacific Ocean and the Arctic during the Winter Storms and Pacific Atmospheric Rivers (WISPAR field campaign. The WISPAR science missions were designed to (1 mprove our understanding of Pacific weather systems and the polar atmosphere; (2 evaluate operational use of unmanned aircraft for investigating these atmospheric events; and (3 demonstrate operational and research applications of a UAS dropsonde system at high latitudes. Dropsondes deployed from the Global Hawk successfully obtained high-resolution profiles of temperature, pressure, humidity, and wind information between the stratosphere and surface. The 35 m wingspan Global Hawk, which can soar for ~ 31 h at altitudes up to ~ 20 km, was remotely operated from NASA's Dryden Flight Research Center at Edwards Air Force Base (AFB in California. During the 25 h polar flight on 9–10 March 2011, the Global Hawk released 35 sondes between the North Slope of Alaska and 85° N latitude, marking the first UAS Arctic dropsonde mission of its kind. The polar flight transected an unusually cold polar vortex, notable for an associated record-level Arctic ozone loss, and documented polar boundary layer variations over a sizable ocean–ice lead feature. Comparison of dropsonde observations with atmospheric reanalyses reveal that, for this day, large-scale structures such as the polar vortex and air masses are captured by the reanalyses, while smaller-scale features, including low-level jets and inversion depths, are mischaracterized. The successful Arctic dropsonde deployment demonstrates the capability of the Global Hawk to conduct operations in harsh, remote regions. The limited comparison with other measurements and reanalyses highlights the potential value of Arctic atmospheric dropsonde observations where routine in situ measurements are practically nonexistent.

  17. Millimeter Wave Atmospheric Radiometry Observations.

    Science.gov (United States)

    1981-03-27

    structure of the atmosphere would be very important. Rufton [20] combined thermal sensor technology for microthermal measurements with radiosonde...fromT2 h n relationships with CT(h) at least for optical effects. Bufton obtained the mean-square temperature difference between two microthermal probes

  18. Atmospheric extinction coefficients and night sky brightness at the Xuyi Observation Station

    International Nuclear Information System (INIS)

    Zhang Hui-Hua; Liu Xiao-Wei; Zhang Hua-Wei; Xiang Mao-Sheng; Yuan Hai-Bo; Zhao Hai-Bin; Yao Jin-Sheng

    2013-01-01

    We present measurements of the optical broadband atmospheric extinction coefficients and the night sky brightness at the Xuyi Observation Station of Purple Mountain Observatory. The measurements are based on CCD imaging data taken in the Sloan Digital Sky Survey's g, r and i bands with the Xuyi 1.04/1.20 m Schmidt Telescope for the Xuyi Schmidt Telescope Photometric Survey of the Galactic Anti-center (XSTPS-GAC), the photometric part of the Digital Sky Survey of the Galactic Anti-center (DSS-GAC). The data were collected during more than 140 winter nights from 2009 to 2011. We find that the atmospheric extinction coefficients for the g, r and i bands are 0.69, 0.55 and 0.38 mag/airmass, respectively, based on observations taken on several photometric nights. The night sky brightness determined from images with good quality has median values of 21.7, 20.8 and 20.0 mag arcsec −2 and reaches 22.1, 21.2 and 20.4 mag arcsec −2 under the best observing conditions for the g, r and i bands, respectively. The relatively large extinction coefficients compared with other good astronomical observing sites are mainly due to the relatively low elevation (i.e. 180 m) and high humidity at the station.

  19. Implementing earth observation and advanced satellite based atmospheric sounders for water resource and climate modelling

    DEFF Research Database (Denmark)

    Boegh, E.; Dellwik, Ebba; Hahmann, Andrea N.

    2010-01-01

    This paper discusses preliminary remote sensing (MODIS) based hydrological modelling results for the Danish island Sjælland (7330 km2) in relation to project objectives and methodologies of a new research project “Implementing Earth observation and advanced satellite based atmospheric sounders....... For this purpose, a) internal catchment processes will be studied using a Distributed Temperature Sensing (DTS) system, b) Earth observations will be used to upscale from field to regional scales, and c) at the largest scale, satellite based atmospheric sounders and meso-scale climate modelling will be used...

  20. Information Content Analysis for Selection of Optimal JWST  Observing Modes for Transiting Exoplanet Atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Batalha, Natasha E. [Department of Astronomy and Astrophysics, Pennsylvania State University, State College, PA 16802 (United States); Line, M. R., E-mail: neb149@psu.edu [School of Earth and Space Exploration, Arizona State University, Phoenix, AZ 85282 (United States)

    2017-04-01

    The James Webb Space Telescope ( JWST ) is nearing its launch date of 2018, and is expected to revolutionize our knowledge of exoplanet atmospheres. In order to specifically identify which observing modes will be most useful for characterizing a diverse range of exoplanetary atmospheres, we use an information content (IC) based approach commonly used in the studies of solar system atmospheres. We develop a system based upon these IC methods to trace the instrumental and atmospheric model phase space in order to identify which observing modes are best suited for particular classes of planets, focusing on transmission spectra. Specifically, the atmospheric parameter space we cover is T  = 600–1800 K, C/O = 0.55–1, [M/H] = 1–100 × Solar for an R  = 1.39 R{sub J}, M  = 0.59 M{sub J} planet orbiting a WASP-62-like star. We also explore the influence of a simplified opaque gray cloud on the IC. We find that obtaining broader wavelength coverage over multiple modes is preferred over higher precision in a single mode given the same amount of observing time. Regardless of the planet temperature and composition, the best modes for constraining terminator temperatures, C/O ratios, and metallicity are NIRISS SOSS+NIRSpec G395. If the target’s host star is dim enough such that the NIRSpec prism is applicable, then it can be used instead of NIRISS SOSS+NIRSpec G395. Lastly, observations that use more than two modes should be carefully analyzed because sometimes the addition of a third mode results in no gain of information. In these cases, higher precision in the original two modes is favorable.

  1. An Operator Perturbation Method of Polarized Line Transfer V ...

    Indian Academy of Sciences (India)

    tribpo

    imate Lambda Iteration) method to the resonance scattering in spectral lines formed in the presence of weak magnetic fields. The method is based on an operator perturbation approach, and can efficiently give solutions for oriented vector magnetic fields in the solar atmosphere. Key words. ... 1999 for observational.

  2. Limb-darkening coefficients from line-blanketed non-LTE hot-star model atmospheres

    Science.gov (United States)

    Reeve, D. C.; Howarth, I. D.

    2016-02-01

    We present grids of limb-darkening coefficients computed from non-local thermodynamic equilibrium (non-LTE), line-blanketed TLUSTY model atmospheres, covering effective-temperature and surface-gravity ranges of 15-55 kK and 4.75 dex (cgs) down to the effective Eddington limit, at 2×, 1×, 0.5× (Large Magellanic Cloud), 0.2× (Small Magellanic Cloud), and 0.1× solar. Results are given for the Bessell UBVRICJKHL, Sloan ugriz, Strömgren ubvy, WFCAM ZYJHK, Hipparcos, Kepler, and Tycho passbands, in each case characterized by several different limb-darkening `laws'. We examine the sensitivity of limb darkening to temperature, gravity, metallicity, microturbulent velocity, and wavelength, and make a comparison with LTE models. The dependence on metallicity is very weak, but limb darkening is a moderately strong function of log g in this temperature regime.

  3. A CLOUDINESS INDEX FOR TRANSITING EXOPLANETS BASED ON THE SODIUM AND POTASSIUM LINES: TENTATIVE EVIDENCE FOR HOTTER ATMOSPHERES BEING LESS CLOUDY AT VISIBLE WAVELENGTHS

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Kevin, E-mail: kevin.heng@csh.unibe.ch [University of Bern, Center for Space and Habitability, Sidlerstrasse 5, CH-3012, Bern (Switzerland)

    2016-07-20

    We present a dimensionless index that quantifies the degree of cloudiness of the atmosphere of a transiting exoplanet. Our cloudiness index is based on measuring the transit radii associated with the line center and wing of the sodium or potassium line. In deriving this index, we revisited the algebraic formulae for inferring the isothermal pressure scale height from transit measurements. We demonstrate that the formulae of Lecavelier et al. and Benneke and Seager are identical: the former is inferring the temperature while assuming a value for the mean molecular mass and the latter is inferring the mean molecular mass while assuming a value for the temperature. More importantly, these formulae cannot be used to distinguish between cloudy and cloud-free atmospheres. We derive values of our cloudiness index for a small sample of seven hot Saturns/Jupiters taken from Sing et al. We show that WASP-17b, WASP-31b, and HAT-P-1b are nearly cloud-free at visible wavelengths. We find the tentative trend that more irradiated atmospheres tend to have fewer clouds consisting of sub-micron-sized particles. We also derive absolute sodium and/or potassium abundances ∼10{sup 2} cm{sup −3} for WASP-17b, WASP-31b, and HAT-P-1b (and upper limits for the other objects). Higher-resolution measurements of both the sodium and potassium lines, for a larger sample of exoplanetary atmospheres, are needed to confirm or refute this trend.

  4. Modeling of Red Giant and AGB Stars Atmospheres: Constraints from VLTI and HST Observations

    Science.gov (United States)

    Rau, Gioia

    2018-04-01

    The chemical enrichment of the Universe is considerably affected by the contributions of low-to-intermediate mass stars through the mass-loss provided via their stellar winds. First, we will present our investigation in the near-IR with VLTI/GRAVITY (Wittkowski, Rau, et al., in prep.). Our aim was to verify at different epochs the model-predicted variability of the visibility spectra. We use CODEX model atmospheres, as well as best-fit 3D radiation hydrodynamic simulations (e.g. Freytag et al., 2017), for comparison with the observations. Our preliminary results on R Peg suggest a decreasing contribution by extended CO layers as the star transitions from maximum to minimum phase. Second, we will show a preliminary modeling of UV spectra obtained with HST/GHRS that contain chromospheric emission lines of, e.g., Mg II and Fe II. Via Sobolev with Exact Integration (SEI) modeling, we determined for the two M-giant stars γ Cru and µ Gem the characteristics of their winds (turbulence, acceleration, and opacity), and their average global mass-loss rates (Rau, Carpenter et al., in prep.). Finally, we briefly discuss the impact of instruments on board JWST in progressing this investigation.

  5. The behaviour of the atmosphere of σ scorpii

    International Nuclear Information System (INIS)

    Costa, A.; Ringuelet, A.

    1985-01-01

    The β CMa star σ Scorpii has been observed spectroscopically along two cycles. It has been found that absorption lines representing different depths in the atmosphere (excluding the transition region) yield different radial velocity curves; the amplitudes decrease and the γ's become more negative in the outermost layers. Ca II lambda 3933 A has a chromospheric component. (author)

  6. CO Spectral Line Energy Distributions in Galactic Sources: Empirical Interpretation of Extragalactic Observations

    Energy Technology Data Exchange (ETDEWEB)

    Indriolo, Nick; Bergin, E. A. [Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109 (United States); Goicoechea, J. R.; Cernicharo, J. [Grupo de Astrofísica Molecular, Instituto de Ciencia de Materiales de Madrid (CSIC) E-28049 Madrid (Spain); Gerin, M.; Gusdorf, A. [LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, École normale supérieure, F-75005, Paris (France); Lis, D. C. [LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-75014, Paris (France); Schilke, P., E-mail: nindriolo@stsci.edu [I. Physikalisches Institut der Universität zu Köln, Zülpicher Str. 77, D-50937 Köln (Germany)

    2017-02-10

    The relative populations in rotational transitions of CO can be useful for inferring gas conditions and excitation mechanisms at work in the interstellar medium. We present CO emission lines from rotational transitions observed with Herschel /HIFI in the star-forming cores Orion S, Orion KL, Sgr B2(M), and W49N. Integrated line fluxes from these observations are combined with those from Herschel /PACS observations of the same sources to construct CO spectral line energy distributions (SLEDs) from 5≤ J{sub u} ≤ 48. These CO SLEDs are compared to those reported in other galaxies, with the intention of empirically determining which mechanisms dominate excitation in such systems. We find that CO SLEDs in Galactic star-forming cores cannot be used to reproduce those observed in other galaxies, although the discrepancies arise primarily as a result of beam filling factors. The much larger regions sampled by the Herschel beams at distances of several megaparsecs contain significant amounts of cooler gas, which dominate the extragalactic CO SLEDs, in contrast to observations of Galactic star-forming regions, which are focused specifically on cores containing primarily hot molecular gas.

  7. MAVEN Observations of Escaping Planetary Ions from the Martian Atmosphere: Mass, Velocity, and Spatial Distributions

    Science.gov (United States)

    Dong, Yaxue; Fang, Xiaohua; Brain, D. A.; McFadden, James P.; Halekas, Jasper; Connerney, Jack

    2015-04-01

    The Mars-solar wind interaction accelerates and transports planetary ions away from the Martian atmosphere through a number of processes, including ‘pick-up’ by electromagnetic fields. The MAVEN spacecraft has made routine observations of escaping planetary ions since its arrival at Mars in September 2014. The SupraThermal And Thermal Ion Composition (STATIC) instrument measures the ion energy, mass, and angular spectra. It has detected energetic planetary ions during most of the spacecraft orbits, which are attributed to the pick-up process. We found significant variations in the escaping ion mass and velocity distributions from the STATIC data, which can be explained by factors such as varying solar wind conditions, contributions of particles from different source locations and different phases during the pick-up process. We also study the spatial distributions of different planetary ion species, which can provide insight into the physics of ion escaping process and enhance our understanding of atmospheric erosion by the solar wind. Our results will be further interpreted within the context of the upstream solar wind conditions measured by the MAVEN Solar Wind Ion Analyzer (SWIA) instrument and the magnetic field environment measured by the Magnetometer (MAG) instrument. Our study shows that the ion spatial distribution in the Mars-Sun-Electric-Field (MSE) coordinate system and the velocity space distribution with respect to the local magnetic field line can be used to distinguish the ions escaping through the polar plume and those through the tail region. The contribution of the polar plume ion escape to the total escape rate will also be discussed.

  8. UAV-borne coherent doppler lidar for marine atmospheric boundary layer observations

    Science.gov (United States)

    Wu, Songhua; Wang, Qichao; Liu, Bingyi; Liu, Jintao; Zhang, Kailin; Song, Xiaoquan

    2018-04-01

    A compact UAV-borne Coherent Doppler Lidar (UCDL) has been developed at the Ocean University of China for the observation of wind profile and boundary layer structure in Marine Atmospheric Boundary Layer (MABL). The design, specifications and motion-correction methodology of the UCDL are presented. Preliminary results of the first flight campaign in Hailing Island in December 2016 is discussed.

  9. Intercomparison of three microwave/infrared high resolution line-by-line radiative transfer codes

    Science.gov (United States)

    Schreier, Franz; Milz, Mathias; Buehler, Stefan A.; von Clarmann, Thomas

    2018-05-01

    An intercomparison of three line-by-line (lbl) codes developed independently for atmospheric radiative transfer and remote sensing - ARTS, GARLIC, and KOPRA - has been performed for a thermal infrared nadir sounding application assuming a HIRS-like (High resolution Infrared Radiation Sounder) setup. Radiances for the 19 HIRS infrared channels and a set of 42 atmospheric profiles from the "Garand dataset" have been computed. The mutual differences of the equivalent brightness temperatures are presented and possible causes of disagreement are discussed. In particular, the impact of path integration schemes and atmospheric layer discretization is assessed. When the continuum absorption contribution is ignored because of the different implementations, residuals are generally in the sub-Kelvin range and smaller than 0.1 K for some window channels (and all atmospheric models and lbl codes). None of the three codes turned out to be perfect for all channels and atmospheres. Remaining discrepancies are attributed to different lbl optimization techniques. Lbl codes seem to have reached a maturity in the implementation of radiative transfer that the choice of the underlying physical models (line shape models, continua etc) becomes increasingly relevant.

  10. Non-LTE model atmosphere analysis of Nova Cygni 1992

    Science.gov (United States)

    Hauschildt, P. H.; Starrfield, S.; Austin, S.; Wagner, R. M.; Shore, S. N.; Sonneborn, G.

    1994-01-01

    We use spherically symmetric non-local thermodynamic equilibrium (non-LTE), line-blanketed, expanding model atmospheres to analyze the International Ultraviolet Explorer (IUE) and optical spectra of Nova Cygni 1992 during the early phases of its outburst. We find that the first IUE spectrum obtained just after discovery on 1992 February 20, is best reproduced by a model atmosphere with a steep density gradient and homologous expansion, whereas the IUE and optical spectra obtained on February 24 show an extended, optically thick, wind structure. Therefore, we distinguish two phases of the early evolution of the nova photosphere: the initial, rapid, 'fireball' phase and the subsequent, much longer, optically thick 'wind' phase. The importance of line-blanketing in nova spectra is demonstrated. Our preliminary abundance analysis implies that hydrogen is depeleted in the ejecta, corresponding to abundance enhancements of Fe by a factor of approximately 2 and of CNO by more than a factor of 10 when compared to solar abundances. The synthetic spectra reproduce both the observed pseudo-continua as well as most of the observed features from the UV to the optical spectral range and demonstrate the importance of obtaining nearly simultaneous UV and optical spectra for performing accurate analyses of expanding stellar atmospheres (for both novae and supernovae).

  11. Observed atmospheric composition change during 1972-2009

    Energy Technology Data Exchange (ETDEWEB)

    T#Latin Small Letter O With Stroke#rseth, K.

    2012-07-01

    From the preface: The main objective of the European Monitoring and Evaluation Programme (EMEP) is to provide governments with information on the deposition and concentration of air pollutants, as well as the quantity and significance of the long-range transmission of air pollutants across boundaries. A network of stations undertakes observations of chemical and physical variables linked to damage to human health and the environment, in particular acidification, eutrophication, photochemical oxidants, heavy metals, persistent organic pollutants and particulate matter. The information provided by EMEP is also fundamental for improving the knowledge of climate change and to assess rural and urban air quality. Supplemented with emission inventories, modelling of atmospheric chemistry and deposition, and integrated assessment modelling, the work of EMEP form the basis for legally binding emission reduction protocols under the UNECE Convention on Long-range Transboundary Air Pollution (www.unece.org/env/lrtap).(Author)

  12. Observations of leaf stomatal conductance at the canopy scale: an atmospheric modeling perspective

    International Nuclear Information System (INIS)

    Avissar, R.

    1993-01-01

    Plant stomata play a key role in the redistribution of energy received on vegetated land into sensible and latent heat. As a result, they have a considerable impact on the atmospheric planetary boundary layer, the hydrologic cycle, the climate, and the weather. Current parameterizations of the stomatal mechanism in state-of-the-art atmospheric models are based on empirical relations that are established at the leaf scale between stomatal conductance and environmental conditions. In order to evaluate these parameterizations, an experiment was carried out on a potato field in New Jersey during the summer of 1989. Stomatal conductances were measured within a small homogeneous area in the middle of the potato field and under a relatively broad range of atmospheric conditions. A large variability of stomatal conductances was observed. This variability, which was associated with the variability of micro-environmental and physiological conditions that is found even in a homogeneous canopy, cannot be simulated explicitly on the scale of a single agricultural field and,a fortiori, on the scale of atmospheric models. Furthermore, this variability could not be related to the environmental conditions measured at a height of 2 m above the plant canopy simultaneously with the conductances, reinforcing the concept of scale decoupling suggested by Jarvis and McNaughton (1986) and McNaughton and Jarvis (1991). Thus, for atmospheric modeling purposes, a parameterization of stomatal conductance at the canopy scale using external environmental forcing conditions seems more appropriate than a parameterization based on leaf-scale stomatal conductance, as currently adopted in state-of-the-art atmospheric models. The measured variability was characterized by a lognormal probability density function (pdf) that remained relatively stable during the entire measuring period. These observations support conclusions by McNaughton and Jarvis (1991) that, unlike current parameterizations, a

  13. Observations of leaf stomatal conductance at the canopy scale: an atmospheric modeling perspective

    International Nuclear Information System (INIS)

    Avissar, R.

    1993-01-01

    Plant stomata play a key role in the redistribution of energy received on vegetated land into sensible and latent heat. As a result, they have a considerable impact on the atmospheric planetary boundary layer, the hydrologic cycle, the climate, and the weather. Current parameterizations of the stomatal mechanism in state-of-the-art atmospheric models are based on empirical relations that are established at the leaf scale between stomatal conductance and environmental conditions. In order to evaluate these parameterizations, an experiment was carried out on a potato field in New Jersey during the summer of 1989. Stomatal conductances were measured within a small homogeneous area in the middle of the potato field and under a relatively broad range of atmospheric conditions. A large variability of stomatal conductances was observed. This variability, which was associated with the variability of micro-environmental and physiological conditions that is found even in a homogeneous canopy, cannot be simulated explicitly on the scale of a single agricultural field and, a fortiori, on the scale of atmospheric models. Furthermore, this variability could not be related to the environmental conditions measured at a height of 2 m above the plant canopy simultaneously with the conductances, reinforcing the concept of scale decoupling suggested by Jarvis and McNaughton (1986) and McNaughton and Jarvis (1991). Thus, for atmospheric modeling purposes, a parameterization of stomatal conductance at the canopy scale using external environmental forcing conditions seems more appropriate than a parameterization based on leaf-scale stomatal conductance, as currently adopted in state-of-the-art atmospheric models. The measured variability was characterized by a lognormal probability density function (pdf) that remained relatively stable during the entire measuring period. These observations support conclusions by McNaughton and Jarvis (1991) that, unlike current parameterizations, a

  14. Weather and atmosphere observation with the ATOM all-sky camera

    Directory of Open Access Journals (Sweden)

    Jankowsky Felix

    2015-01-01

    Full Text Available The Automatic Telescope for Optical Monitoring (ATOM for H.E.S.S. is an 75 cm optical telescope which operates fully automated. As there is no observer present during observation, an auxiliary all-sky camera serves as weather monitoring system. This device takes an all-sky image of the whole sky every three minutes. The gathered data then undergoes live-analysis by performing astrometric comparison with a theoretical night sky model, interpreting the absence of stars as cloud coverage. The sky monitor also serves as tool for a meteorological analysis of the observation site of the the upcoming Cherenkov Telescope Array. This overview covers design and benefits of the all-sky camera and additionally gives an introduction into current efforts to integrate the device into the atmosphere analysis programme of H.E.S.S.

  15. Visualization in hydrological and atmospheric modeling and observation

    Science.gov (United States)

    Helbig, C.; Rink, K.; Kolditz, O.

    2013-12-01

    In recent years, visualization of geoscientific and climate data has become increasingly important due to challenges such as climate change, flood prediction or the development of water management schemes for arid and semi-arid regions. Models for simulations based on such data often have a large number of heterogeneous input data sets, ranging from remote sensing data and geometric information (such as GPS data) to sensor data from specific observations sites. Data integration using such information is not straightforward and a large number of potential problems may occur due to artifacts, inconsistencies between data sets or errors based on incorrectly calibrated or stained measurement devices. Algorithms to automatically detect various of such problems are often numerically expensive or difficult to parameterize. In contrast, combined visualization of various data sets is often a surprisingly efficient means for an expert to detect artifacts or inconsistencies as well as to discuss properties of the data. Therefore, the development of general visualization strategies for atmospheric or hydrological data will often support researchers during assessment and preprocessing of the data for model setup. When investigating specific phenomena, visualization is vital for assessing the progress of the ongoing simulation during runtime as well as evaluating the plausibility of the results. We propose a number of such strategies based on established visualization methods that - are applicable to a large range of different types of data sets, - are computationally inexpensive to allow application for time-dependent data - can be easily parameterized based on the specific focus of the research. Examples include the highlighting of certain aspects of complex data sets using, for example, an application-dependent parameterization of glyphs, iso-surfaces or streamlines. In addition, we employ basic rendering techniques allowing affine transformations, changes in opacity as well

  16. Estimating atmospheric visibility using synergy of MODIS data and ground-based observations

    Science.gov (United States)

    Komeilian, H.; Mohyeddin Bateni, S.; Xu, T.; Nielson, J.

    2015-05-01

    Dust events are intricate climatic processes, which can have adverse effects on human health, safety, and the environment. In this study, two data mining approaches, namely, back-propagation artificial neural network (BP ANN) and supporting vector regression (SVR), were used to estimate atmospheric visibility through the synergistic use of Moderate Resolution Imaging Spectroradiometer (MODIS) Level 1B (L1B) data and ground-based observations at fourteen stations in the province of Khuzestan (southwestern Iran), during 2009-2010. Reflectance and brightness temperature in different bands (from MODIS) along with in situ meteorological data were input to the models to estimate atmospheric visibility. The results show that both models can accurately estimate atmospheric visibility. The visibility estimates from the BP ANN network had a root-mean-square error (RMSE) and Pearson's correlation coefficient (R) of 0.67 and 0.69, respectively. The corresponding RMSE and R from the SVR model were 0.59 and 0.71, implying that the SVR approach outperforms the BP ANN.

  17. Observed variations in U.S. frost timing linked to atmospheric circulation patterns.

    Science.gov (United States)

    Strong, Courtenay; McCabe, Gregory J

    2017-05-23

    Several studies document lengthening of the frost-free season within the conterminous United States (U.S.) over the past century, and report trends in spring and fall frost timing that could stem from hemispheric warming. In the absence of warming, theory and case studies link anomalous frost timing to atmospheric circulation anomalies. However, recent efforts to relate a century of observed changes in U.S. frost timing to various atmospheric circulations yielded only modest correlations, leaving the relative importance of circulation and warming unclear. Here, we objectively partition the U.S. into four regions and uncover atmospheric circulations that account for 25-48% of spring and fall-frost timing. These circulations appear responsive to historical warming, and they consistently account for more frost timing variability than hemispheric or regional temperature indices. Reliable projections of future variations in growing season length depend on the fidelity of these circulation patterns in global climate models.

  18. Image isocon observations of emission lines in the spectrum of lambda Cephei

    International Nuclear Information System (INIS)

    Hutchings, J.B.; Sanyal, A.

    1976-01-01

    Line profiles of the lambda lambda 4640, 4686 emission lines were observed in the spectrum of lambda Cep, with high time resolution, and high signal-to-noise ratio. Profile changes above the 1 percent level can occur within hours. Possible periodicities in profile changes suggest a connection with rapid stellar rotation. The lambda 4686 profile is consistent with a rotating nonspherical envelope

  19. Land-Surface-Atmosphere Coupling in Observations and Models

    Directory of Open Access Journals (Sweden)

    Alan K Betts

    2009-07-01

    Full Text Available The diurnal cycle and the daily mean at the land-surface result from the coupling of many physical processes. The framework of this review is largely conceptual; looking for relationships and information in the coupling of processes in models and observations. Starting from the surface energy balance, the role of the surface and cloud albedos in the shortwave and longwave fluxes is discussed. A long-wave radiative scaling of the diurnal temperature range and the night-time boundary layer is summarized. Several aspects of the local surface energy partition are presented: the role of soilwater availability and clouds; vector methods for understanding mixed layer evolution, and the coupling between surface and boundary layer that determines the lifting condensation level. Moving to larger scales, evaporation-precipitation feedback in models is discussed; and the coupling of column water vapor, clouds and precipitation to vertical motion and moisture convergence over the Amazon. The final topic is a comparison of the ratio of surface shortwave cloud forcing to the diabatic precipitation forcing of the atmosphere in ERA-40 with observations.

  20. The Nitrous Oxide (N2O) Budget: Constraints from Atmospheric Observations and Models

    Science.gov (United States)

    Tian, H.; Thompson, R.; Canadell, J.; Winiwarter, W.; Tian, H.; Thompson, R.; Prather, M. J.

    2017-12-01

    The increasing global abundance of N2O poses a threat to human health and society over this coming century through both climate change and ozone depletion. In the sense of greenhouse gases, N2O ranks third behind CO2 and CH4. In the sense of ozone depletion, N2O stands alone. In order to identify the cause of these increases and hopefully reverse them, we need to have a thorough understanding of the sources and sinks (a.k.a. the budget) of N2O and how they can be altered. A bottom-up approach to the budget evaluates individual biogeochemical sources of N2O from the land and ocean; whereas, a top-down approach uses atmospheric observations of the variability, combined with modeling of the atmospheric chemistry and transport, to infer the magnitude of sources and sinks throughout the Earth system. This paper reviews top-down approaches using atmospheric data; a similar top-down approach can be taken with oceanic measurements of N2O, but is not covered here. Stratospheric chemistry is the predominant loss of N2O, and here we review how a merging of new measurements with stratospheric chemistry models is able to provide a constrained budget for the global N2O sink. N2O surface sources are transported and mixed throughout the atmosphere, providing positive anomalies in the N2O abundance (mole fraction of N2O with respect to dry air); while N2O-depleted air from the stratosphere provides negative anomalies. With accurate atmospheric transport models, including for stratosphere-troposphere exchange, the observed tropospheric variability in N2O is effectively a fingerprint of the location and magnitude of sources. This inverse modeling of sources is part of the top-down constraints and is reviewed here.

  1. Atmospheres of central stars

    International Nuclear Information System (INIS)

    Hummer, D.G.

    1978-01-01

    The author presents a brief summary of atmospheric models that are of possible relevance to the central stars of planetary nebulae, and then discusses the extent to which these models accord with the observations of both nebulae and central stars. Particular attention is given to the significance of the very high Zanstra temperature implied by the nebulae He II lambda 4686 A line, and to the discrepancy between the Zanstra He II temperature and the considerably lower temperatures suggested by the appearance of the visual spectrum for some of these objects. (Auth.)

  2. Assessing Greenhouse Gas emissions in the Greater Toronto Area using atmospheric observations (Invited)

    Science.gov (United States)

    Vogel, F. R.; Chan, E.; Huang, L.; Levin, I.; Worthy, D.

    2013-12-01

    Urban areas are said to be responsible for approximately 75% of anthropogenic Greenhouse Gases (GHGs) emissions while comprising only two percent of the land area [1]. This limited spatial expansion should facilitate a monitoring of anthropogenic GHGs from atmospheric observations. As major sources of emissions, cities also have a huge potential to drive emissions reductions. To effectively manage emissions, cities must however, first measure and report these publicly [2]. Modelling studies and measurements of CO2 from fossil fuel burning (FFCO2) in densely populated areas does, however, pose several challenges: Besides continuous in-situ observations, i.e. finding an adequate atmospheric transport model, a sufficiently fine-grained FFCO2 emission model and the proper background reference observations to distinguish the large-scale from the local/urban contributions to the observed FFCO2 concentration offsets ( ΔFFCO2) are required. Pilot studies which include the data from two 'sister sites*' in the vicinity of Toronto, Canada helped to derive flux estimates for Non-CO2 GHGs [3] and improve our understanding of urban FFCO2 emissions. Our 13CO2 observations reveal that the contribution of natural gas burning (mostly due to domestic heating) account for 80%×7% of FFCO2 emissions in the Greater Toronto Area (GTA) during winter. Our 14CO2 observations in the GTA, furthermore, show that the local offset of CO2 (ΔCO2) between our two sister sites can be largely attributed to urban FFCO2 emissions. The seasonal cycle of the observed ΔFFCO2 in Toronto, combined with high-resolution atmospheric modeling, helps to independently assess the contribution from different emission sectors (transportation, primary energy and industry, domestic heating) as predicted by a dedicated city-scale emission inventory, which deviates from a UNFCCC-based inventory. [1] D. Dodman. 2009. Blaming cities for climate change? An analysis of urban greenhouse gas emissions inventories

  3. Differences in rain rate intensities between TRMM observations and community atmosphere model simulations

    Science.gov (United States)

    Deng, Yi; Bowman, Kenneth P.; Jackson, Charles

    2007-01-01

    Precipitation related latent heating is important in driving the atmospheric general circulation and in generating intraseasonal to decadal atmospheric variability. Our ability to project future climate change, especially trends in costly precipitation extremes, hinges upon whether coupled GCMs capture processes that affect precipitation characteristics. Our study compares the tropical-subtropical precipitation characteristics of simulations by the NCAR CAM3.1 atmospheric GCM and observations derived from the NASA Tropical Rainfall Measuring Mission (TRMM) satellite. Despite a fairly good simulation of the annual mean rain rate, CAM rains about 10-50% more often than the real world and fails to capture heavy rainfall associated with deep convective systems over subtropical South America and U.S. Southern Plains. When it rains, there is a likelihood of 0.96-1.0 that it rains lightly in the model, compared to values of 0.84-1.0 in TRMM data. On the other hand, the likelihood of the occurrence of moderate to heavy rainfall is an order of magnitude higher in observations (0.12-0.2) than that in the model (model compensates for the lack of heavy precipitation through raining more frequently within the light rain category, which leads to an annual rainfall amount close to what is observed. CAM captures the qualitative change of rain rate PDF from a "dry" oceanic to a "wet" oceanic region, but it fails to simulate the change of precipitation characteristics from an oceanic region to a land region where thunderstorm rainfall dominates.

  4. Forecasting global atmospheric CO2

    International Nuclear Information System (INIS)

    Agusti-Panareda, A.; Massart, S.; Boussetta, S.; Balsamo, G.; Beljaars, A.; Engelen, R.; Jones, L.; Peuch, V.H.; Chevallier, F.; Ciais, P.; Paris, J.D.; Sherlock, V.

    2014-01-01

    A new global atmospheric carbon dioxide (CO 2 ) real-time forecast is now available as part of the preoperational Monitoring of Atmospheric Composition and Climate - Interim Implementation (MACC-II) service using the infrastructure of the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS). One of the strengths of the CO 2 forecasting system is that the land surface, including vegetation CO 2 fluxes, is modelled online within the IFS. Other CO 2 fluxes are prescribed from inventories and from off-line statistical and physical models. The CO 2 forecast also benefits from the transport modelling from a state-of-the-art numerical weather prediction (NWP) system initialized daily with a wealth of meteorological observations. This paper describes the capability of the forecast in modelling the variability of CO 2 on different temporal and spatial scales compared to observations. The modulation of the amplitude of the CO 2 diurnal cycle by near-surface winds and boundary layer height is generally well represented in the forecast. The CO 2 forecast also has high skill in simulating day-to-day synoptic variability. In the atmospheric boundary layer, this skill is significantly enhanced by modelling the day-to-day variability of the CO 2 fluxes from vegetation compared to using equivalent monthly mean fluxes with a diurnal cycle. However, biases in the modelled CO 2 fluxes also lead to accumulating errors in the CO 2 forecast. These biases vary with season with an underestimation of the amplitude of the seasonal cycle both for the CO 2 fluxes compared to total optimized fluxes and the atmospheric CO 2 compared to observations. The largest biases in the atmospheric CO 2 forecast are found in spring, corresponding to the onset of the growing season in the Northern Hemisphere. In the future, the forecast will be re-initialized regularly with atmospheric CO 2 analyses based on the assimilation of CO 2 products retrieved from satellite

  5. A phase-space approach to atmospheric dynamics based on observational data. Theory and applications

    International Nuclear Information System (INIS)

    Wang Risheng.

    1994-01-01

    This thesis is an attempt to develop systematically a phase-space approach to the atmospheric dynamics based on the theoretical achievement and application experiences in nonlinear time-series analysis. In particular, it is concerned with the derivation of quantities for describing the geometrical structure of the observed dynamics in phase-space (dimension estimation) and the examination of the observed atmospheric fluctuations in the light of phase-space representation. The thesis is, therefore composed of three major parts, i.e. an general survey of the theory of statistical approaches to dynamic systems, the methodology designed for the present study and specific applications with respect to dimension estimation and to a phase-space analysis of the tropical stratospheric quasi-biennial oscillation. (orig./KW)

  6. Internal gravity waves in Titan's atmosphere observed by Voyager radio occultation

    Science.gov (United States)

    Hinson, D. P.; Tyler, G. L.

    1983-01-01

    The radio scintillations caused by scattering from small-scale irregularities in Titan's neutral atmosphere during a radio occultation of Voyager 1 by Titan are investigated. Intensity and frequency fluctuations occurred on time scales from about 0.1 to 1.0 sec at 3.6 and 13 cm wavelengths whenever the radio path passed within 90 km of the surface, indicating the presence of variations in refractivity on length scales from a few hundred meters to a few kilometers. Above 25 km, the altitude profile of intensity scintillations closely agrees with the predictions of a simple theory based on the characteristics of internal gravity waves propagating with little or no attenuation through the vertical stratification in Titan's atmosphere. These observations support a hypothesis of stratospheric gravity waves, possibly driven by a cloud-free convective region in the lowest few kilometers of the stratosphere.

  7. Mg II Line Variation of 32 Cygni

    Directory of Open Access Journals (Sweden)

    Young Woon Kang

    1992-12-01

    Full Text Available The Mg II lines have been extracted from the IUE archival spectra of 32 Cygni to investigate the effect of the atmospheric eclipse. The UV light curve has been reduced from the continuum flux at the center wavelength of 2807.5 Å in the IUE spectra. The equivalent width of the Mg II k absoption line has been measured for each spectra. The results of the light variation and flux tracing of the absorption line at the vicinity of the primary eclipse confirmed the atmospheric eclipse. The atmospheric effect lasted until the phase 0.06 in the absorptin line tracing, while it lasted until the phase 0.02 in the UV light curve, respectively.

  8. First observation of the Λ(1405) line shape in electroproduction

    Science.gov (United States)

    Lu, H. Y.; Schumacher, R. A.; Adhikari, K. P.; Adikaram, D.; Aghasyan, M.; Amaryan, M. J.; Pereira, S. Anefalos; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Cole, P. L.; Collins, P.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; Egiyan, H.; Alaoui, A. El; Fassi, L. El; Eugenio, P.; Fedotov, G.; Fegan, S.; Fleming, J. A.; Gabrielyan, M.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Harrison, N.; Heddle, D.; Hicks, K.; Ho, D.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, A.; Kubarovsky, V.; Kuleshov, S. V.; Lewis, S.; Livingston, K.; MacGregor, I. J. D.; Martinez, D.; Mayer, M.; McKinnon, B.; Meyer, C. A.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moriya, K.; Moutarde, H.; Munevar, E.; Camacho, C. Munoz; Nadel-Turonski, P.; Nepali, C. S.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Park, S.; Pasyuk, E.; Peng, P.; Phelps, E.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Raue, B. A.; Rimal, D.; Ripani, M.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stoler, P.; Strauch, S.; Taiuti, M.; Tang, W.; Tian, Ye; Tkachenko, S.; Torayev, B.; Vernarsky, B.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Weygand, D. P.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.

    2013-10-01

    We report the first observation of the line shape of the Λ(1405) from electroproduction, and show that it is not a simple Breit-Wigner resonance. Electroproduction of K+Λ(1405) off the proton was studied by using data from CLAS at Jefferson Lab in the range 1.0line shape. In our fits, the line shape corresponds approximately to predictions of a two-pole meson-baryon picture of the Λ(1405), with a lower mass pole near 1368 MeV/c2 and a higher mass pole near 1423 MeV/c2. Furthermore, with increasing photon virtuality the mass distribution shifts toward the higher mass pole.

  9. Spatial Variations of Poloidal and Toroidal Mode Field Line Resonances Observed by MMS

    Science.gov (United States)

    Le, G.; Chi, P. J.; Strangeway, R. J.; Russell, C. T.; Slavin, J. A.; Anderson, B. J.; Kepko, L.; Nakamura, R.; Plaschke, F.; Torbert, R. B.

    2017-12-01

    Field line resonances (FLRs) are magnetosphere's responses to solar wind forcing and internal instabilities generated by solar wind-magnetospheric interactions. They are standing waves along the Earth's magnetic field lines oscillating in either poloidal or toroidal modes. The two types of waves have their unique frequency characteristics. The eigenfrequency of FLRs is determined by the length of the field line and the plasma density, and thus gradually changes with L. For toroidal mode oscillations with magnetic field perturbations in the azimuthal direction, ideal MHD predicts that each field line oscillates independently with its own eigenfrequency. For poloidal mode waves with field lines oscillating radially, their frequency cannot change with L easily as L shells need to oscillate in sync to avoid efficient damping due to phase mixing. Observations, mainly during quiet times, indeed show that poloidal mode waves often exhibit nearly constant frequency across L shells. Our recent observations, on the other hand, reveal a clear L-dependent frequency trend for a long lasting storm-time poloidal wave event, indicating the wave can maintain its power with changing frequencies for an extended period [Le et al., 2017]. The spatial variation of the frequency shows discrete spatial structures. The frequency remains constant within each discrete structure that spans about 1 REalong L, and changes discretely. We present a follow-up study to investigate spatial variations of wave frequencies using the Wigner-Ville distribution. We examine both poloidal and toroidal waves under different geomagnetic conditions using multipoint observations from MMS, and compare their frequency and occurrence characteristics for insights into their generation mechanisms. Reference: Le, G., et al. (2017), Global observations of magnetospheric high-m poloidal waves during the 22 June 2015 magnetic storm, Geophys. Res. Lett., 44, 3456-3464, doi:10.1002/2017GL073048.

  10. On the possibility of space objects invasion observations into the Earth's atmosphere with the help of a multifunctional polarimeter

    Science.gov (United States)

    Nevodovskyi, P. V.; Steklov, A. F.; Vidmachenko, A. P.

    2018-05-01

    Relevance of the tasks associated with the observation of the invasion of space objects into the Earth's atmosphere increases with each passing year. We used astronomical panoramic polarimeter for carrying out of polarimetric observations of objects, that flying into the atmosphere of the Earth from the surrounding outer space.

  11. A NON-ISOTHERMAL THEORY FOR INTERPRETING SODIUM LINES IN TRANSMISSION SPECTRA OF EXOPLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Kevin; Lavie, Baptiste [University of Bern, Physics Institute, Center for Space and Habitability, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Wyttenbach, Aurélien; Ehrenreich, David; Lovis, Christophe [Observatoire de l’Université de Genève, 51 chemin des Maillettes, CH-1290 Sauverny (Switzerland); Sing, David K., E-mail: kevin.heng@csh.unibe.ch [Astrophysics Group, School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)

    2015-04-10

    We present a theory for interpreting the sodium lines detected in transmission spectra of exoplanetary atmospheres. Previous analyses employed the isothermal approximation and dealt only with the transit radius. By recognizing the absorption depth and the transit radius as being independent observables, we develop a theory for jointly interpreting both quantities, which allows us to infer the temperatures and number densities associated with the sodium lines. We are able to treat a non-isothermal situation with a constant temperature gradient. Our novel diagnostics take the form of simple-to-use algebraic formulae and require measurements of the transit radii (and their corresponding absorption depths) at line center and in the line wing for both sodium lines. We apply our diagnostics to the HARPS data of HD 189733b, confirm the upper atmospheric heating reported by Huitson et al., derive a temperature gradient of 0.4376 ± 0.0154 K km{sup −1}, and find densities ∼1–10{sup 4} cm{sup −3}.

  12. Infrared radiation models for atmospheric methane

    Science.gov (United States)

    Cess, R. D.; Kratz, D. P.; Caldwell, J.; Kim, S. J.

    1986-01-01

    Mutually consistent line-by-line, narrow-band and broad-band infrared radiation models are presented for methane, a potentially important anthropogenic trace gas within the atmosphere. Comparisons of the modeled band absorptances with existing laboratory data produce the best agreement when, within the band models, spurious band intensities are used which are consistent with the respective laboratory data sets, but which are not consistent with current knowledge concerning the intensity of the infrared fundamental band of methane. This emphasizes the need for improved laboratory band absorptance measurements. Since, when applied to atmospheric radiation calculations, the line-by-line model does not require the use of scaling approximations, the mutual consistency of the band models provides a means of appraising the accuracy of scaling procedures. It is shown that Curtis-Godson narrow-band and Chan-Tien broad-band scaling provide accurate means of accounting for atmospheric temperature and pressure variations.

  13. Why is observable radio recombination line emission from galactic HII regions always close to LTE

    International Nuclear Information System (INIS)

    Shaver, P.A.

    1980-01-01

    There is no evidence for significant deviations from LTE in single-dish observations of radio recombination line emission from galactic HII regions. This is in agreement with the known properties of HII regions, particularly their density variations and limited range of excitation parameters; the optimum configuration for strong observable non-LTE effects, low electron density and high emission measure, simply does not exist in galactic HII regions, and the observed lines are emitted under near-LTE conditions. Models of the Orion Nebulae and NGC 6604 are presented which fit all available data and show only weak stimulated emission. It is concluded that reliable electron temperatures can indeed be obtained from straightforward analysis of appropriate radio recombination lines. (orig.)

  14. Coupling between the lower and middle atmosphere observed during a very severe cyclonic storm 'Madi'

    Science.gov (United States)

    Hima Bindu, H.; Venkat Ratnam, M.; Yesubabu, V.; Narayana Rao, T.; Eswariah, S.; Naidu, C. V.; Vijaya Bhaskara Rao, S.

    2018-04-01

    Synoptic-scale systems like cyclones can generate broad spectrum of waves, which propagate from its source to the middle atmosphere. Coupling between the lower and middle atmosphere over Tirupati (13.6°N, 79.4°E) is studied during a very severe cyclonic storm 'Madi' (06-13 December 2013) using Weather Research and Forecast (WRF) model assimilated fields and simultaneous meteor radar observations. Since high temporal and spatial measurements are difficult to obtain during these disturbances, WRF model simulations are obtained by assimilating conventional and satellite observations using 3DVAR technique. The obtained outputs are validated for their consistency in predicting cyclone track and vertical structure by comparing them with independent observations. The good agreement between the assimilated outputs and independent observations prompted us to use the model outputs to investigate the gravity waves (GWs) and tides over Tirupati. GWs with the periods 1-5 h are observed with clear downward phase propagation in the lower stratosphere. These upward propagating waves obtained from the model are also noticed in the meteor radar horizontal wind observations in the MLT region (70-110 km). Interestingly, enhancement in the tidal activity in both the zonal and meridional winds in the mesosphere and lower thermosphere (MLT) region is noticed during the peak cyclonic activity except the suppression of semi-diurnal tide in meridional wind. A very good agreement in the tidal activity is also observed in the horizontal winds in the troposphere and lower stratosphere from the WRF model outputs and ERA5. These results thus provide evidence on the vertical coupling of lower and middle atmosphere induced by the tropical cyclone.

  15. 3D MODELING OF GJ1214b's ATMOSPHERE: FORMATION OF INHOMOGENEOUS HIGH CLOUDS AND OBSERVATIONAL IMPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Charnay, B.; Meadows, V.; Misra, A.; Arney, G. [Astronomy Department, University of Washington, Seattle, WA 98125 (United States); Leconte, J., E-mail: bcharnay@uw.edu [Canadian Institute for Theoretical Astrophysics, 60 St George Street, University of Toronto, Toronto, ON M5S 3H8 (Canada)

    2015-11-01

    The warm sub-Neptune GJ1214b has a featureless transit spectrum that may be due to the presence of high and thick clouds or haze. Here, we simulate the atmosphere of GJ1214b with a 3D General Circulation Model for cloudy hydrogen-dominated atmospheres, including cloud radiative effects. We show that the atmospheric circulation is strong enough to transport micrometric cloud particles to the upper atmosphere and generally leads to a minimum of cloud at the equator. By scattering stellar light, clouds increase the planetary albedo to 0.4–0.6 and cool the atmosphere below 1 mbar. However, the heating by ZnS clouds leads to the formation of a stratospheric thermal inversion above 10 mbar, with temperatures potentially high enough on the dayside to evaporate KCl clouds. We show that flat transit spectra consistent with Hubble Space Telescope observations are possible if cloud particle radii are around 0.5 μm, and that such clouds should be optically thin at wavelengths >3 μm. Using simulated cloudy atmospheres that fit the observed spectra we generate transit, emission, and reflection spectra and phase curves for GJ1214b. We show that a stratospheric thermal inversion would be readily accessible in near- and mid-infrared atmospheric spectral windows. We find that the amplitude of the thermal phase curves is strongly dependent on metallicity, but only slightly impacted by clouds. Our results suggest that primary and secondary eclipses and phase curves observed by the James Webb Space Telescope in the near- to mid-infrared should provide strong constraints on the nature of GJ1214b's atmosphere and clouds.

  16. Numerical simulations of sheared magnetic lines at the solar null line

    Science.gov (United States)

    Kuźma, B.; Murawski, K.; Solov'ev, A.

    2015-05-01

    Aims: We perform numerical simulations of sheared magnetic lines at the magnetic null line configuration of two magnetic arcades that are settled in a gravitationally stratified and magnetically confined solar corona. Methods: We developed a general analytical model of a 2.5D solar atmospheric structure. As a particular application of this model, we adopted it for the curved magnetic field lines with an inverted Y shape that compose the null line above two magnetic arcades, which are embedded in the solar atmosphere that is specified by the realistic temperature distribution. The physical system is described by 2.5D magnetohydrodynamic equations that are numerically solved by the FLASH code. Results: The magnetic field line shearing, implemented about 200 km below the transition region, results in Alfvén and magnetoacoustic waves that are able to penetrate solar coronal regions above the magnetic null line. As a result of the coupling of these waves, partial reflection from the transition region and scattering from inhomogeneous regions the Alfvén waves experience fast attenuation on time scales comparable to their wave periods, and the physical system relaxes in time. The attenuation time grows with the large amplitude and characteristic growing time of the shearing. Conclusions: By having chosen a different magnetic flux function, the analytical model we devised can be adopted to derive equilibrium conditions for a diversity of 2.5D magnetic structures in the solar atmosphere. Movie associated to Fig. 5 is available in electronic form at http://www.aanda.org

  17. Atmospheric aerosol layers over Bangkok Metropolitan Region from CALIPSO observations

    Science.gov (United States)

    Bridhikitti, Arika

    2013-06-01

    Previous studies suggested that aerosol optical depth (AOD) from the Earth Observing System satellite retrievals could be used for inference of ground-level air quality in various locations. This application may be appropriate if pollution in elevated atmospheric layers is insignificant. This study investigated the significance of elevated air pollution layers over the Bangkok Metropolitan Region (BMR) from all available aerosol layer scenes taken from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) for years 2007 to 2011. The results show that biomass burning smoke layers alone were the most frequently observed. The smoke layers accounted for high AOD variations and increased AOD levels. In the dry seasons, the smoke layers alone with high AOD levels were likely brought to the BMR via northeasterly to easterly prevailing winds and found at altitudes above the typical BMR mixing heights of approximately 0.7 to 1.5 km. The smoke should be attributed to biomass burning emissions outside the BMR.

  18. Infrared radiation models for atmospheric ozone

    Science.gov (United States)

    Kratz, David P.; Ces, Robert D.

    1988-01-01

    A hierarchy of line-by-line, narrow-band, and broadband infrared radiation models are discussed for ozone, a radiatively important atmospheric trace gas. It is shown that the narrow-band (Malkmus) model is in near-precise agreement with the line-by-line model, thus providing a means of testing narrow-band Curtis-Godson scaling, and it is found that this scaling procedure leads to errors in atmospheric fluxes of up to 10 percent. Moreover, this is a direct consequence of the altitude dependence of the ozone mixing ratio. Somewhat greater flux errors arise with use of the broadband model, due to both a lesser accuracy of the broadband scaling procedure and to inherent errors within the broadband model, despite the fact that this model has been tuned to the line-by-line model.

  19. Simulation and observation of line-slip structures in columnar structures of soft spheres

    Science.gov (United States)

    Winkelmann, J.; Haffner, B.; Weaire, D.; Mughal, A.; Hutzler, S.

    2017-07-01

    We present the computed phase diagram of columnar structures of soft spheres under pressure, of which the main feature is the appearance and disappearance of line slips, the shearing of adjacent spirals, as pressure is increased. A comparable experimental observation is made on a column of bubbles under forced drainage, clearly exhibiting the expected line slip.

  20. Global Atmosphere Watch Workshop on Measurement-Model ...

    Science.gov (United States)

    The World Meteorological Organization’s (WMO) Global Atmosphere Watch (GAW) Programme coordinates high-quality observations of atmospheric composition from global to local scales with the aim to drive high-quality and high-impact science while co-producing a new generation of products and services. In line with this vision, GAW’s Scientific Advisory Group for Total Atmospheric Deposition (SAG-TAD) has a mandate to produce global maps of wet, dry and total atmospheric deposition for important atmospheric chemicals to enable research into biogeochemical cycles and assessments of ecosystem and human health effects. The most suitable scientific approach for this activity is the emerging technique of measurement-model fusion for total atmospheric deposition. This technique requires global-scale measurements of atmospheric trace gases, particles, precipitation composition and precipitation depth, as well as predictions of the same from global/regional chemical transport models. The fusion of measurement and model results requires data assimilation and mapping techniques. The objective of the GAW Workshop on Measurement-Model Fusion for Global Total Atmospheric Deposition (MMF-GTAD), an initiative of the SAG-TAD, was to review the state-of-the-science and explore the feasibility and methodology of producing, on a routine retrospective basis, global maps of atmospheric gas and aerosol concentrations as well as wet, dry and total deposition via measurement-model

  1. Results of an interactively coupled atmospheric chemistry – general circulation model: Comparison with observations

    Directory of Open Access Journals (Sweden)

    R. Hein

    Full Text Available The coupled climate-chemistry model ECHAM4.L39(DLR/CHEM is presented which enables a simultaneous treatment of meteorology and atmospheric chemistry and their feedbacks. This is the first model which interactively combines a general circulation model with a chemical model, employing most of the important reactions and species necessary to describe the stratospheric and upper tropospheric ozone chemistry, and which is computationally fast enough to allow long-term integrations with currently available computer resources. This is possible as the model time-step used for the chemistry can be chosen as large as the integration time-step for the dynamics. Vertically the atmosphere is discretized by 39 levels from the surface up to the top layer which is centred at 10 hPa, with a relatively high vertical resolution of approximately 700 m near the extra-tropical tropopause. We present the results of a control simulation representing recent conditions (1990 and compare it to available observations. The focus is on investigations of stratospheric dynamics and chemistry relevant to describe the stratospheric ozone layer. ECHAM4.L39(DLR/CHEM reproduces main features of stratospheric dynamics in the arctic vortex region, including stratospheric warming events. This constitutes a major improvement compared to earlier model versions. However, apparent shortcomings in Antarctic circulation and temperatures persist. The seasonal and interannual variability of the ozone layer is simulated in accordance with observations. Activation and deactivation of chlorine in the polar stratospheric vortices and their inter-hemispheric differences are reproduced. Considering methane oxidation as part of the dynamic-chemistry feedback results in an improved representation of the spatial distribution of stratospheric water vapour concentrations. The current model constitutes a powerful tool to investigate, for instance, the combined direct and indirect effects of anthropogenic

  2. Regional scale variations of atmospheric CO2 and CH4 from satellite observation

    International Nuclear Information System (INIS)

    Ru, F; Lei, L; Guan, X; Bu, R; Qi, J

    2014-01-01

    To identify the sources, sinks and changes of atmospheric CO 2 and CH 4 , this study investigates the spatio-temporal changes of atmospheric CO 2 and CH 4 concentration on the regional scale by the satellite observations. In this paper, choosing the land region of China as the study area, we investigate the spatio-temporal changes of atmospheric CO 2 and CH 4 concentrations using the data of the CO 2 dry air mixing ratio (XCO 2 ), and the CH 4 dry air mixing ratio (XCH 4 ), retrieved by the Greenhouse Gases Observing Satellite (GOSAT) from Jan. 2010 to Dec. 2012. The results show that (1) both XCO 2 and XCH 4 show higher concentrations in southeastern regions than that in the northwestern, and tend to yearly increasing from 2010 to 2013; (2) XCO 2 shows obvious seasonal change with higher values in the spring than that in summer. The seasonal peak-to-peak amplitude is 8 ppm and the annual growth is about 2 ppm. XCH 4 , however, does not show a seasonal change; (3) With regard to different land-use backgrounds, XCO 2 shows larger concentrations over the areas of urban agglomeration than that over the grasslands and deserts, and XCH 4 shows lower concentrations over deserts than that over the Yangtze River Delta region and Sichuan Basin

  3. Development of Innovative Technology to Provide Low-Cost Surface Atmospheric Observations

    Science.gov (United States)

    Kucera, Paul; Steinson, Martin

    2016-04-01

    Accurate and reliable real-time monitoring and dissemination of observations of surface weather conditions is critical for a variety of societal applications. Applications that provide local and regional information about temperature, precipitation, moisture, and winds, for example, are important for agriculture, water resource monitoring, health, and monitoring of hazard weather conditions. In many regions in Africa (and other global locations), surface weather stations are sparsely located and/or of poor quality. Existing stations have often been sited incorrectly, not well-maintained, and have limited communications established at the site for real-time monitoring. The US National Weather Service (NWS) International Activities Office (IAO) in partnership with University Corporation for Atmospheric Research (UCAR)/National Center for Atmospheric Research (NCAR) and funded by the United States Agency for International Development (USAID) Office of Foreign Disaster Assistance (OFDA) has started an initiative to develop and deploy low-cost weather instrumentation in sparsely observed regions of the world. The goal is to provide observations for environmental monitoring, and early warning alert systems that can be deployed at weather services in developing countries. Instrumentation is being designed using innovative new technologies such as 3D printers, Raspberry Pi computing systems, and wireless communications. The initial effort is focused on designing a surface network using GIS-based tools, deploying an initial network in Zambia, and providing training to Zambia Meteorological Department (ZMD) staff. The presentation will provide an overview of the project concepts, design of the low cost instrumentation, and initial experiences deploying a surface network deployment in Zambia.

  4. Mercury's Atmosphere and Magnetosphere: MESSENGER Third Flyby Observations

    Science.gov (United States)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Johnson, Catherine L.; Gloeckler, George; Killen, Rosemary M.; Krimigis, Stamatios M.; McClintock, William; McNutt, Ralph L., Jr.; hide

    2009-01-01

    MESSENGER's third flyby of Mercury en route to orbit insertion about the innermost planet took place on 29 September 2009. The earlier 14 January and 6 October 2008 encounters revealed that Mercury's magnetic field is highly dipolar and stable over the 35 years since its discovery by Mariner 10; that a structured, temporally variable exosphere extends to great altitudes on the dayside and forms a long tail in the anti-sunward direction; a cloud of planetary ions encompasses the magnetosphere from the dayside bow shock to the downstream magnetosheath and magnetotail; and that the magnetosphere undergoes extremely intense magnetic reconnect ion in response to variations in the interplanetary magnetic field. Here we report on new results derived from observations from MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS), Magnetometer (MAG), and Energetic Particle and Plasma Spectrometer (EPPS) taken during the third flyby.

  5. Spatio-temporal variability of the polar middle atmosphere. Insights from over 30 years of research satellite observations

    Energy Technology Data Exchange (ETDEWEB)

    Lahoz, W.A.; Orsolini, Y.J.; Manney, G.L.; Minschwaner, K.; Allen, D.R.; Errera, Q.; Jackson, D.R.; Lambert, A.; Lee, J.; Pumphrey, H.; Schwartz, M.; Wu, D.

    2012-07-01

    We discuss the insights that research satellite observations from the last 30 years have provided on the spatio-temporal variability of the polar middle atmosphere. Starting from the time of the NASA LIMS (Limb Infrared Monitor of the Stratosphere) and TOMS (Total Ozone Mapping Spectrometer) instruments, both launched in 1978, we show how these observations have augmented our knowledge of the polar middle atmosphere, in particular how information on ozone and tracers has augmented our knowledge of: (i) the spatial and temporal characteristics of the wintertime polar stratosphere and the summertime circulation; and (ii) the roles of chemistry and transport in determining the stratospheric ozone distribution. We address the increasing joint use of observations and models, in particular in data assimilation, in contributing to this understanding. Finally, we outline requirements to allow continuation of the wealth of information on the polar middle atmosphere provided by research satellites over the last 30 years.(Author)

  6. Spectroscopic observations of Nova Cygni 1975: The coronal line region revisited

    International Nuclear Information System (INIS)

    Ferland, G.J.; Lambert, D.L.; Woodman, J.H.

    1986-01-01

    A synopsis of the McDonald Observatory spectrophotometric observations of Nova Cyg 1975 (V1500 Cyg) is presented. We present these data in a form in which they can be readily accessed in the future, and also study the continous spectrum during the early nebular phase. We show that (1) the remnant probably maintained a luminosity at or above the Eddington limit for at least a year after outburst, (2) free-free emission from the coronal line region made a significant contribution to the optical continuum, and (3) the coronal line region was probably a significant source of ionizing radiation. The energetics of this nova appear to be dominated by the lift-off energy from the white dwarf and radiation from the coronal line region. Thus the light curve of Nova Cyg may tell more about the cooling of the coronal line region than about the decline of the central object. In appendices we discuss the argon abundance of Nova Cyg (less than 8 times solar) and describe how to obtain copies of the McDonald nova data

  7. Atmospheric ammonia measurements along the coastal lines of Southeastern China: Implications for inorganic nitrogen deposition to coastal waters

    Science.gov (United States)

    Wu, Shui-Ping; Dai, Lu-Hong; Wei, Ya; Zhu, Heng; Zhang, Yin-Ju; Schwab, James J.; Yuan, Chung-Shin

    2018-03-01

    Ambient NH3 concentrations were determined using Ogawa passive samplers along the coastal lines of southeast China from June 2015 to May 2017. Additional monitoring of PM2.5 and precipitation around Xiamen Bay during the period from November 2015 to May 2017 were carried out to estimate atmospheric inorganic nitrogen (IN) deposition to the bay. Distinct seasonal variations of ambient NH3 were observed with summer averages 1.41-5.56 times higher than winter, which agreed well with the seasonal trend of air temperature. Nitrate concentrations (pNO3-) in PM2.5 were significantly higher than ammonium concentrations (pNH4+), and both species showed higher concentrations in winter and spring and lower values in summer and fall which were influenced mainly by the monsoon cycle, gas-to-particle transformation process and rain washout. Paired t-testing revealed that no significant differences of pNO3- and pNH4+ between the urban and suburban sites around the Xiamen Bay. Unlike pNO3- and pNH4+, there were no clear seasonal trends for NH4+ and NO3- concentrations in precipitation samples (wNH4+ and wNO3-). On average, the deposition of IN consisted of NH3-N (27.4-28.2%) and pNO3--N (25.9-26.8%), followed by pNH4+-N (17.0-17.7%), wNH4+-N (14.5%), wNO3--N (13.3-13.8%) and NO2-N (0.35-0.46%); and showed distinct seasonal trends with higher values in winter/spring and lower values in summer/fall. In 2016, the total IN deposition was determined to be 36.45 and 35.92 kg N ha-1 at the urban and suburban sites around the Xiamen Bay, respectively. The proportion of IN deposition to total IN loads (terrestrial + atmospheric), varied over the range of 7.1-13.3% depending on the data source of riverine influx. Our observations revealed that the total IN deposition could account for 9.6-25.1% (based on primary productivity over Taiwan Strait) and 1.7-5.3% (based on primary productivity in Guangdong coastal region) of new productivity in Xiamen Bay, respectively. As an important nutrient

  8. Non-Maxwellian Analysis of the Transition-region Line Profiles Observed by the Interface Region Imaging Spectrograph

    Energy Technology Data Exchange (ETDEWEB)

    Dudík, Jaroslav; Dzifčáková, Elena [Astronomical Institute of the Czech Academy of Sciences, Fričova 298, 251 65 Ondřejov (Czech Republic); Polito, Vanessa; Testa, Paola [Smithsonian Astrophysical Observatory, 60 Garden Street, MS 58, Cambridge, MA 02138 (United States); Zanna, Giulio Del, E-mail: dudik@asu.cas.cz [Department of Applied Mathematics and Theoretical Physics, CMS, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

    2017-06-10

    We investigate the nature of the spectral line profiles for transition-region (TR) ions observed with the Interface Region Imaging Spectrograph (IRIS) . In this context, we analyzed an active-region observation performed by IRIS in its 1400 Å spectral window. The TR lines are found to exhibit significant wings in their spectral profiles, which can be well fitted with a non-Maxwellian κ distribution. The fit with a κ distribution can perform better than a double-Gaussian fit, especially for the strongest line, Si iv 1402.8 Å. Typical values of κ found are about 2, occurring in a majority of spatial pixels where the TR lines are symmetric, i.e., the fit can be performed. Furthermore, all five spectral lines studied (from Si iv, O iv, and S iv) appear to have the same full-width at half-maximum irrespective of whether the line is an allowed or an intercombination transition. A similar value of κ is obtained for the electron distribution by the fitting of the line intensities relative to Si iv 1402.8 Å, if photospheric abundances are assumed. The κ distributions, however, do not remove the presence of non-thermal broadening. Instead, they actually increase the non-thermal width. This is because, for κ distributions, TR ions are formed at lower temperatures. The large observed non-thermal width lowers the opacity of the Si iv line sufficiently enough for this line to become optically thin.

  9. THE FORMATION OF IRIS DIAGNOSTICS. VII. THE FORMATION OF THE O i 135.56 NM LINE IN THE SOLAR ATMOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Hsiao-Hsuan; Carlsson, Mats, E-mail: h.h.lin@astro.uio.no, E-mail: mats.carlsson@astro.uio.no [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway)

    2015-11-01

    The O i 135.56 nm line is covered by NASA's Interface Region Imaging Spectrograph (IRIS) small explorer mission which studies how the solar atmosphere is energized. We study here the formation and diagnostic potential of this line by means of non-local thermodynamic equilibrium modeling employing both 1D semi-empirical and 3D radiation magnetohydrodynamic models. We study the basic formation mechanisms and derive a quintessential model atom that incorporates essential atomic physics for the formation of the O i 135.56 nm line. This atomic model has 16 levels and describes recombination cascades through highly excited levels by effective recombination rates. The ionization balance O i/O ii is set by the hydrogen ionization balance through charge exchange reactions. The emission in the O i 135.56 nm line is dominated by a recombination cascade and the line is optically thin. The Doppler shift of the maximum emission correlates strongly with the vertical velocity in its line forming region, which is typically located at 1.0–1.5 Mm height. The total intensity of the line emission is correlated with the square of the electron density. Since the O i 135.56 nm line is optically thin, the width of the emission line is a very good diagnostic of non-thermal velocities. We conclude that the O i 135.56 nm line is an excellent probe of the middle chromosphere, and compliments other powerful chromospheric diagnostics of IRIS such as the Mg ii h and k lines and the C ii lines around 133.5 nm.

  10. Chemical composition and effective temperatures of metallic line white dwarfs

    International Nuclear Information System (INIS)

    Hammond, G.L.

    1974-01-01

    Model atmosphere techniques have been employed to determine the composition, effective temperatures, radii, masses and surface gravities of white dwarfs Ross 640 and van Maanen 2. The non-gray, LTE, convective, constant flux models employed collisional damping constants for the Ca II H and K lines that were measured in a laboratory device that simulated white dwarf atmospheric conditions. Ross 640 was found to have an extremely helium-rich composition and T/sub eff/ = 8500K, while the observed properties of van Maanen 2 were fitted best by a model with 91 percent helium, 9 percent hydrogen and T/sub eff/ = 6100K. The laboratory measurements of pressure shifts for the Ca II lines casts some doubt on the interpretation of recent radial velocity determinations for van Maanen 2. (U.S.)

  11. Spectrophotometry of emission-line stars in the magellanic clouds

    Science.gov (United States)

    Bohannan, Bruce

    1990-01-01

    The strong emission lines in the most luminous stars in the Magellanic Clouds indicate that these stars have such strong stellar winds that their photospheres are so masked that optical absorption lines do not provide an accurate measure of photospheric conditions. In the research funded by this grant, temperatures and gravities of emission-line stars both in the Large (LMC) and Small Magellanic Clouds (SMC) have been measured by fitting of continuum ultraviolet-optical fluxes observed with IUE with theoretical model atmospheres. Preliminary results from this work formed a major part of an invited review 'The Distribution of Types of Luminous Blue Variables'. Interpretation of the IUE observations obtained in this grant and archive data were also included in a talk at the First Boulder-Munich Hot Stars Workshop. Final results of these studies are now being completed for publication in refereed journals.

  12. ESA Atmospheric Toolbox

    Science.gov (United States)

    Niemeijer, Sander

    2017-04-01

    The ESA Atmospheric Toolbox (BEAT) is one of the ESA Sentinel Toolboxes. It consists of a set of software components to read, analyze, and visualize a wide range of atmospheric data products. In addition to the upcoming Sentinel-5P mission it supports a wide range of other atmospheric data products, including those of previous ESA missions, ESA Third Party missions, Copernicus Atmosphere Monitoring Service (CAMS), ground based data, etc. The toolbox consists of three main components that are called CODA, HARP and VISAN. CODA provides interfaces for direct reading of data from earth observation data files. These interfaces consist of command line applications, libraries, direct interfaces to scientific applications (IDL and MATLAB), and direct interfaces to programming languages (C, Fortran, Python, and Java). CODA provides a single interface to access data in a wide variety of data formats, including ASCII, binary, XML, netCDF, HDF4, HDF5, CDF, GRIB, RINEX, and SP3. HARP is a toolkit for reading, processing and inter-comparing satellite remote sensing data, model data, in-situ data, and ground based remote sensing data. The main goal of HARP is to assist in the inter-comparison of datasets. By appropriately chaining calls to HARP command line tools one can pre-process datasets such that two datasets that need to be compared end up having the same temporal/spatial grid, same data format/structure, and same physical unit. The toolkit comes with its own data format conventions, the HARP format, which is based on netcdf/HDF. Ingestion routines (based on CODA) allow conversion from a wide variety of atmospheric data products to this common format. In addition, the toolbox provides a wide range of operations to perform conversions on the data such as unit conversions, quantity conversions (e.g. number density to volume mixing ratios), regridding, vertical smoothing using averaging kernels, collocation of two datasets, etc. VISAN is a cross-platform visualization and

  13. Intercomparison of middle-atmospheric wind in observations and models

    Directory of Open Access Journals (Sweden)

    R. Rüfenacht

    2018-04-01

    Full Text Available Wind profile information throughout the entire upper stratosphere and lower mesosphere (USLM is important for the understanding of atmospheric dynamics but became available only recently, thanks to developments in remote sensing techniques and modelling approaches. However, as wind measurements from these altitudes are rare, such products have generally not yet been validated with (other observations. This paper presents the first long-term intercomparison of wind observations in the USLM by co-located microwave radiometer and lidar instruments at Andenes, Norway (69.3° N, 16.0° E. Good correspondence has been found at all altitudes for both horizontal wind components for nighttime as well as daylight conditions. Biases are mostly within the random errors and do not exceed 5–10 m s−1, which is less than 10 % of the typically encountered wind speeds. Moreover, comparisons of the observations with the major reanalyses and models covering this altitude range are shown, in particular with the recently released ERA5, ECMWF's first reanalysis to cover the whole USLM region. The agreement between models and observations is very good in general, but temporally limited occurrences of pronounced discrepancies (up to 40 m s−1 exist. In the article's Appendix the possibility of obtaining nighttime wind information about the mesopause region by means of microwave radiometry is investigated.

  14. Observation of atmospheric peroxides during Wangdu Campaign 2014 at a rural site in the North China Plain

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2016-09-01

    Full Text Available Measurements of atmospheric peroxides were made during Wangdu Campaign 2014 at Wangdu, a rural site in the North China Plain (NCP in summer 2014. The predominant peroxides were detected to be hydrogen peroxide (H2O2, methyl hydroperoxide (MHP and peroxyacetic acid (PAA. The observed H2O2 reached up to 11.3 ppbv, which was the highest value compared with previous observations in China at summer time. A box model simulation based on the Master Chemical Mechanism and constrained by the simultaneous observations of physical parameters and chemical species was performed to explore the chemical budget of atmospheric peroxides. Photochemical oxidation of alkenes was found to be the major secondary formation pathway of atmospheric peroxides, while contributions from alkanes and aromatics were of minor importance. The comparison of modeled and measured peroxide concentrations revealed an underestimation during biomass burning events and an overestimation on haze days, which were ascribed to the direct production of peroxides from biomass burning and the heterogeneous uptake of peroxides by aerosols, respectively. The strengths of the primary emissions from biomass burning were on the same order of the known secondary production rates of atmospheric peroxides during the biomass burning events. The heterogeneous process on aerosol particles was suggested to be the predominant sink for atmospheric peroxides. The atmospheric lifetime of peroxides on haze days in summer in the NCP was about 2–3 h, which is in good agreement with the laboratory studies. Further comprehensive investigations are necessary to better understand the impact of biomass burning and heterogeneous uptake on the concentration of peroxides in the atmosphere.

  15. Optimizing hydroxyl airglow retrievals from long-slit astronomical spectroscopic observations

    Directory of Open Access Journals (Sweden)

    C. Franzen

    2017-08-01

    Full Text Available Astronomical spectroscopic observations from ground-based telescopes contain background emission lines from the terrestrial atmosphere's airglow. In the near infrared, this background is composed mainly of emission from Meinel bands of hydroxyl (OH, which is produced in highly excited vibrational states by reduction of ozone near 90 km. This emission contains a wealth of information on the chemical and dynamical state of the Earth's atmosphere. However, observation strategies and data reduction processes are usually optimized to minimize the influence of these features on the astronomical spectrum. Here we discuss a measurement technique to optimize the extraction of the OH airglow signal itself from routine J-, H-, and K-band long-slit astronomical spectroscopic observations. As an example, we use data recorded from a point-source observation by the Nordic Optical Telescope's intermediate-resolution spectrograph, which has a spatial resolution of approximately 100 m at the airglow layer. Emission spectra from the OH vibrational manifold from v′  =  9 down to v′  =  3, with signal-to-noise ratios up to 280, have been extracted from 10.8 s integrations. Rotational temperatures representative of the background atmospheric temperature near 90 km, the mesosphere and lower thermosphere region, can be fitted to the OH rotational lines with an accuracy of around 0.7 K. Using this measurement and analysis technique, we derive a rotational temperature distribution with v′ that agrees with atmospheric model conditions and the preponderance of previous work. We discuss the derived rotational temperatures from the different vibrational bands and highlight the potential for both the archived and future observations, which are at unprecedented spatial and temporal resolutions, to contribute toward the resolution of long-standing problems in atmospheric physics.

  16. Verification of land-atmosphere coupling in forecast models, reanalyses and land surface models using flux site observations.

    Science.gov (United States)

    Dirmeyer, Paul A; Chen, Liang; Wu, Jiexia; Shin, Chul-Su; Huang, Bohua; Cash, Benjamin A; Bosilovich, Michael G; Mahanama, Sarith; Koster, Randal D; Santanello, Joseph A; Ek, Michael B; Balsamo, Gianpaolo; Dutra, Emanuel; Lawrence, D M

    2018-02-01

    We confront four model systems in three configurations (LSM, LSM+GCM, and reanalysis) with global flux tower observations to validate states, surface fluxes, and coupling indices between land and atmosphere. Models clearly under-represent the feedback of surface fluxes on boundary layer properties (the atmospheric leg of land-atmosphere coupling), and may over-represent the connection between soil moisture and surface fluxes (the terrestrial leg). Models generally under-represent spatial and temporal variability relative to observations, which is at least partially an artifact of the differences in spatial scale between model grid boxes and flux tower footprints. All models bias high in near-surface humidity and downward shortwave radiation, struggle to represent precipitation accurately, and show serious problems in reproducing surface albedos. These errors create challenges for models to partition surface energy properly and errors are traceable through the surface energy and water cycles. The spatial distribution of the amplitude and phase of annual cycles (first harmonic) are generally well reproduced, but the biases in means tend to reflect in these amplitudes. Interannual variability is also a challenge for models to reproduce. Our analysis illuminates targets for coupled land-atmosphere model development, as well as the value of long-term globally-distributed observational monitoring.

  17. Automatic on-line monitoring of atmospheric volatile organic compounds: Gas chromatography-mass spectrometry and gas chromatography-flame ionization detection as complementary systems

    International Nuclear Information System (INIS)

    Blas, Maite de; Navazo, Marino; Alonso, Lucio; Durana, Nieves; Iza, Jon

    2011-01-01

    Traditionally air quality networks have been carrying out the continuous, on-line measurement of volatile organic compounds (VOC) in ambient air with GC-FID. In this paper some identification and coelution problems observed while using this technique in long-term measurement campaigns are described. In order to solve these problems a GC-MS was set up and operated simultaneously with a GC-FID for C 2 -C 11 VOCs measurement. There are few on-line, unattended, long term measurements of atmospheric VOCs performed with GC-MS. In this work such a system has been optimized for that purpose, achieving good repeatability, linearity, and detection limits of the order of the GC-FID ones, even smaller in some cases. VOC quantification has been made by using response factors, which is not frequent in on-line GC-MS. That way, the identification and coelution problems detected in the GC-FID, which may led to reporting erroneous data, could be corrected. The combination of GC-FID and GC-MS as complementary techniques for the measurement of speciated VOCs in ambient air at sub-ppbv levels is proposed. Some results of the measurements are presented, including concentration values for some compounds not found until now on public ambient air VOC databases, which were identified and quantified combining both techniques. Results may also help to correct previously published VOC data with wrongly identified compounds by reprocessing raw chromatographic data.

  18. An Analysis of Cassini Observations Regarding the Structure of Jupiter's Equatorial Atmosphere

    Science.gov (United States)

    Choi, David S.; Simon-Miller, Amy A.

    2012-01-01

    A variety of intriguing atmospheric phenomena reside on both sides of Jupiter's equator. 5-micron bright hot spots and opaque plumes prominently exhibit dynamic behavior to the north, whereas compact, dark chevron-shaped features and isolated anticyclonic disturbances periodically occupy the southern equatorial latitudes. All of these phenomena are associated with the vertical and meridional perturbations of Rossby waves disturbing the mean atmospheric state. As previous observational analysis and numerical simulations have investigated the dynamics of the region, an examination of the atmosphere's vertical structure though radiative transfer analysis is necessary for improved understanding of this unique environment. Here we present preliminary analysis of a multispectral Cassini imaging data set acquired during the spacecraft's flyby of Jupiter in 2000. We evaluated multiple methane and continuum spectral channels at available viewing angles to improve constraints on the vertical structure of the haze and cloud layers comprising these interesting features. Our preliminary results indicate distinct differences in the structure for both hemispheres. Upper troposphere hazes and cloud layers are prevalent in the northern equatorial latitudes, but are not present in corresponding southern latitudes. Continued analysis will further constrain the precise structure present in these phenomena and the differences between them.

  19. A tethered balloon system for observation of atmospheric temperature inversion

    International Nuclear Information System (INIS)

    Hayashi, Takashi; Kakuta, Michio

    1979-05-01

    In environmental assessment of near-shore nuclear plants, information is often required on the development of internal boundary layer (IBL) and associated fumigation condition. Single tower data is not sufficient to clarify the site-dependent IBL structure that affects the atmospheric diffusion in shoreline-stack-site boundary complex. A tethered balloon system has been developed, which comprises a fixed point kitoon and a car-borne small balloon. The system enables us to measure the detailed time-space distribution of temperature without much man-power. The system and example of field observations with it are described. (author)

  20. Near Real Time website for IASI observations of atmospheric anomalies

    Science.gov (United States)

    Hayer, Catherine; Grainger, Don; Marsh, Kevin; Carboni, Elisa; Ventress, Lucy; Smith, Andrew

    2014-05-01

    Rapid analysis of satellite observations of the state of the atmosphere and the contaminant levels within it can be used for pollution monitoring, forest fire detection and volcanic activity monitoring. There are numerous operational satellite instruments for which this is possible. The IASI instruments, currently flying on board the MetOp-A and MetOp-B satellite platforms, are used to produce Near Real Time (NRT) data using analysis algorithms developed by Oxford University. The data is then displayed on a website within 3 hours of measurement. This allows for the semi-continuous monitoring of the state of the atmosphere over most of the globe, both in daylight and at night. Global coverage is achieved 4 times per day, which is a significant advantage over most of the alternatives, either geostationary, giving limited spatial coverage, or UV instruments which are only able to observe during the daylight side of the orbit. The website includes flags for atmospheric contaminants detectable by IASI, including dust, biomass burning-derived species and volcanic ash and SO2. In the near future, the website will be developed to also include a quantitative estimate of the mass loading of SO2 contained within any volcanic cloud. Emissions of volcanic products, such as ash and SO2, are useful indicators of a change in the activity level of a volcano. Since many volcanoes are only monitored by remote sensing methods, such as satellite instruments, this can be the only such indicator available. These emissions are also dangerous to passing aircraft, causing damage to external surfaces of the plane and to the engines, sometimes leading to failure. Evacuation of regions surrounding volcanoes, and cessation or diversion of air traffic around actively erupting volcanoes is costly and highly disruptive but is sometimes required. Up to date information is of critical importance as to when to make these sensitive decisions. An archive of data will be available to allow for easy

  1. Land-atmosphere interaction and disaster-causing process of drought in northern China: observation and experiment (DroughtPEX_China)

    Science.gov (United States)

    Li, Yaohui

    2017-04-01

    Drought is one of the most common and frequent nature disasters in the world, particularly in China under the continental monsoonal climate with great variation. About thirty percent of economic loss caused by natural disasters is contributed by droughts in China, which is by far the most damaging weather disasters because of its long duration and extensive hazard areas. Droughts not only have a serious impact on the agriculture, water resources, ecology, natural environment, but also seriously affect the socio-economic such as human health, energy and transportation. Worsely, under the background of climate change, droughts in show increases in frequency, duration and scope in many places around the world, particularly northern China. Nowadays, droughts have aroused extensive concern of the scientists, governments and international community, and became one of the important scientific issues in geoscience research. However, most of researches on droughts in China so far were focused on the causes or regulars of one type of droughts (the atmosphere, agriculture or hydrological) from the perspective of the atmospheric circulation anomalies. Few of them considered a whole cycle of the drought-forming process from atmosphere-land interaction to agricultural/ecological one in terms of the land-atmosphere interaction; meanwhile, the feedback mechanism with the drought and land-atmosphere interaction is still unclear as well. All of them is because of lack of the relevant comprehensive observation experiment. "Land-atmosphere interaction and disaster-causing process of drought in northern China: observation and experiment" (DroughtPEX_China)is just launched in this requirement and background. DroughtPEX_China is supported by Special Scientific Research Fund of Public Welfare Industry (Meteorological) of China (Grant No.GYHY201506001)—"Drought Meteorology Scientific Research Project—the disaster-causing process and mechanism of drought in northern China". This project

  2. An observational study of the evolution of the atmospheric boundary-layer over Cabo Frio, Brazil

    Directory of Open Access Journals (Sweden)

    S. H. Franchito

    2007-08-01

    Full Text Available The effect of coastal upwelling on the evolution of the atmospheric boundary layer (ABL in Cabo Frio (Brazil is investigated. For this purpose, radiosounding data collected in two experiments made during the austral summer (upwelling case and austral winter (no upwelling case are analysed. The results show that during the austral summer, cold waters that crop up near the Cabo Frio coast favour the formation of an atmospheric stable layer, which persists during the upwelling episode. Due to the low SSTs, the descending branch of the sea-breeze circulation is located close to the coast, inhibiting the development of a mixed layer mainly during the day. At night, with the reduction of the land-sea thermal contrast the descending motion is weaker, allowing a vertical mixing. The stable ABL favours the formation of a low level jet, which may also contribute to the development of a nocturnal atmospheric mixed layer. During the austral winter, due to the higher SSTs observed near the coast, the ABL is less stable compared with that in the austral summer. Due to warming, a mixed layer is observed during the day. The observed vertical profiles of the zonal winds show that the easterlies at low levels are stronger in the austral summer, indicating that the upwelling modulates the sea-breeze signal, thus confirming model simulations.

  3. Land–biosphere–atmosphere interactions over the Tibetan plateau from MODIS observations

    International Nuclear Information System (INIS)

    Jin, Menglin S; Mullens, Terrence J

    2012-01-01

    Eleven years (2000–10) of monthly observations from the National Aeronautics and Space Administration (NASA) Terra Moderate-resolution Imaging Spectroradiometer (MODIS) show the diurnal, seasonal, and inter-annual variations of skin temperature over the Tibetan plateau (75–100°E, 27–45°N) at 0.05° × 0.05° resolution. A slight warming trend is observed during this period of time, although the relatively short duration of the observation makes such a trend uncertain. More importantly, using the most recent climatology of land skin temperature, spatially high correlation coefficients are found among normalized difference vegetation index (NDVI), water vapor and cloud relations, indicating that the land surface, vegetation and atmosphere influence one another. Such a quantitative understanding of these relationships at high spatial resolution would be helpful for modeling the biosphere–atmosphere–land surface interaction processes over the Tibetan plateau. (letter)

  4. Quasi-periodic fluctuations of atmospheric pressure and cosmic rays observed in the stratosphere

    International Nuclear Information System (INIS)

    Kodama, Masahiro; Abe, Toshiaki; Sakai, Takasuke; Kato, Masato; Kogami, Shinichi.

    1976-01-01

    Quasi-periodicities of barometric pressure and cosmic ray intensity, with 5.5-minute period and one hour persistency, have been observed by means of a high-precision barometer and a large plastic scintillation counter in a balloon at an altitude of --18 km over the Pacific Ocean. From characteristics of such short period fluctuations, it is suggested that the observed pressure fluctuation may possibly be caused by the internal atmospheric gravity wave whose amplitude and wave length are --30 m and --30 km respectively. (auth.)

  5. Atmospheric-Pressure Plasma Interaction with Soft Materials as Fundamental Processes in Plasma Medicine.

    Science.gov (United States)

    Takenaka, Kosuke; Miyazaki, Atsushi; Uchida, Giichiro; Setsuhara, Yuichi

    2015-03-01

    Molecular-structure variation of organic materials irradiated with atmospheric pressure He plasma jet have been investigated. Optical emission spectrum in the atmospheric-pressure He plasma jet has been measured. The spectrum shows considerable emissions of He lines, and the emission of O and N radicals attributed to air. Variation in molecular structure of Polyethylene terephthalate (PET) film surface irradiated with the atmospheric-pressure He plasma jet has been observed via X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). These results via XPS and FT-IR indicate that the PET surface irradiated with the atmospheric-pressure He plasma jet was oxidized by chemical and/or physical effect due to irradiation of active species.

  6. IRIS Observations of Spicules and Structures Near the Solar Limb

    Science.gov (United States)

    Alissandrakis, C. E.; Vial, J.-C.; Koukras, A.; Buchlin, E.; Chane-Yook, M.

    2018-02-01

    We have analyzed Interface Region Imaging Spectrograph (IRIS) spectral and slit-jaw observations of a quiet region near the South Pole. In this article we present an overview of the observations, the corrections, and the absolute calibration of the intensity. We focus on the average profiles of strong (Mg ii h and k, C ii and Si iv), as well as of weak spectral lines in the near ultraviolet (NUV) and the far ultraviolet (FUV), including the Mg ii triplet, thus probing the solar atmosphere from the low chromosphere to the transition region. We give the radial variation of bulk spectral parameters as well as line ratios and turbulent velocities. We present measurements of the formation height in lines and in the NUV continuum from which we find a linear relationship between the position of the limb and the intensity scale height. We also find that low forming lines, such as the Mg ii triplet, show no temporal variations above the limb associated with spicules, suggesting that such lines are formed in a homogeneous atmospheric layer and, possibly, that spicules are formed above the height of 2''. We discuss the spatio-temporal structure of the atmosphere near the limb from images of intensity as a function of position and time. In these images, we identify p-mode oscillations in the cores of lines formed at low heights above the photosphere, slow-moving bright features in O i and fast-moving bright features in C ii. Finally, we compare the Mg ii k and h line profiles, together with intensity values of the Balmer lines from the literature, with computations from the PROM57Mg non-LTE model, developed at the Institut d' Astrophysique Spatiale, and estimated values of the physical parameters. We obtain electron temperatures in the range of {˜} 8000 K at small heights to {˜} 20 000 K at large heights, electron densities from 1.1× 10^{11} to 4× 10^{10} cm^{-3} and a turbulent velocity of {˜} 24 km s^{-1}.

  7. Solar polarimetry in the K I D2 line : A novel possibility for a stratospheric balloon

    Science.gov (United States)

    Quintero Noda, C.; Villanueva, G. L.; Katsukawa, Y.; Solanki, S. K.; Orozco Suárez, D.; Ruiz Cobo, B.; Shimizu, T.; Oba, T.; Kubo, M.; Anan, T.; Ichimoto, K.; Suematsu, Y.

    2018-03-01

    Of the two solar lines, K I D1 and D2, almost all attention so far has been devoted to the D1 line, as D2 is severely affected by an O2 atmospheric band. This, however, makes the latter appealing for balloon and space observations from above (most of) the Earth's atmosphere. We estimate the residual effect of the O2 band on the K I D2 line at altitudes typical for stratospheric balloons. Our aim is to study the feasibility of observing the 770 nm window. Specifically, this paper serves as a preparation for the third flight of the Sunrise balloon-borne observatory. The results indicate that the absorption by O2 is still present, albeit much weaker, at the expected balloon altitude. We applied the obtained O2 transmittance to K I D2 synthetic polarimetric spectra and found that in the absence of line-of-sight motions, the residual O2 has a negligible effect on the K I D2 line. On the other hand, for Doppler-shifted K I D2 data, the residual O2 might alter the shape of the Stokes profiles. However, the residual O2 absorption is sufficiently weak at stratospheric levels that it can be divided out if appropriate measurements are made, something that is impossible at ground level. Therefore, for the first time with Sunrise III, we will be able to perform polarimetric observations of the K I D2 line and, consequently, we will have improved access to the thermodynamics and magnetic properties of the upper photosphere from observations of the K I lines.

  8. B33C-0612: Evaluation of Simulated Biospheric Carbon Dioxide Fluxes and Atmospheric Concentrations Using Global in Situ Observations

    Science.gov (United States)

    Philip, Sajeev; Johnson, Matthew S.; Potter, Christopher S.; Genovese, Vanessa

    2016-01-01

    Atmospheric mixing ratios of carbon dioxide (CO2) are largely controlled by anthropogenic emission sources and biospheric sources/sinks. Global biospheric fluxes of CO2 are controlled by complex processes facilitating the exchange of carbon between terrestrial ecosystems and the atmosphere. These processes which play a key role in these terrestrial ecosystem-atmosphere carbon exchanges are currently not fully understood, resulting in large uncertainties in the quantification of biospheric CO2 fluxes. Current models with these inherent deficiencies have difficulties simulating the global carbon cycle with high accuracy. We are developing a new modeling platform, GEOS-Chem-CASA by integrating the year-specific NASA-CASA (National Aeronautics and Space Administration - Carnegie Ames Stanford Approach) biosphere model with the GEOS-Chem (Goddard Earth Observation System-Chemistry) chemical transport model to improve the simulation of atmosphere-terrestrial ecosystem carbon exchange. We use NASA-CASA to explicitly represent the exchange of CO2 between terrestrial ecosystem and atmosphere by replacing the baseline GEOS-Chem land net CO2 flux and forest biomass burning CO2 emissions. We will present the estimation and evaluation of these "bottom-up" land CO2 fluxes, simulated atmospheric mixing ratios, and forest disturbance changes over the last decade. In addition, we will present our initial comparison of atmospheric column-mean dry air mole fraction of CO2 predicted by the model and those retrieved from NASA's OCO-2 (Orbiting Carbon Observatory-2) satellite instrument and model-predicted surface CO2 mixing ratios with global in situ observations. This evaluation is the first step necessary for our future work planned to constrain the estimates of biospheric carbon fluxes through "top-down" inverse modeling, which will improve our understanding of the processes controlling atmosphere-terrestrial ecosystem greenhouse gas exchanges, especially over regions which lack in

  9. Atmospheric methane variability at the Peterhof station (Russia): ground-based observations and modeling

    Science.gov (United States)

    Makarova, Maria; Kirner, Oliver; Poberovskii, Anatoliy; Imhasin, Humud; Timofeyev, Yuriy; Virolainen, Yana; Makarov, Boris

    2014-05-01

    The Peterhof station (59.88 N, 29.83 E, 20 m asl) for atmospheric monitoring was founded by Saint - Petersburg State University, Russia. FTIR (Fourier transform IR) observations of methane total column are being carried out by Bruker IFS125 HR since 2009. The study presents a joint analysis of experimental data and EMAC (ECHAM/MESSy Atmospheric Chemistry model) model simulations for Peterhof over the period of 2009-2012. It was shown that CH4 total columns (TC) and column-averaged dry-air mole fractions (MF) obtained from observations are higher than model results with the difference of 1.3% and 0.3 % respectively. The correlation coefficients between FTIR and EMAC data are statistically significant (with 95% confidence) and equal to 0.82 ± 0.08 and 0.4 ± 0.1 for TC and MF of CH4 respectively. The high correlation for TCs shows that EMAC adequately reproduces CH4 variability due to meteorological processes in the atmosphere. On the other hand, the relatively low correlation coefficient for CH4 MF probably indicates an insufficiently precise knowledge of sources and sinks of the atmospheric methane. Amplitudes of the mean annual cycle of CH4 TC for experimental and model datasets (2009-2012) are of 2.1 % and 1.5 % respectively. The same amplitudes calculated for MF are less than for TC: 1.1% for FTIR and 0.6% for EMAC. Difference between FTIR and EMAC annual variations has pronounced seasonality with a maximum in September - November. It could be attributed to the underestimation of methane natural sources in the emission inventory used for EMAC simulations or by relatively coarse horizontal grid of the model (2.8°x2.8°). The analysis of modeling results allowed us to estimate the influence of the limited number of sunny days with FTIR measurement (i.e. specific meteorological conditions which usually take place during FTIR observations) on obtained FTIR estimates of the mean levels of TC and MF over 2009-2012. The systematic shifts of FTIR mean levels of TC and

  10. An adaptive observer for on-line tool wear estimation in turning, Part I: Theory

    Science.gov (United States)

    Danai, Kourosh; Ulsoy, A. Galip

    1987-04-01

    On-line sensing of tool wear has been a long-standing goal of the manufacturing engineering community. In the absence of any reliable on-line tool wear sensors, a new model-based approach for tool wear estimation has been proposed. This approach is an adaptive observer, based on force measurement, which uses both parameter and state estimation techniques. The design of the adaptive observer is based upon a dynamic state model of tool wear in turning. This paper (Part I) presents the model, and explains its use as the basis for the adaptive observer design. This model uses flank wear and crater wear as state variables, feed as the input, and the cutting force as the output. The suitability of the model as the basis for adaptive observation is also verified. The implementation of the adaptive observer requires the design of a state observer and a parameter estimator. To obtain the model parameters for tuning the adaptive observer procedures for linearisation of the non-linear model are specified. The implementation of the adaptive observer in turning and experimental results are presented in a companion paper (Part II).

  11. Narrow absorption lines with two observations from the Sloan Digital Sky Survey

    Science.gov (United States)

    Chen, Zhi-Fu; Gu, Qiu-Sheng; Chen, Yan-Mei; Cao, Yue

    2015-07-01

    We assemble 3524 quasars from the Sloan Digital Sky Survey (SDSS) with repeated observations to search for variations of the narrow C IV λ λ 1548,1551 and Mg II λ λ 2796,2803 absorption doublets in spectral regions shortward of 7000 Å in the observed frame, which corresponds to time-scales of about 150-2643 d in the quasar rest frame. In these quasar spectra, we detect 3580 C IV absorption systems with zabs = 1.5188-3.5212 and 1809 Mg II absorption systems with zabs = 0.3948-1.7167. In term of the absorber velocity (β) distribution in the quasar rest frame, we find a substantial number of C IV absorbers with β Hacker et al. However, in our Mg II absorption sample, we find that neither shows variable absorption with confident levels of >4σ for λ2796 lines and >3σ for λ2803 lines.

  12. Using the Pairs of Lines Broadened by Collisions with Neutral and Charged Particles for Gas Temperature Determination of Argon Non-Thermal Plasmas at Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Cristina Yubero

    2017-10-01

    Full Text Available The spectroscopic method for gas temperature determination in argon non-thermal plasmas sustained at atmospheric pressure proposed recently by Spectrochimica Acta Part B 129 14 (2017—based on collisional broadening measurements of selected pairs of argon atomic lines, has been applied to other pairs of argon atomic lines, and the discrepancies found in some of these results have been analyzed. For validation purposes, the values of the gas temperature obtained using the different pairs of lines have been compared with the rotational temperatures derived from the OH ro-vibrational bands, using the Boltzmann-plot technique.

  13. Filtration of lager beer with microsieves: Flux, permeate haze and in-line microscope observations

    NARCIS (Netherlands)

    Kuiper, S.; van Rijn, C.J.M.; Nijdam, W.; Raspe, Onno; van Wolferen, Hendricus A.G.M.; Krijnen, Gijsbertus J.M.; Elwenspoek, Michael Curt

    2002-01-01

    Membrane fouling during filtration of lager beer with microsieves was studied through in-line microscope observations. It was observed that the main fouling was caused by micrometre-sized particles, presumably aggregated proteins. These particles formed flocks covering parts of the membrane surface.

  14. Detection of HD in the atmospheres of Uranus and Neptune : a new determination of the D/H ratio

    NARCIS (Netherlands)

    Feuchtgruber, H; Lellouch, E; Bezard, B; Encrenaz, T; de Graauw, T.; Davis, GR

    Observations with the Short Wavelength Spectrometer (SWS) onboard the Infrared Space Observatory (ISO) have led to the first unambiguous detection of HD in the atmospheres of Uranus and Neptune, from its R(2) rotational line at 37.7 mu m Using S(0) and S(1) quadrupolar lines of H(2) at 28.2 and 17.0

  15. Atmospheric gravity waves due to the Tohoku-Oki tsunami observed in the thermosphere by GOCE

    NARCIS (Netherlands)

    Garcia, R.F.; Doornbos, E.N.; Bruinsma, S.; Hebert, H.

    2014-01-01

    Oceanic tsunami waves couple with atmospheric gravity waves, as previously observed through ionospheric and airglow perturbations. Aerodynamic velocities and density variations are computed from Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) accelerometer and thruster data during

  16. Ultraviolet photometry from the orbiting astronomical observatory. XVI - The stellar Lyman-alpha absorption line

    Science.gov (United States)

    Savage, B. D.; Panek, R. J.

    1974-01-01

    The stellar Lyman-alpha line at 1216 A was observed in 29 lightly reddened stars of spectral type B2.5 to B9 by a far-UV spectrophotometer on OAO-2. The equivalent widths obtained range from 15 A at type B2.5 to 65 A at type B8; in the late-B stars, the L-alpha line removes 2 to 3% of the total stellar flux. In this sampling, the strength of the L-alpha line correlates well with measures of the Balmer discontinuity and Balmer line strengths; luminosity classification does not seem to affect the line strength. The observed line widths also agree with the predictions of Mihala's grid of non-LTE model atmospheres. In some cases, the L-alpha line influences the interstellar column densities reported in the interstellar OAO-2 L-alpha survey. Hence, these data toward lightly reddened B2 and B1.5 stars should be regarded as upper limits only.

  17. Observational Evidence of Magnetic Reconnection for Brightenings and Transition Region Arcades in IRIS Observations

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jie; Li, Hui; Feng, Li [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, CAS, Nanjing 210008 (China); Schmieder, Brigitte; Pariat, Etienne [LESIA, Observatoire de Paris, Section de Meudon, F-92195, Meudon Principal Cedex (France); Zhu, Xiaoshuai [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Grubecka, Michalina, E-mail: nj.lihui@pmo.ac.cn [Astronomical Institute, University of Wrocław, Kopernika 11, 51-622, Wrocław (Poland)

    2017-02-10

    By using a new method of forced-field extrapolation, we study the emerging flux region AR11850 observed by the Interface Region Imaging Spectrograph and Solar Dynamical Observatory . Our results suggest that the bright points (BPs) in this emerging region exhibit responses in lines formed from the upper photosphere to the transition region, which have relatively similar morphologies. They have an oscillation of several minutes according to the Atmospheric Imaging Assembly data at 1600 and 1700 Å. The ratio between the BP intensities measured in 1600 and 1700 Å filtergrams reveals that these BPs are heated differently. Our analysis of the Helioseismic and Magnetic Imager vector magnetic field and the corresponding topology in AR11850 indicates that the BPs are located at the polarity inversion line and most of them are related to magnetic reconnection or cancelation. The heating of the BPs might be different due to different magnetic topology. We find that the heating due to the magnetic cancelation would be stronger than the case of bald patch reconnection. The plasma density rather than the magnetic field strength could play a dominant role in this process. Based on physical conditions in the lower atmosphere, our forced-field extrapolation shows consistent results between the bright arcades visible in slit-jaw image 1400 Å and the extrapolated field lines that pass through the bald patches. It provides reliable observational evidence for testing the mechanism of magnetic reconnection for the BPs and arcades in the emerging flux region, as proposed in simulation studies.

  18. Effects of Velocity Parameters of the Wind on the Line Formation for 32 CYG

    Directory of Open Access Journals (Sweden)

    Kyung-Mee Kim

    1999-12-01

    Full Text Available We calculate the theoretical line profiles in order to investigate the influence of various velocity parameters. Line profiles are calculated by using the exponential velocoty law with two acceleration regions for orbital phases 0.70 and 0.06. From this compttation we find that the influence of the wind velocity gradient on a giant star is more important in the region near the star than in the region away from the star. The observed lines show stronger emission than the calculated line profiles and we interpret the difference is caused by the inhomogeniety in the atmosphere of 32 Cyg.

  19. Double-observer line transect surveys with Markov-modulated Poisson process models for animal availability.

    Science.gov (United States)

    Borchers, D L; Langrock, R

    2015-12-01

    We develop maximum likelihood methods for line transect surveys in which animals go undetected at distance zero, either because they are stochastically unavailable while within view or because they are missed when they are available. These incorporate a Markov-modulated Poisson process model for animal availability, allowing more clustered availability events than is possible with Poisson availability models. They include a mark-recapture component arising from the independent-observer survey, leading to more accurate estimation of detection probability given availability. We develop models for situations in which (a) multiple detections of the same individual are possible and (b) some or all of the availability process parameters are estimated from the line transect survey itself, rather than from independent data. We investigate estimator performance by simulation, and compare the multiple-detection estimators with estimators that use only initial detections of individuals, and with a single-observer estimator. Simultaneous estimation of detection function parameters and availability model parameters is shown to be feasible from the line transect survey alone with multiple detections and double-observer data but not with single-observer data. Recording multiple detections of individuals improves estimator precision substantially when estimating the availability model parameters from survey data, and we recommend that these data be gathered. We apply the methods to estimate detection probability from a double-observer survey of North Atlantic minke whales, and find that double-observer data greatly improve estimator precision here too. © 2015 The Authors Biometrics published by Wiley Periodicals, Inc. on behalf of International Biometric Society.

  20. Fire weather conditions and fire-atmosphere interactions observed during low-intensity prescribed fires - RxCADRE 2012

    Science.gov (United States)

    Craig B. Clements; Neil P. Lareau; Daisuke Seto; Jonathan Contezac; Braniff Davis; Casey Teske; Thomas J. Zajkowski; Andrew T. Hudak; Benjamin C. Bright; Matthew B. Dickinson; Bret W. Butler; Daniel Jimenez; J. Kevin. Hiers

    2016-01-01

    The role of fire-atmosphere coupling on fire behaviour is not well established, and to date few field observations have been made to investigate the interactions between fire spread and fire-induced winds. Therefore, comprehensive field observations are needed to better understand micrometeorological aspects of fire spread. To address this need, meteorological...

  1. Iterative approach to self-adapting and altitude-dependent regularization for atmospheric profile retrievals.

    Science.gov (United States)

    Ridolfi, Marco; Sgheri, Luca

    2011-12-19

    In this paper we present the IVS (Iterative Variable Strength) method, an altitude-dependent, self-adapting Tikhonov regularization scheme for atmospheric profile retrievals. The method is based on a similar scheme we proposed in 2009. The new method does not need any specifically tuned minimization routine, hence it is more robust and faster. We test the self-consistency of the method using simulated observations of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). We then compare the new method with both our previous scheme and the scalar method currently implemented in the MIPAS on-line processor, using both synthetic and real atmospheric limb measurements. The IVS method shows very good performances.

  2. Pluto's atmosphere

    International Nuclear Information System (INIS)

    Elliot, J.L.; Dunham, E.W.; Bosh, A.S.; Slivan, S.M.; Young, L.A.

    1989-01-01

    Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates observations; fits of the model to the immersion and emersion lightcurves exhibit no significant derived atmosphere-structure differences. Assuming a pure methane atmosphere, surface pressures of the order of 3 microbars are consistent with the occultation data. 43 references

  3. Observations and Modeling of Thermal Structure in the Lower Atmosphere and the Upward Propagation of Tides into the Thermosphere

    Science.gov (United States)

    Wilson, R. J.; Kahre, M.

    2017-01-01

    Thermal tides are the atmospheric response to diurnally varying thermal forcing resulting from radiative and convective heat transfer from the surface and from aerosol and gaseous heating within the atmosphere. Tides include sun-synchronous (migrating) waves driven in response to solar heating and additional non-migrating waves resulting from longitudinal variations in the distributions of topography, dust aerosol and water ice clouds. The systematic spatial mapping of temperature over 5 Mars years by the Mars Climate Sounder (MCS) has yielded a well-defined climatology of seasonally-varying temperature structures in the lower atmosphere, from 5 to 80 km. Tide theory and Mars global circulation model (MGCM) simulations are a fruitful framework for relating temperature observations to thermal forcing by aerosol fields [1]. The analysis of density and temperature fields derived from MAVEN IUVS and NGIMS observations have revealed the presence of predominantly zonal wave 2 and 3 features at altitudes of 100-170 km that are almost certainly non-migrating tides propagating upward from the lower atmosphere [2,3]. In this presentation we will use the MCS climatology and MGCM simulations to relate the density variations seen by MAVEN with the seasonally varying tide activity in the lower atmosphere. Large amplitude perturbations in density are most sensitive to the tide components with the longest vertical wavelengths in temperature, which are well resolved in MCS observations.

  4. Observations of Recent Arctic Sea Ice Volume Loss and Its Impact on Ocean-Atmosphere Energy Exchange and Ice Production

    Science.gov (United States)

    Kurtz, N. T.; Markus, T.; Farrell, S. L.; Worthen, D. L.; Boisvert, L. N.

    2011-01-01

    Using recently developed techniques we estimate snow and sea ice thickness distributions for the Arctic basin through the combination of freeboard data from the Ice, Cloud, and land Elevation Satellite (ICESat) and a snow depth model. These data are used with meteorological data and a thermodynamic sea ice model to calculate ocean-atmosphere heat exchange and ice volume production during the 2003-2008 fall and winter seasons. The calculated heat fluxes and ice growth rates are in agreement with previous observations over multiyear ice. In this study, we calculate heat fluxes and ice growth rates for the full distribution of ice thicknesses covering the Arctic basin and determine the impact of ice thickness change on the calculated values. Thinning of the sea ice is observed which greatly increases the 2005-2007 fall period ocean-atmosphere heat fluxes compared to those observed in 2003. Although there was also a decline in sea ice thickness for the winter periods, the winter time heat flux was found to be less impacted by the observed changes in ice thickness. A large increase in the net Arctic ocean-atmosphere heat output is also observed in the fall periods due to changes in the areal coverage of sea ice. The anomalously low sea ice coverage in 2007 led to a net ocean-atmosphere heat output approximately 3 times greater than was observed in previous years and suggests that sea ice losses are now playing a role in increasing surface air temperatures in the Arctic.

  5. THE IMPORTANCE OF NEBULAR CONTINUUM AND LINE EMISSION IN OBSERVATIONS OF YOUNG MASSIVE STAR CLUSTERS

    International Nuclear Information System (INIS)

    Reines, Amy E.; Nidever, David L.; Whelan, David G.; Johnson, Kelsey E.

    2010-01-01

    In this spectroscopic study of infant massive star clusters, we find that continuum emission from ionized gas rivals the stellar luminosity at optical wavelengths. In addition, we find that nebular line emission is significant in many commonly used broadband Hubble Space Telescope (HST) filters including the F814W I-band, the F555W V-band, and the F435W B-band. Two young massive clusters (YMCs) in the nearby starburst galaxy NGC 4449 were targeted for follow-up spectroscopic observations after Reines et al. discovered an F814W I-band excess in their photometric study of radio-detected clusters in the galaxy. The spectra were obtained with the Dual Imaging Spectrograph (DIS) on the 3.5 m Apache Point Observatory (APO) telescope and have a spectral range of ∼3800-9800 A. We supplement these data with HST and Sloan Digital Sky Survey photometry of the clusters. By comparing our data to the Starburst99 and GALEV evolutionary synthesis models, we find that nebular continuum emission competes with the stellar light in our observations and that the relative contribution from the nebular continuum is largest in the U- and I-bands, where the Balmer (3646 A) and Paschen jumps (8207 A) are located. The spectra also exhibit strong line emission including the [S III] λλ9069, 9532 lines in the HST F814W I-band. We find that the combination of nebular continuum and line emission can account for the F814W I-band excess previously found by Reines et al. In an effort to provide a benchmark for estimating the impact of ionized gas emission on photometric observations of young massive stellar populations, we compute the relative contributions of the stellar continuum, nebular continuum, and emission lines to the total observed flux of a 3 Myr old cluster through various HST filter/instrument combinations, including filters in the Wide Field Camera 3. We urge caution when comparing observations of YMCs to evolutionary synthesis models since nebular continuum and line emission can

  6. Models for infrared atmospheric radiation

    Science.gov (United States)

    Tiwari, S. N.

    1976-01-01

    Line and band models for infrared spectral absorption are discussed. Radiative transmittance and integrated absorptance of Lorentz, Doppler, and voigt line profiles were compared for a range of parameters. It was found that, for the intermediate path lengths, the combined Lorentz-Doppler (Voigt) profile is essential in calculating the atmospheric transmittance. Narrow band model relations for absorptance were used to develop exact formulations for total absorption by four wide band models. Several continuous correlations for the absorption of a wide band model were compared with the numerical solutions of the wide band models. By employing the line-by-line and quasi-random band model formulations, computational procedures were developed for evaluating transmittance and upwelling atmospheric radiance. Homogeneous path transmittances were calculated for selected bands of CO, CO2, and N2O and compared with experimental measurements. The upwelling radiance and signal change in the wave number interval of the CO fundamental band were also calculated.

  7. The CEOS Atmospheric Composition Constellation: Enhancing the Value of Space-Based Observations

    Science.gov (United States)

    Eckman, Richard; Zehner, Claus; Al-Saadi, Jay

    2015-01-01

    The Committee on Earth Observation Satellites (CEOS) coordinates civil space-borne observations of the Earth. Participating agencies strive to enhance international coordination and data exchange and to optimize societal benefit. In recent years, CEOS has collaborated closely with the Group on Earth Observations (GEO) in implementing the Global Earth Observing System of Systems (GEOSS) space-based objectives. The goal of the CEOS Atmospheric Composition Constellation (ACC) is to collect and deliver data to improve monitoring, assessment and predictive capabilities for changes in the ozone layer, air quality and climate forcing associated with changes in the environment through coordination of existing and future international space assets. A project to coordinate and enhance the science value of a future constellation of geostationary sensors measuring parameters relevant to air quality supports the forthcoming European Sentinel-4, Korean GEMS, and US TEMPO missions. Recommendations have been developed for harmonization to mutually improve data quality and facilitate widespread use of the data products.

  8. A virtual remote sensing observation network for continuous, near-real-time monitoring of atmospheric instability

    Science.gov (United States)

    Toporov, Maria; Löhnert, Ulrich; Potthast, Roland; Cimini, Domenico; De Angelis, Francesco

    2017-04-01

    Short-term forecasts of current high-resolution numerical weather prediction models still have large deficits in forecasting the exact temporal and spatial location of severe, locally influenced weather such as summer-time convective storms or cool season lifted stratus or ground fog. Often, the thermodynamic instability - especially in the boundary layer - plays an essential role in the evolution of weather events. While the thermodynamic state of the atmosphere is well measured close to the surface (i.e. 2 m) by in-situ sensors and in the upper troposphere by satellite sounders, the planetary boundary layer remains a largely under-sampled region of the atmosphere where only sporadic information from radiosondes or aircraft observations is available. The major objective of the presented DWD-funded project ARON (Extramural Research Programme) is to overcome this observational gap and to design an optimized network of ground based microwave radiometers (MWR) and compact Differential Absorption Lidars (DIAL) for a continuous, near-real-time monitoring of temperature and humidity in the atmospheric boundary layer in order to monitor thermodynamic (in)stability. Previous studies showed, that microwave profilers are well suited for continuously monitoring the temporal development of atmospheric stability (i.e. Cimini et al., 2015) before the initiation of deep convection, especially in the atmospheric boundary layer. However, the vertical resolution of microwave temperature profiles is best in the lowest kilometer above the surface, decreasing rapidly with increasing height. In addition, humidity profile retrievals typically cannot be resolved with more than two degrees of freedom for signal, resulting in a rather poor vertical resolution throughout the troposphere. Typical stability indices used to assess the potential of convection rely on temperature and humidity values not only in the region of the boundary layer but also in the layers above. Therefore, satellite

  9. NEPTUNE'S DYNAMIC ATMOSPHERE FROM KEPLER K2 OBSERVATIONS: IMPLICATIONS FOR BROWN DWARF LIGHT CURVE ANALYSES.

    Science.gov (United States)

    Simon, Amy A; Rowe, Jason F; Gaulme, Patrick; Hammel, Heidi B; Casewell, Sarah L; Fortney, Jonathan J; Gizis, John E; Lissauer, Jack J; Morales-Juberias, Raul; Orton, Glenn S; Wong, Michael H; Marley, Mark S

    2016-02-01

    Observations of Neptune with the Kepler Space Telescope yield a 49 day light curve with 98% coverage at a 1 minute cadence. A significant signature in the light curve comes from discrete cloud features. We compare results extracted from the light curve data with contemporaneous disk-resolved imaging of Neptune from the Keck 10-m telescope at 1.65 microns and Hubble Space Telescope visible imaging acquired nine months later. This direct comparison validates the feature latitudes assigned to the K2 light curve periods based on Neptune's zonal wind profile, and confirms observed cloud feature variability. Although Neptune's clouds vary in location and intensity on short and long timescales, a single large discrete storm seen in Keck imaging dominates the K2 and Hubble light curves; smaller or fainter clouds likely contribute to short-term brightness variability. The K2 Neptune light curve, in conjunction with our imaging data, provides context for the interpretation of current and future brown dwarf and extrasolar planet variability measurements. In particular we suggest that the balance between large, relatively stable, atmospheric features and smaller, more transient, clouds controls the character of substellar atmospheric variability. Atmospheres dominated by a few large spots may show inherently greater light curve stability than those which exhibit a greater number of smaller features.

  10. Energetic Electron Acceleration Observed by MMS in the Vicinity of an X-Line Crossing

    Science.gov (United States)

    Jaynes, A. N.; Turner, D. L.; Wilder, F. D.; Osmane, A.; Baker, D. N.; Blake, J. B.; Fennell, J. F.; Cohen, I. J.; Mauk, B. H.; Reeves, G. D.; hide

    2016-01-01

    During the first months of observations, the Magnetospheric Multiscale Fly's Eye Energetic Particle Spectrometer instrument has observed several instances of electron acceleration up to greater than 100 keV while in the vicinity of the dayside reconnection region. While particle acceleration associated with magnetic reconnection has been seen to occur up to these energies in the tail region, it had not yet been reported at the magnetopause. This study reports on observations of electron acceleration up to hundreds of keV that were recorded on 19 September 2015 around 1000 UT, in the midst of an X-line crossing. In the region surrounding the X-line, whistler-mode and broadband electrostatic waves were observed simultaneously with the appearance of highly energetic electrons which exhibited significant energization in the perpendicular direction. The mechanisms by which particles may be accelerated via reconnection-related processes are intrinsic to understanding particle dynamics among a wide range of spatial scales and plasma environments.

  11. Seven years of recent European net terrestrial carbon dioxide exchange constrained by atmospheric observations

    NARCIS (Netherlands)

    Peters, W.; Krol, M. C.; van der Werf, G. R.; Houweling, S.; Jones, C. D.; Hughes, J.; Schaefer, K.; Masarie, K. A.; Jacobson, A. R.; Miller, J. B.; Cho, C. H.; Ramonet, M.; Schmidt, M.; Ciattaglia, L.; Apadula, F.; Heltai, D.; Meinhardt, F.; di Sarra, A. G.; Piacentino, S.; Sferlazzo, D.; Aalto, T.; Hatakka, J.; StröM, J.; Haszpra, L.; Meijer, H. A J; van Der Laan, S.; Neubert, R. E M; Jordan, A.; Rodó, X.; Morguí, J. A.; Vermeulen, A. T.; Popa, Maria Elena; Rozanski, K.; Zimnoch, M.; Manning, A. C.; Leuenberger, M.; Uglietti, C.; Dolman, A. J.; Ciais, P.; Heimann, M.; Tans, P.

    2010-01-01

    We present an estimate of net ecosystem exchange (NEE) of CO2 in Europe for the years 2001-2007. It is derived with a data assimilation that uses a large set of atmospheric CO2 mole fraction observations (∼70 000) to guide relatively simple descriptions of terrestrial and oceanic net exchange, while

  12. Seven years of recent European net terrestrial carbon dioxide exchange constrained by atmospheric observations

    NARCIS (Netherlands)

    Peters, W.; Krol, M.C.; Werf, van der G.R.; Houweling, S.; Jones, C.D.; Hughes, J.; Schaefer, K.; Masarie, K.A.

    2010-01-01

    We present an estimate of net ecosystem exchange (NEE) of CO2 in Europe for the years 2001–2007. It is derived with a data assimilation that uses a large set of atmospheric CO2 mole fraction observations (~70 000) to guide relatively simple descriptions of terrestrial and oceanic net exchange, while

  13. Seven years of recent European net terrestrial carbon dioxide exchange constrained by atmospheric observations

    NARCIS (Netherlands)

    Peters, W.; Krol, M; van der Werf, G. R.; Houweling, S.; Jones, C. D.; Hughes, J.; Schaefer, K.; Masarie, K. A.; Jacobson, A. R.; Miller, J. B.; Cho, C. H.; Ramonet, M.; Schmidt, M.; Ciattaglia, L.; Apadula, F.; Helta, D.; Meinhardt, F.; di Sarra, A. G.; Piacentino, S.; Sferlazzo, D.; Aalto, T.; Hatakka, J.; Strom, J.; Haszpra, L.; Meijer, H. A. J.; van der Laan, S.; Neubert, R. E. M.; Jordan, A.; Rodo, X.; Morgui, J. -A.; Vermeulen, A. T.; Popa, E.; Rozanski, K.; Zimnoch, M.; Manning, A. C.; Leuenberger, M.; Uglietti, C.; Dolman, A. J.; Ciais, P.; Heimann, M.; Tans, P. P.; Heltai, D.; Ström, J.

    We present an estimate of net ecosystem exchange (NEE) of CO(2) in Europe for the years 2001-2007. It is derived with a data assimilation that uses a large set of atmospheric CO(2) mole fraction observations (similar to 70 000) to guide relatively simple descriptions of terrestrial and oceanic net

  14. Commentary Relative to the Emission Spectrum of the Solar Atmosphere: Further Evidence for a Distinct Solar Surface

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-07-01

    Full Text Available The chromosphere and corona of the Sun represent tenuous regions which are characterized by numerous optically thin emission lines in the ultraviolet and X-ray bands. When observed from the center of the solar disk outward, these emission lines experience modest brightening as the limb is approached. The intensity of many ultraviolet and X-ray emission lines nearly doubles when observation is extended just beyond the edge of the disk. These findings indicate that the solar body is opaque in this frequency range and that an approximately two fold greater region of the solar atmosphere is being sampled outside the limb. These observations provide strong support for the presence of a distinct solar surface. Therefore, the behavior of the emission lines in this frequency range constitutes the twenty fifth line of evidence that the Sun is comprised of condensed matter

  15. Using commercial software products for atmospheric remote sensing

    Science.gov (United States)

    Kristl, Joseph A.; Tibaudo, Cheryl; Tang, Kuilian; Schroeder, John W.

    2002-02-01

    The Ontar Corporation (www.Ontar.com) has developed several products for atmospheric remote sensing to calculate radiative transport, atmospheric transmission, and sensor performance in both the normal atmosphere and the atmosphere disturbed by battlefield conditions of smoke, dust, explosives and turbulence. These products include: PcModWin: Uses the USAF standard MODTRAN model to compute the atmospheric transmission and radiance at medium spectral resolution (2 cm-1) from the ultraviolet/visible into the infrared and microwave regions of the spectrum. It can be used for any geometry and atmospheric conditions such as aerosols, clouds and rain. PcLnWin: Uses the USAF standard FASCOD model to compute atmospheric transmission and emission at high (line-by-line) spectral resolution using the HITRAN 2000 database. It can be used over the same spectrum from the UV/visible into the infrared and microwave regions of the spectrum. HitranPC: Computes the absolute high (line-by-line) spectral resolution transmission spectrum of the atmosphere for different temperatures and pressures. HitranPC is a user-friendly program developed by the University of South Florida (USF) and uses the international standard molecular spectroscopic database, HITRAN. LidarPC: A computer program to calculate the Laser Radar/L&n Equation for hard targets and atmospheric backscatter using manual input atmospheric parameters or HitranPC and BETASPEC - transmission and backscatter calculations of the atmosphere. Also developed by the University of South Florida (USF). PcEosael: is a library of programs that mathematically describe aspects of electromagnetic propagation in battlefield environments. 25 modules are connected but can be exercised individually. Covers eight general categories of atmospheric effects, including gases, aerosols and laser propagation. Based on codes developed by the Army Research Lab. NVTherm: NVTherm models parallel scan, serial scan, and staring thermal imagers that operate

  16. A New Method to Comprehensively Diagnose Shock Waves in the Solar Atmosphere Based on Simultaneous Spectroscopic and Imaging Observations

    Science.gov (United States)

    Ruan, Wenzhi; Yan, Limei; He, Jiansen; Zhang, Lei; Wang, Linghua; Wei, Yong

    2018-06-01

    Shock waves are believed to play an important role in plasma heating. The shock-like temporal jumps in radiation intensity and Doppler shift have been identified in the solar atmosphere. However, a quantitative diagnosis of the shocks in the solar atmosphere is still lacking, seriously hindering the understanding of shock dissipative heating of the solar atmosphere. Here, we propose a new method to realize the goal of the shock quantitative diagnosis, based on Rankine–Hugoniot equations and taking the advantages of simultaneous imaging and spectroscopic observations from, e.g., IRIS (Interface Region Imaging Spectrograph). Because of this method, the key parameters of shock candidates can be derived, such as the bulk velocity and temperature of the plasma in the upstream and downstream, the propagation speed and direction. The method is applied to the shock candidates observed by IRIS, and the overall characteristics of the shocks are revealed quantitatively for the first time. This method is also tested with the help of forward modeling, i.e., virtual observations of simulated shocks. The parameters obtained from the method are consistent with the parameters of the shock formed in the model and are independent of the viewing direction. Therefore, the method we proposed here is applicable to the quantitative and comprehensive diagnosis of the observed shocks in the solar atmosphere.

  17. Theoretical and experimental study on broadband terahertz atmospheric transmission characteristics

    International Nuclear Information System (INIS)

    Guo Shi-Bei; Zhong Kai; Wang Mao-Rong; Liu Chu; Xu De-Gang; Yao Jian-Quan; Xiao Yong; Wang Wen-Peng

    2017-01-01

    Broadband terahertz (THz) atmospheric transmission characteristics from 0 to 8 THz are theoretically simulated based on a standard Van Vleck–Weisskopf line shape, considering 1696 water absorption lines and 298 oxygen absorption lines. The influences of humidity, temperature, and pressure on the THz atmospheric absorption are analyzed and experimentally verified with a Fourier transform infrared spectrometer (FTIR) system, showing good consistency. The investigation and evaluation on high-frequency atmospheric windows are good supplements to existing data in the low-frequency range and lay the foundation for aircraft-based high-altitude applications of THz communication and radar. (paper)

  18. Observations of the 18-cm OH lines in Herbig--Haro objects and reflection nebulae

    International Nuclear Information System (INIS)

    Pashchenko, M.I.; Rudnitskii, G.M.

    1980-01-01

    In 1978 various Herbig--Haro objects and R-associations (containing reflection nebulae) were observed in the principal (1665, 1667 MHz) lines of the ground state of the hydroxyl molecule with the large radio telescope of the Station Radioastronomique de Nancay. OH emission was detected near 36 of the 63 objects examined. In most cases the line profiles have a simple, single-peaked structure, with a line width of 1--3 km/sec. The OH emission probably originates in interstellar dust clouds surrounding the HH objects and R-associations. Some implications of these results are discussed briefly

  19. Registering upper atmosphere parameters in East Siberia with Fabry—Perot Interferometer KEO Scientific "Arinae"

    Science.gov (United States)

    Vasilyev, Roman; Artamonov, Maksim; Beletsky, Aleksandr; Zherebtsov, Geliy; Medvedeva, Irina; Mikhalev, Aleksandr; Syrenova, Tatyana

    2017-09-01

    We describe the Fabry–Perot interferometer designed to study Earth’s upper atmosphere. We propose a modification of the existing data processing method for determining the Doppler shift and Doppler widening and also for separating the observed line intensity and the background intensity. The temperature and wind velocity derived from these parameters are compared with physical characteristics obtained from modeling (NRLMSISE-00, HWM14). We demonstrate that the temperature is determined from the oxygen 630 nm line irrespective of the hydroxyl signal existing in interference patterns. We show that the interferometer can obtain temperature from the oxygen 557.7 nm line in case of additional calibration of the device. The observed wind velocity mainly agrees with model data. Night variations in the red and green oxygen lines quite well coincide with those in intensities obtained by devices installed nearby the interferometer.

  20. Accelerated line-by-line calculations for the radiative transfer of trace gases related to climate studies

    International Nuclear Information System (INIS)

    Clough, S.A.

    1993-01-01

    In the present study we are studying the effects of including carbon dioxide, ozone, methane, and the halocarbons in addition to water vapor in the radiating atmosphere. The study has focused on two principal issues: the effect on the spectral fluxes and cooling rates of carbon dioxide, ozone and the halocarbons at 1990 concentration levels and the change in fluxes and cooling rates as a consequence of the anticipated ten year change in the profiles of these species. For the latter study the water vapor profiles have been taken as invariant in time. The radiative line-by-line calculations using LBLRTM (Line-By-Line Radiative Transfer Model) have been performed for tropical (TRP), mid-latitude winter (MLW) and mid-latitude summer (MLS) model atmospheres. The halocarbons considered in the present study are CCl 4 , CFC-11, CFC-12 and CFC-22. In addition to considering the radiative effects of carbon dioxide at 355 ppM, the assumed current level, we have also obtained results for doubled carbon dioxide at 710 ppM. An important focus of the current research effort is the effect of the ozone depletion profile on atmospheric radiative effects

  1. Plasma density enhancements created by the ionization of the Earth's upper atmosphere by artificial electron beams

    DEFF Research Database (Denmark)

    Neubert, Torsten; Banks, P.M.

    line) and down-going differential energy flux. The equations are solved numerically, using the MSIS atmospheric model and the IRI ionospheric model. The results from the model compare well with recent observations from the CHARGE 2 sounding rocket experiment. Two aspects of the beam-neutral atmosphere...... interaction are discussed: First we investigate the limits on the electron beam current that can be emitted from a space. craft without substantial spacecraft charging. This question is important because the charging of the spacecraft to positive potentials limits the current and the escape energy of the beam...... electrons and thereby limits the ionization of the neutral atmosphere. As an example we find from CHARGE 2 observations and from the model calculations that below about 180 km, secondary electrons generated through the ionization of the neutral atmosphere by 1-10 keV electron beams from sounding rockets...

  2. Absorption-line strengths of 18 late-type spiral galaxies observed with SAURON

    NARCIS (Netherlands)

    Ganda, Katia; Peletier, Reynier F.; McDermid, Richard M.; Falcon-Barroso, Jesus; de Zeeuw, P. T.; Bacon, Roland; Cappellari, Michele; Davies, Roger L.; Emsellem, Eric; Krajnovic, Davor; Kuntschner, Harald; Sarzi, Marc; van de Ven, Glenn

    2007-01-01

    We present absorption line strength maps for a sample of 18 Sb-Sd galaxies observed using the integral-field spectrograph SAURON operating at the William Herschel Telescope on La Palma, as part of a project devoted to the investigation of the kinematics and stellar populations of late-type spirals,

  3. CO2 non-LTE limb emissions in Mars' atmosphere as observed by OMEGA/Mars Express

    Science.gov (United States)

    Piccialli, A.; López-Valverde, M. A.; Määttänen, A.; González-Galindo, F.; Audouard, J.; Altieri, F.; Forget, F.; Drossart, P.; Gondet, B.; Bibring, J. P.

    2016-06-01

    We report on daytime limb observations of Mars upper atmosphere acquired by the OMEGA instrument on board the European spacecraft Mars Express. The strong emission observed at 4.3 μm is interpreted as due to CO2 fluorescence of solar radiation and is detected at a tangent altitude in between 60 and 110 km. The main value of OMEGA observations is that they provide simultaneously spectral information and good spatial sampling of the CO2 emission. In this study we analyzed 98 dayside limb observations spanning over more than 3 Martian years, with a very good latitudinal and longitudinal coverage. Thanks to the precise altitude sounding capabilities of OMEGA, we extracted vertical profiles of the non-local thermodynamic equilibrium (non-LTE) emission at each wavelength and we studied their dependence on several geophysical parameters, such as the solar illumination and the tangent altitude. The dependence of the non-LTE emission on solar zenith angle and altitude follows a similar behavior to that predicted by the non-LTE model. According to our non-LTE model, the tangent altitude of the peak of the CO2 emission varies with the thermal structure, but the pressure level where the peak of the emission is found remains constant at ˜0.03 ± 0.01 Pa, . This non-LTE model prediction has been corroborated by comparing SPICAM and OMEGA observations. We have shown that the seasonal variations of the altitude of constant pressure levels in SPICAM stellar occultation retrievals correlate well with the variations of the OMEGA peak emission altitudes, although the exact pressure level cannot be defined with the spectroscopy for the investigation of the characteristics of the atmosphere of Venus (SPICAM) nighttime data. Thus, observed changes in the altitude of the peak emission provide us information on the altitude of the 0.03 Pa pressure level. Since the pressure at a given altitude is dictated by the thermal structure below, the tangent altitude of the peak emission represents

  4. Potentialities and Limits of ICESAT-2 Observation for Atmospheric Aerosol Investigation

    Directory of Open Access Journals (Sweden)

    Mona L.

    2016-01-01

    Full Text Available ICESat-2(Ice, Cloud, and land Elevation Satellite-2, slated for launch in 2017, will continue the important observations of ice-sheet elevation change, sea-ice freeboard, and vegetation canopy height begun by ICESat in 2003. Among the other potential applications, ICESat-2 could provide some information about atmospheric aerosol over Polar Regions thanks to the lidar instrument. In this context, it is essential to demonstrate the ICESat-2 capability of providing vertical profiles of the aerosol backscatter coefficient and to define its potentialities and limits. First results of this investigation are reported and will be presented at the conference.

  5. The Atmospheric Scanning Electron Microscope with open sample space observes dynamic phenomena in liquid or gas.

    Science.gov (United States)

    Suga, Mitsuo; Nishiyama, Hidetoshi; Konyuba, Yuji; Iwamatsu, Shinnosuke; Watanabe, Yoshiyuki; Yoshiura, Chie; Ueda, Takumi; Sato, Chikara

    2011-12-01

    Although conventional electron microscopy (EM) requires samples to be in vacuum, most chemical and physical reactions occur in liquid or gas. The Atmospheric Scanning Electron Microscope (ASEM) can observe dynamic phenomena in liquid or gas under atmospheric pressure in real time. An electron-permeable window made of pressure-resistant 100 nm-thick silicon nitride (SiN) film, set into the bottom of the open ASEM sample dish, allows an electron beam to be projected from underneath the sample. A detector positioned below captures backscattered electrons. Using the ASEM, we observed the radiation-induced self-organization process of particles, as well as phenomena accompanying volume change, including evaporation-induced crystallization. Using the electrochemical ASEM dish, we observed tree-like electrochemical depositions on the cathode. In silver nitrate solution, we observed silver depositions near the cathode forming incidental internal voids. The heated ASEM dish allowed observation of patterns of contrast in melting and solidifying solder. Finally, to demonstrate its applicability for monitoring and control of industrial processes, silver paste and solder paste were examined at high throughput. High resolution, imaging speed, flexibility, adaptability, and ease of use facilitate the observation of previously difficult-to-image phenomena, and make the ASEM applicable to various fields. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Multi-wavelength Spectral Analysis of Ellerman Bombs Observed by FISS and IRIS

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Jie; Ding, M. D. [School of Astronomy and Space Science, Nanjing University, Nanjing 210023 (China); Cao, Wenda, E-mail: dmd@nju.edu.cn [Big Bear Solar Observatory, New Jersey Institute of Technology, 40386 North Shore Lane, Big Bear City, CA 92314-9672 (United States)

    2017-04-01

    Ellerman bombs (EBs) are a kind of solar activity that is suggested to occur in the lower solar atmosphere. Recent observations using the Interface Region Imaging Spectrograph (IRIS) show connections between EBs and IRIS bombs (IBs), which imply that EBs might be heated to a much higher temperature (8 × 10{sup 4} K) than previous results. Here we perform a spectral analysis of EBs simultaneously observed by the Fast Imaging Solar Spectrograph and IRIS. The observational results show clear evidence of heating in the lower atmosphere, indicated by the wing enhancement in H α , Ca ii 8542 Å, and Mg ii triplet lines and also by brightenings in images of the 1700 Å and 2832 Å ultraviolet continuum channels. Additionally, the intensity of the Mg ii triplet line is correlated with that of H α when an EB occurs, suggesting the possibility of using the triplet as an alternative way to identify EBs. However, we do not find any signal in IRIS hotter lines (C ii and Si iv). For further analysis, we employ a two-cloud model to fit the two chromospheric lines (H α and Ca ii 8542 Å) simultaneously, and obtain a temperature enhancement of 2300 K for a strong EB. This temperature is among the highest of previous modeling results, albeit still insufficient to produce IB signatures at ultraviolet wavelengths.

  7. Ellerman bombs and UV bursts: reconnection at different atmospheric layers?

    Science.gov (United States)

    Hansteen, V. H.; Ortiz-Carbonell, A. N.; Rouppe van der Voort, L.

    2017-12-01

    The emergence of magnetic flux through the photosphere and into the outer solar atmosphere produces, amongst many other phenomena, the appearance of Ellerman bombs (EBs) in the photosphere. EBs are observed in the wings of H(alpha) and are highly likely to be due to reconnection in the photosphere, below the chromospheric canopy. However, signs of the reconnection process are also observed in several other spectral lines, typical of the chromosphere or transition region. An example are the UV bursts observed in the transition region lines of Si IV. In this work we analyze high cadence coordinated observations between the 1-m Swedish Solar Telescope and the IRIS spacecraft in order to study the possible relationship between reconnection events at different layers in the atmosphere, and in particular, the timing history between them. High cadence, high resolution H-alpha images from the SST provide us with the positions, timings and trajectories of Ellerman bombs in an emerging flux region. Simultaneous co-aligned IRIS slit-jaw images at 1400 and 1330 A and detailed Si IV spectra from the fast spectrograph raster allow us to study the transition region counterparts of those photospheric Ellerman bombs. Our main goal is to study whether there is a temporal relationship between the appearance of an EB and the appearance of a UV burst. Eventually we would like to investigate whether reconnection happens at discrete heights, or as a reconnection sheet spanning several layers at the same time.

  8. HIFISTARS Herschel/HIFI observations of VY Canis Majoris. Molecular-line inventory of the envelope around the largest known star

    Science.gov (United States)

    Alcolea, J.; Bujarrabal, V.; Planesas, P.; Teyssier, D.; Cernicharo, J.; De Beck, E.; Decin, L.; Dominik, C.; Justtanont, K.; de Koter, A.; Marston, A. P.; Melnick, G.; Menten, K. M.; Neufeld, D. A.; Olofsson, H.; Schmidt, M.; Schöier, F. L.; Szczerba, R.; Waters, L. B. F. M.

    2013-11-01

    Aims: The study of the molecular gas in the circumstellar envelopes of evolved stars is normally undertaken by observing lines of CO (and other species) in the millimetre-wave domain. In general, the excitation requirements of the observed lines are low at these wavelengths, and therefore these observations predominantly probe the cold outer envelope while studying the warm inner regions of the envelopes normally requires sub-millimetre (sub-mm) and far-infrared (FIR) observational data. Methods: To gain insight into the physical conditions and kinematics of the warm (100-1000 K) gas around the red hyper-giant VY CMa, we performed sensitive high spectral resolution observations of molecular lines in the sub-mm/FIR using the HIFI instrument of the Herschel Space Observatory. We observed CO, H2O, and other molecular species, sampling excitation energies from a few tens to a few thousand K. These observations are part of the Herschel guaranteed time key program HIFISTARS. Results: We detected the J = 6-5, J = 10-9, and J = 16-15 lines of 12CO and 13CO at ~100, 300, and 750 K above the ground state (and the 13CO J = 9-8 line). These lines are crucial for improving the modelling of the internal layers of the envelope around VY CMa. We also detected 27 lines of H2O and its isotopomers, and 96 lines of species such as NH3, SiO, SO, SO2 HCN, OH and others, some of them originating from vibrationally excited levels. Three lines were not unambiguously assigned. Conclusions: Our observations confirm that VY CMa's envelope must consist of two or more detached components. The molecular excitation in the outer layers is significantly lower than in the inner ones, resulting in strong self-absorbed profiles in molecular lines that are optically thick in this outer envelope, for instance, low-lying lines of H2O. Except for the most abundant species, CO and H2O, most of the molecular emission detected at these sub-mm/FIR wavelengths arise from the central parts of the envelope. The

  9. Analysis of the lambda 5696 Carbon III line in the O stars

    International Nuclear Information System (INIS)

    Cardona-Nunez, O.

    1978-01-01

    Lines of twice-ionized Carbon, specifically lambda 5695 and lambda 8500, in the O stars were analyzed on the basis of a detailed solution of the coupled statistical-equilibrium and transfer equations for a multilevel, multiline, multi-ion ensemble. It is significant that these plane-parallel non-LTE statistical equilibrium calculations reproduce successfully the observed emission a lambda 5696 and absorption at lambda 8500. The 3p 1 P 0 -3d 1 D transition is found to come into emission at the observed temperatures for both main-sequence and low-gravity objects. The equivalent widths of the emission and absorption lines agree very well with those measured for O stars. In these stars the basic physical mechanism responsible for this phenomenon is the overpopulation of 3d by means of direct recombination and cascades from upper states (with dielectronic recombination taking part in the earliest types) with subsequent cascade to 3p. The 3p state is drained by the two-electron transitions coupling 3p to the 2p 2 ( 1 S, 1 D) states; emission in the 3s 1 S-3p 1 P 0 line is thus prevented. The mechanism of formation of C III is different from that of N III because of dielectronic recombination is not necessary in the former case. The fact that the C III emission line can be produced in a static nonextended atmosphere in radiative equilibrium indicates that the presence of emission lines is not sufficient evidence for the existence of extended atmospheres

  10. The helium line formation in late-type stars: Pt. 1

    International Nuclear Information System (INIS)

    Batalha, C.C.; De La Reza, R.

    1989-01-01

    The formation of helium lines and continua in an atmospheric model representing the medium quiet sun has been investigated considering principally the influence of: (i) changes in the temperature gradient at Transition Region (TR); (ii) the coronal radiation and (iii) the overlapping of He II Lyα at 304 A and the continuum radiation of He I at λ≤504 A. By diminishing the thermal gradient in the Transition Region a large part of the helium observations are reproduced. This is the case for the He II resonance λ304 line which is collisionally controlled and is formed at 1.0 x 10 5 K, and the He I resonance line at 584 A which is also collisionally controlled but is formed at deeper layers with a mean temperature of 2.5 x 10 4 K. The He II continuum at 228 A as well as the Lβ line at 256 A can be adjusted to observations if a characteristic solar coronal flux is incident on the optimized Transition Region. (author)

  11. Astronomical and Atmospheric Observations in the Anglo-Saxon Chronicle and in Bede

    Science.gov (United States)

    Härke, H.

    2012-01-01

    Textual sources of the early Middle Ages (fifth to tenth centuries AD) contain more astronomical observations than is popularly assumed. The Anglo-Saxon Chronicle lists some 40 observations of astronomical and atmospheric events for the just over 600 years it covers. But the contexts in which these are set show that eclipses, comets, meteor showers and aurorae were seen as portents of evil events, not as objects of early scientific curiosity. The case of Bede in the early eighth century shows that this was true, to an extent, even for the educated ecclesiastical elite. BedeÕs eclipse records also appear to show that astronomical events could be used to explain unusual phenomena such as the postulated volcanic Ôdust-veilÕ event of AD 536.

  12. Inferring giant planets from ALMA millimeter continuum and line observations in (transition) disks

    Science.gov (United States)

    Facchini, S.; Pinilla, P.; van Dishoeck, E. F.; de Juan Ovelar, M.

    2018-05-01

    Context. Radial gaps or cavities in the continuum emission in the IR-mm wavelength range are potential signatures of protoplanets embedded in their natal protoplanetary disk are. Hitherto, models have relied on the combination of mm continuum observations and near-infrared scattered light images to put constraints on the properties of embedded planets. Atacama Large Millimeter/submillimeter Array (ALMA) observations are now probing spatially resolved rotational line emission of CO and other chemical species. These observations can provide complementary information on the mechanism carving the gaps in dust and additional constraints on the purported planet mass. Aims: We investigate whether the combination of ALMA continuum and CO line observations can constrain the presence and mass of planets embedded in protoplanetary disks. Methods: We post-processed azimuthally averaged 2D hydrodynamical simulations of planet-disk models, in which the dust densities and grain size distributions are computed with a dust evolution code that considers radial drift, fragmentation, and growth. The simulations explored various planet masses (1 MJ ≤ Mp ≤ 15 MJ) and turbulent parameters (10-4 ≤ α ≤ 10-3). The outputs were then post-processed with the thermochemical code DALI, accounting for the radially and vertically varying dust properties. We obtained the gas and dust temperature structures, chemical abundances, and synthetic emission maps of both thermal continuum and CO rotational lines. This is the first study combining hydrodynamical simulations, dust evolution, full radiative transfer, and chemistry to predict gas emission of disks hosting massive planets. Results: All radial intensity profiles of 12CO, 13CO, and C18O show a gap at the planet location. The ratio between the location of the gap as seen in CO and the peak in the mm continuum at the pressure maximum outside the orbit of the planet shows a clear dependence on planet mass and is independent of disk

  13. Observational description of the atmospheric and oceanic boundary layers over the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Marcelo Dourado

    2001-01-01

    Full Text Available Time evolution of atmospheric and oceanic boundary layers are described for an upwelling region in the Atlantic Ocean located in Cabo Frio, Brazil (23°00'S, 42°08'W. The observations were obtained during a field campaign carried out by the "Instituto de Estudos do Mar Almirante Paulo Moreira", on board of the oceanographic ship Antares of the Brazilian Navy, between July 7 and 10 of 1992. The analysis shown here was based on 19 simultaneous vertical soundings of atmosphere and ocean, carried out consecutively every 4 hours. The period of observation was characterized by a passage of a cold front that penetrated in Cabo Frio on July 6. During the cold front passage the vertical extension of atmospheric (and oceanic mixed layer varied from 200 m (and 13 m to 1000 m (and 59 m. These changes occurred in the first day of observation and were followed by an increase of 1.2°C in the oceanic mixed layer temperature and by a decrease of 6 K and 6 g/kg in the virtual potential temperature and specific humidity of the atmospheric mixed layer. The short time scale variations in the ocean can be explained in terms of the substitution of cold upwelling water by warm downwelling water regime, as the surface winds shift from pre-frontal NE to post-frontal SSW during the cold front passage in Cabo Frio. The large vertical extent of the atmospheric mixed layer can be explained in terms of an intensification of the thermal mixing induced by the warming of the oceanic upper layers combined with the cooling of the lower atmospheric layers during the cold front passage. An intensification of the mechanical mixing, observed during the cold front passage, may also be contributing to the observed variations in the vertical extent of both layers.A evolução temporal das camadas limites atmosféricas e oceânicas são descritas para a região de ressurgência do Oceano Atlântico localizada em Cabo Frio. As observações foram obtidas durante a campanha de medidas

  14. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    International Nuclear Information System (INIS)

    Tanaka, Hiromasa; Mizuno, Masaaki; Toyokuni, Shinya; Maruyama, Shoichi; Kodera, Yasuhiro; Terasaki, Hiroko; Adachi, Tetsuo; Kato, Masashi; Kikkawa, Fumitaka; Hori, Masaru

    2015-01-01

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established

  15. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hiromasa [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Mizuno, Masaaki [Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Toyokuni, Shinya [Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Maruyama, Shoichi [Department of Nephrology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kodera, Yasuhiro [Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Terasaki, Hiroko [Department of Ophthalmology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Adachi, Tetsuo [Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu (Japan); Kato, Masashi [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kikkawa, Fumitaka [Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Hori, Masaru [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-12-15

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  16. Open-source Software for Exoplanet Atmospheric Modeling

    Science.gov (United States)

    Cubillos, Patricio; Blecic, Jasmina; Harrington, Joseph

    2018-01-01

    I will present a suite of self-standing open-source tools to model and retrieve exoplanet spectra implemented for Python. These include: (1) a Bayesian-statistical package to run Levenberg-Marquardt optimization and Markov-chain Monte Carlo posterior sampling, (2) a package to compress line-transition data from HITRAN or Exomol without loss of information, (3) a package to compute partition functions for HITRAN molecules, (4) a package to compute collision-induced absorption, and (5) a package to produce radiative-transfer spectra of transit and eclipse exoplanet observations and atmospheric retrievals.

  17. A telescope for observation from space of extreme lightnings in the upper atmosphere

    International Nuclear Information System (INIS)

    Nam, S.; Artikova, S.; Chung, T.; Garipov, G.; Jeon, J.A.; Jeong, S.; Jin, J.Y.; Khrenov, B.A.; Kim, J.E.; Kim, M.; Kim, Y.K.; Klimov, P.; Lee, J.; Lee, H.Y.; Na, G.W.; Oh, S.J.; Panasyuk, M.; Park, I.H.; Park, J.H.; Park, Y.-S.

    2008-01-01

    A new type of telescope with a wide field-of-view and functions of fast zoom-in has been introduced. Two kinds of MEMS (Micro-Electro-Mechanical Systems) micromirrors, digital and analog, are used for reflectors of the telescope, placed at different focal lengths. We apply this technology to the observation from space of TLE (Transient Luminous Events), extremely large transient sparks occurring at the upper atmosphere. TLE are one type of important backgrounds to be understood for future space observation of UHECR (Ultra-High Energy Cosmic Rays). The launch of the payload carried by a Russian microsatellite is foreseen in the middle of 2008

  18. Characterising fifteen years of continuous atmospheric radon activity observations at Cape Point (South Africa)

    Science.gov (United States)

    Botha, R.; Labuschagne, C.; Williams, A. G.; Bosman, G.; Brunke, E.-G.; Rossouw, A.; Lindsay, R.

    2018-03-01

    This paper describes and discusses fifteen years (1999-2013) of continuous hourly atmospheric radon (222Rn) monitoring at the coastal low-altitude Southern Hemisphere Cape Point Station in South Africa. A strong seasonal cycle is evident in the observed radon concentrations, with maxima during the winter months, when air masses arriving at the Cape Point station from over the African continental surface are more frequently observed, and minima during the summer months, when an oceanic fetch is predominant. An atmospheric mean radon activity concentration of 676 ± 2 mBq/m3 is found over the 15-year record, having a strongly skewed distribution that exhibits a large number of events falling into a compact range of low values (corresponding to oceanic air masses), and a smaller number of events with high radon values spread over a wide range (corresponding to continental air masses). The mean radon concentration from continental air masses (1 004 ± 6 mBq/m3) is about two times higher compared to oceanic air masses (479 ± 3 mBq/m3). The number of atmospheric radon events observed is strongly dependent on the wind direction. A power spectral Fast Fourier Transform analysis of the 15-year radon time series reveals prominent peaks at semi-diurnal, diurnal and annual timescales. Two inter-annual radon periodicities have been established, the diurnal 0.98 ± 0.04 day-1 and half-diurnal 2.07 ± 0.15 day-1. The annual peak reflects major seasonal changes in the patterns of offshore versus onshore flow associated with regional/hemispheric circulation patterns, whereas the diurnal and semi-diurnal peaks together reflect the influence of local nocturnal radon build-up over land, and the interplay between mesoscale sea/land breezes. The winter-time diurnal radon concentration had a significant decrease of about 200 mBq/m3 (17%) while the summer-time diurnal radon concentration revealed nearly no changes. A slow decline in the higher radon percentiles (75th and 95th) for the

  19. Mars MetNet Mission - Martian Atmospheric Observational Post Network

    Science.gov (United States)

    Hari, Ari-Matti; Haukka, Harri; Aleksashkin, Sergey; Arruego, Ignacio; Schmidt, Walter; Genzer, Maria; Vazquez, Luis; Siikonen, Timo; Palin, Matti

    2017-04-01

    accelerometer combined with a 3-axis gyrometer. The data will be sent via auxiliary beacon antenna throughout the descent phase starting shortly after separation from the spacecraft. MetNet Mission payload instruments are specially designed to operate under very low power conditions. MNL flexible solar panels provides a total of approximately 0.7-0.8 W of electric power during the daylight time. As the provided power output is insufficient to operate all instruments simultaneously they are activated sequentially according to a specially designed cyclogram table which adapts itself to the different environmental constraints. 3. Mission Status he eventual goal is to create a network of atmospheric observational posts around the Martian surface. Even if the MetNet mission is focused on the atmospheric science, the mission payload will also include additional kinds of geophysical instrumentation. The next step is the MetNet Precursor Mission that will demonstrate the technical robustness and scientific capabilities of the MetNet type of landing vehicle. Definition of the Precursor Mission and discussions on launch opportunities are currently under way. The first MetNet Science Payload Precursors have already been successfully completed, e,g, the REMS/MSL and DREAMS/Exomars-2016. The next MetNet Payload Precursors will be METEO/Exomars-2018 and MEDA/Mars-2020. The baseline program development funding exists for the next seven years. Flight unit manufacture of the payload bay takes about 18 months, and it will be commenced after the Precursor Mission has been defined. References [1] http://metnet.fmi.fi

  20. Line by Line CO2 Absorption in the Atmosphere for Input Data to Calculate Global Warming, David C. Smith, DCS Lasers & Optics LLC, Old Saybrook CT 06475

    Science.gov (United States)

    Smith, D. C.

    2012-12-01

    Compter modeling of global climate change require an input (asssumption) of the forcing function for CO2 absorption. All codes use a long term forcing function of ~ 4 W/M2. (IPCC 2007 Summary for Policymakers. In:Climate Change 2007. The Physical Sciences Basis.Contributions of Working Group 1 to the Fourth Assessment Report of the IPCC, Cambridge U. Press N.Y.)..This is based on a band model of the CO2 rotational/vibrational absorption where a band of absorption averages over all the rotational levels of the vibration transition. (Ramananathan,V.,et al, J. of Geophysical Research,Vol 84 C8,p4949,Aug.1979).. The model takes into account the line width,the spacing between lines and identifies 10 CO2 bands.. This approach neglects the possibility that the peak absorption transitions in a band can "use up" all of the earths IR radiation at that wavelength and does not contribute to global warming no matter how much the CO2 is increased. The lines in the wings of a band increase their absorption as the CO2 is increased. However, the lines that are lost are the strong absorbers and those that are added are the weaker absorption lines. When a band begins to use up the IR then the net result of increasing the atmospheric CO2 is a decrease in the absorption change. This presentation calculates the absorption of each line individualy using the Behr's Law Approach. The dependence of the absorption and line width of each transition as a function of altitude is accounted for. The temperature dependence of the absorption with altitude is not and an evaluation of this error is given. For doubling CO2 from 320ppm to 640 ppm, the calculation gives a forcing function of 1.1 W/M2. The results show the importance of using individual lines to calculate the CO2 contribution to global warming, We can speculate on the imact and anticipate a computer code calculation of a factor of 4 less global warming than the published results.

  1. Hard X-ray observations of the Her X-1 line feature

    International Nuclear Information System (INIS)

    Manchanda, R.K.; Vialetto, G.; Bazzano, A.; La Padula, C.; Polcaro, V.F.; Ubertini, P.

    1982-01-01

    We have carried out two observations separated by a year in 1980 and 1981 during the mid-on phase of Her X-1, by using xenon filled multi-wire proportional chambers. This paper presents the time-averaged spectral results of Her X-1 in the 15-150 keV energy range. The possible case of the line centroid variability seen during 1980 experiment is also discussed. (orig./WL)

  2. Improving the Ni I atomic model for solar and stellar atmospheric models

    International Nuclear Information System (INIS)

    Vieytes, M. C.; Fontenla, J. M.

    2013-01-01

    Neutral nickel (Ni I) is abundant in the solar atmosphere and is one of the important elements that contribute to the emission and absorption of radiation in the spectral range between 1900 and 3900 Å. Previously, the Solar Radiation Physical Modeling (SRPM) models of the solar atmosphere only considered a few levels of this species. Here, we improve the Ni I atomic model by taking into account 61 levels and 490 spectral lines. We compute the populations of these levels in full NLTE using the SRPM code and compare the resulting emerging spectrum with observations. The present atomic model significantly improves the calculation of the solar spectral irradiance at near-UV wavelengths, which is important for Earth atmospheric studies, and particularly for ozone chemistry.

  3. Improving the Ni I atomic model for solar and stellar atmospheric models

    Energy Technology Data Exchange (ETDEWEB)

    Vieytes, M. C. [Instituto de de Astronomía y Física del Espacio, CONICET and UNTREF, Buenos Aires (Argentina); Fontenla, J. M., E-mail: mariela@iafe.uba.ar, E-mail: johnf@digidyna.com [North West Research Associates, 3380 Mitchell Lane, Boulder, CO 80301 (United States)

    2013-06-01

    Neutral nickel (Ni I) is abundant in the solar atmosphere and is one of the important elements that contribute to the emission and absorption of radiation in the spectral range between 1900 and 3900 Å. Previously, the Solar Radiation Physical Modeling (SRPM) models of the solar atmosphere only considered a few levels of this species. Here, we improve the Ni I atomic model by taking into account 61 levels and 490 spectral lines. We compute the populations of these levels in full NLTE using the SRPM code and compare the resulting emerging spectrum with observations. The present atomic model significantly improves the calculation of the solar spectral irradiance at near-UV wavelengths, which is important for Earth atmospheric studies, and particularly for ozone chemistry.

  4. Rotational and High-resolution Infrared Spectrum of HC3N: Global Ro-vibrational Analysis and Improved Line Catalog for Astrophysical Observations

    Science.gov (United States)

    Bizzocchi, Luca; Tamassia, Filippo; Laas, Jacob; Giuliano, Barbara M.; Degli Esposti, Claudio; Dore, Luca; Melosso, Mattia; Canè, Elisabetta; Pietropolli Charmet, Andrea; Müller, Holger S. P.; Spahn, Holger; Belloche, Arnaud; Caselli, Paola; Menten, Karl M.; Garrod, Robin T.

    2017-11-01

    HC3N is a ubiquitous molecule in interstellar environments, from external galaxies to Galactic interstellar clouds, star-forming regions, and planetary atmospheres. Observations of its rotational and vibrational transitions provide important information on the physical and chemical structures of the above environments. We present the most complete global analysis of the spectroscopic data of HC3N. We recorded the high-resolution infrared spectrum from 450 to 1350 cm-1, a region dominated by the intense {ν }5 and {ν }6 fundamental bands, located at 660 and 500 cm-1, respectively, and their associated hot bands. Pure rotational transitions in the ground and vibrationally excited states were recorded in the millimeter and submillimeter regions in order to extend the frequency range so far considered in previous investigations. All of the transitions from the literature and from this work involving energy levels lower than 1000 cm-1 were fitted together to an effective Hamiltonian. Because of the presence of various anharmonic resonances, the Hamiltonian includes a number of interaction constants, in addition to the conventional rotational and vibrational l-type resonance terms. The data set contains about 3400 ro-vibrational lines of 13 bands and some 1500 pure rotational lines belonging to 12 vibrational states. More than 120 spectroscopic constants were determined directly from the fit, without any assumption deduced from theoretical calculations or comparisons with similar molecules. An extensive list of highly accurate rest frequencies was produced to assist astronomical searches and data interpretation. These improved data enabled a refined analysis of the ALMA observations toward Sgr B2(N2).

  5. Observational tests for the evolution of massive stars in nearby galaxies

    International Nuclear Information System (INIS)

    Leitherer, C.

    1990-01-01

    Population synthesis calculations applicable to the massive stellar content in nearby galaxies are presented. Stellar evolution calculations are combined with mass loss, model atmospheres with line blanketing, and a spectral type calibration to compute observable parameters of massive stars as a function of the star formation rate and the initial mass function slope. The number of O stars of given spectral types, the number of W-R stars, supernova rates, and fluxes of ionizing photons are predicted. Important constraints for the theories of stellar atmospheres and stellar evolution can be derived from observations if stellar number counts and ionizing flux data are available. 94 refs

  6. South African carbon observations: CO2 measurements for land, atmosphere and ocean

    CSIR Research Space (South Africa)

    Feig, Gregor T

    2017-11-01

    Full Text Available , Mudau AE, Monteiro PMS. South African carbon observations: CO2 measurements for land, atmosphere and ocean. S Afr J Sci. 2017;113(11/12), Art. #a0237, 4 pages. http://dx.doi. org/10.17159/sajs.2017/a0237 Carbon dioxide plays a central role in earth... References 1. Houghton RA. Balancing the global carbon budget. Annu Rev Earth Planet Sci. 2007;35:313–347. https://doi.org/10.1146/annurev. earth.35.031306.140057 2. Denman KL. Climate change, ocean processes and ocean iron fertilization. Mar Ecol Prog Ser...

  7. A global climatology of stratospheric gravity waves from Atmospheric Infrared Sounder observations

    Science.gov (United States)

    Hoffmann, Lars; Xue, Xianghui; Alexander, M. Joan

    2014-05-01

    We present the results of a new study that aims on the detection and classification of `hotspots' of stratospheric gravity waves on a global scale. The analysis is based on a nine-year record (2003 to 2011) of radiance measurements by the Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite. We detect the presence of stratospheric gravity waves based on 4.3 micron brightness temperature variances. Our method is optimized for peak events, i.e., strong gravity wave events for which the local variance considerably exceeds background levels. We estimated the occurrence frequencies of these peak events for different seasons and time of day and used the results to find local maxima of gravity wave activity. In addition, we use AIRS radiances at 8.1 micron to simultaneously detect convective events, including deep convection in the tropics and mesoscale convective systems at mid latitudes. We classified the gravity waves according to their sources, based on seasonal occurrence frequencies for convection and by means of topographic data. Our study reproduces well-known hotspots of gravity waves, e.g., the mountain wave hotspots at the Andes and the Antarctic Peninsula or the convective hotspot during the thunderstorm season over the North American Great Plains. However, the high horizontal resolution of the AIRS observations also helped us to locate several smaller hotspots, which were partly unknown or poorly studied so far. Most of these smaller hotspots are found near orographic features like small mountain ranges, in coastal regions, in desert areas, or near isolated islands. This new study will help to select the most promising regions and seasons for future observational studies of gravity waves. Reference: Hoffmann, L., X. Xue, and M. J. Alexander, A global view of stratospheric gravity wave hotspots located with Atmospheric Infrared Sounder observations, J. Geophys. Res., 118, 416-434, doi:10.1029/2012JD018658, 2013.

  8. Approach to simultaneously denoise and invert backscatter and extinction from photon-limited atmospheric lidar observations.

    Science.gov (United States)

    Marais, Willem J; Holz, Robert E; Hu, Yu Hen; Kuehn, Ralph E; Eloranta, Edwin E; Willett, Rebecca M

    2016-10-10

    Atmospheric lidar observations provide a unique capability to directly observe the vertical column of cloud and aerosol scattering properties. Detector and solar-background noise, however, hinder the ability of lidar systems to provide reliable backscatter and extinction cross-section estimates. Standard methods for solving this inverse problem are most effective with high signal-to-noise ratio observations that are only available at low resolution in uniform scenes. This paper describes a novel method for solving the inverse problem with high-resolution, lower signal-to-noise ratio observations that are effective in non-uniform scenes. The novelty is twofold. First, the inferences of the backscatter and extinction are applied to images, whereas current lidar algorithms only use the information content of single profiles. Hence, the latent spatial and temporal information in noisy images are utilized to infer the cross-sections. Second, the noise associated with photon-counting lidar observations can be modeled using a Poisson distribution, and state-of-the-art tools for solving Poisson inverse problems are adapted to the atmospheric lidar problem. It is demonstrated through photon-counting high spectral resolution lidar (HSRL) simulations that the proposed algorithm yields inverted backscatter and extinction cross-sections (per unit volume) with smaller mean squared error values at higher spatial and temporal resolutions, compared to the standard approach. Two case studies of real experimental data are also provided where the proposed algorithm is applied on HSRL observations and the inverted backscatter and extinction cross-sections are compared against the standard approach.

  9. Wide angle Michelson Doppler imaging interferometer. [measuring atmospheric emissions

    Science.gov (United States)

    Shepherd, G. G.

    1980-01-01

    The optical system, stepping control, phase and modulation depth, array detector, and directions sensor are described for a specialized type of Michelson interferometer which works at sufficiently high resolution to measure the line widths and Doppler shifts of naturally occurring atmospheric emissions. With its imaging capability, the instrument can potentially supply this data independently for each element of the 100 x 100 detector array. The experiment seeks: (1) to obtain vertical profiles of atmospheric winds and temperatures as functions of latitude by observing near the limb; (2) to acquire exploratory wind and temperature data on smaller scale structures in airglow irregularities and in auroral forms; and (3) to collaborate with other Spacelab experiments, such as barium cloud releases, in providing wind and temperature data.

  10. Peri-acetabular radiolucent lines: inter- and intra-observer agreement on post-operative radiographs

    OpenAIRE

    Kneif, D.; Downing, M.; Ashcroft, G. P.; Gibson, P.; Knight, D.; Ledingham, W.; Hutchison, J.

    2005-01-01

    Peri-acetabular radiolucent lines (RLLs) seen on “early” post-operative radiographs have been identified as a potential predictor of long-term implant performance. This study examines the inter- and intra-observer variation encountered when assessing such radiographs. Four consultant orthopaedic surgeons assessed the presence, extent and width of RLLs in 220 radiographs performed on 50 patients taken one to two weeks, six weeks, six months and one year following surgery. Inter-observer agreem...

  11. Evaluating the Capacity of Global CO2 Flux and Atmospheric Transport Models to Incorporate New Satellite Observations

    Science.gov (United States)

    Kawa, S. R.; Collatz, G. J.; Erickson, D. J.; Denning, A. S.; Wofsy, S. C.; Andrews, A. E.

    2007-01-01

    As we enter the new era of satellite remote sensing for CO2 and other carbon cyclerelated quantities, advanced modeling and analysis capabilities are required to fully capitalize on the new observations. Model estimates of CO2 surface flux and atmospheric transport are required for initial constraints on inverse analyses, to connect atmospheric observations to the location of surface sources and sinks, and ultimately for future projections of carbon-climate interactions. For application to current, planned, and future remotely sensed CO2 data, it is desirable that these models are accurate and unbiased at time scales from less than daily to multi-annual and at spatial scales from several kilometers or finer to global. Here we focus on simulated CO2 fluxes from terrestrial vegetation and atmospheric transport mutually constrained by analyzed meteorological fields from the Goddard Modeling and Assimilation Office for the period 1998 through 2006. Use of assimilated meteorological data enables direct model comparison to observations across a wide range of scales of variability. The biospheric fluxes are produced by the CASA model at lxi degrees on a monthly mean basis, modulated hourly with analyzed temperature and sunlight. Both physiological and biomass burning fluxes are derived using satellite observations of vegetation, burned area (as in GFED-2), and analyzed meteorology. For the purposes of comparison to CO2 data, fossil fuel and ocean fluxes are also included in the transport simulations. In this presentation we evaluate the model's ability to simulate CO2 flux and mixing ratio variability in comparison to in situ observations at sites in Northern mid latitudes and the continental tropics. The influence of key process representations is inferred. We find that the model can resolve much of the hourly to synoptic variability in the observations, although there are limits imposed by vertical resolution of boundary layer processes. The seasonal cycle and its

  12. Atmospheric Fluctuation Measurements with the Palomar Testbed Interferometer

    Science.gov (United States)

    Linfield, R. P.; Lane, B. F.; Colavita, M. M.; PTI Collaboration

    Observations of bright stars with the Palomar Testbed Interferometer, at a wavelength of 2.2 microns, have been used to measure atmospheric delay fluctuations. The delay structure function Dτ(Δ t) was calculated for 66 scans (each >= 120s in length) on seven nights in 1997 and one in 1998. For all except one scan, Dτ exhibited a clean power law shape over the time interval 50-500 msec. Over shorter time intervals, the effect of the delay line servo loop corrupts Dτ. Over longer time intervals (usually starting at > 1s), the slope of Dτ decreases, presumably due to some combination of saturation e.g. finite turbulent layer thickness) and the effect of the finite wind speed crossing time on our 110 m baseline. The mean power law slopes for the eight nights ranged from 1.16 to 1.36, substantially flatter than the value of 1.67 for three dimensional Kolmogorov turbulence. Such sub-Kolmogorov slopes will result in atmospheric seeling (θ) that improves rapidly with increasing wavelength: θ propto λ1-(2β), where β is the observed power law slope of Dτ. The atmospheric errors in astrometric measurements with an interferometer will average down more quickly than in the Kolmogorov case.

  13. Using the van der Waals broadening of the spectral atomic lines to measure the gas temperature of an argon microwave plasma at atmospheric pressure

    International Nuclear Information System (INIS)

    Yubero, C.; Dimitrijevic, M.S.; Garcia, M.C.; Calzada, M.D.

    2007-01-01

    The ro-vibrational emission spectra of the molecular species are usually used to measure the gas temperature of a discharge at atmospheric pressure. However, under some experimental conditions, it is difficult to detect them. In order to overcome this difficulty and obtain the temperature, there are methods based on the relation between the gas temperature and the van der Waals broadening of argon atomic spectral lines with a Stark contribution negligible. In this work, we propose a method based on this relation but for lines with a Stark broadening comparable with the van der Waals one

  14. Ultraviolet observations of cool stars. III. Chromospheric and coronal lines in α Tauri, β Geminorum, and α Bootis

    International Nuclear Information System (INIS)

    McClintock, W.; Linsky, J.L.; Henry, R.C.; Moos, H.W.; Gerola, H.

    1975-01-01

    The ultraviolet spectrometer of the Princeton Experiment Package aboard the Copernicus satellite has been used to obtain high-resolution measurements of Lα, the Mg ii lambda2800 doublet, and upper limits on the Si iii lambda1206 line in the K giants α Tau and β Gem. The intensities and line shapes are compared with earlier observations of α Boo. The Lα and Mg ii profiles for α Tau resemble those for α Boo, in that they are highly asymmetrical, while β Gem shows much more symmetrical profiles. The asymmetries for all lines except for those of α Boo and Mg ii lines of α Tau could be due to interstellar absorption. In the case of β Gem only, the O v intercombination line at 1218 A is observed, suggesting a well-developed corona substantially cooler than that of the Sun. The Lα profiles of α Tau and β Gem are consistent with the low interstellar hydrogen abundance in the solar neighborhood previously obtained from a similar observation of the α Boo Lα profile. The strength of the Mg ii lambda2796 line can be used to measure transition region and coronal pressures, and indicates a decrease in both with later spectral type and/or increasing luminosity

  15. Limb darkening laws for two exoplanet host stars derived from 3D stellar model atmospheres. Comparison with 1D models and HST light curve observations

    Science.gov (United States)

    Hayek, W.; Sing, D.; Pont, F.; Asplund, M.

    2012-03-01

    We compare limb darkening laws derived from 3D hydrodynamical model atmospheres and 1D hydrostatic MARCS models for the host stars of two well-studied transiting exoplanet systems, the late-type dwarfs HD 209458 and HD 189733. The surface brightness distribution of the stellar disks is calculated for a wide spectral range using 3D LTE spectrum formation and opacity sampling⋆. We test our theoretical predictions using least-squares fits of model light curves to wavelength-integrated primary eclipses that were observed with the Hubble Space Telescope (HST). The limb darkening law derived from the 3D model of HD 209458 in the spectral region between 2900 Å and 5700 Å produces significantly better fits to the HST data, removing systematic residuals that were previously observed for model light curves based on 1D limb darkening predictions. This difference arises mainly from the shallower mean temperature structure of the 3D model, which is a consequence of the explicit simulation of stellar surface granulation where 1D models need to rely on simplified recipes. In the case of HD 189733, the model atmospheres produce practically equivalent limb darkening curves between 2900 Å and 5700 Å, partly due to obstruction by spectral lines, and the data are not sufficient to distinguish between the light curves. We also analyze HST observations between 5350 Å and 10 500 Å for this star; the 3D model leads to a better fit compared to 1D limb darkening predictions. The significant improvement of fit quality for the HD 209458 system demonstrates the higher degree of realism of 3D hydrodynamical models and the importance of surface granulation for the formation of the atmospheric radiation field of late-type stars. This result agrees well with recent investigations of limb darkening in the solar continuum and other observational tests of the 3D models. The case of HD 189733 is no contradiction as the model light curves are less sensitive to the temperature stratification of

  16. A quasi-continuous observation of the α-transition of Fe1+xS by Moessbauer line tracking

    International Nuclear Information System (INIS)

    Mendoza Zelis, P.; Pasquevich, G. A.; Veiga, A.; Fernandez van Raap, M. B.; Sanchez, F. H.

    2010-01-01

    Moessbauer absorption line tracking methodology, under a constant velocity strategy, is used for a quasi-continuous observation of the α-transition on slightly non stoichiometric Fe 1+x S alloy. To this end, two strategies were applied: an intelligent absorption line tracking with a control algorithm that uses the data measured in the previous region to establish the position of the next partial spectral range; and a predetermined line tracking in which temperature evolution of a partial spectral region of interest (ROI) is programmed. The latter uses results from the former, in order to achieve a quasi-continuous partial spectral observation. These experiments clearly demonstrate that line tracking allows a more efficient use of the radioactive source, as the effort is concentrated in a partial region of the spectra from which the desired information can be obtained.

  17. Atmospheric Electricity

    Science.gov (United States)

    Aplin, Karen; Fischer, Georg

    2018-02-01

    Electricity occurs in atmospheres across the Solar System planets and beyond, spanning spectacular lightning displays in clouds of water or dust, to more subtle effects of charge and electric fields. On Earth, lightning is likely to have existed for a long time, based on evidence from fossilized lightning strikes in ancient rocks, but observations of planetary lightning are necessarily much more recent. The generation and observations of lightning and other atmospheric electrical processes, both from within-atmosphere measurements, and spacecraft remote sensing, can be readily studied using a comparative planetology approach, with Earth as a model. All atmospheres contain charged molecules, electrons, and/or molecular clusters created by ionization from cosmic rays and other processes, which may affect an atmosphere's energy balance both through aerosol and cloud formation, and direct absorption of radiation. Several planets are anticipated to host a "global electric circuit" by analogy with the circuit occurring on Earth, where thunderstorms drive current of ions or electrons through weakly conductive parts of the atmosphere. This current flow may further modulate an atmosphere's radiative properties through cloud and aerosol effects. Lightning could potentially have implications for life through its effects on atmospheric chemistry and particle transport. It has been observed on many of the Solar System planets (Earth, Jupiter, Saturn, Uranus, and Neptune) and it may also be present on Venus and Mars. On Earth, Jupiter, and Saturn, lightning is thought to be generated in deep water and ice clouds, but discharges can be generated in dust, as for terrestrial volcanic lightning, and on Mars. Other, less well-understood mechanisms causing discharges in non-water clouds also seem likely. The discovery of thousands of exoplanets has recently led to a range of further exotic possibilities for atmospheric electricity, though lightning detection beyond our Solar System

  18. Ultra-High Resolution Spectroscopic Remote Sensing: A Microscope on Planetary Atmospheres

    Science.gov (United States)

    Kostiuk, Theodor

    2010-01-01

    Remote sensing of planetary atmospheres is not complete without studies of all levels of the atmosphere, including the dense cloudy- and haze filled troposphere, relatively clear and important stratosphere and the upper atmosphere, which are the first levels to experience the effects of solar radiation. High-resolution spectroscopy can provide valuable information on these regions of the atmosphere. Ultra-high spectral resolution studies can directly measure atmospheric winds, composition, temperature and non-thermal phenomena, which describe the physics and chemistry of the atmosphere. Spectroscopy in the middle to long infrared wavelengths can also probe levels where dust of haze limit measurements at shorter wavelength or can provide ambiguous results on atmospheric species abundances or winds. A spectroscopic technique in the middle infrared wavelengths analogous to a radio receiver. infrared heterodyne spectroscopy [1], will be describe and used to illustrate the detailed study of atmospheric phenomena not readily possible with other methods. The heterodyne spectral resolution with resolving power greater than 1,000.000 measures the true line shapes of emission and absorption lines in planetary atmospheres. The information on the region of line formation is contained in the line shapes. The absolute frequency of the lines can be measured to I part in 100 ,000,000 and can be used to accurately measure the Doppler frequency shift of the lines, directly measuring the line-of-sight velocity of the gas to --Im/s precision (winds). The technical and analytical methods developed and used to measure and analyze infrared heterodyne measurements will be described. Examples of studies on Titan, Venus, Mars, Earth, and Jupiter will be presented. 'These include atmospheric dynamics on slowly rotating bodies (Titan [2] and Venus [3] and temperature, composition and chemistry on Mars 141, Venus and Earth. The discovery and studies of unique atmospheric phenomena will also be

  19. HIFISTARS Herschel/HIFI observations of VY Canis Majoris. Molecular-line inventory of the envelope around the largest known star

    NARCIS (Netherlands)

    Alcolea, J.; Bujarrabal, V.; Planesas, P.; Teyssier, D.; Cernicharo, J.; De Beck, E.; Decin, L.; Dominik, C.; Justtanont, K.; de Koter, A.; Marston, A.P.; Melnick, G.; Menten, K.M.; Neufeld, D.A.; Olofsson, H.; Schmidt, M.; Schöier, F.L.; Szczerba, R.; Waters, L.B.F.M.

    2013-01-01

    Aims. The study of the molecular gas in the circumstellar envelopes of evolved stars is normally undertaken by observing lines of CO (and other species) in the millimetre-wave domain. In general, the excitation requirements of the observed lines are low at these wavelengths, and therefore these

  20. Collision and radiative processes in emission of atmospheric carbon dioxide

    Science.gov (United States)

    Smirnov, B. M.

    2018-05-01

    The peculiarities of the spectroscopic properties of CO2 molecules in air due to vibration-rotation radiative transitions are analyzed. The absorption coefficient due to atmospheric carbon dioxide and other atmospheric components is constructed within the framework of the standard atmosphere model, on the basis of classical molecular spectroscopy and the regular model for the spectroscopy absorption band. The radiative flux from the atmosphere toward the Earth is represented as that of a blackbody, and the radiative temperature for emission at a given frequency is determined with accounting for the local thermodynamic equilibrium, a small gradient of the tropospheric temperature and a high optical thickness of the troposphere for infrared radiation. The absorption band model with an absorption coefficient averaged over the frequency and line-by-line model are used for evaluating the radiative flux from the atmosphere to the Earth which values are nearby for these models and are equal W m‑2 for the contemporary concentration of atmospheric CO2 molecules and W m‑2 at its doubled value. The absorption band model is not suitable to calculate the radiative flux change at doubling of carbon dioxide concentration because averaging over oscillations decreases the range where the atmospheric optical thickness is of the order of one, and just this range determines this change. The line-by-line method gives the change of the global temperature K as a result of doubling the carbon dioxide concentration. The contribution to the global temperature change due to anthropogenic injection of carbon dioxide in the atmosphere, i.e. resulted from combustion of fossil fuels, is approximately 0.02 K now.

  1. Export of Atmospheric Mercury from East Asia Observed at Various Monitoring Sites in Taiwan

    Science.gov (United States)

    Sheu, G.; Lin, N.; Wang, J.; Lee, C.; Chang, S.

    2009-12-01

    East Asia is the major atmospheric mercury (Hg) source region in the world due to the excessive coal combustion, industrial emission, and biomass burning in this area. Nonetheless, studies concerning the export of atmospheric Hg from East Asia are still limited. Accordingly, atmospheric Hg has been measured at various sites in Taiwan to study its temporal and spatial distribution, and the significance of long-range transport from the East Asian continent as well. Here we report the data collected in Fu-guei-jiao (121.97°E, 25.47°N, ~30 m a.s.l.), Mt. Bamboo (121.54°E, 25.19°N, 1025 m a.s.l.), and Lulin Atmospheric Background Station (LABS; 120.87°E, 23.47°N, 2862 m a.s.l.) to discuss the atmospheric Hg export from the East Asian continent. Twenty-four hour-integrated total atmospheric Hg (THg) samples were manually collected in Fu-guei-jiao and Mt. Bamboo in 2007-2008 and quantified by dual amalgamation CVAFS. On the other hand, continuous measurements of gaseous elemental Hg (GEM), reactive gaseous Hg (RGM), and particulate Hg (PHg) at LABS began since April 13, 2006 using the Tekran 2537A/1130/1135 speciation system. Mean(±S.D.) THg concentrations were 2.09±0.71 and 1.86±0.50 ng m-3 for Fu-guei-jiao and Mt. Bamboo, respectively. At LABS between April 2006 and April 2009, the mean(±S.D.) concentrations of GEM, RGM and PHg were 1.77±0.54 ng m-3, 22.4±43.8 pg m-3 and 6.3±10.9 pg m-3, respectively. Evident seasonal distribution in THg/GEM concentrations was observed at all sites with higher values usually occurred between fall and spring when the air masses were mainly from the East Asian continent, indicating the influence of the East Asian atmospheric Hg outflow. This also demonstrated that the atmospheric Hg export is occurring both in the boundary layer and in the free troposphere. Concentrations of PHg were usually low at LABS; however, elevated values were detected in spring when the Indochina Peninsula biomass burning plumes frequently affected

  2. Discrepancies between calculated and observed Fe XVII and Ni XIX solar coronal lines

    Energy Technology Data Exchange (ETDEWEB)

    Loulergue, M [Observatoire de Paris, Section de Meudon, 92 (France); Nussbaumer, H [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1975-12-01

    The 36-levels model atom Fe/sup +16/ of Loulergue and Nussbaumer (1973) is extended to a 51-levels atom including n=4 configuration. The earlier conclusion that relative intensities among the Fe XVII lines are not sufficiently sensitive to variations in electron densities and electron temperature to deduce these parameters from observed intensity ratios still holds. Discrepancies between calculated and observed relative intensities in Fe XVII and Ni XIX are attributed to blends or misidentifications.

  3. Timing Sunsets with Smartphones: Proof of Concept for a Citizen Science Project that Quantifies the Atmosphere and Supports Astronomical Observations

    Science.gov (United States)

    Wilson, Teresa; Kantamneni, A.; Bartlett, J. L.; Nemiroff, R. J.

    2014-01-01

    Current models that predict the times of sunrise and sunset are only accurate, typically, to a few minutes. Variations in atmospheric refraction contribute to the differences between computed and observed times. At high latitudes, slight changes in refraction can cause the Sun to remain continuously above the horizon instead of appearing to set. A substantial collection of observations would help constrain atmospheric models, which should, in turn, complement astronomical observations through improved understanding of air stability, refraction, and transparency. We report on a small project recording data from a few smartphones as a proof of concept for a possible larger scale citizen science effort.

  4. Mathematical modeling of atmospheric fine particle-associated primary organic compound concentrations

    Science.gov (United States)

    Rogge, Wolfgang F.; Hildemann, Lynn M.; Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.

    1996-08-01

    An atmospheric transport model has been used to explore the relationship between source emissions and ambient air quality for individual particle phase organic compounds present in primary aerosol source emissions. An inventory of fine particulate organic compound emissions was assembled for the Los Angeles area in the year 1982. Sources characterized included noncatalyst- and catalyst-equipped autos, diesel trucks, paved road dust, tire wear, brake lining dust, meat cooking operations, industrial oil-fired boilers, roofing tar pots, natural gas combustion in residential homes, cigarette smoke, fireplaces burning oak and pine wood, and plant leaf abrasion products. These primary fine particle source emissions were supplied to a computer-based model that simulates atmospheric transport, dispersion, and dry deposition based on the time series of hourly wind observations and mixing depths. Monthly average fine particle organic compound concentrations that would prevail if the primary organic aerosol were transported without chemical reaction were computed for more than 100 organic compounds within an 80 km × 80 km modeling area centered over Los Angeles. The monthly average compound concentrations predicted by the transport model were compared to atmospheric measurements made at monitoring sites within the study area during 1982. The predicted seasonal variation and absolute values of the concentrations of the more stable compounds are found to be in reasonable agreement with the ambient observations. While model predictions for the higher molecular weight polycyclic aromatic hydrocarbons (PAH) are in agreement with ambient observations, lower molecular weight PAH show much higher predicted than measured atmospheric concentrations in the particle phase, indicating atmospheric decay by chemical reactions or evaporation from the particle phase. The atmospheric concentrations of dicarboxylic acids and aromatic polycarboxylic acids greatly exceed the contributions that

  5. Pluto's atmosphere in 2015 from high-resolution spectroscopy

    Science.gov (United States)

    Roe, Henry G.; Cook, Jason C.; Mace, Gregory N.; Holler, Bryan J.; Young, Leslie A.; McLane, Jacob N.; Jaffe, Daniel T.

    2015-11-01

    Pluto's thin N2/CH4 atmosphere is in vapor-pressure equilibrium with ices on its surface. The atmosphere evolves seasonally with the varying insolation pattern on Pluto's heterogenous surface, perhaps even largely freezing out to the surface during the coldest portion of Pluto's year. We use high-resolution (R≈25,000-50,000) near-infrared spectroscopy to resolve atmospheric methane absorption lines from Pluto's continuum spectra, as well as separate Pluto's atmospheric lines from the telluric spectrum. In addition to measuring the abundance and temperature of Pluto's atmospheric CH4, with broad wavelength coverage we are able to search for the inevitable products of N2/CH4 photochemistry. In 2015 we are undertaking an intensive campaign using NIRSPEC at Keck Observatory and IGRINS (Immersion Grating INfrared Spectrometer) at McDonald Observatory to coincide with the New Horizons Pluto encounter. We will report initial results from this 2015 campaign and compare the state of Pluto's atmosphere at the time of the New Horizons encounter with earlier years.

  6. Observable Effects of Atmospheric Pollution on Outpatient and Inpatient Morbidity in Bulgaria.

    Science.gov (United States)

    Platikanova, Magdalena; Penkova-Radicheva, Mariana

    2016-04-01

    One of Europe's most well-developed industrial regions is found in the Republic of Bulgaria. The industrialization of the region has a big impact on air pollution. Thermal power plant "Maritza East" (the largest of its kind in southeastern Europe), the army training range, machine manufacturers, household heating and high volume of automobile traffic are all major sources of pollution in the region. A five year study (2009-2013) followed yearly concentrations of principal atmospheric pollutants such as sulfur dioxide, dust, nitrogen dioxide, lead aerosols and hydrogen sulfide, and the way in which those levels had an effect on morbidity (outpatient and inpatient medical care) in the area. Statistical processing of data has been completed to represent and analyze the collected data in nonparametric and alternative format. Atmospheric pollution affects human health directly through pathological changes in the human organism. The registered outpatient care provided for the period 2009-2013 is highest for diseases of the cardiovascular system (11.85%), the respiratory system (17.34%) and the genitourinary system (9.76%). The registered rate of hospitalization for the same period is for diseases of the digestive system (11.90%), the cardiovascular system (11.85%), respiratory system (10.86%) and the genitourinary system (8.88%). The observed period shows a decrease in average yearly concentrations of the principal atmospheric pollutants in the industrial region (Bulgaria) and reflects a decrease in morbidity based on outpatient care and an increase in morbidity by inpatient care (hospitalization). Our findings should be corroborated in future longitudinal studies.

  7. Land and Atmosphere Near-Real-Time Capability for Earth Observing System

    Science.gov (United States)

    Murphy, Kevin J.

    2011-01-01

    The past decade has seen a rapid increase in availability and usage of near-real-time data from satellite sensors. The EOSDIS (Earth Observing System Data and Information System) was not originally designed to provide data with sufficiently low latency to satisfy the requirements for near-real-time users. The EOS (Earth Observing System) instruments aboard the Terra, Aqua and Aura satellites make global measurements daily, which are processed into higher-level 'standard' products within 8-40 hours of observation and then made available to users, primarily earth science researchers. However, applications users, operational agencies, and even researchers desire EOS products in near-real-time to support research and applications, including numerical weather and climate prediction and forecasting, monitoring of natural hazards, ecological/invasive species, agriculture, air quality, disaster relief and homeland security. These users often need data much sooner than routine science processing allows, usually within 3 hours, and are willing to trade science product quality for timely access. While Direct Broadcast provides more timely access to data, it does not provide global coverage. In 2002, a joint initiative between NASA (National Aeronautics and Space Administration), NOAA (National Oceanic and Atmospheric Administration), and the DOD (Department of Defense) was undertaken to provide data from EOS instruments in near-real-time. The NRTPE (Near Real Time Processing Effort) provided products within 3 hours of observation on a best-effort basis. As the popularity of these near-real-time products and applications grew, multiple near-real-time systems began to spring up such as the Rapid Response System. In recognizing the dependence of customers on this data and the need for highly reliable and timely data access, NASA's Earth Science Division sponsored the Earth Science Data and Information System Project (ESDIS)-led development of a new near-real-time system called

  8. The Chemistry of Atmosphere-Forest Exchange (CAFE Model – Part 2: Application to BEARPEX-2007 observations

    Directory of Open Access Journals (Sweden)

    G. M. Wolfe

    2011-02-01

    Full Text Available In a companion paper, we introduced the Chemistry of Atmosphere-Forest Exchange (CAFE model, a vertically-resolved 1-D chemical transport model designed to probe the details of near-surface reactive gas exchange. Here, we apply CAFE to noontime observations from the 2007 Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX-2007. In this work we evaluate the CAFE modeling approach, demonstrate the significance of in-canopy chemistry for forest-atmosphere exchange and identify key shortcomings in the current understanding of intra-canopy processes.

    CAFE generally reproduces BEARPEX-2007 observations but requires an enhanced radical recycling mechanism to overcome a factor of 6 underestimate of hydroxyl (OH concentrations observed during a warm (~29 °C period. Modeled fluxes of acyl peroxy nitrates (APN are quite sensitive to gradients in chemical production and loss, demonstrating that chemistry may perturb forest-atmosphere exchange even when the chemical timescale is long relative to the canopy mixing timescale. The model underestimates peroxy acetyl nitrate (PAN fluxes by 50% and the exchange velocity by nearly a factor of three under warmer conditions, suggesting that near-surface APN sinks are underestimated relative to the sources. Nitric acid typically dominates gross dry N deposition at this site, though other reactive nitrogen (NOy species can comprise up to 28% of the N deposition budget under cooler conditions. Upward NO2 fluxes cause the net above-canopy NOy flux to be ~30% lower than the gross depositional flux. CAFE under-predicts ozone fluxes and exchange velocities by ~20%. Large uncertainty in the parameterization of cuticular and ground deposition precludes conclusive attribution of non-stomatal fluxes to chemistry or surface uptake. Model-measurement comparisons of vertical concentration gradients for several emitted species suggests that the lower canopy airspace may be

  9. On the influence of the finite thickness of sources on the internal conversion lines observed in beta spectrometer

    International Nuclear Information System (INIS)

    Pecequilo, B.R.S.

    1976-01-01

    Electron lines are simulated by a Monte Carlo method in a digital computer in order to obtain an analytical formula to calculate the energy and the relative intensity of electron conversion lines when observed by beta spectrometry. The electrons come from the own thickness of the source. Computer program that simulate these lines is presented. In order to test the method, a direct comparison of the K-line of Hg-198 with the same line as simulated by the computer, is done [pt

  10. Estimation of Regional Carbon Balance from Atmospheric Observations

    Science.gov (United States)

    Denning, S.; Uliasz, M.; Skidmore, J.

    2002-12-01

    Variations in the concentration of CO2 and other trace gases in time and space contain information about sources and sinks at regional scales. Several methods have been developed to quantitatively extract this information from atmospheric measurements. Mass-balance techniques depend on the ability to repeatedly sample the same mass of air, which involves careful attention to airmass trajectories. Inverse and adjoint techniques rely on decomposition of the source field into quasi-independent "basis functions" that are propagated through transport models and then used to synthesize optimal linear combinations that best match observations. A recently proposed method for regional flux estimation from continuous measurements at tall towers relies on time-mean vertical gradients, and requires careful trajectory analysis to map the estimates onto regional ecosystems. Each of these techniques is likely to be applied to measurements made during the North American Carbon Program. We have also explored the use of Bayesian synthesis inversion at regional scales, using a Lagrangian particle dispersion model driven by mesoscale transport fields. Influence functions were calculated for each hypothetical observation in a realistic diurnally-varying flow. These influence functions were then treated as basis functions for the purpose of separate inversions for daytime photosynthesis and 24-hour mean ecosystem respiration. Our results highlight the importance of estimating CO2 fluxes through the lateral boundaries of the model. Respiration fluxes were well constrained by one or two hypothetical towers, regardless of inflow fluxes. Time-varying assimilation fluxes were less well constrained, and much more dependent on knowledge of inflow fluxes. The small net difference between respiration and photosynthesis was the most difficult to determine, being extremely sensitive to knowledge of inflow fluxes. Finally, we explored the feasibility of directly incorporating mid-day concentration

  11. Constraining Line-of-sight Confusion in the Corona Using Linearly Polarized Observations of the Infrared FeXIII 1075nm and SiX 1430nm Emission Lines

    Science.gov (United States)

    Dima, G. I.; Kuhn, J. R.; Berdyugina, S.

    2017-12-01

    Measurements of the coronal magnetic field are difficult because of the intrinsically faint emission of coronal plasma and the large spurious background due to the bright solar disk. This work addresses the problem of resolving the confusion of the line-of-sight (LOS) integration through the optically-thin corona being observed. Work on developing new measuring techniques based on single-point inversions using the Hanle effect has already been described (Dima et al. 2016). It is important to develop a technique to assess when the LOS confusion makes comparing models and observations problematic. Using forward integration of synthetic emission through magnetohydrodynamic (MHD) models together with simultaneous linearly polarized observations of the FeXIII 1075nm and SiX 1430nm emission lines allows us to assess LOS confusion. Since the lines are both in the Hanle saturated regime their polarization angles are expected to be aligned as long as the gas is sampling the same magnetic field. If significant contributions to the emission is taking place from different regions along the LOS due to the additive nature of the polarized brightness the measured linear polarization between the two lines will be offset. The size of the resolution element is important for this determination since observing larger coronal regions will confuse the variation along the LOS with that in the plane-of-sky. We also present comparisons between synthetic linearly polarized emission through a global MHD model and observations of the same regions obtained using the 0.5m Scatter-free Observatory for Limb Active Regions and Coronae (SOLARC) telescope located on Haleakala, Maui. This work is being done in preparation for the type of observations that will become possible when the next generation 4m DKIST telescope comes online in 2020.

  12. Towards a more objective evaluation of modelled land-carbon trends using atmospheric CO2 and satellite-based vegetation activity observations

    Directory of Open Access Journals (Sweden)

    D. Dalmonech

    2013-06-01

    Full Text Available Terrestrial ecosystem models used for Earth system modelling show a significant divergence in future patterns of ecosystem processes, in particular the net land–atmosphere carbon exchanges, despite a seemingly common behaviour for the contemporary period. An in-depth evaluation of these models is hence of high importance to better understand the reasons for this disagreement. Here, we develop an extension for existing benchmarking systems by making use of the complementary information contained in the observational records of atmospheric CO2 and remotely sensed vegetation activity to provide a novel set of diagnostics of ecosystem responses to climate variability in the last 30 yr at different temporal and spatial scales. The selection of observational characteristics (traits specifically considers the robustness of information given that the uncertainty of both data and evaluation methodology is largely unknown or difficult to quantify. Based on these considerations, we introduce a baseline benchmark – a minimum test that any model has to pass – to provide a more objective, quantitative evaluation framework. The benchmarking strategy can be used for any land surface model, either driven by observed meteorology or coupled to a climate model. We apply this framework to evaluate the offline version of the MPI Earth System Model's land surface scheme JSBACH. We demonstrate that the complementary use of atmospheric CO2 and satellite-based vegetation activity data allows pinpointing of specific model deficiencies that would not be possible by the sole use of atmospheric CO2 observations.

  13. Searching for the 3.5 keV Line in the Stacked Suzaku Observations of Galaxy Clusters

    Science.gov (United States)

    Bulbul, Esra; Markevitch, Maxim; Foster, Adam; Miller, Eric; Bautz, Mark; Lowenstein, Mike; Randall, Scott W.; Smith, Randall K.

    2016-01-01

    We perform a detailed study of the stacked Suzaku observations of 47 galaxy clusters, spanning a redshift range of 0.01-0.45, to search for the unidentified 3.5 keV line. This sample provides an independent test for the previously detected line. We detect a 2sigma-significant spectral feature at 3.5 keV in the spectrum of the full sample. When the sample is divided into two subsamples (cool-core and non-cool core clusters), the cool-core subsample shows no statistically significant positive residuals at the line energy. A very weak (approx. 2sigma confidence) spectral feature at 3.5 keV is permitted by the data from the non-cool-core clusters sample. The upper limit on a neutrino decay mixing angle of sin(sup 2)(2theta) = 6.1 x 10(exp -11) from the full Suzaku sample is consistent with the previous detections in the stacked XMM-Newton sample of galaxy clusters (which had a higher statistical sensitivity to faint lines), M31, and Galactic center, at a 90% confidence level. However, the constraint from the present sample, which does not include the Perseus cluster, is in tension with previously reported line flux observed in the core of the Perseus cluster with XMM-Newton and Suzaku.

  14. Synchronized observations of bright points from the solar photosphere to the corona

    Science.gov (United States)

    Tavabi, Ehsan

    2018-05-01

    One of the most important features in the solar atmosphere is the magnetic network and its relationship to the transition region (TR) and coronal brightness. It is important to understand how energy is transported into the corona and how it travels along the magnetic field lines between the deep photosphere and chromosphere through the TR and corona. An excellent proxy for transportation is the Interface Region Imaging Spectrograph (IRIS) raster scans and imaging observations in near-ultraviolet (NUV) and far-ultraviolet (FUV) emission channels, which have high time, spectral and spatial resolutions. In this study, we focus on the quiet Sun as observed with IRIS. The data with a high signal-to-noise ratio in the Si IV, C II and Mg II k lines and with strong emission intensities show a high correlation with TR bright network points. The results of the IRIS intensity maps and dopplergrams are compared with those of the Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) instruments onboard the Solar Dynamical Observatory (SDO). The average network intensity profiles show a strong correlation with AIA coronal channels. Furthermore, we applied simultaneous observations of the magnetic network from HMI and found a strong relationship between the network bright points in all levels of the solar atmosphere. These features in the network elements exhibited regions of high Doppler velocity and strong magnetic signatures. Plenty of corona bright points emission, accompanied by the magnetic origins in the photosphere, suggest that magnetic field concentrations in the network rosettes could help to couple the inner and outer solar atmosphere.

  15. ULTRAVIOLET AND EXTREME-ULTRAVIOLET EMISSIONS AT THE FLARE FOOTPOINTS OBSERVED BY ATMOSPHERE IMAGING ASSEMBLY

    Energy Technology Data Exchange (ETDEWEB)

    Qiu Jiong; Longcope, Dana W.; Liu Wenjuan [Department of Physics, Montana State University, Bozeman, MT 59717-3840 (United States); Sturrock, Zoe [Department of Applied Mathematics, University of St. Andrews (United Kingdom); Klimchuk, James A. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2013-09-01

    A solar flare is composed of impulsive energy release events by magnetic reconnection, which forms and heats flare loops. Recent studies have revealed a two-phase evolution pattern of UV 1600 A emission at the feet of these loops: a rapid pulse lasting for a few seconds to a few minutes, followed by a gradual decay on timescales of a few tens of minutes. Multiple band EUV observations by the Atmosphere Imaging Assembly further reveal very similar signatures. These two phases represent different but related signatures of an impulsive energy release in the corona. The rapid pulse is an immediate response of the lower atmosphere to an intense thermal conduction flux resulting from the sudden heating of the corona to high temperatures (we rule out energetic particles due to a lack of significant hard X-ray emission). The gradual phase is associated with the cooling of hot plasma that has been evaporated into the corona. The observed footpoint emission is again powered by thermal conduction (and enthalpy), but now during a period when approximate steady-state conditions are established in the loop. UV and EUV light curves of individual pixels may therefore be separated into contributions from two distinct physical mechanisms to shed light on the nature of energy transport in a flare. We demonstrate this technique using coordinated, spatially resolved observations of UV and EUV emissions from the footpoints of a C3.2 thermal flare.

  16. A SAR Observation and Numerical Study on Ocean Surface Imprints of Atmospheric Vortex Streets

    Directory of Open Access Journals (Sweden)

    William G. Pichel

    2008-05-01

    Full Text Available The sea surface imprints of Atmospheric Vortex Street (AVS off Aleutian Volcanic Islands, Alaska were observed in two RADARSAT-1 Synthetic Aperture Radar (SAR images separated by about 11 hours. In both images, three pairs of distinctive vortices shedding in the lee side of two volcanic mountains can be clearly seen. The length and width of the vortex street are about 60-70 km and 20 km, respectively. Although the AVS’s in the two SAR images have similar shapes, the structure of vortices within the AVS is highly asymmetrical. The sea surface wind speed is estimated from the SAR images with wind direction input from Navy NOGAPS model. In this paper we present a complete MM5 model simulation of the observed AVS. The surface wind simulated from the MM5 model is in good agreement with SAR-derived wind. The vortex shedding rate calculated from the model run is about 1 hour and 50 minutes. Other basic characteristics of the AVS including propagation speed of the vortex, Strouhal and Reynolds numbers favorable for AVS generation are also derived. The wind associated with AVS modifies the cloud structure in the marine atmospheric boundary layer. The AVS cloud pattern is also observed on a MODIS visible band image taken between the two RADARSAT SAR images. An ENVISAT advance SAR image taken 4 hours after the second RADARSAT SAR image shows that the AVS has almost vanished.

  17. Characterization of NOx emission in the suburbs of Tokyo based on simultaneous and real-time observations of atmospheric Ox and NOx

    Science.gov (United States)

    Matsumoto, J.

    2013-12-01

    .1 ppbv for Ox and 0.5 ppbv for NOx (60-s integration, S/N = 3). The observation test in the suburbs of Tokyo was conducted in April 2013 at Tokorozawa Campus, Waseda University. During the campaign, 48 cases of ';NOx spikes', for which NOx levels significantly varied in the second time scale due to local NOx emission, were captured. NO2/NOx ratio in the exhaust gas was estimated as the slope of regression line between 1-s series data of Ox and those of NOx observed during each spike. The average of acquired NO2/NOx ratio was 0.10. Thus, as a result of observations of real atmosphere, the present NO2/NOx ratio in the exhaust gases in the suburbs of Tokyo was 0.10 as average, which was mainly due to exhausts of automobiles. However, when the individual cases were considered, NO2/NOx could vary from 0.00 to 0.30. Such a wide range of NO2/NOx ratio may be due to (1) difference of source types (eg. automobiles, power generator) and (2) difference of conditions of sources (eg. engines, filters of exhaust). For example, NO2/NOx ratio for hybrid electric vehicles may be different from those for conventional cars. When diffusion of such new model cars can change NOx emission in near future, the present method of simultaneous and real-time monitoring of Ox and NOx in the atmosphere can be useful and promising for characterization of NOx emission.

  18. RR LYRAE ATMOSPHERICS: WRINKLES OLD AND NEW. A PREVIEW

    International Nuclear Information System (INIS)

    Preston, George W.

    2011-01-01

    I report some results of an echelle spectroscopic survey of RR Lyrae stars begun in 2006 that I presented in my Henry Norris Lecture of 2010 January 4. Topics include (1) atmospheric velocity gradients, (2) phase-dependent envelope turbulence as it relates to Peterson's discoveries of axial rotation on the horizontal branch and to Stothers' explanation of the Blazhko effect, (3) the three apparitions of hydrogen emission during a pulsation cycle, (4) the occurrence of He I lines in emission and absorption, (5) detection of He II emission and metallic line doubling in Blazhko stars, and finally (6) speculation about what helium observations of RR Lyrae stars in omega Centauri might tell us about the putative helium populations and the horizontal branch of that strange globular cluster.

  19. UV spectroscopy including ISM line absorption: of the exciting star of Abell 35

    Science.gov (United States)

    Ziegler, M.; Rauch, T.; Werner, K.; Kruk, J. W.

    Reliable spectral analysis that is based on high-resolution UV observations requires an adequate, simultaneous modeling of the interstellar line absorption and reddening. In the case of the central star of the planetary nebula Abell 35, BD-22 3467, we demonstrate our current standard spectral-analysis method that is based on the Tübingen NLTE Model-Atmosphere Package (TMAP). We present an on- going spectral analysis of FUSE and HST/STIS observations of BD-22 3467.

  20. Atmospheric correction of Earth-observation remote sensing images ...

    Indian Academy of Sciences (India)

    The physics underlying the problem of solar radiation propagations that takes into account ... SART code (Spherical Atmosphere Radiation. Transfer) ... The use of Monte Carlo sampling ..... length because this soil is formed by clay and sand.

  1. Observation of hard X-rays line emission from Her X-1

    Energy Technology Data Exchange (ETDEWEB)

    Polcaro, V.F.; Bazzano, A.; la Padula, C.; Ubertini, P.; Vialetto, G.; Manchanda, R.K.; Damle, S.V.

    1982-04-01

    We present the results of a hard X-ray measurement of the binary source Her X-1, carried out with a balloon borne X-ray telescope consisting of two Multiwire Proportional Counters, having 900 cm/sup 2/ sensitive area each and spectral resolution of 15% and 24% FWHM respectively at 60 keV. The source was observed during the 'Mid-on' state. Our data confirm the previously reported high energy emission line overimposed on the low energy thermal spectrum.

  2. An Inequality Constrained Least-Squares Approach as an Alternative Estimation Procedure for Atmospheric Parameters from VLBI Observations

    Science.gov (United States)

    Halsig, Sebastian; Artz, Thomas; Iddink, Andreas; Nothnagel, Axel

    2016-12-01

    On its way through the atmosphere, radio signals are delayed and affected by bending and attenuation effects relative to a theoretical path in vacuum. In particular, the neutral part of the atmosphere contributes considerably to the error budget of space-geodetic observations. At the same time, space-geodetic techniques become more and more important in the understanding of the Earth's atmosphere, because atmospheric parameters can be linked to the water vapor content in the atmosphere. The tropospheric delay is usually taken into account by applying an adequate model for the hydrostatic component and by additionally estimating zenith wet delays for the highly variable wet component. Sometimes, the Ordinary Least Squares (OLS) approach leads to negative estimates, which would be equivalent to negative water vapor in the atmosphere and does, of course, not reflect meteorological and physical conditions in a plausible way. To cope with this phenomenon, we introduce an Inequality Constrained Least Squares (ICLS) method from the field of convex optimization and use inequality constraints to force the tropospheric parameters to be non-negative allowing for a more realistic tropospheric parameter estimation in a meteorological sense. Because deficiencies in the a priori hydrostatic modeling are almost fully compensated by the tropospheric estimates, the ICLS approach urgently requires suitable a priori hydrostatic delays. In this paper, we briefly describe the ICLS method and validate its impact with regard to station positions.

  3. Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration.

    Science.gov (United States)

    Sheard, Michael A; Ghent, Matthew V; Cabral, Daniel J; Lee, Joanne C; Khankaldyyan, Vazgen; Ji, Lingyun; Wu, Samuel Q; Kang, Min H; Sposto, Richard; Asgharzadeh, Shahab; Reynolds, C Patrick

    2015-05-15

    Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. Copyright © 2015. Published by Elsevier Inc.

  4. A TEMPERATURE AND ABUNDANCE RETRIEVAL METHOD FOR EXOPLANET ATMOSPHERES

    International Nuclear Information System (INIS)

    Madhusudhan, N.; Seager, S.

    2009-01-01

    We present a new method to retrieve molecular abundances and temperature profiles from exoplanet atmosphere photometry and spectroscopy. We run millions of one-dimensional (1D) atmosphere models in order to cover the large range of allowed parameter space. In order to run such a large number of models, we have developed a parametric pressure-temperature (P-T) profile coupled with line-by-line radiative transfer, hydrostatic equilibrium, and energy balance, along with prescriptions for non-equilibrium molecular composition and energy redistribution. The major difference from traditional 1D radiative transfer models is the parametric P-T profile, which essentially means adopting energy balance only at the top of the atmosphere and not in each layer. We see the parametric P-T model as a parallel approach to the traditional exoplanet atmosphere models that rely on several free parameters to encompass unknown absorbers and energy redistribution. The parametric P-T profile captures the basic physical features of temperature structures in planetary atmospheres (including temperature inversions), and fits a wide range of published P-T profiles, including those of solar system planets. We apply our temperature and abundance retrieval method to the atmospheres of two transiting exoplanets, HD 189733b and HD 209458b, which have the best Spitzer and Hubble Space Telescope data available. For HD 189733b, we find efficient day-night redistribution of energy in the atmosphere, and molecular abundance constraints confirming the presence of H 2 O, CO, CH 4 , and CO 2 . For HD 209458b, we confirm and constrain the dayside thermal inversion in an average 1D temperature profile. We also report independent detections of H 2 O, CO, CH 4 , and CO 2 on the dayside of HD 209458b, based on six-channel Spitzer photometry. We report constraints for HD 189733b due to individual data sets separately; a few key observations are variable in different data sets at similar wavelengths. Moreover, a

  5. Shift of the Magnetopause Reconnection Line to the Winter Hemisphere Under Southward IMF Conditions: Geotail and MMS Observations

    Science.gov (United States)

    Kitamura, N.; Hasegawa, H.; Saito, Y.; Shinohara, I.; Yokota, S.; Nagai, T.; Pollock, C. J.; Giles, B. L.; Moore, T. E.; Dorelli, J. C.; hide

    2016-01-01

    At 02:13 UT on 18 November 2015 when the geomagnetic dipole was tilted by -27deg, the MMS spacecraft observed southward reconnection jets near the subsolar magnetopause under southward and dawnward interplanetary magnetic field conditions. Based on four-spacecraft estimations of the magnetic field direction near the separatrix and the motion and direction of the current sheet, the location of the reconnection line was estimated to be approx.1.8 R(sub E) or further northward of MMS. The Geotail spacecraft at GSM Z approx. 1.4 R(sub E) also observed southward reconnection jets at the dawnside magnetopause 30-40 min later. The estimated reconnection line location was northward of GSM Z approx.2 R(sub E). This crossing occurred when MMS observed purely southward magnetic fields in the magnetosheath. The simultaneous observations are thus consistent with the hypothesis that the dayside magnetopause reconnection line shifts from the subsolar point toward the northem (winter) hemisphere due to the effect of geomagnetic dipole tilt.

  6. Southeast Atmosphere Studies: learning from model-observation syntheses

    Science.gov (United States)

    Concentrations of atmospheric trace species in the United States have changed dramatically over the past several decades in response to pollution control strategies, shifts in domestic energy policy and economics, and economic development (and resulting emission changes) elsewher...

  7. Global observations and modeling of atmosphere-surface exchange of elemental mercury: a critical review

    Science.gov (United States)

    Zhu, Wei; Lin, Che-Jen; Wang, Xun; Sommar, Jonas; Fu, Xuewu; Feng, Xinbin

    2016-04-01

    Reliable quantification of air-surface fluxes of elemental Hg vapor (Hg0) is crucial for understanding mercury (Hg) global biogeochemical cycles. There have been extensive measurements and modeling efforts devoted to estimating the exchange fluxes between the atmosphere and various surfaces (e.g., soil, canopies, water, snow, etc.) in the past three decades. However, large uncertainties remain due to the complexity of Hg0 bidirectional exchange, limitations of flux quantification techniques and challenges in model parameterization. In this study, we provide a critical review on the state of science in the atmosphere-surface exchange of Hg0. Specifically, the advancement of flux quantification techniques, mechanisms in driving the air-surface Hg exchange and modeling efforts are presented. Due to the semi-volatile nature of Hg0 and redox transformation of Hg in environmental media, Hg deposition and evasion are influenced by multiple environmental variables including seasonality, vegetative coverage and its life cycle, temperature, light, moisture, atmospheric turbulence and the presence of reactants (e.g., O3, radicals, etc.). However, the effects of these processes on flux have not been fundamentally and quantitatively determined, which limits the accuracy of flux modeling. We compile an up-to-date global observational flux database and discuss the implication of flux data on the global Hg budget. Mean Hg0 fluxes obtained by micrometeorological measurements do not appear to be significantly greater than the fluxes measured by dynamic flux chamber methods over unpolluted surfaces (p = 0.16, one-tailed, Mann-Whitney U test). The spatiotemporal coverage of existing Hg0 flux measurements is highly heterogeneous with large data gaps existing in multiple continents (Africa, South Asia, Middle East, South America and Australia). The magnitude of the evasion flux is strongly enhanced by human activities, particularly at contaminated sites. Hg0 flux observations in East

  8. Antarctic observations available for IMS correlative analyses

    International Nuclear Information System (INIS)

    Rycroft, M.J.

    1982-01-01

    A review is provided of the wide-ranging observational programs of 25 stations operating on and around the continent of Antarctica during the International Magnetospheric Study (IMS). Attention is given to observations of geomagnetism, short period fluctuations of the earth's electromagnetic field, observations of the ionosphere and of whistler mode signals, observational programs in ionospheric and magnetospheric physics, upper atmosphere physics observations, details of magnetospheric programs conducted at Kerguelen, H-component magnetograms, magnetic field line oscillations, dynamic spectra of whistlers, and the variation of plasmapause position derived from recorded whistlers. The considered studies suggest that, in principle, if the level of magnetic activity is known, predictions can be made concerning the time at which the trough occurs, and the shape and the movement of the main trough

  9. Constraining atmospheric ammonia emissions through new observations with an open-path, laser-based sensor

    Science.gov (United States)

    Sun, Kang

    As the third most abundant nitrogen species in the atmosphere, ammonia (NH3) is a key component of the global nitrogen cycle. Since the industrial revolution, humans have more than doubled the emissions of NH3 to the atmosphere by industrial nitrogen fixation, revolutionizing agricultural practices, and burning fossil fuels. NH3 is a major precursor to fine particulate matter (PM2.5), which has adverse impacts on air quality and human health. The direct and indirect aerosol radiative forcings currently constitute the largest uncertainties for future climate change predictions. Gas and particle phase NH3 eventually deposits back to the Earth's surface as reactive nitrogen, leading to the exceedance of ecosystem critical loads and perturbation of ecosystem productivity. Large uncertainties still remain in estimating the magnitude and spatiotemporal patterns of NH3 emissions from all sources and over a range of scales. These uncertainties in emissions also propagate to the deposition of reactive nitrogen. To improve our understanding of NH3 emissions, observational constraints are needed from local to global scales. The first part of this thesis is to provide quality-controlled, reliable NH3 measurements in the field using an open-path, quantum cascade laser-based NH3 sensor. As the second and third part of my research, NH3 emissions were quantified from a cattle feedlot using eddy covariance (EC) flux measurements, and the similarities between NH3 turbulent fluxes and those of other scalars (temperature, water vapor, and CO2) were investigated. The fourth part involves applying a mobile laboratory equipped with the open-path NH3 sensor and other important chemical/meteorological measurements to quantify fleet-integrated NH3 emissions from on-road vehicles. In the fifth part, the on-road measurements were extended to multiple major urban areas in both the US and China in the context of five observation campaigns. The results significantly improved current urban NH3

  10. The Development of New Atmospheric Models for K and M DwarfStars with Exoplanets

    Science.gov (United States)

    Linsky, Jeffrey L.

    2018-01-01

    The ultraviolet and X-ray emissions of host stars play critical roles in the survival and chemical composition of the atmospheres of their exoplanets. The need to measure and understand this radiative output, in particular for K and M dwarfs, is the main rationale for computing a new generation of stellar models that includes magnetically heated chromospheres and coronae in addition to their photospheres. We describe our method for computing semi-empirical models that includes solutions of the statistical equilibrium equations for 52 atoms and ions and of the non-LTE radiative transfer equations for all important spectral lines. The code is an offspring of the Solar Radiation Physical Modelling system (SRPM) developed by Fontenla et al. (2007--2015) to compute one-dimensional models in hydrostatic equilibrium to fit high-resolution stellar X-ray to IR spectra. Also included are 20 diatomic molecules and their more than 2 million spectral lines. Our-proof-of-concept model is for the M1.5 V star GJ 832 (Fontenla et al. ApJ 830, 154 (2016)). We will fit the line fluxes and profiles of X-ray lines and continua observed by Chandra and XMM-Newton, UV lines observed by the COS and STIS instruments on HST (N V, C IV, Si IV, Si III, Mg II, C II, and O I), optical lines (including H$\\alpha$, Ca II, Na I), and continua. These models will allow us to compute extreme-UV spectra, which are unobservable but required to predict the hydrodynamic mass-loss rate from exoplanet atmospheres, and to predict panchromatic spectra of new exoplanet host stars discovered after the end of the HST mission.This work is supported by grant HST-GO-15038 from the Space Telescope Science Institute to the Univ. of Colorado

  11. Evidence of redshifts in the average solar line profiles of C IV and Si IV from OSO-8 observations

    Science.gov (United States)

    Roussel-Dupre, D.; Shine, R. A.

    1982-01-01

    Line profiles of C IV and Si V obtained by the Colorado spectrometer on OSO-8 are presented. It is shown that the mean profiles are redshifted with a magnitude varying from 6-20 km/s, and with a mean of 12 km/s. An apparent average downflow of material in the 50,000-100,000 K temperature range is measured. The redshifts are observed in the line center positions of spatially and temporally averaged profiles and are measured either relative to chromospheric Si I lines or from a comparison of sun center and limb profiles. The observations of 6-20 km/s redshifts place constraints on the mechanisms that dominate EUV line emission since it requires a strong weighting of the emission in regions of downward moving material, and since there is little evidence for corresponding upward moving materials in these lines.

  12. Reconstruction of past variations of (delta)13C in atmospheric CO2 from i vertical distribution observed in the firn at Dome Fuji, Antarctica

    International Nuclear Information System (INIS)

    Sugawara, S.

    2003-01-01

    Temporal variations of (delta) 13 C of atmospheric CO 2 in the past have been reconstructed from the (delta) 13 C values of CO 2 observed in firn at Dome Fuji, Antarctica. The effective diffusivities of CO 2 in firn were estimated for Dome Fuji and another Antarctic site, H72. The age distributions of 13 CO 2 in firn were first calculated by using a one-dimensional diffusion model, and then the past values of the atmospheric (delta) 13 C were derived by using an iterative procedure so that the calculated and observed vertical profiles of (delta) 13 C of CO 2 in firn agreed with each other. This reconstruction method was also applied to the CH 4 concentration to confirm its validity. The values of the atmospheric (delta) 13 C thus estimated were in good agreement with those from direct atmospheric measurements at Syowa Station, Antarctica, even for the levelling off of the secular decrease observed in the first half of the 1990s. The statistical uncertainty of the iterative procedure was examined by adding normal pseudo-random numbers to the observed (delta) 13 C values in firn. We also calculated the (delta) 13 C values for firn at H72 using the reconstructed history of the atmospheric (delta) 13 C, and its vertical profile was found to be in close agreement with the observational result

  13. Observation and analysis of speciated atmospheric mercury in Shangri-La, Tibetan Plateau, China

    Science.gov (United States)

    Zhang, H.; Fu, X. W.; Lin, C.-J.; Wang, X.; Feng, X. B.

    2015-01-01

    This study reports the concentrations and potential sources of speciated atmospheric mercury at the Shangri-La Atmosphere Watch Regional Station (SAWRS), a pristine high-altitude site (3580 m a.s.l.) in Tibetan Plateau, China. Total gaseous mercury (TGM, defined as the sum of gaseous elemental mercury, GEM, and gaseous oxidized mercury, GOM), GOM and particulate-bound mercury (PBM) were monitored from November 2009 to November 2010 to investigate the characteristics and potential influence of the Indian summer monsoon (ISM) and the Westerlies on atmospheric transport of mercury. The mean concentrations (± standard deviation) of TGM, PBM and GOM were 2.55 ± 0.73 ng m-3, 38.82 ± 31.26 pg m-3 and 8.22 ± 7.90 pg m-3, respectively. A notable seasonal pattern of TGM concentrations was observed with higher concentrations at the beginning and the end of the ISM season. High TGM concentrations (> 2.5 ng m-3) were associated with the transport of dry air that carried regional anthropogenic emissions from both Chinese domestic and foreign (e.g., Myanmar, Bay of Bengal, and northern India) sources based on analysis of HYSPLIT4 back trajectories. Somewhat lower PBM and GOM levels during the ISM period were attributed to the enhanced wet scavenging. The high GOM and PBM were likely caused by local photo-chemical transformation under low RH and the domestic biofuel burning in cold seasons.

  14. An Observational Diagnostic for Distinguishing Between Clouds and Haze in Hot Exoplanet Atmospheres

    Science.gov (United States)

    Kempton, Eliza; Bean, Jacob; Parmentier, Vivien

    2018-01-01

    The nature of aerosols in hot exoplanet atmospheres is one of the primary vexing questions facing the exoplanet field. The complex chemistry, multiple formation pathways, and lack of easily identifiable spectral features associated with aerosols make it especially challenging to constrain their key properties. We present a transmission spectroscopy technique to identify the primary aerosol formation mechanism for the most highly irradiated hot Jupiters (HIHJs). The technique is based on the idea that the two key types of aerosols -- photochemically generated hazes and equilibrium condensate clouds -- are expected to form and persist in different regions of a highly irradiated planet's atmosphere. Haze can only be produced on the permanent daysides of tidally-locked hot Jupiters, and will be carried downwind by atmospheric dynamics to the evening terminator (seen as the trailing limb during transit). Clouds can only form in cooler regions on the night side and morning terminator of HIHJs (seen as the leading limb during transit). Because opposite limbs are expected to be impacted by different types of aerosols, ingress and egress spectra, which primarily probe opposing sides of the planet, will reveal the dominant aerosol formation mechanism. We show that the benchmark HIHJ, WASP-121b, has a transmission spectrum consistent with partial aerosol coverage and that ingress-egress spectroscopy would constrain the location and formation mechanism of those aerosols. In general, we find that observations with JWST and potentially with HST should be able to distinguish between clouds and haze for currently known HIHJs.

  15. A quasi-continuous observation of the {alpha}-transition of Fe{sub 1+x}S by Moessbauer line tracking

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza Zelis, P., E-mail: pmendoza@fisica.unlp.edu.ar; Pasquevich, G. A.; Veiga, A.; Fernandez van Raap, M. B.; Sanchez, F. H. [Universidad Nacional de La Plata, CONICET, Depto. de Fisica, Fac. Ciencias Exactas, Instituto de Fisica La Plata (Argentina)

    2010-01-15

    Moessbauer absorption line tracking methodology, under a constant velocity strategy, is used for a quasi-continuous observation of the {alpha}-transition on slightly non stoichiometric Fe{sub 1+x}S alloy. To this end, two strategies were applied: an intelligent absorption line tracking with a control algorithm that uses the data measured in the previous region to establish the position of the next partial spectral range; and a predetermined line tracking in which temperature evolution of a partial spectral region of interest (ROI) is programmed. The latter uses results from the former, in order to achieve a quasi-continuous partial spectral observation. These experiments clearly demonstrate that line tracking allows a more efficient use of the radioactive source, as the effort is concentrated in a partial region of the spectra from which the desired information can be obtained.

  16. Verification of atmospheric diffusion models using data of long term atmospheric diffusion experiments

    International Nuclear Information System (INIS)

    Tamura, Junji; Kido, Hiroko; Hato, Shinji; Homma, Toshimitsu

    2009-03-01

    Straight-line or segmented plume models as atmospheric diffusion models are commonly used in probabilistic accident consequence assessment (PCA) codes due to cost and time savings. The PCA code, OSCAAR developed by Japan Atomic Energy Research Institute (Present; Japan Atomic Energy Agency) uses the variable puff trajectory model to calculate atmospheric transport and dispersion of released radionuclides. In order to investigate uncertainties involved with the structure of the atmospheric dispersion/deposition model in OSCAAR, we have introduced the more sophisticated computer codes that included regional meteorological models RAMS and atmospheric transport model HYPACT, which were developed by Colorado State University, and comparative analyses between OSCAAR and RAMS/HYPACT have been performed. In this study, model verification of OSCAAR and RAMS/HYPACT was conducted using data of long term atmospheric diffusion experiments, which were carried out in Tokai-mura, Ibaraki-ken. The predictions by models and the results of the atmospheric diffusion experiments indicated relatively good agreements. And it was shown that model performance of OSCAAR was the same degree as it of RAMS/HYPACT. (author)

  17. Taking the atmosphere's pulse: The application of GC-IRMS to stable isotopes in atmospheric trace gases

    International Nuclear Information System (INIS)

    Lowe, D.C.; Ferretti, D.J.; Francey, R.J.; Allison, C.E.

    2001-01-01

    Since the industrial revolution, the abundance of many atmospheric trace gases has changed significantly. This is of concern because many of these trace species play a fundamental role in determining physical and chemical properties of the atmosphere important for maintaining life on earth. The impacts of the changes have been studied by a combination of analytical and theoretical modelling techniques. Stable isotope measurements made by conventional dual inlet IRMS for example, have provided valuable constraints on the budgets and removal mechanisms of key atmospheric trace gases. Unfortunately, in most cases, the application of these methods has been limited, because large air samples and cumbersome off line processing techniques are required to pre-concentrate enough gas for analysis. GC-IRMS offers a very attractive alternative because it combines on line processing with air sample size requirements typically 1000 times less than used in conventional techniques. In this article we focus on the requirements imposed on GC-IRMS by some of the current applications in atmospheric trace gas research. In addition, we examine some of the analytical and calibration aspects of the method applied to this kind of work. We finish with a summary of some of the comparative advantages and disadvantages of the GC-IRMS technique and some suggestions for future research using the method applied to specific atmospheric trace gases. (author)

  18. Observations of Fe XIV Line Intensity Variations in the Solar Corona During the 21 August 2017 Solar Eclipse

    Science.gov (United States)

    Johnson, Payton; Ladd, Edwin

    2018-01-01

    We present time- and spatially-resolved observations of the inner solar corona in the 5303 Å line of Fe XIV, taken during the 21 August 2017 solar eclipse from a field observing site in Crossville, TN. These observations are used to characterize the intensity variations in this coronal emission line, and to compare with oscillation predictions from models for heating the corona by magnetic wave dissipation.The observations were taken with two Explore Scientific ED 102CF 102 mm aperture triplet apochromatic refractors. One system used a DayStar custom-built 5 Å FWHM filter centered on the Fe XIV coronal spectral line and an Atik Titan camera for image collection. The setup produced images with a pixel size of 2.15 arcseconds (~1.5 Mm at the distance to the Sun), and a field of view of 1420 x 1060 arcseconds, covering approximately 20% of the entire solar limb centered near the emerging sunspot complex AR 2672. We obtained images with an exposure time of 0.22 seconds and a frame rate of 2.36 Hz, for a total of 361 images during totality.An identical, co-aligned telescope/camera system observed the same portion of the solar corona, but with a 100 Å FWHM Baader Planetarium solar continuum filter centered on a wavelength of 5400 Å. Images with an exposure time of 0.01 seconds were obtained with a frame rate of 4.05 Hz. These simultaneous observations are used as a control to monitor brightness variations not related to coronal line oscillations.

  19. Urban light pollution - The effect of atmospheric aerosols on astronomical observations at night

    Science.gov (United States)

    Joseph, Joachim H.; Mekler, Yuri; Kaufman, Yoram J.

    1991-01-01

    The transfer of diffuse city light from a localized source through a dust-laden atmosphere with optical depth less than 0.5 has been analyzed in the source-observer plane on the basis of an approximate treatment. The effect on several types of astronomical observation at night has been studied, considering different size distributions and amounts as well as particle shapes of the aerosols. The analysis is made in terms of the signal-to-noise ratios for a given amount of aerosol. The model is applied to conditions at the Wise Astronomical Observatory in the Negev desert, and limiting backgrounds for spectroscopy, photometry, and photography of stars and extended objects have been calculated for a variety of signal-to-noise ratios. Applications to observations with different equipment at various distances from an urban area of any size are possible. Due to the use of signal-to-noise ratios, the conclusions are different for the different experimental techniques used in astronomy.

  20. Carbon Abundances In The Light Of 3D Model Stellar Atmospheres

    DEFF Research Database (Denmark)

    Collet, Remo

    Classical spectroscopic analyses of late-type stars generally rely on the interpretation of observations with the use of stationary, one-dimensional (1D), hydrostatic model stellar atmospheres. In recent years, however, there has been significant development in the field of three-dimensional (3D......) hydrodynamic modelling of stellar atmospheres and stellar spectra. In this contribution, I describe quantitatively the impact of realistic, time-dependent, 3D hydrodynamic model atmospheres on the spectroscopic determination of carbon abundances from CH molecular lines for stars with a wide range of stellar...... parameters and compositions. I show that the differences with respect to classical analyses based on 1D models can be significant in very metal-poor stars and of the order of -0.5 to -1 dex in terms of logarithmic abundances of these important elements. I also examine the dependence of differential 3D-1D...

  1. Observations of radio emission in the 18 cm hydroxyl lines in the direction of Herbig-Haro objects and reflection nebulae

    International Nuclear Information System (INIS)

    Pashchenko, M.I.; Rudnitskij, G.M.

    1980-01-01

    In 1978 observations of Herbig-Haro objects and R associations in the 1665 and 1667 MHz main lines of the ground state of the OH molecule have been carried out at the Large radio telescope of the Nancay Radio Astronomy Station (France). Out of the 63 objects searched, the OH emission has been observed in 36 directions. In most cases, the observed line profiles have a simple singlepeak structure, with the line widths of 1-3 km/s. This emission most probably originates in interstellar dust clouds surrounding the Herbig-Haro objects and R associations. Some consequences of the results obtained are briefly discussed. Results of observations show that the quantity of strong maser radio sources near Herbig-Haro objects is not large

  2. Spectroscopy of chromospheric lines of giants in the globular cluster

    Science.gov (United States)

    Dupree, A. K.; Hartmann, Lee; Smith, Graeme H.; Rodgers, A. W.; Roberts, W. H.; Zucker, D. B.

    1994-01-01

    Spectroscopic observations of chromospheric transitions (Mg II, H-alpha, and Ca II K) from two red giants (A31 and A59) in the globular cluster NGC 6572 were made with the Goddard High Resolution Spectrograph on the Hubble Space Telescope and the coude spectrograph of the 1.9 m telescope at the Mount Stromlo Observatory. These measurements give evidence for chromospheric activity and outward motions within the atmospheres. The surface flux of the Mg II emission is comparable to that in disk population giants of similar (B-V) color. The Mg II profiles are asymmetric, which is most likely caused by absorption in an expanding stellar atmosphere and/or by possible interstellar features. Notches are found in the core of the H-alpha line of A59, which are similar to those found in Cepheids. This suggests that shocks are present in the atmosphere of A59 and indicates that hydrodynamic phenomena are influencing the levvel of chromospheric emission and producing upper atmospheric motions which may lead to mass loss.

  3. GMTR: two-dimensional geo-fit multitarget retrieval model for michelson interferometer for passive atmospheric sounding/environmental satellite observations.

    Science.gov (United States)

    Carlotti, Massimo; Brizzi, Gabriele; Papandrea, Enzo; Prevedelli, Marco; Ridolfi, Marco; Dinelli, Bianca Maria; Magnani, Luca

    2006-02-01

    We present a new retrieval model designed to analyze the observations of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), which is on board the ENVironmental SATellite (ENVISAT). The new geo-fit multitarget retrieval model (GMTR) implements the geo-fit two-dimensional inversion for the simultaneous retrieval of several targets including a set of atmospheric constituents that are not considered by the ground processor of the MIPAS experiment. We describe the innovative solutions adopted in the inversion algorithm and the main functionalities of the corresponding computer code. The performance of GMTR is compared with that of the MIPAS ground processor in terms of accuracy of the retrieval products. Furthermore, we show the capability of GMTR to resolve the horizontal structures of the atmosphere. The new retrieval model is implemented in an optimized computer code that is distributed by the European Space Agency as "open source" in a package that includes a full set of auxiliary data for the retrieval of 28 atmospheric targets.

  4. Simultaneous observations of SAO and QBO in winds, temperature and ozone in the tropical middle atmosphere over Thumba (8.5 N, 77 E)

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Karanam Kishore; Swain, Debadatta; John, Sherine Rachel; Ramkumar, Geetha [Vikram Sarabhai Space Center, Space Physics Laboratory, Thiruvananthapuram (India)

    2011-11-15

    Owing to the importance of middle atmosphere, recently, a Middle Atmospheric Dynamics (MIDAS) program was carried out during the period 2002-2007 at Thumba (8.5 N, 77 E). The measurements under this program, involving regular radiosonde/rocket flights as well as atmospheric radars, provided long period observations of winds and temperature in the middle atmospheric region from which waves and oscillations as well as their forcing mechanisms particularly in the low-latitude middle atmosphere could be analyzed. However, a detailed analysis of the forcing mechanisms remains incomplete due to the lack of important measurements like ozone which is a significant contributor to atmospheric dynamics. Presently, profiles of ozone are available from TIMED/SABER (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broad Emission Radiometry) satellite globally from about 15 to 100 km, over multiple years since 2002. In this regard, a comprehensive study has been carried out on ozone and its variability at Quasi Biennial Oscillation (QBO) and Semiannual Oscillation (SAO) scales using TIMED/SABER ozone observations during the MIDAS campaign period. Before using the TIMED/SABER ozone measurements, an inter-comparison has been carried out with in situ measurements of ozone obtained under the Southern Hemisphere Additional Ozonesondes (SHADOZ) campaign for the year 2007 at few stations. The inter-comparison showed very good agreement between SABER and ozonesonde derived ozone profiles. After validating the SABER observations, ozone profiles are used extensively to study the QBO and SAO along with temperature and winds in the 20-100 km height region. It is known that the SAO in mesosphere and stratosphere are in opposite phases, but the present study for the first time reports the aspect of opposite phases in the mesosphere itself. Thus, the present work attempts to study the long-period oscillations in stratosphere and mesosphere in ozone

  5. Comparative analysis of atmosphere temperature variability for Northern Eurasia based on the Reanalysis and in-situ observed data

    Science.gov (United States)

    Shulgina, T.; Genina, E.; Gordov, E.; Nikitchuk, K.

    2009-04-01

    At present numerous data archives which include meteorological observations as well as climate processes modeling data are available for Earth Science specialists. Methods of mathematical statistics are widely used for their processing and analysis. In many cases they represent the only way of quantitative assessment of the meteorological and climatic information. Unified set of analysis methods allows us to compare climatic characteristics calculated on the basis of different datasets with the purpose of performing more detailed analysis of climate dynamics for both regional and global levels. The report presents the results of comparative analysis of atmosphere temperature behavior for the Northern Eurasia territory for the period from 1979 to 2004 based on the NCEP/NCAR Reanalysis, NCEP/DOE Reanalysis AMIP II, JMA/CRIEPI JRA-25 Reanalysis, ECMWF ERA-40 Reanalysis data and observation data obtained from meteorological stations of the former Soviet Union. Statistical processing of atmosphere temperature data included analysis of time series homogeneity of climate indices approved by WMO, such as "Number of frost days", "Number of summer days", "Number of icing days", "Number of tropical nights", etc. by means of parametric methods of mathematical statistics (Fisher and Student tests). That allowed conducting comprehensive research of spatio-temporal features of the atmosphere temperature. Analysis of the atmosphere temperature dynamics revealed inhomogeneity of the data obtained for large observation intervals. Particularly, analysis performed for the period 1979 - 2004 showed the significant increase of the number of frost and icing days approximately by 1 day for every 2 years and decrease roughly by 1 day for 2 years for the number of summer days. Also it should be mentioned that the growth period mean temperature have increased by 1.5 - 2° C for the time period being considered. The usage of different Reanalysis datasets in conjunction with in-situ observed

  6. MMS Observations of Electron-Scale Filamentary Currents in the Reconnection Exhaust and Near the X Line

    Science.gov (United States)

    Phan, T. D.; Eastwood, J. P.; Cassak, P. A.; Oieroset, M.; Gosling, J. T.; Gershman, D. J.; Mozer, F. S.; Shay, M. A.; Fujimoto, M.; Daughton, W.; hide

    2016-01-01

    We report Magnetospheric Multiscale observations of macroscopic and electron-scale current layers in asymmetric reconnection. By intercomparing plasma, magnetic, and electric field data at multiple crossings of a reconnecting magnetopause on 22 October 2015, when the average interspacecraft separation was approximately 10 km, we demonstrate that the ion and electron moments are sufficiently accurate to provide reliable current density measurements at 30ms cadence. These measurements, which resolve current layers narrower than the interspacecraft separation, reveal electron-scale filamentary Hall currents and electron vorticity within the reconnection exhaust far downstream of the X line and even in the magnetosheath. Slightly downstream of the X line, intense (up to 3 µA/m2) electron currents, a super-Alfvenic outflowing electron jet, and nongyrotropic crescent shape electron distributions were observed deep inside the ion-scale magnetopause current sheet and embedded in the ion diffusion region. These characteristics are similar to those attributed to the electron dissipation/diffusion region around the X line.

  7. Atmospheric pressure plasma-assisted femtosecond laser engraving of aluminium

    Science.gov (United States)

    Gerhard, Christoph; Gimpel, Thomas; Tasche, Daniel; Koch née Hoffmeister, Jennifer; Brückner, Stephan; Flachenecker, Günter; Wieneke, Stephan; Schade, Wolfgang; Viöl, Wolfgang

    2018-05-01

    In this contribution, we report on the impact of direct dielectric barrier discharge argon plasma at atmospheric pressure on femtosecond laser engraving of aluminium. It is shown that the assisting plasma strongly affects the surface geometry and formation of spikes of both laser-engraved single lines and patterns of adjacent lines with an appropriate overlap. Further, it was observed that the overall ablation depth is significantly increased in case of large-scale patterning whereas no notable differences in ablation depth are found for single lines. Several possible mechanisms and underlying effects of this behaviour are suggested. The increase in ablation depth is supposed to be due to a plasma-induced removal of debris particles from the cutting point via charging and oxidation as supported by EDX analysis of the re-solidified debris. Furthermore, the impact of a higher degree of surface wrinkling as well as direct interactions of plasma species with the aluminium surface on the ablation process are discussed.

  8. Millimeter-wave molecular line observations of the Tornado nebula

    International Nuclear Information System (INIS)

    Sakai, D.; Oka, T.; Tanaka, K.; Matsumura, S.; Miura, K.; Takekawa, S.

    2014-01-01

    We report the results of millimeter-wave molecular line observations of the Tornado Nebula (G357.7-0.1), which is a bright radio source behind the Galactic center region. A 15' × 15' area was mapped in the J = 1-0 lines of CO, 13 CO, and HCO + with the Nobeyama Radio Observatory 45 m telescope. The Very Large Array archival data of OH at 1720 MHz were also reanalyzed. We found two molecular clouds with separate velocities, V LSR = –14 km s –1 and +5 km s –1 . These clouds show rough spatial anti-correlation. Both clouds are associated with OH 1720 MHz emissions in the area overlapping with the Tornado Nebula. The spatial and velocity coincidence indicates violent interaction between the clouds and the Tornado Nebula. Modestly excited gas prefers the position of the Tornado 'head' in the –14 km s –1 cloud, also suggesting the interaction. Virial analysis shows that the +5 km s –1 cloud is more tightly bound by self-gravity than the –14 km s –1 cloud. We propose a formation scenario for the Tornado Nebula; the +5 km s –1 cloud collided into the –14 km s –1 cloud, generating a high-density layer behind the shock front, which activates a putative compact object by Bondi-Hoyle-Lyttleton accretion to eject a pair of bipolar jets.

  9. Development of Innovative Technology to Provide Low-Cost Surface Atmospheric Observations in Data Sparse Regions

    Science.gov (United States)

    Kucera, Paul; Steinson, Martin

    2017-04-01

    Accurate and reliable real-time monitoring and dissemination of observations of surface weather conditions is critical for a variety of societal applications. Applications that provide local and regional information about temperature, precipitation, moisture, and winds, for example, are important for agriculture, water resource monitoring, health, and monitoring of hazard weather conditions. In many regions of the World, surface weather stations are sparsely located and/or of poor quality. Existing stations have often been sited incorrectly, not well-maintained, and have limited communications established at the site for real-time monitoring. The University Corporation for Atmospheric Research (UCAR)/National Center for Atmospheric Research (NCAR), with support from USAID, has started an initiative to develop and deploy low-cost weather instrumentation in sparsely observed regions of the world. The project is focused on improving weather observations for environmental monitoring and early warning alert systems on a regional to global scale. Instrumentation that has been developed use innovative new technologies such as 3D printers, Raspberry Pi computing systems, and wireless communications. The goal of the project is to make the weather station designs, software, and processing tools an open community resource. The weather stations can be built locally by agencies, through educational institutions, and residential communities as a citizen effort to augment existing networks to improve detection of natural hazards for disaster risk reduction. The presentation will provide an overview of the open source weather station technology and evaluation of sensor observations for the initial networks that have been deployed in Africa.

  10. Experimental observation on asymmetric energy flux within the forbidden frequency band in the LC transmission line

    International Nuclear Information System (INIS)

    Tao Feng; Chen Weizhong; Pan Junting; Xu Wen; Du Sidan

    2012-01-01

    We study the energy flux in a nonlinear electrical transmission line consisting of two coupled segments which are identical in structure and different in parameters. The asymmetry of energy flux caused by nonlinear wave has been observed experimentally in the forbidden band of the line. The experiment shows whether the energy can flow through the transmission line depends on the amplitude of the boundary driving voltages, which can be well explained in the theoretical framework of nonlinear supratransmission. The numerical simulation based on Kirchhoff’s laws further verifies the existence of the asymmetric energy flux in the forbidden band.

  11. Observations of the 12.3 micron Mg I emission line during a major solar flare

    Science.gov (United States)

    Deming, Drake; Jennings, Donald E.; Osherovich, Vladimir; Wiedemann, Gunter; Hewagama, Tilak

    1990-01-01

    The extremely Zeeman-sensitive 12.32 micron Mg I solar emission line was observed during a 3B/X5.7 solar flare on October 24, 1989. When compared to postflare values, Mg I emission-line intensity in the penumbral flare ribbon was 20 percent greater at the peak of the flare in soft X-rays, and the 12 micron continuum intensity was 7 percent greater. The flare also excited the emission line in the umbra where it is normally absent. The umbral flare emission exhibits a Zeeman splitting 200 G less than the adjacent penumbra, suggesting that it is excited at higher altitude. The absolute penumbral magnetic field strength did not change by more than 100 G between the flare peak and postflare period. However, a change in the inclination of the field lines, probably related to the formation and development of the flare loop system, was seen.

  12. Determination of neutrino mass hierarchy by 21 cm line and CMB B-mode polarization observations

    Energy Technology Data Exchange (ETDEWEB)

    Oyama, Yoshihiko, E-mail: oyamayo@post.kek.jp [The Graduate University for Advanced Studies (SOKENDAI), 1-1 Oho, Tsukuba 305-0801 (Japan); Shimizu, Akie [The Graduate University for Advanced Studies (SOKENDAI), 1-1 Oho, Tsukuba 305-0801 (Japan); Kohri, Kazunori [The Graduate University for Advanced Studies (SOKENDAI), 1-1 Oho, Tsukuba 305-0801 (Japan); Institute of Particle and Nuclear Studies, KEK, 1-1 Oho, Tsukuba 305-0801 (Japan)

    2013-01-29

    We focus on the ongoing and future observations for both the 21 cm line and the CMB B-mode polarization produced by a CMB lensing, and study their sensitivities to the effective number of neutrino species, the total neutrino mass, and the neutrino mass hierarchy. We find that combining the CMB observations with future square kilometer arrays optimized for 21 cm line such as Omniscope can determine the neutrino mass hierarchy at 2{sigma}. We also show that a more feasible combination of Planck + POLARBEAR and SKA can strongly improve errors of the bounds on the total neutrino mass and the effective number of neutrino species to be {Delta}{Sigma}m{sub {nu}}{approx}0.12 eV and {Delta}N{sub {nu}}{approx}0.38 at 2{sigma}, respectively.

  13. Hydrogen Balmer Line Broadening in Solar and Stellar Flares

    Energy Technology Data Exchange (ETDEWEB)

    Kowalski, Adam F. [Department of Astrophysical and Planetary Sciences, University of Colorado Boulder, 2000 Colorado Avenue, Boulder, CO 80305 (United States); Allred, Joel C. [NASA/Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States); Uitenbroek, Han [National Solar Observatory, University of Colorado Boulder, 3665 Discovery Drive, Boulder, CO 80303 (United States); Tremblay, Pier-Emmanuel [Department of Physics, University of Warwick, Coventry CV47AL (United Kingdom); Brown, Stephen [School of Physics and Astronomy, Kelvin Building, University of Glasgow, G12 8QQ (United Kingdom); Carlsson, Mats [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Osten, Rachel A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Wisniewski, John P. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States); Hawley, Suzanne L., E-mail: Adam.Kowalski@lasp.colorado.edu [University of Washington Department of Astronomy, 3910 15th Avenue NE, Seattle, WA 98195 (United States)

    2017-03-10

    The broadening of the hydrogen lines during flares is thought to result from increased charge (electron, proton) density in the flare chromosphere. However, disagreements between theory and modeling prescriptions have precluded an accurate diagnostic of the degree of ionization and compression resulting from flare heating in the chromosphere. To resolve this issue, we have incorporated the unified theory of electric pressure broadening of the hydrogen lines into the non-LTE radiative-transfer code RH. This broadening prescription produces a much more realistic spectrum of the quiescent, A0 star Vega compared to the analytic approximations used as a damping parameter in the Voigt profiles. We test recent radiative-hydrodynamic (RHD) simulations of the atmospheric response to high nonthermal electron beam fluxes with the new broadening prescription and find that the Balmer lines are overbroadened at the densest times in the simulations. Adding many simultaneously heated and cooling model loops as a “multithread” model improves the agreement with the observations. We revisit the three-component phenomenological flare model of the YZ CMi Megaflare using recent and new RHD models. The evolution of the broadening, line flux ratios, and continuum flux ratios are well-reproduced by a multithread model with high-flux nonthermal electron beam heating, an extended decay phase model, and a “hot spot” atmosphere heated by an ultrarelativistic electron beam with reasonable filling factors: ∼0.1%, 1%, and 0.1% of the visible stellar hemisphere, respectively. The new modeling motivates future work to understand the origin of the extended gradual phase emission.

  14. Hydrogen Balmer Line Broadening in Solar and Stellar Flares

    International Nuclear Information System (INIS)

    Kowalski, Adam F.; Allred, Joel C.; Uitenbroek, Han; Tremblay, Pier-Emmanuel; Brown, Stephen; Carlsson, Mats; Osten, Rachel A.; Wisniewski, John P.; Hawley, Suzanne L.

    2017-01-01

    The broadening of the hydrogen lines during flares is thought to result from increased charge (electron, proton) density in the flare chromosphere. However, disagreements between theory and modeling prescriptions have precluded an accurate diagnostic of the degree of ionization and compression resulting from flare heating in the chromosphere. To resolve this issue, we have incorporated the unified theory of electric pressure broadening of the hydrogen lines into the non-LTE radiative-transfer code RH. This broadening prescription produces a much more realistic spectrum of the quiescent, A0 star Vega compared to the analytic approximations used as a damping parameter in the Voigt profiles. We test recent radiative-hydrodynamic (RHD) simulations of the atmospheric response to high nonthermal electron beam fluxes with the new broadening prescription and find that the Balmer lines are overbroadened at the densest times in the simulations. Adding many simultaneously heated and cooling model loops as a “multithread” model improves the agreement with the observations. We revisit the three-component phenomenological flare model of the YZ CMi Megaflare using recent and new RHD models. The evolution of the broadening, line flux ratios, and continuum flux ratios are well-reproduced by a multithread model with high-flux nonthermal electron beam heating, an extended decay phase model, and a “hot spot” atmosphere heated by an ultrarelativistic electron beam with reasonable filling factors: ∼0.1%, 1%, and 0.1% of the visible stellar hemisphere, respectively. The new modeling motivates future work to understand the origin of the extended gradual phase emission.

  15. New accurate theoretical line lists of 12CH4 and 13CH4 in the 0-13400 cm-1 range: Application to the modeling of methane absorption in Titan's atmosphere

    Science.gov (United States)

    Rey, Michaël; Nikitin, Andrei V.; Bézard, Bruno; Rannou, Pascal; Coustenis, Athena; Tyuterev, Vladimir G.

    2018-03-01

    The spectrum of methane is very important for the analysis and modeling of Titan's atmosphere but its insufficient knowledge in the near infrared, with the absence of reliable absorption coefficients, is an important limitation. In order to help the astronomer community for analyzing high-quality spectra, we report in the present work the first accurate theoretical methane line lists (T = 50-350 K) of 12CH4 and 13CH4 up to 13400 cm-1 ( > 0.75 μm). These lists are built from extensive variational calculations using our recent ab initio potential and dipole moment surfaces and will be freely accessible via the TheoReTS information system (http://theorets.univ-reims.fr, http://theorets.tsu.ru). Validation of these lists is presented throughout the present paper. For the sample of lines where upper energies were available from published analyses of experimental laboratory 12CH4 spectra, small empirical corrections in positions were introduced that could be useful for future high-resolution applications. We finally apply the TheoRetS line list to model Titan spectra as observed by VIMS and by DISR, respectively onboard Cassini and Huygens. These data are used to check that the TheoReTS line lists are able to model observations. We also make comparisons with other experimental or theoretical line lists. It appears that TheoRetS gives very reliable results better than ExoMol and even than HITRAN2012, except around 1.6 μm where it gives very similar results. We conclude that TheoReTS is suitable to be used for the modeling of planetary radiative transfer and photometry. A re-analysis of spectra recorded by the DISR instrument during the descent of the Huygens probe suggests that the CH4 mixing ratio decreases with altitude in Titan's stratosphere, reaching a value of ∼10-2 above the 110 km altitude.

  16. 100 years aerology in Lindenberg and first long-time observations in the free atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Berger, F.H.; Hantel, M. [Deutscher Wetterdienst, Meteorologisches Observatorium, Lindenberg (Germany)

    2005-10-01

    This contribution gives a short overview of 100 years aerological observation at Lindenberg Observatory. It describes the geographical location and the climatological characteristics of the observatory. The first part of the paper is a short version of the chronicle: It starts with the opening ceremony on October 16, 1905 and considers the main scientific achievements of the observatory from 1905 to 2005, characterized by its directors Assmann, Hergesell, von Ficker, Marten, Koschmieder, Hearth, Beelitz, Robitzsch, Dubois, Gloede, Leiterer, Schwirner, Neisser and Berger. In the second part of the paper we present the results of a time series of the 100 years period for temperature and relative humidity measured by tethered kite and balloon techniques and radiosondes. For both atmospheric parameters we find a positive trend in the lower and a negative trend in the upper troposphere. Finally we discuss our plans, aims, and the difficulties in creating a homogeneous 100 year time series of significant meteorological parameters in the free atmosphere for detailed scientific investigations. (orig.)

  17. Modelling of atmospheric mid-infrared radiative transfer: the AMIL2DA algorithm intercomparison experiment

    International Nuclear Information System (INIS)

    Clarmann, T. von; Hoepfner, M.; Funke, B.; Lopez-Puertas, M.; Dudhia, A.; Jay, V.; Schreier, F.; Ridolfi, M.; Ceccherini, S.; Kerridge, B.J.; Reburn, J.; Siddans, R.

    2003-01-01

    When retrieving atmospheric parameters from radiance spectra, the forward modelling of radiative transfer through the Earth's atmosphere plays a key role, since inappropriate modelling directly maps on to the retrieved state parameters. In the context of pre-launch activities of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) experiment, which is a high resolution limb emission sounder for measurement of atmospheric composition and temperature, five scientific groups intercompared their forward models within the framework of the Advanced MIPAS Level 2 Data Analysis (AMIL2DA) project. These forward models have been developed, or, in certain respects, adapted in order to be used as part of the groups' MIPAS data processing. The following functionalities have been assessed: the calculation of line strengths including non-local thermodynamic equilibrium, the evaluation of the spectral line shape, application of chi-factors and semi-empirical continua, the interpolation of pre-tabulated absorption cross sections in pressure and temperature, line coupling, atmospheric ray tracing, the integration of the radiative transfer equation through an inhomogeneous atmosphere, the convolution of monochromatic spectra with an instrument line shape function, and the integration of the incoming radiances over the instrument field of view

  18. Characteristics of Volcanic Stratospheric Aerosol Layer Observed by CALIOP and Ground Based Lidar at Equatorial Atmosphere Radar Site

    Science.gov (United States)

    Abo, Makoto; Shibata, Yasukuni; Nagasawa, Chikao

    2018-04-01

    We investigated the relation between major tropical volcanic eruptions in the equatorial region and the stratospheric aerosol data, which have been collected by the ground based lidar observations at at Equatorial Atmosphere Radar site between 2004 and 2015 and the CALIOP observations in low latitude between 2006 and 2015. We found characteristic dynamic behavior of volcanic stratospheric aerosol layers over equatorial region.

  19. Validation of Atmosphere/Ionosphere Signals Associated with Major Earthquakes by Multi-Instrument Space-Borne and Ground Observations

    Science.gov (United States)

    Ouzounov, Dimitar; Pulinets, Sergey; Hattori, Katsumi; Parrot, Michel; Liu, J. Y.; Yang, T. F.; Arellano-Baeza, Alonso; Kafatos, M.; Taylor, Patrick

    2012-01-01

    The latest catastrophic earthquake in Japan (March 2011) has renewed interest in the important question of the existence of pre-earthquake anomalous signals related to strong earthquakes. Recent studies have shown that there were precursory atmospheric/ionospheric signals observed in space associated with major earthquakes. The critical question, still widely debated in the scientific community, is whether such ionospheric/atmospheric signals systematically precede large earthquakes. To address this problem we have started to investigate anomalous ionospheric / atmospheric signals occurring prior to large earthquakes. We are studying the Earth's atmospheric electromagnetic environment by developing a multisensor model for monitoring the signals related to active tectonic faulting and earthquake processes. The integrated satellite and terrestrial framework (ISTF) is our method for validation and is based on a joint analysis of several physical and environmental parameters (thermal infrared radiation, electron concentration in the ionosphere, lineament analysis, radon/ion activities, air temperature and seismicity) that were found to be associated with earthquakes. A physical link between these parameters and earthquake processes has been provided by the recent version of Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) model. Our experimental measurements have supported the new theoretical estimates of LAIC hypothesis for an increase in the surface latent heat flux, integrated variability of outgoing long wave radiation (OLR) and anomalous variations of the total electron content (TEC) registered over the epicenters. Some of the major earthquakes are accompanied by an intensification of gas migration to the surface, thermodynamic and hydrodynamic processes of transformation of latent heat into thermal energy and with vertical transport of charged aerosols in the lower atmosphere. These processes lead to the generation of external electric currents in specific

  20. Satellite Sounder Observations of Contrasting Tropospheric Moisture Transport Regimes: Saharan Air Layers, Hadley Cells, and Atmospheric Rivers

    Energy Technology Data Exchange (ETDEWEB)

    Nalli, Nicholas R.; Barnet, Christopher D.; Reale, Tony; Liu, Quanhua; Morris, Vernon R.; Spackman, J. Ryan; Joseph, Everette; Tan, Changyi; Sun, Bomin; Tilley, Frank; Leung, L. Ruby; Wolfe, Daniel

    2016-12-01

    This paper examines the performance of satellite sounder atmospheric vertical moisture proles (AVMP) under tropospheric conditions encompassing moisture contrasts driven by convection and advection transport mechanisms, specifically Atlantic Ocean Saharan air layers (SALs) and Pacific Ocean moisture conveyer belts (MCBs) commonly referred to as atmospheric rivers (ARs), both of these being mesoscale to synoptic meteorological phenomena within the vicinity of subtropical Hadley subsidence zones. Operational AVMP environmental data records retrieved from the Suomi National Polar-orbiting Partnership (SNPP) NOAA-Unique Combined Atmospheric Processing System (NUCAPS) are collocated with dedicated radiosonde observations (RAOBs) obtained from ocean-based intensive field campaigns; these RAOBs provide uniquely independent correlative truth data not assimilated into numerical weather prediction models for satellite sounder validation over open ocean. Using these marine-based data, we empirically assess the performance of the operational NUCAPS AVMP product for detecting and resolving these tropospheric moisture features over otherwise RAOB-sparse regions.

  1. EVIDENCE FOR WIDESPREAD COOLING IN AN ACTIVE REGION OBSERVED WITH THE SDO ATMOSPHERIC IMAGING ASSEMBLY

    International Nuclear Information System (INIS)

    Viall, Nicholeen M.; Klimchuk, James A.

    2012-01-01

    A well-known behavior of EUV light curves of discrete coronal loops is that the peak intensities of cooler channels or spectral lines are reached at progressively later times than hotter channels. This time lag is understood to be the result of hot coronal loop plasma cooling through these lower respective temperatures. However, loops typically comprise only a minority of the total emission in active regions (ARs). Is this cooling pattern a common property of AR coronal plasma, or does it only occur in unique circumstances, locations, and times? The new Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) data provide a wonderful opportunity to answer this question systematically for an entire AR. We measure the time lag between pairs of SDO/AIA EUV channels using 24 hr of images of AR 11082 observed on 2010 June 19. We find that there is a time-lag signal consistent with cooling plasma, just as is usually found for loops, throughout the AR including the diffuse emission between loops for the entire 24 hr duration. The pattern persists consistently for all channel pairs and choice of window length within the 24 hr time period, giving us confidence that the plasma is cooling from temperatures of greater than 3 MK, and sometimes exceeding 7 MK, down to temperatures lower than ∼0.8 MK. This suggests that the bulk of the emitting coronal plasma in this AR is not steady; rather, it is dynamic and constantly evolving. These measurements provide crucial constraints on any model which seeks to describe coronal heating.

  2. Radiation transfer and stellar atmospheres

    Science.gov (United States)

    Swihart, T. L.

    This is a revised and expanded version of the author's Basic Physics of Stellar Atmospheres, published in 1971. The equation of transfer is considered, taking into account the intensity and derived quantities, the absorption coefficient, the emission coefficient, the source function, and special integrals for plane media. The gray atmosphere is discussed along with the nongray atmosphere, and aspects of line formation. Topics related to polarization are explored, giving attention to pure polarized radiation, general polarized radiation, transfer in a magnetic plasma, and Rayleigh scattering and the sunlit sky. Physical and astronomical constants, and a number of problems related to the subjects of the book are presented in an appendix.

  3. Ground-based Observations and Atmospheric Modelling of Energetic Electron Precipitation Effects on Antarctic Mesospheric Chemistry

    Science.gov (United States)

    Newnham, D.; Clilverd, M. A.; Horne, R. B.; Rodger, C. J.; Seppälä, A.; Verronen, P. T.; Andersson, M. E.; Marsh, D. R.; Hendrickx, K.; Megner, L. S.; Kovacs, T.; Feng, W.; Plane, J. M. C.

    2016-12-01

    The effect of energetic electron precipitation (EEP) on the seasonal and diurnal abundances of nitric oxide (NO) and ozone in the Antarctic middle atmosphere during March 2013 to July 2014 is investigated. Geomagnetic storm activity during this period, close to solar maximum, was driven primarily by impulsive coronal mass ejections. Near-continuous ground-based atmospheric measurements have been made by a passive millimetre-wave radiometer deployed at Halley station (75°37'S, 26°14'W, L = 4.6), Antarctica. This location is directly under the region of radiation-belt EEP, at the extremity of magnetospheric substorm-driven EEP, and deep within the polar vortex during Austral winter. Superposed epoch analyses of the ground based data, together with NO observations made by the Solar Occultation For Ice Experiment (SOFIE) onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite, show enhanced mesospheric NO following moderate geomagnetic storms (Dst ≤ -50 nT). Measurements by co-located 30 MHz riometers indicate simultaneous increases in ionisation at 75-90 km directly above Halley when Kp index ≥ 4. Direct NO production by EEP in the upper mesosphere, versus downward transport of NO from the lower thermosphere, is evaluated using a new version of the Whole Atmosphere Community Climate Model incorporating the full Sodankylä Ion Neutral Chemistry Model (WACCM SIC). Model ionization rates are derived from the Polar orbiting Operational Environmental Satellites (POES) second generation Space Environment Monitor (SEM 2) Medium Energy Proton and Electron Detector instrument (MEPED). The model data are compared with observations to quantify the impact of EEP on stratospheric and mesospheric odd nitrogen (NOx), odd hydrogen (HOx), and ozone.

  4. Influence of sintering atmospheres on the aluminium sintering characteristics

    International Nuclear Information System (INIS)

    Mintzer, S.; Bermudez Belkys, S.

    1993-01-01

    This paper describes the aluminium powder (Al) cool compacted (at 95% from theoretical density) which was sintered at 903 K during 4 hours at different atmospheres; oxidizing (air), inert Argon (Ar), Nitrogen (N) and high vacuum. The results obtained show: a) porosity measurements; greater porosity when sintering in Ar and air. b) Metallographic and Scanning observations: many fine pores (< 1 μm) and pore lines distributed at random, at air sintering and greater pores distributed preferentially near the surface, in Ar and N atmospheres. c) Dimensional changes: tendency to contraction of the samples at N and vacuum sintering and expansion in Ar or air. d) Mechanical properties: greater strength and fluence stresses at air and N sintering. The analysis of the results is performed considering sintering modes in presence of an oxide layer and dropped inert gases. (Author)

  5. VHF radar observation of atmospheric winds, associated shears and C2n at a tropical location: interdependence and seasonal pattern

    Directory of Open Access Journals (Sweden)

    A. R. Jain

    Full Text Available The turbulence refractivity structure constant (C2n is an important parameter of the atmosphere. VHF radars have been used extensively for the measurements of C2n. Presently, most of such observations are from mid and high latitudes and only very limited observations are available for equatorial and tropical latitudes. Indian MST radar is an excellent tool for making high-resolution measurements of atmospheric winds, associated shears and turbulence refractivity structure constant (C2n. This radar is located at Gadanki (13.45° N, 79.18° E, a tropical station in India. The objective of this paper is to bring out the height structure of C2n for different seasons using the long series of data (September 1995 – August 1999 from Indian MST radar. An attempt is also made to understand such changes in the height structure of C2n in relation to background atmospheric parameters such as horizontal winds and associated shears. The height structure of C2n, during the summer monsoon and post-monsoon season, shows specific height features that are found to be related to Tropical Easterly Jet (TEJ winds. It is important to examine the nature of the radar back-scatterers and also to understand the causative mechanism of such scatterers. Aspect sensitivity of the received radar echo is examined for this purpose. It is observed that radar back-scatterers at the upper tropospheric and lower stratospheric heights are more anisotropic, with horizontal correlation length of 10–20 m, as compared to those observed at lower and middle tropospheric heights.Key words. Meteorology and atmospheric dynamics (climatology; tropical meteorology; turbulence

  6. Performance of the first ANTARES detector line

    Energy Technology Data Exchange (ETDEWEB)

    Bruijn, R.; Kooijman, P.; Lim, G.; De Wolf, E. [Univ Amsterdam, Inst Hoge Energiefys, NL-1098 XG Amsterdam, (Netherlands); Ageron, M.; Aubert, J.J.; Bertin, V.; Brunner, J.; Busto, J.; Carr, J.; Coyle, P.; Dornic, D.; Escoffier, S.; Hallewell, G.; Lambard, G.; Lavalle, J.; Lelaizant, G.; Louis, F.; Melissas, M.; Payre, P.; Reed, C. [CPPM, CNRS, IN2P3, F-13288 Marseille 9, (France); Ageron, M.; Aubert, J.J.; Bertin, V.; Brunner, J.; Busto, J.; Carr, J.; Coyle, P.; Dornic, D.; Escoffier, S.; Hallewell, G.; Lambard, G.; Lavalle, J.; Lelaizant, G.; Louis, F.; Melissas, M.; Payre, P.; Reed, C. [Univ Aix Marseille 2, F-13288 Marseille 9, (France); Aguilar, J.A.; Bigongiari, C.; Hernandez-Rey, J.J.; Salesa, F.; Toscano, S.; Zornoza, J.D.; Zuniga, J. [Univ Valencia, CSIC, IFIC Inst Fis Corpuscular, Edificios Invest Paterna, Valencia 46071, (Spain); Albert, A.; Castel, D.; Drouhin, D.; Ernenwein, J.P.; Guillard, G. [Univ Houte Alsace, GRPHE, F-68093 Mulhouse, (France); Anton, G.; Auer, R.; Eberl, T.; Fehr, F.; Graf, K.; Hossl, J.; Kalekin, O.; Kappes, A.; Katz, U.; Kopper, C.; Kretschmer, W.; Kuch, S.; Lahmann, R.; Laschinsky, H.; Loucatos, S.; Motz, H.; Naumann, C.; Ostasch, R.; Richardt, C.; Schoeck, F.; Shanidze, R. [Univ Erlangen Nurnberg, Inst Phys, D-91058 Erlangen, (Germany); Anvar, S.; Druillole, F.; Lamare, P.; Le Provost, H. [CEA Saclay, Direct Sci Mat, Inst Rech Fondamentales Univers, Serv Elect Detecteurs et Informat, F-91191 Gif Sur Yvette, (France)

    2009-07-01

    In this paper we report on the data recorded with the first Antares detector line. The line was deployed on 14 February 2006 and was connected to the readout 2 weeks later. Environmental data for one and a half years of running are shown. Measurements of atmospheric muons from data taken from selected runs during the first 6 months of operation are presented. Performance figures in terms of time residuals and angular resolution are given. Finally the angular distribution of atmospheric muons is presented and from this the depth profile of the muon intensity is derived. (authors)

  7. The Small Unmanned Meteorological Observer SUMO. A new tool for atmospheric boundary layer research

    Energy Technology Data Exchange (ETDEWEB)

    Reuder, Joachim; Jonassen, Marius; Mayer, Stephanie [Bergen Univ. (Norway). Geophysical Inst.; Brisset, Pascal [Ecole Nationale de l' Aviation Civile (ENAC), Toulouse (France); Mueller, Martin [Martin Mueller Engineering, Hildesheim (Germany)

    2009-04-15

    The Small Unmanned Meteorological Observer SUMO has been developed as a cost-efficient measurement system with the aim to close the existing observational gap of atmospheric measurement systems in between meteorological masts/towers and radiosondes. The system is highly flexible and has the capability for in-situ ABL measurements with unique spatial and temporal resolution. SUMO is based on a light-weighted styrofoam model airplane, equipped with an autopilot system for autonomous flight missions and in its recent version with meteorological sensors for temperature, humidity and pressure. With its wingspan of 80 cm, its length of 75 cm and a total lift-off weight of 580 g, SUMO is easy to transport and operate even in remote areas with limited infrastructure. During several field campaigns in 2007 and 2008 the system has been successfully tested and operated. Atmospheric profiles of temperature, humidity, wind speed and wind direction have been determined up to 3500 m above ground during the FLOHOF (FLOw over and around HOFsjoekull) field campaign in Central Iceland in July/August 2007. During a 3 week campaign on and around Spitsbergen in February/March 2008 the SUMO system also proved its functionality under polar conditions, reaching altitudes above 1500 m even at ground temperatures of -20 C and wind speeds up to 15 m s{sup -1}. (orig.)

  8. The 1-way on-line coupled atmospheric chemistry model system MECO(n – Part 2: On-line coupling with the Multi-Model-Driver (MMD

    Directory of Open Access Journals (Sweden)

    A. Kerkweg

    2012-01-01

    Full Text Available A new, highly flexible model system for the seamless dynamical down-scaling of meteorological and chemical processes from the global to the meso-γ scale is presented. A global model and a cascade of an arbitrary number of limited-area model instances run concurrently in the same parallel environment, in which the coarser grained instances provide the boundary data for the finer grained instances. Thus, disk-space intensive and time consuming intermediate and pre-processing steps are entirely avoided and the time interpolation errors of common off-line nesting approaches are minimised. More specifically, the regional model COSMO of the German Weather Service (DWD is nested on-line into the atmospheric general circulation model ECHAM5 within the Modular Earth Submodel System (MESSy framework. ECHAM5 and COSMO have previously been equipped with the MESSy infrastructure, implying that the same process formulations (MESSy submodels are available for both models. This guarantees the highest degree of achievable consistency, between both, the meteorological and chemical conditions at the domain boundaries of the nested limited-area model, and between the process formulations on all scales.

    The on-line nesting of the different models is established by a client-server approach with the newly developed Multi-Model-Driver (MMD, an additional component of the MESSy infrastructure. With MMD an arbitrary number of model instances can be run concurrently within the same message passing interface (MPI environment, the respective coarser model (either global or regional is the server for the nested finer (regional client model, i.e. it provides the data required to calculate the initial and boundary fields to the client model. On-line nesting means that the coupled (client-server models exchange their data via the computer memory, in contrast to the data exchange via files on disk in common off-line nesting approaches. MMD consists of a library

  9. Chandra Observations of Pluto's Escaping Atmosphere in Support of the New Horizons Mission

    Science.gov (United States)

    McNutt, Ralph, Jr.

    2013-09-01

    Current models of Pluto's extended N2+CH4 atmosphere are still very uncertain, causing numerous difficulties in optimizing the New Horizons fast flyby operations plan for the dwarf planet. Applying knowledge gained from studying cometary X-ray emission, Chandra ACIS-S photometric imaging of X-rays produced by CXE between the solar wind and Pluto's atmosphere will address both the run of atmospheric density and the interaction of the solar wind with the extended Plutonian atmosphere. Determining the atmosphere's extent and amount of free molecular escape will aid the atmospheric sounding measurements of the NH ALICE instrument, while determining the x-ray luminosity will help the NH PEPSI instrument characterize the solar wind particle environment.

  10. An Observational Diagnostic for Distinguishing between Clouds and Haze in Hot Exoplanet Atmospheres

    International Nuclear Information System (INIS)

    Kempton, Eliza M.-R.; Bean, Jacob L.; Parmentier, Vivien

    2017-01-01

    The nature of aerosols in hot exoplanet atmospheres is one of the primary vexing questions facing the exoplanet field. The complex chemistry, multiple formation pathways, and lack of easily identifiable spectral features associated with aerosols make it especially challenging to constrain their key properties. We propose a transmission spectroscopy technique to identify the primary aerosol formation mechanism for the most highly irradiated hot Jupiters (HIHJs). The technique is based on the expectation that the two key types of aerosols—photochemically generated hazes and equilibrium condensate clouds—are expected to form and persist in different regions of a highly irradiated planet’s atmosphere. Haze can only be produced on the permanent daysides of tidally locked hot Jupiters, and will be carried downwind by atmospheric dynamics to the evening terminator (seen as the trailing limb during transit). Clouds can only form in cooler regions on the nightside and morning terminator of HIHJs (seen as the leading limb during transit). Because opposite limbs are expected to be impacted by different types of aerosols, ingress and egress spectra, which primarily probe opposing sides of the planet, will reveal the dominant aerosol formation mechanism. We show that the benchmark HIHJ, WASP-121b, has a transmission spectrum consistent with partial aerosol coverage and that ingress–egress spectroscopy would constrain the location and formation mechanism of those aerosols. In general, using this diagnostic we find that observations with the James Webb Space Telescope and potentially with the Hubble Space Telescope should be able to distinguish between clouds and haze for currently known HIHJs.

  11. An Observational Diagnostic for Distinguishing between Clouds and Haze in Hot Exoplanet Atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Kempton, Eliza M.-R. [Department of Physics, Grinnell College, 1116 8th Avenue, Grinnell, IA 50112 (United States); Bean, Jacob L. [Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637 (United States); Parmentier, Vivien, E-mail: kemptone@grinnell.edu [Department of Planetary Sciences and Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721 (United States)

    2017-08-20

    The nature of aerosols in hot exoplanet atmospheres is one of the primary vexing questions facing the exoplanet field. The complex chemistry, multiple formation pathways, and lack of easily identifiable spectral features associated with aerosols make it especially challenging to constrain their key properties. We propose a transmission spectroscopy technique to identify the primary aerosol formation mechanism for the most highly irradiated hot Jupiters (HIHJs). The technique is based on the expectation that the two key types of aerosols—photochemically generated hazes and equilibrium condensate clouds—are expected to form and persist in different regions of a highly irradiated planet’s atmosphere. Haze can only be produced on the permanent daysides of tidally locked hot Jupiters, and will be carried downwind by atmospheric dynamics to the evening terminator (seen as the trailing limb during transit). Clouds can only form in cooler regions on the nightside and morning terminator of HIHJs (seen as the leading limb during transit). Because opposite limbs are expected to be impacted by different types of aerosols, ingress and egress spectra, which primarily probe opposing sides of the planet, will reveal the dominant aerosol formation mechanism. We show that the benchmark HIHJ, WASP-121b, has a transmission spectrum consistent with partial aerosol coverage and that ingress–egress spectroscopy would constrain the location and formation mechanism of those aerosols. In general, using this diagnostic we find that observations with the James Webb Space Telescope and potentially with the Hubble Space Telescope should be able to distinguish between clouds and haze for currently known HIHJs.

  12. Detection of sodium in the atmosphere of WASP-69b

    Science.gov (United States)

    Casasayas-Barris, N.; Palle, E.; Nowak, G.; Yan, F.; Nortmann, L.; Murgas, F.

    2017-12-01

    Context. Transit spectroscopy is one of the most commonly used methods to characterize exoplanets' atmospheres. From the ground, these observations are very challenging due to the terrestrial atmosphere and its intrinsic variations, but high-spectral-resolution observations overcome this difficulty by resolving the spectral lines and taking advantage of the different Doppler velocities of the Earth, the host star, and the exoplanet. Aims: We analyze the transmission spectrum around the Na I doublet at 589 nm of the extrasolar planet WASP-69b, a hot Jupiter orbiting a K-type star with a period of 3.868 days, and compare the analysis to that of the well-known hot Jupiter HD 189733b. We also present the analysis of the Rossiter-McLaughlin (RM) effect for WASP-69b. Methods: We observed two transits of WASP-69b with the High Accuracy Radial velocity Planet Searcher (HARPS-North) spectrograph (R = 115 000) at the Telescopio Nazionale Galileo (TNG). We perform a telluric contamination subtraction based on the comparison between the observed spectra and a telluric water model. Then, the common steps of the differential spectroscopy are followed to extract the transmission spectrum. The method is tested with archival transit data of the extensively studied exoplanet HD 189733b, obtained with the HARPS-South spectrograph at ESO 3.6 m telescope, and then applied to WASP-69b data. Results: For HD 189733b, we spectrally resolve the Na I doublet and measure line contrasts of 0.72 ± 0.05% (D2) and 0.51 ± 0.05% (D1), and full width half maximum (FWHM) values of 0.64 ± 0.04 Å (D2) and 0.60 ± 0.06 Å (D1), in agreement with previously published results. For WASP-69b only the contrast of the D2 line can be measured (5.8 ± 0.3%). This corresponds to a detection at the 5σ-level of excess absorption of 0.5 ± 0.1% in a passband of 1.5 Å. A net blueshift of 0.04 Å is measured for HD 189733b and no shift is obtained for WASP-69b. By measuring the RM effect, we get an angular

  13. Validation of Earth atmosphere models using solar EUV observations from the CORONAS and PROBA2 satellites in occultation mode

    Science.gov (United States)

    Slemzin, Vladimir; Ulyanov, Artyom; Gaikovich, Konstantin; Kuzin, Sergey; Pertsov, Andrey; Berghmans, David; Dominique, Marie

    2016-02-01

    Aims: Knowledge of properties of the Earth's upper atmosphere is important for predicting the lifetime of low-orbit spacecraft as well as for planning operation of space instruments whose data may be distorted by atmospheric effects. The accuracy of the models commonly used for simulating the structure of the atmosphere is limited by the scarcity of the observations they are based on, so improvement of these models requires validation under different atmospheric conditions. Measurements of the absorption of the solar extreme ultraviolet (EUV) radiation in the upper atmosphere below 500 km by instruments operating on low-Earth orbits (LEO) satellites provide efficient means for such validation as well as for continuous monitoring of the upper atmosphere and for studying its response to the solar and geomagnetic activity. Method: This paper presents results of measurements of the solar EUV radiation in the 17 nm wavelength band made with the SPIRIT and TESIS telescopes on board the CORONAS satellites and the SWAP telescope on board the PROBA2 satellite in the occulted parts of the satellite orbits. The transmittance profiles of the atmosphere at altitudes between 150 and 500 km were derived from different phases of solar activity during solar cycles 23 and 24 in the quiet state of the magnetosphere and during the development of a geomagnetic storm. We developed a mathematical procedure based on the Tikhonov regularization method for solution of ill-posed problems in order to retrieve extinction coefficients from the transmittance profiles. The transmittance profiles derived from the data and the retrieved extinction coefficients are compared with simulations carried out with the NRLMSISE-00 atmosphere model maintained by Naval Research Laboratory (USA) and the DTM-2013 model developed at CNES in the framework of the FP7 project ATMOP. Results: Under quiet and slightly disturbed magnetospheric conditions during high and low solar activity the extinction coefficients

  14. High resolution transmission spectroscopy as a diagnostic for Jovian exoplanet atmospheres: constraints from theoretical models

    Energy Technology Data Exchange (ETDEWEB)

    Kempton, Eliza M.-R. [Department of Physics, Grinnell College, Grinnell, IA 50112 (United States); Perna, Rosalba [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States); Heng, Kevin, E-mail: kemptone@grinnell.edu [University of Bern, Center for Space and Habitability, Sidlerstrasse 5, CH-3012 Bern (Switzerland)

    2014-11-01

    We present high resolution transmission spectra of giant planet atmospheres from a coupled three-dimensional (3D) atmospheric dynamics and transmission spectrum model that includes Doppler shifts which arise from winds and planetary motion. We model Jovian planets covering more than two orders of magnitude in incident flux, corresponding to planets with 0.9-55 day orbital periods around solar-type stars. The results of our 3D dynamical models reveal certain aspects of high resolution transmission spectra that are not present in simple one-dimensional (1D) models. We find that the hottest planets experience strong substellar to anti-stellar (SSAS) winds, resulting in transmission spectra with net blueshifts of up to 3 km s{sup –1}, whereas less irradiated planets show almost no net Doppler shifts. We find only minor differences between transmission spectra for atmospheres with temperature inversions and those without. Compared to 1D models, peak line strengths are significantly reduced for the hottest atmospheres owing to Doppler broadening from a combination of rotation (which is faster for close-in planets under the assumption of tidal locking) and atmospheric winds. Finally, high resolution transmission spectra may be useful in studying the atmospheres of exoplanets with optically thick clouds since line cores for very strong transitions should remain optically thick to very high altitude. High resolution transmission spectra are an excellent observational test for the validity of 3D atmospheric dynamics models, because they provide a direct probe of wind structures and heat circulation. Ground-based exoplanet spectroscopy is currently on the verge of being able to verify some of our modeling predictions, most notably the dependence of SSAS winds on insolation. We caution that interpretation of high resolution transmission spectra based on 1D atmospheric models may be inadequate, as 3D atmospheric motions can produce a noticeable effect on the absorption

  15. Desorption atmospheric pressure photoionization high-resolution mass spectrometry: a complementary approach for the chemical analysis of atmospheric aerosols.

    Science.gov (United States)

    Parshintsev, Jevgeni; Vaikkinen, Anu; Lipponen, Katriina; Vrkoslav, Vladimir; Cvačka, Josef; Kostiainen, Risto; Kotiaho, Tapio; Hartonen, Kari; Riekkola, Marja-Liisa; Kauppila, Tiina J

    2015-07-15

    On-line chemical characterization methods of atmospheric aerosols are essential to increase our understanding of physicochemical processes in the atmosphere, and to study biosphere-atmosphere interactions. Several techniques, including aerosol mass spectrometry, are nowadays available, but they all suffer from some disadvantages. In this research, desorption atmospheric pressure photoionization high-resolution (Orbitrap) mass spectrometry (DAPPI-HRMS) is introduced as a complementary technique for the fast analysis of aerosol chemical composition without the need for sample preparation. Atmospheric aerosols from city air were collected on a filter, desorbed in a DAPPI source with a hot stream of toluene and nitrogen, and ionized using a vacuum ultraviolet lamp at atmospheric pressure. To study the applicability of the technique for ambient aerosol analysis, several samples were collected onto filters and analyzed, with the focus being on selected organic acids. To compare the DAPPI-HRMS data with results obtained by an established method, each filter sample was divided into two equal parts, and the second half of the filter was extracted and analyzed by liquid chromatography/mass spectrometry (LC/MS). The DAPPI results agreed with the measured aerosol particle number. In addition to the targeted acids, the LC/MS and DAPPI-HRMS methods were found to detect different compounds, thus providing complementary information about the aerosol samples. DAPPI-HRMS showed several important oxidation products of terpenes, and numerous compounds were tentatively identified. Thanks to the soft ionization, high mass resolution, fast analysis, simplicity and on-line applicability, the proposed methodology has high potential in the field of atmospheric research. Copyright © 2015 John Wiley & Sons, Ltd.

  16. Optical aging observation in suspended core tellurite microstructured fibers under atmospheric conditions

    Science.gov (United States)

    Strutynski, C.; Mouawad, O.; Picot-Clémente, J.; Froidevaux, P.; Désévédavy, F.; Gadret, G.; Jules, J.-C.; Kibler, B.; Smektala, F.

    2017-11-01

    Tellurite glasses are good candidates for the development of broadband supercontinuum (SC) laser sources in the 1-5 μm range. At the moment, beside very few exceptions, SC generation in TeO2-based microstructured optical fibers (MOFs) is limited to 3 μm in the mid-infrared (MIR). We present here an observation of an optical aging occurring in six-hole suspended-core tellurite MOFs. When exposed to atmospheric conditions, such fibers show an alteration of their transmission between 3 and 4 μm. This aging phenomenon leads to the growth of strong additional losses in this wavelengths range over time. Impact of the transmission degradation on spectral broadening is studied through numerical simulations of SC generation.

  17. An empirical line-by-line model for the infrared solar transmittance spectrum from 700 to 5000cm{sup -1}

    Energy Technology Data Exchange (ETDEWEB)

    Hase, F. [Institut fuer Meteorologie und Klimaforschung, Forschungszentrum Karlsruhe, Postfach 3640, D-76021 Karlsruhe (Germany)]. E-mail: frank.hase@imk.fzk.de; Demoulin, P. [Institut d' Astrophysique et de Geophysique, allee du VI aout, 17, batiment B5a, B-4000, Liege (Belgium); Sauval, A.J. [Observatoire Royal de Belgique, avenue circulaire, 3, B-1180, Bruxelles (Belgium); Toon, G.C. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Bernath, P.F. [Department of Chemistry, University of Waterloo, Waterloo, Ont., Canada N2L3G1 (Canada); Goldman, A. [Department of Physics, University of Denver, Denver, CO 80208 (United States); Hannigan, J.W. [Atmospheric Chemistry Division, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80303 (United States); Rinsland, C.P. [NASA Langley Research Center, Hampton, VA 23681-2199 (United States)

    2006-12-15

    An empirical line-by-line model for the infrared solar transmittance spectrum is presented. The model can be incorporated into radiative transfer codes to allow fast calculation of all relevant emission and absorption features in the solar spectrum in the mid-infrared region from 700 to 5000cm{sup -1}. The transmittance is modelled as a function of the diameter of the field-of-view centered on the solar disk: the line broadening due to solar rotation as well as center-to-limb variations in strength and width are taken into account for stronger lines. Applications of the model presented here are in the fields of terrestrial remote sensing in the mid-infrared spectral region when the sun is used as radiation source or scattered solar radiation contributes to the measured signal and in the fields of atmospheric radiative transfer algorithms which compute the propagation of infrared solar radiation in the terrestrial atmosphere.

  18. Millimeter-wave molecular line observations of the Tornado nebula

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, D. [Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Oka, T.; Tanaka, K.; Matsumura, S.; Miura, K.; Takekawa, S., E-mail: sakai.daisuke@nao.ac.jp [Department of Physics, Institute of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama, Kanagawa 223-8522 (Japan)

    2014-08-10

    We report the results of millimeter-wave molecular line observations of the Tornado Nebula (G357.7-0.1), which is a bright radio source behind the Galactic center region. A 15' × 15' area was mapped in the J = 1-0 lines of CO, {sup 13}CO, and HCO{sup +} with the Nobeyama Radio Observatory 45 m telescope. The Very Large Array archival data of OH at 1720 MHz were also reanalyzed. We found two molecular clouds with separate velocities, V{sub LSR} = –14 km s{sup –1} and +5 km s{sup –1}. These clouds show rough spatial anti-correlation. Both clouds are associated with OH 1720 MHz emissions in the area overlapping with the Tornado Nebula. The spatial and velocity coincidence indicates violent interaction between the clouds and the Tornado Nebula. Modestly excited gas prefers the position of the Tornado 'head' in the –14 km s{sup –1} cloud, also suggesting the interaction. Virial analysis shows that the +5 km s{sup –1} cloud is more tightly bound by self-gravity than the –14 km s{sup –1} cloud. We propose a formation scenario for the Tornado Nebula; the +5 km s{sup –1} cloud collided into the –14 km s{sup –1} cloud, generating a high-density layer behind the shock front, which activates a putative compact object by Bondi-Hoyle-Lyttleton accretion to eject a pair of bipolar jets.

  19. Total observed organic carbon (TOOC in the atmosphere: a synthesis of North American observations

    Directory of Open Access Journals (Sweden)

    C. L. Heald

    2008-04-01

    Full Text Available Measurements of organic carbon compounds in both the gas and particle phases made upwind, over and downwind of North America are synthesized to examine the total observed organic carbon (TOOC in the atmosphere over this region. These include measurements made aboard the NOAA WP-3 and BAe-146 aircraft, the NOAA research vessel Ronald H. Brown, and at the Thompson Farm and Chebogue Point surface sites during the summer 2004 ICARTT campaign. Both winter and summer 2002 measurements during the Pittsburgh Air Quality Study are also included. Lastly, the spring 2002 observations at Trinidad Head, CA, surface measurements made in March 2006 in Mexico City and coincidentally aboard the C-130 aircraft during the MILAGRO campaign and later during the IMPEX campaign off the northwestern United States are incorporated. Concentrations of TOOC in these datasets span more than two orders of magnitude. The daytime mean TOOC ranges from 4.0 to 456 μgC m−3 from the cleanest site (Trinidad Head to the most polluted (Mexico City. Organic aerosol makes up 3–17% of this mean TOOC, with highest fractions reported over the northeastern United States, where organic aerosol can comprise up to 50% of TOOC. Carbon monoxide concentrations explain 46 to 86% of the variability in TOOC, with highest TOOC/CO slopes in regions with fresh anthropogenic influence, where we also expect the highest degree of mass closure for TOOC. Correlation with isoprene, formaldehyde, methyl vinyl ketone and methacrolein also indicates that biogenic activity contributes substantially to the variability of TOOC, yet these tracers of biogenic oxidation sources do not explain the variability in organic aerosol observed over North America. We highlight the critical need to develop measurement techniques to routinely detect total gas phase VOCs, and to deploy comprehensive suites of TOOC instruments in diverse environments to quantify the ambient evolution of organic carbon from source

  20. Calibration Base Lines for Electronic Distance Measuring Instruments (EDMI)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A calibration base line (CBL) is a precisely measured, straight-line course of approximately 1,400 m used to calibrate Electronic Distance Measuring Instruments...

  1. Observations of atmospheric pollutants at Lhasa during 2014-2015: Pollution status and the influence of meteorological factors.

    Science.gov (United States)

    Duo, Bu; Cui, Lulu; Wang, Zhenzhen; Li, Rui; Zhang, Liwu; Fu, Hongbo; Chen, Jianmin; Zhang, Huifang; Qiong, A

    2018-01-01

    Atmospheric pollutants including SO 2 , NO 2 , CO, O 3 and inhalable particulate matter (PM 2.5 and PM 10 ) were monitored continuously from March 2014 to February 2015 to investigate characteristics of air pollution at Lhasa, Tibetan Plateau. Species exhibited similar seasonal variations except O 3 , with the peaks in winter but low valleys in summer. The maximum O 3 concentration was observed in spring, followed by summer, autumn, and winter. The positive correlation between O 3 and PM 10 in spring indicated similar sources of them, and was assumed to be turbulent transport. Temperature was the dominant meteorological factor for most species in spring. High temperature accelerates O 3 photochemistry, and favors air disturbance which is conductive to dust resuspension in spring. Relative humidity (RH) and atmospheric pressure were the main meteorological factors in summer. RH showed negative correlations with species, while atmospheric pressure posed opposite situation. Wind speed (WS) was the dominant meteorological factor in autumn, the negative correlations between WS and species indicated diffusion by wind. Most species showed non-significant correlations with meteorological factors in winter, indicating the dependence of pollution on source emission rather than restriction by meteorology. Pollution weather character indicated that emissions were from biomass burning and dust suspension, and meteorological factors also played an important role. Air stream injection from the stratosphere was observed during O 3 pollution period. Air parcels from Southwest Asia were observed during air pollution period in winter. An enhancement in air pollutants such as O 3 would be expected in the future, more attention should be given to countermeasures for prevention of air pollution in the future. Copyright © 2017. Published by Elsevier B.V.

  2. Atmospheric Modeling of the Martian Polar Regions: One Mars Year of CRISM EPF Observations of the South Pole

    Science.gov (United States)

    Brown, A. J.; Wolff, M. J.

    2009-03-01

    We have used CRISM Emission Phase Function gimballed observations to investigate atmospheric dust/ice opacity and surface albedo in the south polar region for the first Mars year of MRO operations. This covers the MY28 "dust event" and cap recession.

  3. Louisiana ESI: ROADS (Road Lines)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains the state maintained primary and secondary road network of Louisiana. Vector lines in the data set represent Interstates, U.S. Highways, and...

  4. Mars MetNet Mission - Martian Atmospheric Observational Post Network

    Science.gov (United States)

    Harri, A.-M.; Haukka, H.; Aleksashkin, S.; Arruego, I.; Schmidt, W.; Genzer, M.; Vazquez, L.; Siikonen, T.; Palin, M.

    2017-09-01

    A new kind of planetary exploration mission for Mars is under development in collaboration between the Finnish Meteorological Institute (FMI), Lavochkin Association (LA), Space Research Institute (IKI) and Institutio Nacional de Tecnica Aerospacial (INTA). The Mars MetNet mission is based on a new semi-hard landing vehicle called MetNet Lander (MNL). The scientific payload of the Mars MetNet Precursor [1] mission is divided into three categories: Atmospheric instruments, Optical devices and Composition and structure devices. Each of the payload instruments will provide significant insights in to the Martian atmospheric behavior. The key technologies of the MetNet Lander have been qualified and the electrical qualification model (EQM) of the payload bay has been built and successfully tested.

  5. [Regional atmospheric environment risk source identification and assessment].

    Science.gov (United States)

    Zhang, Xiao-Chun; Chen, Wei-Ping; Ma, Chun; Zhan, Shui-Fen; Jiao, Wen-Tao

    2012-12-01

    Identification and assessment for atmospheric environment risk source plays an important role in regional atmospheric risk assessment and regional atmospheric pollution prevention and control. The likelihood exposure and consequence assessment method (LEC method) and the Delphi method were employed to build a fast and effective method for identification and assessment of regional atmospheric environment risk sources. This method was applied to the case study of a large coal transportation port in North China. The assessment results showed that the risk characteristics and the harm degree of regional atmospheric environment risk source were in line with the actual situation. Fast and effective identification and assessment of risk source has laid an important foundation for the regional atmospheric environmental risk assessment and regional atmospheric pollution prevention and control.

  6. Constraining the Structure of Hot Jupiter Atmospheres Using a Hybrid Version of the NEMESIS Retrieval Algorithm

    Science.gov (United States)

    Badhan, Mahmuda A.; Mandell, Avi M.; Hesman, Brigette; Nixon, Conor; Deming, Drake; Irwin, Patrick; Barstow, Joanna; Garland, Ryan

    2015-11-01

    Understanding the formation environments and evolution scenarios of planets in nearby planetary systems requires robust measures for constraining their atmospheric physical properties. Here we have utilized a combination of two different parameter retrieval approaches, Optimal Estimation and Markov Chain Monte Carlo, as part of the well-validated NEMESIS atmospheric retrieval code, to infer a range of temperature profiles and molecular abundances of H2O, CO2, CH4 and CO from available dayside thermal emission observations of several hot-Jupiter candidates. In order to keep the number of parameters low and henceforth retrieve more plausible profile shapes, we have used a parametrized form of the temperature profile based upon an analytic radiative equilibrium derivation in Guillot et al. 2010 (Line et al. 2012, 2014). We show retrieval results on published spectroscopic and photometric data from both the Hubble Space Telescope and Spitzer missions, and compare them with simulations from the upcoming JWST mission. In addition, since NEMESIS utilizes correlated distribution of absorption coefficients (k-distribution) amongst atmospheric layers to compute these models, updates to spectroscopic databases can impact retrievals quite significantly for such high-temperature atmospheres. As high-temperature line databases are continually being improved, we also compare retrievals between old and newer databases.

  7. X-ray grating observations of recurrent nova T Pyxidis during the 2011 outburst

    Energy Technology Data Exchange (ETDEWEB)

    Tofflemire, Benjamin M.; Orio, Marina [Astronomy Department, University of Wisconsin-Madison, 475 N. Charter St., WI 53711 (United States); Page, Kim L.; Osborne, Julian P. [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Ciroi, Stefano; Cracco, Valentina; Di Mille, Francesco [Department of Physics and Astronomy, Padova University, Vicolo dell' Osservatorio 3, I-35122 Padova (Italy); Maxwell, Michael [Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom)

    2013-12-10

    The recurrent nova T Pyx was observed with the X-ray gratings of Chandra and XMM-Newton, 210 and 235 days, respectively, after the discovery of the 2011 April 14 outburst. The X-ray spectra show prominent emission lines of C, N, and O, with broadening corresponding to an FWHM of ∼2000-3000 km s{sup –1}, and line ratios consistent with high-density plasma in collisional ionization equilibrium. On day 210 we also measured soft X-ray continuum emission that appears to be consistent with a white dwarf (WD) atmosphere at a temperature ∼420,000 K, partially obscured by anisotropic, optically thick ejecta. The X-ray continuum emission is modulated with the photometric and spectroscopic period observed in quiescence. The continuum at day 235 indicated a WD atmosphere at a consistent effective temperature of 25 days earlier, but with a lower flux. The effective temperature indicates a mass of ∼1 M {sub ☉}. The conclusion of partial WD obscuration is supported by the complex geometry of non-spherically symmetric ejecta confirmed in recent optical spectra obtained with the Southern African Large Telescope in November and December of 2012. These spectra exhibited prominent [O III] nebular lines with velocity structures typical of bipolar ejecta.

  8. CORONA, JET, AND RELATIVISTIC LINE MODELS FOR SUZAKU/RXTE/CHANDRA-HETG OBSERVATIONS OF THE CYGNUS X-1 HARD STATE

    International Nuclear Information System (INIS)

    Nowak, Michael A.; Trowbridge, Sarah N.; Davis, John E.; Hanke, Manfred; Wilms, Joern; Markoff, Sera B.; Maitra, Dipankar; Tramper, Frank; Pottschmidt, Katja; Coppi, Paolo

    2011-01-01

    Using Suzaku and the Rossi X-ray Timing Explorer (RXTE), we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard 'low states'. Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the 'focused wind' from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating (HETG). These latter spectra are crucial for revealing the ionized absorption due to the secondary's focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations and jets. All three models require a soft component that we fit with a low temperature disk spectrum with an inner radius of only a few tens of GM/c 2 . All three models also agree that the known spectral break at 10 keV is not solely due to the presence of reflection, but each gives a different underlying explanation for the augmentation of this break. Thus, whereas all three models require that there is a relativistically broadened Fe line, the strength and inner radius of such a line is dependent upon the specific model, thus making premature line-based estimates of the black hole spin in the Cyg X-1 system. We look at the relativistic line in detail, accounting for the narrow Fe emission and ionized absorption detected by HETG. Although the specific relativistic parameters of the line are continuum dependent, none of the broad line fits allow for an inner disk radius that is >40 GM/c 2 .

  9. Line formation in microturbulent magnetic fields

    International Nuclear Information System (INIS)

    Domke, H.; Pavlov, G.G.

    1979-01-01

    The formation of Zeeman lines in Gaussian microturbulent magnetic fields is considered assuming LTE. General formulae are derived for the local mean values of the transfer matrix elements. The cases of one-dimensional (longitudinal), isotropic, and two-dimensional (transversal) magnetic microturbulence are studied in some detail. Asymptotic formulae are given for small mean as well as for small microturbulent magnetic fields. Characteristic effects of magnetic microturbulence on the transfer coefficients are: (i) the broadening of the frequency contours, although only for the case of longitudinal Zeeman effect and longitudinal magnetic microturbulence this effect can be described analogous to Doppler broadening, (ii) the appearance of a pseudo-Zeeman structure for nonlongitudinal magnetic microturbulence, (iii) the reduction of maximal values of circular polarization, and (iv) the appearance of characteristic linear polarization effects due to the anisotropy of the magnetic microturbulence. Line contours and polarization of Zeeman triplets are computed for Milne-Eddington atmospheres. It is shown that magnetic intensification due to microturbulent magnetic fields may be much more efficient than that due to regular fields. The gravity center of a Zeeman line observed in circularly polarized light remains a reasonable measure of the line of sight component of the mean magnetic field for a line strength eta 0 < approx. 2. For saturated lines, the gravity center distance depends significantly on the magnetic microturbulence and its anisotropy. The influence of magnetic microturbulence on the ratio of longitudinal field magnetographic signals shows that unique conclusions about the magnetic microstructure can be drawn from the line ratio measurements only in combination with further spectroscopic data or physical reasoning. (orig.)

  10. Photochemistry in Saturn’s Ring-Shadowed Atmosphere: Photochemistry and Haze Observations

    Science.gov (United States)

    Edgington, Scott G.; Atreya, Sushil K.; Baines, Kevin H.; West, Robert A.; Bjoraker, Gordon L.; Fletcher, Leigh; Momary, Thomas W.; Wilson, Eric; CIRS, ISS, UVIS, VIMS

    2017-10-01

    After 13 years of observing Saturn, Cassini would have ended nearly a half Saturnian year. During this epoch, the ring shadow has moved from covering much of the northern hemisphere to covering a large swath southern hemisphere. The net effect is that the intensity of both ultraviolet and visible sunlight penetrating through the rings to any particular latitude will vary depending on both Saturn’s axis relative to the Sun and the optical thickness of each ring system. In essence, the rings act like semi-transparent venetian blinds. This effect magnifies the effect due to axial tilt alone and acts to turn off photochemistry and haze generation. This effect is seen in both the presence of a bluish Rayleigh-scattering atmosphere in 2004 in the northern hemisphere and color change to blue in the northern hemisphere.Previous work examined the variation of the solar flux as a function of solar inclination, i.e. for each 7.25-year season at Saturn. We report on the impact of the oscillating ring shadow, in addition to variation due to axial tilt, on photolysis and production rates of hydrocarbons and phosphine in Saturn’s stratosphere and upper troposphere. The impact of these production and loss rates on the abundance of long-lived photochemical products leading to haze formation are explored. We assess their impact on a disequilibrium species whose presence in the upper troposphere can be used as a tracer of convective processes in the deeper atmosphere.We will also present our ongoing analysis of Cassini’s CIRS, UVIS, and VIMS datasets that provide an estimate of the evolving haze content. In particular, we will examine how the region inside Saturn’s famous hexagonal jet stream changes over time from a relatively clear atmosphere to a hazy one. We also explore how the hexagon acts like a barrier to transport, isolating Saturn’s north polar region from outside influences of photochemically-generated molecules and haze.The research described in this paper was

  11. Altitude-temporal behaviour of atmospheric ozone, temperature and wind velocity observed at Svalbard

    Czech Academy of Sciences Publication Activity Database

    Petkov, B. H.; Vitale, V.; Svendby, T. M.; Hansen, G. H.; Sobolewski, P. S.; Láska, K.; Elster, Josef; Pavlova, K.; Viola, A.; Mazzola, M.; Lupi, A.; Solomatnikova, A.

    2018-01-01

    Roč. 207, JUL 15 (2018), s. 100-110 ISSN 0169-8095 Institutional support: RVO:67985939 Keywords : Arctic atmosphere * Atmospheric ozone * Ozone depletion Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 3.778, year: 2016

  12. The effect of spectroscopic parameter inaccuracies on ground-based millimeter wave remote sensing of the atmosphere

    International Nuclear Information System (INIS)

    Ryan, Niall J.; Walker, Kaley A.

    2015-01-01

    A sensitivity study was performed to assess the impact that uncertainties in the spectroscopic parameters of atmospheric species have on the retrieval of gas concentrations using the 265–280 GHz region of the electromagnetic spectrum. Errors in the retrieval of O 3 , N 2 O, HNO 3 , and ClO from spectra measured by ground-based radiometers were investigated. The goal of the study was to identify the spectroscopic parameters of these target species, and other interfering species, available in the JPL and HITRAN 2008 catalogues, which contribute the largest error to retrieved atmospheric concentration profiles in order to provide recommendations for new laboratory measurements. The parameters investigated were the line position, line strength, broadening coefficients and their temperature dependence, and pressure shift. Uncertainties in the air broadening coefficients of gases tend to contribute the largest error to retrieved atmospheric concentration profiles. For O 3 and N 2 O, gases with relatively strong spectral signatures, the retrieval is sensitive to uncertainties in the parameters of the main spectral line that is observed. For HNO 3 , the uncertainties in many closely spaced HNO 3 lines can cause large errors in the retrieved profile, and for ClO, the error in the profile is dominated by uncertainties in nearby, stronger O 3 lines. Fourteen spectroscopic parameters are identified, for which updated measurements would have the most impact on the accuracy of ground-based remote sensing of the target species at 265–280 GHz. - Highlights: • The sensitivity of retrievals to spectroscopic parameters is assessed. • Air broadening parameters contribute the most to the error budget. • O 3 and N 2 O retrievals are sensitive to parameters of the target spectral lines. • Many HNO 3 lines in close proximity can cause large errors in HNO 3 retrievals. • ClO retrievals are sensitive to uncertainties in parameters of nearby O 3 lines

  13. Atmospheric CO2 Observations Reveal Strong Correlation Between Regional Net Biospheric Carbon Uptake and Solar-Induced Chlorophyll Fluorescence

    Science.gov (United States)

    Shiga, Yoichi P.; Tadić, Jovan M.; Qiu, Xuemei; Yadav, Vineet; Andrews, Arlyn E.; Berry, Joseph A.; Michalak, Anna M.

    2018-01-01

    Recent studies have shown the promise of remotely sensed solar-induced chlorophyll fluorescence (SIF) in informing terrestrial carbon exchange, but analyses have been limited to either plot level ( 1 km2) or hemispheric/global ( 108 km2) scales due to the lack of a direct measure of carbon exchange at intermediate scales. Here we use a network of atmospheric CO2 observations over North America to explore the value of SIF for informing net ecosystem exchange (NEE) at regional scales. We find that SIF explains space-time NEE patterns at regional ( 100 km2) scales better than a variety of other vegetation and climate indicators. We further show that incorporating SIF into an atmospheric inversion leads to a spatial redistribution of NEE estimates over North America, with more uptake attributed to agricultural regions and less to needleleaf forests. Our results highlight the synergy of ground-based and spaceborne carbon cycle observations.

  14. Comparison of Solar Fine Structure Observed Simultaneously in Lyα and Mg II h

    Science.gov (United States)

    Schmit, D.; Sukhorukov, A. V.; De Pontieu, B.; Leenaarts, J.; Bethge, C.; Winebarger, A.; Auchère, F.; Bando, T.; Ishikawa, R.; Kano, R.; Kobayashi, K.; Narukage, N.; Trujillo Bueno, J.

    2017-10-01

    The Chromospheric Lyman Alpha Spectropolarimeter (CLASP) observed the Sun in H I Lyα during a suborbital rocket flight on 2015 September 3. The Interface Region Imaging Telescope (IRIS) coordinated with the CLASP observations and recorded nearly simultaneous and co-spatial observations in the Mg II h and k lines. The Mg II h and Lyα lines are important transitions, energetically and diagnostically, in the chromosphere. The canonical solar atmosphere model predicts that these lines form in close proximity to each other and so we expect that the line profiles will exhibit similar variability. In this analysis, we present these coordinated observations and discuss how the two profiles compare over a region of quiet Sun at viewing angles that approach the limb. In addition to the observations, we synthesize both line profiles using a 3D radiation-MHD simulation. In the observations, we find that the peak width and the peak intensities are well correlated between the lines. For the simulation, we do not find the same relationship. We have attempted to mitigate the instrumental differences between IRIS and CLASP and to reproduce the instrumental factors in the synthetic profiles. The model indicates that formation heights of the lines differ in a somewhat regular fashion related to magnetic geometry. This variation explains to some degree the lack of correlation, observed and synthesized, between Mg II and Lyα. Our analysis will aid in the definition of future observatories that aim to link dynamics in the chromosphere and transition region.

  15. Comparison of Solar Fine Structure Observed Simultaneously in Ly α and Mg ii h

    Energy Technology Data Exchange (ETDEWEB)

    Schmit, D. [Bay Area Environmental Research Institute, 625 2nd Street, Suite 209, Petaluma, CA 94952 (United States); Sukhorukov, A. V.; Leenaarts, J. [Institute for Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern NO-0315 Oslo (Norway); De Pontieu, B. [Lockheed Martin Solar and Astrophysics Laboratory, Building 252, 3176 Porter Drive, Palo Alto, CA 94304 (United States); Bethge, C.; Winebarger, A.; Kobayashi, K. [NASA Marshall Space Flight Center, ZP 13, Huntsville, AL 35812 (United States); Auchère, F. [Institut d’Astrophysique Spatiale, CNRS/Univ. Paris-Sud 11, Bâtiment 121, F-91405 Orsay (France); Bando, T.; Kano, R.; Narukage, N. [National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Ishikawa, R. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Bueno, J. Trujillo [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)

    2017-10-01

    The Chromospheric Lyman Alpha Spectropolarimeter (CLASP) observed the Sun in H i Ly α during a suborbital rocket flight on 2015 September 3. The Interface Region Imaging Telescope ( IRIS ) coordinated with the CLASP observations and recorded nearly simultaneous and co-spatial observations in the Mg ii h and k lines. The Mg ii h and Ly α lines are important transitions, energetically and diagnostically, in the chromosphere. The canonical solar atmosphere model predicts that these lines form in close proximity to each other and so we expect that the line profiles will exhibit similar variability. In this analysis, we present these coordinated observations and discuss how the two profiles compare over a region of quiet Sun at viewing angles that approach the limb. In addition to the observations, we synthesize both line profiles using a 3D radiation-MHD simulation. In the observations, we find that the peak width and the peak intensities are well correlated between the lines. For the simulation, we do not find the same relationship. We have attempted to mitigate the instrumental differences between IRIS and CLASP and to reproduce the instrumental factors in the synthetic profiles. The model indicates that formation heights of the lines differ in a somewhat regular fashion related to magnetic geometry. This variation explains to some degree the lack of correlation, observed and synthesized, between Mg ii and Ly α . Our analysis will aid in the definition of future observatories that aim to link dynamics in the chromosphere and transition region.

  16. Balloon observation of the binary X-ray source Her X-1 1.24 sec pulsation and cyclotron line emission

    International Nuclear Information System (INIS)

    Pietsch, W.; Reppin, C.; Truemper, J.; Voges, W.; Kendziorra, E.; Staubert, R.; Tuebingen Univ.

    1978-01-01

    During a balloon observation from Palestine, Texas, the authors detected for the first time the 1.24 sec pulsation of Hercules X-1 in the hard X-ray range up to 70 keV and discovered strong line emission in its spectrum at 58 keV. They estimated a line flux of 3x10 -3 photons cm -2 sec -1 and a line width of less than 12 keV. The phenomenon is interpreted as electron cyclotron emission at the basic frequency emitted by the hot polar plasma of the rotating neutron star. The line measured leads to a magnetic field strength of 5.3x10 12 gauss. In further observations during a balloon campaign in Sept./Oct. 1977 the authors confirmed the existence of the line emission and for the first time found pulsed X-ray emission above 15 keV during the 'short on' - and 'off'-state of the Her X-1 35 day cycle. The pulse to interpulse ratio seems to vary with the 35 day phase

  17. International Comprehensive Ocean Atmosphere Data Set (ICOADS) And NCEI Global Marine Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — International Comprehensive Ocean Atmosphere Data Set (ICOADS) consists of digital data set DSI-1173, archived at the National Center for Environmental Information...

  18. Thermal infrared sounding observations of lower atmospheric variances at Mars and their implications for gravity wave activity: a preliminary examination

    Science.gov (United States)

    Heavens, N. G.

    2017-12-01

    It has been recognized for over two decades that the mesoscale statistical variance observed by Earth-observing satellites at temperature-sensitive frequencies above the instrumental noise floor is a measure of gravity wave activity. These types of observation have been made by a variety of satellite instruments have been an important validation tool for gravity wave parameterizations in global and mesoscale models. At Mars, the importance of topographic and non-topographic sources of gravity waves for the general circulation is now widely recognized and the target of recent modeling efforts. However, despite several ingenious studies, gravity wave activity near hypothetical lower atmospheric sources has been poorly and unsystematically characterized, partly because of the difficulty of separating the gravity wave activity from baroclinic wave activity and the thermal tides. Here will be presented a preliminary analysis of calibrated radiance variance at 15.4 microns (635-665 cm-1) from nadir, off-nadir, and limb observations by the Mars Climate Sounder on board Mars Reconnaissance Orbiter. The overarching methodology follows Wu and Waters (1996, 1997). Nadir, off-nadir, and lowest detector limb observations should sample variability with vertical weighting functions centered high in the lower atmosphere (20-30 km altitude) and full width half maximum (FWHM) 20 km but be sensitive to gravity waves with different horizontal wavelengths and slightly different vertical wavelengths. This work is supported by NASA's Mars Data Analysis Program (NNX14AM32G). References Wu, D.L. and J.W. Waters, 1996, Satellite observations of atmospheric variances: A possible indication of gravity waves, GRL, 23, 3631-3634. Wu D.L. and J.W. Waters, 1997, Observations of Gravity Waves with the UARS Microwave Limb Sounder. In: Hamilton K. (eds) Gravity Wave Processes. NATO ASI Series (Series I: Environmental Change), vol 50. Springer, Berlin, Heidelberg.

  19. A Comparison between Predicted and Observed Atmospheric States and their Effects on Infrasonic Source Time Function Inversion at Source Physics Experiment 6

    Science.gov (United States)

    Aur, K. A.; Poppeliers, C.; Preston, L. A.

    2017-12-01

    The Source Physics Experiment (SPE) consists of a series of underground chemical explosions at the Nevada National Security Site (NNSS) designed to gain an improved understanding of the generation and propagation of physical signals in the near and far field. Characterizing the acoustic and infrasound source mechanism from underground explosions is of great importance to underground explosion monitoring. To this end we perform full waveform source inversion of infrasound data collected from the SPE-6 experiment at distances from 300 m to 6 km and frequencies up to 20 Hz. Our method requires estimating the state of the atmosphere at the time of each experiment, computing Green's functions through these atmospheric models, and subsequently inverting the observed data in the frequency domain to obtain a source time function. To estimate the state of the atmosphere at the time of the experiment, we utilize the Weather Research and Forecasting - Data Assimilation (WRF-DA) modeling system to derive a unified atmospheric state model by combining Global Energy and Water Cycle Experiment (GEWEX) Continental-scale International Project (GCIP) data and locally obtained sonde and surface weather observations collected at the time of the experiment. We synthesize Green's functions through these atmospheric models using Sandia's moving media acoustic propagation simulation suite (TDAAPS). These models include 3-D variations in topography, temperature, pressure, and wind. We compare inversion results using the atmospheric models derived from the unified weather models versus previous modeling results and discuss how these differences affect computed source waveforms with respect to observed waveforms at various distances. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy's National Nuclear

  20. Observations of chromospheric lines from OSO-8

    International Nuclear Information System (INIS)

    Grossmann-Doerth, U.; Kneer, F.; Uexkuell, M. v.; Artzner, G.E.; Vial, J.C.

    1980-01-01

    The line profiles of Lα, Ca II K and Mg II k were measured with the spectrometer of the Laboratoire de Physique Stellaire et Planetaire on board of OSO-8. The results of these measurements are presented. (orig.)

  1. Atmosphere-ionosphere coupling from convectively generated gravity waves

    Science.gov (United States)

    Azeem, Irfan; Barlage, Michael

    2018-04-01

    Ionospheric variability impacts operational performances of a variety of technological systems, such as HF communication, Global Positioning System (GPS) navigation, and radar surveillance. The ionosphere is not only perturbed by geomagnetic inputs but is also influenced by atmospheric tides and other wave disturbances propagating from the troposphere to high altitudes. Atmospheric Gravity Waves (AGWs) excited by meteorological sources are one of the largest sources of mesoscale variability in the ionosphere. In this paper, Total Electron Content (TEC) data from networks of GPS receivers in the United States are analyzed to investigate AGWs in the ionosphere generated by convective thunderstorms. Two case studies of convectively generated gravity waves are presented. On April 4, 2014 two distinct large convective systems in Texas and Arkansas generated two sets of concentric AGWs that were observed in the ionosphere as Traveling Ionospheric Disturbances (TIDs). The period of the observed TIDs was 20.8 min, the horizontal wavelength was 182.4 km, and the horizontal phase speed was 146.4 m/s. The second case study shows TIDs generated from an extended squall line on December 23, 2015 stretching from the Gulf of Mexico to the Great Lakes in North America. Unlike the concentric wave features seen in the first case study, the extended squall line generated TIDs, which exhibited almost plane-parallel phase fronts. The TID period was 20.1 min, its horizontal wavelength was 209.6 km, and the horizontal phase speed was 180.1 m/s. The AGWs generated by both of these meteorological events have large vertical wavelength (>100 km), which are larger than the F2 layer thickness, thus allowing them to be discernible in the TEC dataset.

  2. The ~ 2400-year cycle in atmospheric radiocarbon concentration: bispectrum of 14C data over the last 8000 years

    Directory of Open Access Journals (Sweden)

    S. S. Vasiliev

    2002-01-01

    Full Text Available We have carried out power spectrum, time-spectrum and bispectrum analyses of the long-term series of the radiocarbon concentrations deduced from measurements of the radiocarbon content in tree rings for the last 8000 years. Classical harmonic analysis of this time series shows a number of periods: 2400, 940, 710, 570, 500, 420, 360, 230, 210 and 190 years. A principle feature of the time series is the long period of ~ 2400 years, which is well known. The lines with periods of 710, 420 and 210 years are found to be the primary secular components of power spectrum. The complicated structure of the observed power spectrum is the result of ~ 2400-year modulation of primary secular components. The modulation induces the appearance of two side lines for every primary one, namely lines with periods of 940 and 570 years, of 500 and 360 years, and 230 and 190 years. The bispectral analysis shows that the parameters of carbon exchange system varied with the ~ 2400-year period during the last 8000 years. Variations of these parameters appear to be a climate effect on the rate of transfer of 14C between the atmosphere and the the ocean.Key words. Meteorology and atmospheric dynamics (climatology; ocean-atmosphere interaction; paleoclimatology

  3. Astronomy and Atmospheric Optics

    Science.gov (United States)

    Cowley, Les; Gaina, Alex

    2011-12-01

    The authors discusse the insuccess of the observation of the Total Eclipse of the Moon from 10 december 2011 in Romania and relate them with meteoconditions. Only a very short part of the last penumbral phase was observed, while the inital part and the totality was not observed due to very dense clouds. The change in color and brightness during this phase was signaled. Meanwhile, there is an area of science where clouds are of great use and interest. This area is Atmospheric optics, while the science which study clouds is meteorology. Clouds in combination with Solar and Moon light could give rise to a variety of strange, rare and unobvious phenomena in the atmosphere (sky), sometimes confused with Unidentified Flying Objects (UFO). The importance of meteorology for astronomy and atmospheric optics is underlined and an invitation to astronomers to use unfavourable days for athmospheric observations was sent. The web address of the site by Les Cowley, designed for atmospheric optics phenomena is contained in the text of the entry.

  4. Large wind ripples on Mars: A record of atmospheric evolution

    Science.gov (United States)

    Lapotre, M G; Ewing, R C; Lamb, M P; Fischer, W W; Grotzinger, J P; Rubin, D M; Lewis, K W; Ballard, M; Day, Mitch D.; Gupta, S.; Banham, S G; Bridges, N T; Des Marais, D J; Fraeman, A A; Grant, J A; Herkenhoff, Kenneth E.; Ming, D W; Mischna, M A; Rice, M S; Sumner, D A; Vasavada, A R; Yingst, R A

    2016-01-01

    Wind blowing over sand on Earth produces decimeter-wavelength ripples and hundred-meter– to kilometer-wavelength dunes: bedforms of two distinct size modes. Observations from the Mars Science Laboratory Curiosity rover and the Mars Reconnaissance Orbiter reveal that Mars hosts a third stable wind-driven bedform, with meter-scale wavelengths. These bedforms are spatially uniform in size and typically have asymmetric profiles with angle-of-repose lee slopes and sinuous crest lines, making them unlike terrestrial wind ripples. Rather, these structures resemble fluid-drag ripples, which on Earth include water-worked current ripples, but on Mars instead form by wind because of the higher kinematic viscosity of the low-density atmosphere. A reevaluation of the wind-deposited strata in the Burns formation (about 3.7 billion years old or younger) identifies potential wind-drag ripple stratification formed under a thin atmosphere.

  5. Large wind ripples on Mars: A record of atmospheric evolution

    Science.gov (United States)

    Lapotre, M. G. A.; Ewing, R. C.; Lamb, M. P.; Fischer, W. W.; Grotzinger, J. P.; Rubin, D. M.; Lewis, K. W.; Ballard, M. J.; Day, M.; Gupta, S.; Banham, S. G.; Bridges, N. T.; Des Marais, D. J.; Fraeman, A. A.; Grant, J. A.; Herkenhoff, K. E.; Ming, D. W.; Mischna, M. A.; Rice, M. S.; Sumner, D. A.; Vasavada, A. R.; Yingst, R. A.

    2016-07-01

    Wind blowing over sand on Earth produces decimeter-wavelength ripples and hundred-meter- to kilometer-wavelength dunes: bedforms of two distinct size modes. Observations from the Mars Science Laboratory Curiosity rover and the Mars Reconnaissance Orbiter reveal that Mars hosts a third stable wind-driven bedform, with meter-scale wavelengths. These bedforms are spatially uniform in size and typically have asymmetric profiles with angle-of-repose lee slopes and sinuous crest lines, making them unlike terrestrial wind ripples. Rather, these structures resemble fluid-drag ripples, which on Earth include water-worked current ripples, but on Mars instead form by wind because of the higher kinematic viscosity of the low-density atmosphere. A reevaluation of the wind-deposited strata in the Burns formation (about 3.7 billion years old or younger) identifies potential wind-drag ripple stratification formed under a thin atmosphere.

  6. Thermal Band Atmospheric Correction Using Atmospheric Profiles Derived from Global Positioning System Radio Occultation and the Atmospheric Infrared Sounder

    Science.gov (United States)

    Pagnutti, Mary; Holekamp, Kara; Stewart, Randy; Vaughan, Ronald D.

    2006-01-01

    This Rapid Prototyping Capability study explores the potential to use atmospheric profiles derived from GPS (Global Positioning System) radio occultation measurements and by AIRS (Atmospheric Infrared Sounder) onboard the Aqua satellite to improve surface temperature retrieval from remotely sensed thermal imagery. This study demonstrates an example of a cross-cutting decision support technology whereby NASA data or models are shown to improve a wide number of observation systems or models. The ability to use one data source to improve others will be critical to the GEOSS (Global Earth Observation System of Systems) where a large number of potentially useful systems will require auxiliary datasets as input for decision support. Atmospheric correction of thermal imagery decouples TOA radiance and separates surface emission from atmospheric emission and absorption. Surface temperature can then be estimated from the surface emission with knowledge of its emissivity. Traditionally, radiosonde sounders or atmospheric models based on radiosonde sounders, such as the NOAA (National Oceanic & Atmospheric Administration) ARL (Air Resources Laboratory) READY (Real-time Environmental Application and Display sYstem), provide the atmospheric profiles required to perform atmospheric correction. Unfortunately, these types of data are too spatially sparse and too infrequently taken. The advent of high accuracy, global coverage, atmospheric data using GPS radio occultation and AIRS may provide a new avenue for filling data input gaps. In this study, AIRS and GPS radio occultation derived atmospheric profiles from the German Aerospace Center CHAMP (CHAllenging Minisatellite Payload), the Argentinean Commission on Space Activities SAC-C (Satellite de Aplicaciones Cientificas-C), and the pair of NASA GRACE (Gravity Recovery and Climate Experiment) satellites are used as input data in atmospheric radiative transport modeling based on the MODTRAN (MODerate resolution atmospheric

  7. An Information-theoretic Approach to Optimize JWST Observations and Retrievals of Transiting Exoplanet Atmospheres

    Science.gov (United States)

    Howe, Alex R.; Burrows, Adam; Deming, Drake

    2017-01-01

    We provide an example of an analysis to explore the optimization of observations of transiting hot Jupiters with the James Webb Space Telescope (JWST) to characterize their atmospheres based on a simple three-parameter forward model. We construct expansive forward model sets for 11 hot Jupiters, 10 of which are relatively well characterized, exploring a range of parameters such as equilibrium temperature and metallicity, as well as considering host stars over a wide range in brightness. We compute posterior distributions of our model parameters for each planet with all of the available JWST spectroscopic modes and several programs of combined observations and compute their effectiveness using the metric of estimated mutual information per degree of freedom. From these simulations, clear trends emerge that provide guidelines for designing a JWST observing program. We demonstrate that these guidelines apply over a wide range of planet parameters and target brightnesses for our simple forward model.

  8. AN INFORMATION-THEORETIC APPROACH TO OPTIMIZE JWST OBSERVATIONS AND RETRIEVALS OF TRANSITING EXOPLANET ATMOSPHERES

    Energy Technology Data Exchange (ETDEWEB)

    Howe, Alex R.; Burrows, Adam [Department of Astronomy, University of Michigan, 1085 S. University, Ann Arbor, MI 48109 (United States); Deming, Drake, E-mail: arhowe@umich.edu, E-mail: burrows@astro.princeton.edu, E-mail: ddeming@astro.umd.edu [Department of Astronomy, University of Maryland College Park, MD 20742 (United States)

    2017-01-20

    We provide an example of an analysis to explore the optimization of observations of transiting hot Jupiters with the James Webb Space Telescope ( JWST ) to characterize their atmospheres based on a simple three-parameter forward model. We construct expansive forward model sets for 11 hot Jupiters, 10 of which are relatively well characterized, exploring a range of parameters such as equilibrium temperature and metallicity, as well as considering host stars over a wide range in brightness. We compute posterior distributions of our model parameters for each planet with all of the available JWST spectroscopic modes and several programs of combined observations and compute their effectiveness using the metric of estimated mutual information per degree of freedom. From these simulations, clear trends emerge that provide guidelines for designing a JWST observing program. We demonstrate that these guidelines apply over a wide range of planet parameters and target brightnesses for our simple forward model.

  9. MOLECULAR LINE OBSERVATIONS OF THE CARBON-RICH CIRCUMSTELLAR ENVELOPE CIT 6 AT 7 mm WAVELENGTHS

    Energy Technology Data Exchange (ETDEWEB)

    Chau, Wayne; Zhang Yong; Nakashima, Jun-ichi; Kwok, Sun [Department of Physics, University of Hong Kong (Hong Kong); Deguchi, Shuji [Nobeyama Radio Observatory, National Astronomical Observatory, Minamimaki, Minamisaku, Nagano 384-1305 (Japan)

    2012-11-20

    We present a {lambda}7 mm spectral line survey of the carbon-rich circumstellar envelope (CSE) CIT 6 using the 45 m telescope at the Nobeyama Radio Observatory. A total of 25 spectral features belonging to five molecular species (HC{sub 3}N, HC{sub 5}N, HC{sub 7}N, SiO, and CS) are detected, enabling us to investigate the chemistry of cyanopolyyne chains. The line strengths are compared with those of the proto-typical carbon-rich CSE IRC+10216. The results show that the cyanopolyyne molecules are enhanced in CIT 6, suggesting that it is more evolved than IRC+10216. In order to investigate the structure of CIT 6, we have constructed a three-dimensional spatiokinematic model. By comparing the observed line profiles with the models, we conclude that this envelope is asymmetric and is composed of several incomplete shells.

  10. SPITZER TRANSITS OF THE SUPER-EARTH GJ1214b AND IMPLICATIONS FOR ITS ATMOSPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Fraine, Jonathan D.; Deming, Drake [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Gillon, Michaeel; Jehin, Emmanueel [Institute d' Astrophysique et de Geophysique, Universite de Liege, Liege (Belgium); Demory, Brice-Olivier; Benneke, Bjoern; Seager, Sara [Department of Earth, Atmospheric and Planetary Sciences, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Lewis, Nikole K. [Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Knutson, Heather [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Desert, Jean-Michel, E-mail: jfraine@astro.umd.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

    2013-03-10

    We observed the transiting super-Earth exoplanet GJ1214b using warm Spitzer at 4.5 {mu}m wavelength during a 20 day quasi-continuous sequence in 2011 May. The goals of our long observation were to accurately define the infrared transit radius of this nearby super-Earth, to search for the secondary eclipse, and to search for other transiting planets in the habitable zone of GJ1214. We here report results from the transit monitoring of GJ1214b, including a reanalysis of previous transit observations by Desert et al. In total, we analyze 14 transits of GJ1214b at 4.5 {mu}m, 3 transits at 3.6 {mu}m, and 7 new ground-based transits in the I+z band. Our new Spitzer data by themselves eliminate cloudless solar composition atmospheres for GJ1214b, and methane-rich models from Howe and Burrows. Using our new Spitzer measurements to anchor the observed transit radii of GJ1214b at long wavelengths, and adding new measurements in I+z, we evaluate models from Benneke and Seager and Howe and Burrows using a {chi}{sup 2} analysis. We find that the best-fit model exhibits an increase in transit radius at short wavelengths due to Rayleigh scattering. Pure water atmospheres are also possible. However, a flat line (no atmosphere detected) remains among the best of the statistically acceptable models, and better than pure water atmospheres. We explore the effect of systematic differences among results from different observational groups, and we find that the Howe and Burrows tholin-haze model remains the best fit, even when systematic differences among observers are considered.

  11. A possible edge effect in enhanced network. [solar K-line observations by multichannel spectrometer

    Science.gov (United States)

    Jones, H. P.; Brown, D. R.

    1977-01-01

    K-line observations of enhanced network taken with the NASA/SPO Multichannel Spectrometer on September 28, 1975, in support of OSO-8 are discussed. The data show a correlation between core brightness and asymmetry for spatial scans which cross enhanced network boundaries. The implications of this result concerning mass flow in and near supergranule boundaries are discussed.

  12. Power line emission 50/60 Hz and Schumann resonances observed by microsatellite Chibis-M in the Earth's ionosphere

    Science.gov (United States)

    Dudkin, Denys; Pilipenko, Vyacheslav; Dudkin, Fedir; Pronenko, Vira; Klimov, Stanislav

    2015-04-01

    The overhead power lines are the sources of intense wideband electromagnetic (EM) emission, especially in ELF-VLF range, because of significant length (up to a few thousand kilometers) and strong 50/60 Hz currents with noticeable distortion. The radiation efficiency of the power line emission (PLE) increases with the harmonic order, so they are well observed by ground-based EM sensors. However their observations by low orbiting satellites (LEO) are very rare, particularly at basic harmonic 50/60 Hz, because of the ionospheric plasma opacity in ELF band. The Schumann resonance (SR) is the narrow-band EM noise that occurs due to the global thunderstorm activity in the Earth-ionosphere cavity. The first five eigenmodes of the SR are 7.8, 14.3, 20.8, 27.3 and 33.8 Hz and, thus, SR harmonics are also strongly absorbed by the Earth ionosphere. The published numerical simulations show that the penetration depth of such an ELF emission into the Earth's ionosphere is limited to 50-70 km for electric field and 120-240 km for magnetic field. From this follows, that PLE and SR can hardly ever be detected by LEO satellites, i.e. above the F-layer of ionosphere. In spite of this fact, these emissions were recently observed with use of the electric field antennas placed on the satellites C/NOFS (USA) and Chibis-M (Russia). Microsatellite Chibis-M was launched on January 24, 2012, at 23:18:30 UTC from the cargo ship "Progress M-13M" to circular orbit with altitude ~500 km and inclination ~52° . Chibis-M mass is about 40 kg where one third is a scientific instrumentation. The dimensions of the microsatellite case are 0.26x0.26x0.54 m with the outside mounted solar panels, service and scientific instrumentation. The main scientific objective of Chibis-M is the theoretical model verification for the atmospheric gamma-ray bursts. It requires the study of the accompanying EM processes such as the plasma waves produced by the lightning discharges in the VLF band. Chibis-M decayed on 15

  13. Atmospheric mercury concentrations observed at ground-based monitoring sites globally distributed in the framework of the GMOS network

    Directory of Open Access Journals (Sweden)

    F. Sprovieri

    2016-09-01

    Full Text Available Long-term monitoring of data of ambient mercury (Hg on a global scale to assess its emission, transport, atmospheric chemistry, and deposition processes is vital to understanding the impact of Hg pollution on the environment. The Global Mercury Observation System (GMOS project was funded by the European Commission (http://www.gmos.eu and started in November 2010 with the overall goal to develop a coordinated global observing system to monitor Hg on a global scale, including a large network of ground-based monitoring stations, ad hoc periodic oceanographic cruises and measurement flights in the lower and upper troposphere as well as in the lower stratosphere. To date, more than 40 ground-based monitoring sites constitute the global network covering many regions where little to no observational data were available before GMOS. This work presents atmospheric Hg concentrations recorded worldwide in the framework of the GMOS project (2010–2015, analyzing Hg measurement results in terms of temporal trends, seasonality and comparability within the network. Major findings highlighted in this paper include a clear gradient of Hg concentrations between the Northern and Southern hemispheres, confirming that the gradient observed is mostly driven by local and regional sources, which can be anthropogenic, natural or a combination of both.

  14. Observations of the 63 micron forbidden O I line in Herbig-Haro objects

    International Nuclear Information System (INIS)

    Cohen, M.; Hollenbach, D.J.; Haas, M.R.; Erickson, E.F.

    1988-01-01

    The paper presents observations of the 63 micron forbidden O I line from Herbig-Haro objects and their exciting stars. Forbidden O I 63 micron emission is detected toward the HH-exciting stars T Tau, DG Tau, L1551 IRS 5, and toward the HH objects HH 7-11, HH 42A, and HH 43 which are displaced from their exciting stars. The forbidden O I emission is associated with these flows on the basis of its spatial coincidence and its negative radial velocities. If the exciting stars drive bipolar flows in which the 63 micron emission follows that at 6300 A, the absence of redshifted 63 micron lines from the three exciting stars might indicate that the disks hypothesized to overlie the receding lobes of these flows are still optically thick in the far-infrared. 50 references

  15. The spatial intensity distribution of selected emission lines for Herbig-Haro 1 - Comparison between theory and observations

    International Nuclear Information System (INIS)

    Noriega-Crespo, A.; Bohm, K.H.; Raga, A.C.

    1989-01-01

    In this paper, it is shown that most of the spatial intensity distribution of 11 selected emission lines for Herbig-Haro 1 (including the forbidden S II emission lines at 6731 A and 4069 A, the forbidden O III line at 5007 A, and the forbidden O II line at 3727 A) can be explained by a bow shock with a shock velocity of about 150-200 km/sec at the stagnation point, and under the assumption that the gas entering the shock is fully preionized. The results are based on three spectrograms (with a total exposure time of 180 min) obtained consecutively. Specifically, the ratios of each of the forbidden lines to H-alpha were studied, which permitted a critical test of the model. The agreement between the theoretical predictions and the observations was found to be remarkable, considering the complex geometry that a bow shock could have. 38 refs

  16. Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration

    Energy Technology Data Exchange (ETDEWEB)

    Sheard, Michael A., E-mail: msheard@chla.usc.edu [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Ghent, Matthew V., E-mail: mattghent@gmail.com [Department of Pathology, Keck School of Medicine, University of Southern California, Health Sciences Campus, Los Angeles, CA 90089 (United States); Cabral, Daniel J., E-mail: dcabral14@gmail.com [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); Lee, Joanne C., E-mail: joannebarnhart@gmail.com [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); Khankaldyyan, Vazgen, E-mail: khangaldian@yahoo.com [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Ji, Lingyun, E-mail: lingyun.ji@med.usc.edu [Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Division of Hematology-Oncology, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Wu, Samuel Q., E-mail: swu@chla.usc.edu [Medical Genetics, Children' s Hospital Los Angeles, 4650 Sunset Blvd., Los Angeles, CA 90027 (United States); Kang, Min H., E-mail: min.kang@ttuhsc.edu [Cancer Center and Departments of Cell Biology & Biochemistry, Pharmacology & Neuroscience, Internal Medicine and Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (United States); and others

    2015-05-15

    Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. - Highlights: • Establishing new ALL cell lines in 5% oxygen resulted in higher glycolytic expression and function. • Establishing new ALL cell lines in 5% oxygen resulted in higher proliferation and lower cell death. • The divergent metabolic phenotypes selected in 5% and 20% oxygen are semi-permanent.

  17. Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration

    International Nuclear Information System (INIS)

    Sheard, Michael A.; Ghent, Matthew V.; Cabral, Daniel J.; Lee, Joanne C.; Khankaldyyan, Vazgen; Ji, Lingyun; Wu, Samuel Q.; Kang, Min H.

    2015-01-01

    Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. - Highlights: • Establishing new ALL cell lines in 5% oxygen resulted in higher glycolytic expression and function. • Establishing new ALL cell lines in 5% oxygen resulted in higher proliferation and lower cell death. • The divergent metabolic phenotypes selected in 5% and 20% oxygen are semi-permanent

  18. On the analysis of line profile variations: A statistical approach

    International Nuclear Information System (INIS)

    McCandliss, S.R.

    1988-01-01

    This study is concerned with the empirical characterization of the line profile variations (LPV), which occur in many of and Wolf-Rayet stars. The goal of the analysis is to gain insight into the physical mechanisms producing the variations. The analytic approach uses a statistical method to quantify the significance of the LPV and to identify those regions in the line profile which are undergoing statistically significant variations. Line positions and flux variations are then measured and subject to temporal and correlative analysis. Previous studies of LPV have for the most part been restricted to observations of a single line. Important information concerning the range and amplitude of the physical mechanisms involved can be obtained by simultaneously observing spectral features formed over a range of depths in the extended mass losing atmospheres of massive, luminous stars. Time series of a Wolf-Rayet and two of stars with nearly complete spectral coverage from 3940 angstrom to 6610 angstrom and with spectral resolution of R = 10,000 are analyzed here. These three stars exhibit a wide range of both spectral and temporal line profile variations. The HeII Pickering lines of HD 191765 show a monotonic increase in the peak rms variation amplitude with lines formed at progressively larger radii in the Wolf-Rayet star wind. Two times scales of variation have been identified in this star: a less than one day variation associated with small scale flickering in the peaks of the line profiles and a greater than one day variation associated with large scale asymmetric changes in the overall line profile shapes. However, no convincing period phenomena are evident at those periods which are well sampled in this time series

  19. ST radar observations of atmospheric waves over mountainous areas: a review

    Directory of Open Access Journals (Sweden)

    J. Röttger

    2000-07-01

    Full Text Available Lee and mountain waves are dominant dynamic processes in the atmosphere above mountain areas. ST VHF radars had been intensively used to investigate these wave processes. These studies are summarized in this work. After discussing features of long-period quasi-stationary lee waves, attention is drawn to the frequent occurrence of freely propagating waves of shorter periods, which seem to be more common and characteristic for wave processes generated over mountainous areas. Characteristics of these waves such as their relation to the topography and background winds, the possibility of trapping by and breaking in the tropopause region and their propagation into the stratosphere is investigated. These orographically produced waves transport energy and momentum into the troposphere and stratosphere, which is considered an important contribution to the kinetic energy of the lower atmosphere. The occurrence of inertia-gravity waves in the stratosphere had been confused with lee waves, which is discussed in conclusion. Finally further questions on mountain and lee waves are drawn up, which remain to be solved and where investigations with ST radars could play a fundamental role.Key words: Meteorology and atmospheric dynamics (Middle atmosphere dynamics; Waves and tides; Instruments and techniques

  20. A Search for Water in a Super-Earth Atmosphere: High-resolution Optical Spectroscopy of 55Cancri e

    Energy Technology Data Exchange (ETDEWEB)

    Esteves, Lisa J. [Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada); De Mooij, Ernst J. W.; Watson, Chris [Astrophysics Research Centre, School of Mathematics and Physics, Queens University, Belfast (United Kingdom); Jayawardhana, Ray [Physics and Astronomy, York University, Toronto, Ontario L3T 3R1 (Canada); De Kok, Remco, E-mail: esteves@astro.utoronto.ca, E-mail: ernst.demooij@dcu.ie, E-mail: c.a.watson@qub.ac.uk, E-mail: rayjay@yorku.ca, E-mail: r.j.de.kok@sron.nl [Leiden Observatory, Leiden University, Postbus 9513, 2300 RA, Leiden (Netherlands)

    2017-06-01

    We present the analysis of high-resolution optical spectra of four transits of 55Cnc e, a low-density super-Earth that orbits a nearby Sun-like star in under 18 hr. The inferred bulk density of the planet implies a substantial envelope, which, according to mass–radius relationships, could be either a low-mass extended or a high-mass compact atmosphere. Our observations investigate the latter scenario, with water as the dominant species. We take advantage of the Doppler cross-correlation technique, high-spectral resolution, and the large wavelength coverage of our observations to search for the signature of thousands of optical water absorption lines. Using our observations with HDS on the Subaru telescope and ESPaDOnS on the Canada–France–Hawaii Telescope, we are able to place a 3 σ lower limit of 10 g mol{sup −1} on the mean-molecular weight of 55Cnc e’s water-rich (volume mixing ratio >10%), optically thin atmosphere, which corresponds to an atmospheric scale-height of ∼80 km. Our study marks the first high-spectral resolution search for water in a super-Earth atmosphere, and demonstrates that it is possible to recover known water-vapor absorption signals in a nearby super-Earth atmosphere, using high-resolution transit spectroscopy with current ground-based instruments.

  1. HIGH METALLICITY AND NON-EQUILIBRIUM CHEMISTRY IN THE DAYSIDE ATMOSPHERE OF HOT-NEPTUNE GJ 436b

    International Nuclear Information System (INIS)

    Madhusudhan, N.; Seager, S.

    2011-01-01

    We present a detailed analysis of the dayside atmosphere of the hot-Neptune GJ 436b, based on recent Spitzer observations. We report statistical constraints on the thermal and chemical properties of the planetary atmosphere, study correlations between the various molecular species, and discuss scenarios of equilibrium and non-equilibrium chemistry in GJ 436b. We model the atmosphere with a one-dimensional line-by-line radiative transfer code with parameterized molecular abundances and temperature structure. We explore the model parameter space with 10 6 models, using a Markov chain Monte Carlo scheme. Our results encompass previous findings, indicating a paucity of methane, an overabundance of CO and CO 2 , and a slight underabundance of H 2 O, as compared to equilibrium chemistry with solar metallicity. The concentrations of the species are highly correlated. Our best-fit, and most plausible, constraints require a CH 4 mixing ratio of 10 -7 to10 -6 , with CO ≥10 -3 , CO 2 ∼10 -6 to10 -4 , and H 2 O ≤10 -4 ; higher CH 4 would require much higher CO and CO 2 . Based on calculations of equilibrium and non-equilibrium chemistry, we find that the observed abundances can potentially be explained by a combination of high metallicity (∼10x solar) and vertical mixing with K zz ∼ 10 6 -10 7 cm 2 s -1 . The inferred metallicity is enhanced over that of the host star which is known to be consistent with solar metallicity. Our constraints rule out a dayside thermal inversion in GJ 436b. We emphasize that the constraints reported in this work depend crucially on the observations in the two Spitzer channels at 3.6 μm and 4.5 μm. Future observations with warm Spitzer and with the James Webb Space Telescope will be extremely important to improve upon the present constraints on the abundances of carbon species in the dayside atmosphere of GJ 436b.

  2. Quantitation of triacylglycerols in edible oils by off-line comprehensive two-dimensional liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using a single column.

    Science.gov (United States)

    Wei, Fang; Hu, Na; Lv, Xin; Dong, Xu-Yan; Chen, Hong

    2015-07-24

    In this investigation, off-line comprehensive two-dimensional liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using a single column has been applied for the identification and quantification of triacylglycerols in edible oils. A novel mixed-mode phenyl-hexyl chromatographic column was employed in this off-line two-dimensional separation system. The phenyl-hexyl column combined the features of traditional C18 and silver-ion columns, which could provide hydrophobic interactions with triacylglycerols under acetonitrile conditions and can offer π-π interactions with triacylglycerols under methanol conditions. When compared with traditional off-line comprehensive two-dimensional liquid chromatography employing two different chromatographic columns (C18 and silver-ion column) and using elution solvents comprised of two phases (reversed-phase/normal-phase) for triacylglycerols separation, the novel off-line comprehensive two-dimensional liquid chromatography using a single column can be achieved by simply altering the mobile phase between acetonitrile and methanol, which exhibited a much higher selectivity for the separation of triacylglycerols with great efficiency and rapid speed. In addition, an approach based on the use of response factor with atmospheric pressure chemical ionization mass spectrometry has been developed for triacylglycerols quantification. Due to the differences between saturated and unsaturated acyl chains, the use of response factors significantly improves the quantitation of triacylglycerols. This two-dimensional liquid chromatography-mass spectrometry system was successfully applied for the profiling of triacylglycerols in soybean oils, peanut oils and lord oils. A total of 68 triacylglycerols including 40 triacylglycerols in soybean oils, 50 triacylglycerols in peanut oils and 44 triacylglycerols in lord oils have been identified and quantified. The liquid chromatography-mass spectrometry data were analyzed

  3. Improvement of Cooling Technology through Atmosphere Gas Management

    Energy Technology Data Exchange (ETDEWEB)

    Renard, Michel; Dosogne, Edgaar; Crutzen, Jean Pierre; Raick, Jean Mare [DREVER INTERNATIONAL S.A., Liege (Belgium); Ji, Ma Jia; Jun, Lv; Zhi, Ma Bing [SHOUGANG Cold Rolling Mill Headquarter, Beijin (China)

    2009-12-15

    The production of advanced high strength steels requires the improvement of cooling technology. The use of high cooling rates allows relatively low levels of expensive alloying additions to ensure sufficient hardenability. In classical annealing and hot-dip galvanizing lines a mixing station is used to provide atmosphere gas containing 3-5% hydrogen and 97-95% nitrogen in the various sections of the furnace, including the rapid cooling section. Heat exchange enhancement in this cooling section can be insured by the increased hydrogen concentration. Driver international developed a patented improvement of cooling technology based on the following features: pure hydrogen gas is injected only in the rapid cooling section whereas the different sections of the furnace are supplied with pure nitrogen gas: the control of flows through atmosphere gas management allows to get high hydrogen concentration in cooling section and low hydrogen content in the other furnace zones. This cooling technology development insures higher cooling rates without additional expensive hydrogen gas consumption and without the use of complex sealing equipment between zones. In addition reduction in electrical energy consumption is obtained. This atmosphere control development can be combined with geometrical design improvements in order to get optimised cooling technology providing high cooling rates as well as reduced strip vibration amplitudes. Extensive validation of theoretical research has been conducted on industrial lines. New lines as well as existing lines, with limited modifications, can be equipped with this new development. Up to now this technology has successfully been implemented on 6 existing and 7 new lines in Europe and Asia.

  4. A global perspective on atmospheric blocking using GPS radio occultation – one decade of observations

    Directory of Open Access Journals (Sweden)

    L. Brunner

    2017-12-01

    Full Text Available Atmospheric blocking represents a weather pattern where a stationary high-pressure system weakens or reverses the climatological westerly flow at mid-latitudes for up to several weeks. It is closely connected to strong anomalies in key atmospheric variables such as geopotential height, temperature, and humidity. Here we provide, for the first time, a comprehensive, global perspective on atmospheric blocking and related impacts by using an observation-based data set from Global Positioning System (GPS radio occultation (RO from 2006 to 2016. The main blocking regions in both hemispheres and seasonal variations are found to be represented well in RO data. The effect of blocking on vertically resolved temperature and humidity anomalies in the troposphere and lower stratosphere is investigated for blocking regions in the Northern and Southern hemispheres, respectively. We find a statistically significant correlation of blocking with positive temperature anomalies, exceeding 3 K in the troposphere, and a reversal above the tropopause with negative temperature anomalies below −3 K in the lower stratosphere. Specific humidity is positively correlated with temperature throughout the troposphere with larger anomalies revealed in the Southern Hemisphere. At the eastern and equatorward side of the investigated blocking regions, a band of tropospheric cold anomalies reveals advection of cold air by anticyclonic motion around blocking highs, which is less distinct in the Southern Hemisphere due to stronger zonal flow. We find GPS RO to be a promising new data set for blocking research that gives insight into the vertical atmospheric structure, especially in light of the expected increase in data coverage that future missions will provide.

  5. Submillimeter and millimeter observations of solar system objects

    International Nuclear Information System (INIS)

    Muhleman, D.O.

    1988-01-01

    Planetary atmospheres and satellite surfaces are observed with the three element array at Caltech's Owens Valley Radio Observatory, Caltech's submillimeter telescope on Mauna Kea and at the 12-meter telescope at Kitt Peak. Researchers are primarily interested in spectroscopy of the atmospheres of Venus, Mars and Titan and the continuum structure of Saturn Rings, Galilean satellites, Neptune and Uranus. During the last year researchers completed a supersynthesis of the Saturn system at 2.8 mm with spatial resolution of 3 arc sec. They just completed a 4-confuguration synthesis of Venus in the CO absorption line. They hope to recover the wind patterns in the altitude range from 60 to 100 km where winds have never been measured. Two important questions are being investigated: (1) how high in the Venus atmosphere do 4-day winds extend, and (2) can we produce experiment proof (or disproof) of the subsolar-to-anti-solar flow (Dickenson winds) predicted by general circulation models

  6. The state of greenhouse gases in the atmosphere using global observations through 2013

    Science.gov (United States)

    Tarasova, Oksana; Koide, Hiroshi; Dlugokencky, Ed; Montzka, Stephen A.; Keeling, Ralph; Tanhua, Toste; Lorenzoni, Laura

    2015-04-01

    We present results from the tenth annual Greenhouse Gas Bulletin (http://www.wmo.int/pages/prog/arep/gaw/ ghg/GHGbulletin.html) of the World Meteorological Organization (WMO). The results are based on research and observations performed by laboratories contributing to the WMO Global Atmosphere Watch (GAW) Programme (www.wmo.int/gaw). The Bulletin presents results of global analyses of observational data collected according to GAW recommended practices and submitted to the World Data Center for Greenhouse Gases (WDCGG), and for the first time, it includes a summary of ocean acidification. Bulletins are prepared by the WMO/GAW Scientific Advisory Group for Greenhouse Gases (http://www.wmo.int/pages/prog/arep/gaw/ScientificAdvisoryGroups.html) in collaboration with WDCGG. The summary of ocean acidification and trends in ocean pCO2 was jointly produced by the International Ocean Carbon Coordination Project (IOCCP) of the Intergovernmental Oceanographic Commission of UNESCO (IOC-UNESCO), the Scientific Committee on Oceanic Research (SCOR), and the Ocean Acidification International Coordination Centre (OA-ICC) of the International Atomic Energy Agency (IAEA). The tenth Bulletin included a special edition published prior to the United Nations Climate Summit in September 2014. The scope of this edition was to demonstrate the level of emission reduction necessary to stabilize radiative forcing by long-lived greenhouse gases. It shows in particular that a reduction in radiative forcing from its current level (2.92 W m-2 in 2013) requires significant reductions in anthropogenic emissions of all major greenhouse gases. Observations used for global analysis are collected at more than 100 marine and terrestrial sites worldwide for CO2 and CH4 and at a smaller number of sites for other greenhouse gases. Globally averaged dry-air mole fractions of carbon dioxide, methane and nitrous oxide derived from this network reached new highs in 2013, with CO2 at 396.0 ± 0.1 ppm, CH4 at

  7. Neutral molecular cluster formation of sulfuric acid–dimethylamine observed in real time under atmospheric conditions

    CERN Document Server

    Kürten, Andreas; Simon, Mario; Sipilä, Mikko; Sarnela, Nina; Junninen, Heikki; Adamov, Alexey; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Donahue, Neil M; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Hutterli, Manuel; Kangasluoma, Juha; Kirkby, Jasper; Laaksonen, Ari; Lehtipalo, Katrianne; Leiminger, Markus; Makhmutov, Vladimir; Mathot, Serge; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud P; Riccobono, Francesco; Rissanen, Matti P; Rondo, Linda; Schobesberger, Siegfried; Seinfeld, John H; Steiner, Gerhard; Tomé, António; Tröstl, Jasmin; Winkler, Paul M; Williamson, Christina; Wimmer, Daniela; Ye, Penglin; Baltensperger, Urs; Carslaw, Kenneth S; Kulmala, Markku; Worsnop, Douglas R; Curtius, Joachim

    2014-01-01

    For atmospheric sulfuric acid (SA) concentrations the presence of dimethylamine (DMA) at mixing ratios of several parts per trillion by volume can explain observed boundary layer new particle formation rates. However, the concentration and molecular composition of the neutral (uncharged) clusters have not been reported so far due to the lack of suitable instrumentation. Here we report on experiments from the Cosmics Leaving Outdoor Droplets chamber at the European Organization for Nuclear Research revealing the formation of neutral particles containing up to 14 SA and 16 DMA molecules, corresponding to a mobility diameter of about 2 nm, under atmospherically relevant conditions. These measurements bridge the gap between the molecular and particle perspectives of nucleation, revealing the fundamental processes involved in particle formation and growth. The neutral clusters are found to form at or close to the kinetic limit where particle formation is limited only by the collision rate of SA molecules. Even tho...

  8. Bombs and Flares at the Surface and Lower Atmosphere of the Sun

    Energy Technology Data Exchange (ETDEWEB)

    Hansteen, V. H.; Pereira, T. M. D.; Carlsson, M.; Van der Voort, L. Rouppe [Institute of Theoretical Astrophysics, University of Oslo, Norway, PB 1029 Blindern, NO-0315 Oslo (Norway); Archontis, V. [School of Mathematics and Statistics, St. Andrews University, St. Andrews, KY169SS (United Kingdom); Leenaarts, J. [Institute for Solar Physics, Dept. of Astronomy, Stockholm University, Roslagstullbacken 21 SE-10691 Stockholm (Sweden)

    2017-04-10

    A spectacular manifestation of solar activity is the appearance of transient brightenings in the far wings of the H α line, known as Ellerman bombs (EBs). Recent observations obtained by the Interface Region Imaging Spectrograph have revealed another type of plasma “bombs” (UV bursts) with high temperatures of perhaps up to 8 × 10{sup 4} K within the cooler lower solar atmosphere. Realistic numerical modeling showing such events is needed to explain their nature. Here, we report on 3D radiative magnetohydrodynamic simulations of magnetic flux emergence in the solar atmosphere. We find that ubiquitous reconnection between emerging bipolar magnetic fields can trigger EBs in the photosphere, UV bursts in the mid/low chromosphere and small (nano-/micro-) flares (10{sup 6} K) in the upper chromosphere. These results provide new insights into the emergence and build up of the coronal magnetic field and the dynamics and heating of the solar surface and lower atmosphere.

  9. MISTiC Winds, a Micro-Satellite Constellation Approach to High Resolution Observations of the Atmosphere using Infrared Sounding and 3D Winds Measurements

    Science.gov (United States)

    Maschhoff, K. R.; Polizotti, J. J.; Aumann, H. H.; Susskind, J.

    2017-12-01

    MISTiCTM Winds is an approach to improve short-term weather forecasting based on a miniature high resolution, wide field, thermal emission spectrometry instrument that will provide global tropospheric vertical profiles of atmospheric temperature and humidity at high (3-4 km) horizontal and vertical ( 1 km) spatial resolution. MISTiC's extraordinarily small size, payload mass of less than 15 kg, and minimal cooling requirements can be accommodated aboard a ESPA-Class (50 kg) micro-satellite. Low fabrication and launch costs enable a LEO sun-synchronous sounding constellation that would provide frequent IR vertical profiles and vertically resolved atmospheric motion vector wind observations in the troposphere. These observations are highly complementary to present and emerging environmental observing systems, and would provide a combination of high vertical and horizontal resolution not provided by any other environmental observing system currently in operation. The spectral measurements that would be provided by MISTiC Winds are similar to those of NASA's Atmospheric Infrared Sounder. These new observations, when assimilated into high resolution numerical weather models, would revolutionize short-term and severe weather forecasting, save lives, and support key economic decisions in the energy, air transport, and agriculture arenas-at much lower cost than providing these observations from geostationary orbit. In addition, this observation capability would be a critical tool for the study of transport processes for water vapor, clouds, pollution, and aerosols. In this third year of a NASA Instrument incubator program, the compact infrared spectrometer has been integrated into an airborne version of the instrument for high-altitude flights on a NASA ER2. The purpose of these airborne tests is to examine the potential for improved capabilities for tracking atmospheric motion-vector wind tracer features, and determining their height using hyper-spectral sounding and

  10. Observational Characterization of the Downward Atmospheric Longwave Radiation at the Surface in the City of São Paulo

    NARCIS (Netherlands)

    Wilde Barbaro, E.; Oliveira, A.P.; Soares, J.; Codato, G.; Ferreira, M.J.; Mlakar, P.; Boznar, M.Z.; Escobedo, J.

    2010-01-01

    This work describes the seasonal and diurnal variations of downward longwave atmospheric irradiance (LW) at the surface in São Paulo, Brazil, using 5-min-averaged values of LW, air temperature, relative humidity, and solar radiation observed continuously and simultaneously from 1997 to 2006 on a

  11. Radio and television interference caused by corona discharges from high-voltage transmission lines

    International Nuclear Information System (INIS)

    Sarmadi, M.

    1996-01-01

    Increase in power utility loads in industrialized countries, as well as developing countries, demands a higher level of transmission line voltage. Radio interference (RI) problems have been determined to be a limiting factor in selecting the size of transmission line conductors. Transmission line noise is primarily caused by corona discharges in the immediate vicinity of the conductor. It has been observed that discharges occur during both half-cycles of the applied voltage, but positive corona is usually predominant at AM radio frequencies range with practical high-voltage and extra high-voltage transmission lines. The corona radio noise effect is highly dependent upon the presence of particles on the surface of the conductor and the increase of the electrical gradient beyond the breakdown value of the air. Therefore, corona radio noise varies significantly with the weather and atmospheric conditions and generally increases by 10 to 30 dB in foul weather

  12. New observations and models of circumstellar CO line emission of AGB stars in the Herschel SUCCESS programme

    Science.gov (United States)

    Danilovich, T.; Teyssier, D.; Justtanont, K.; Olofsson, H.; Cerrigone, L.; Bujarrabal, V.; Alcolea, J.; Cernicharo, J.; Castro-Carrizo, A.; García-Lario, P.; Marston, A.

    2015-09-01

    Context. Asymptotic giant branch (AGB) stars are in one of the latest evolutionary stages of low to intermediate-mass stars. Their vigorous mass loss has a significant effect on the stellar evolution, and is a significant source of heavy elements and dust grains for the interstellar medium. The mass-loss rate can be well traced by carbon monoxide (CO) line emission. Aims: We present new Herschel/HIFI and IRAM 30 m telescope CO line data for a sample of 53 galactic AGB stars. The lines cover a fairly large range of excitation energy from the J = 1 → 0 line to the J = 9 → 8 line, and even the J = 14 → 13 line in a few cases. We perform radiative transfer modelling for 38 of these sources to estimate their mass-loss rates. Methods: We used a radiative transfer code based on the Monte Carlo method to model the CO line emission. We assume spherically symmetric circumstellar envelopes that are formed by a constant mass-loss rate through a smoothly accelerating wind. Results: We find models that are consistent across a broad range of CO lines for most of the stars in our sample, i.e., a large number of the circumstellar envelopes can be described with a constant mass-loss rate. We also find that an accelerating wind is required to fit, in particular, the higher-J lines and that a velocity law will have a significant effect on the model line intensities. The results cover a wide range of mass-loss rates (~10-8 to 2 × 10-5 M⊙ yr-1) and gas expansion velocities (2 to 21.5 km s-1) , and include M-, S-, and C-type AGB stars. Our results generally agree with those of earlier studies, although we tend to find slightly lower mass-loss rates by about 40%, on average. We also present "bonus" lines detected during our CO observations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Based on observations carried out with the IRAM 30 m Telescope. IRAM is

  13. Accident consequence assessments with different atmospheric dispersion models

    International Nuclear Information System (INIS)

    Panitz, H.J.

    1989-11-01

    An essential aim of the improvements of the new program system UFOMOD for Accident Consequence Assessments (ACAs) was to substitute the straight-line Gaussian plume model conventionally used in ACA models by more realistic atmospheric dispersion models. To identify improved models which can be applied in ACA codes and to quantify the implications of different dispersion models on the results of an ACA, probabilistic comparative calculations with different atmospheric dispersion models have been performed. The study showed that there are trajectory models available which can be applied in ACAs and that they provide more realistic results of ACAs than straight-line Gaussian models. This led to a completely novel concept of atmospheric dispersion modelling in which two different distance ranges of validity are distinguished: the near range of some ten kilometres distance and the adjacent far range which are assigned to respective trajectory models. (orig.) [de

  14. Unexpected temporal evolution of atomic spectral lines of aluminum in a laser induced breakdown spectroscopy experiment

    International Nuclear Information System (INIS)

    Saad, Rawad; L'Hermite, Daniel; Bousquet, Bruno

    2014-01-01

    The temporal evolution of the laser induced breakdown (LIBS) signal of a pure aluminum sample was studied under nitrogen and air atmospheres. In addition to the usual decrease of signal due to plasma cooling, unexpected temporal evolutions were observed for a spectral lines of aluminum, which revealed the existence of collisional energy transfer effects. Furthermore, molecular bands of AlN and AlO were observed in the LIBS spectra, indicating recombination of aluminum with the ambient gas. Within the experimental conditions reported in this study, both collisional energy transfer and recombination processes occurred around 1.5 μs after the laser shot. This highlights the possible influence of collisional and chemical effects inside the plasma that can play a role on LIBS signals. - Highlights: • Persistence of two Al I lines related to the 61,844 cm −1 energy level only under nitrogen atmosphere. • Collisional energy transfer effect exists between aluminum and nitrogen. • Observation of molecular band of AlN (under nitrogen) and AlO (under air) after a delay time of 1.5 µs. • 20% of oxygen in air is sufficient to annihilate both the collisional energy transfer effect and the AlN molecular formation

  15. A New Metric for Land-Atmosphere Coupling Strength: Applications on Observations and Modeling

    Science.gov (United States)

    Tang, Q.; Xie, S.; Zhang, Y.; Phillips, T. J.; Santanello, J. A., Jr.; Cook, D. R.; Riihimaki, L.; Gaustad, K.

    2017-12-01

    A new metric is proposed to quantify the land-atmosphere (LA) coupling strength and is elaborated by correlating the surface evaporative fraction and impacting land and atmosphere variables (e.g., soil moisture, vegetation, and radiation). Based upon multiple linear regression, this approach simultaneously considers multiple factors and thus represents complex LA coupling mechanisms better than existing single variable metrics. The standardized regression coefficients quantify the relative contributions from individual drivers in a consistent manner, avoiding the potential inconsistency in relative influence of conventional metrics. Moreover, the unique expendable feature of the new method allows us to verify and explore potentially important coupling mechanisms. Our observation-based application of the new metric shows moderate coupling with large spatial variations at the U.S. Southern Great Plains. The relative importance of soil moisture vs. vegetation varies by location. We also show that LA coupling strength is generally underestimated by single variable methods due to their incompleteness. We also apply this new metric to evaluate the representation of LA coupling in the Accelerated Climate Modeling for Energy (ACME) V1 Contiguous United States (CONUS) regionally refined model (RRM). This work is performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-734201

  16. Atmospheres of Brown Dwarfs

    Science.gov (United States)

    Wang, Ruoyan; Seay, Christopher

    2018-01-01

    We construct a grid of brown dwarf model atmospheres spanning a wide range of atmospheric metallicity (0.3x ≤ met ≤ 100x), C/O ratios (0.25x ≤ C/O ≤ 2.5x), and cloud properties, encompassing atmospheres of effective temperatures 200 ≤ Teff ≤ 2400 K and gravities 2.5 ≤ log g ≤ 5.5. We produce the expected temperature-pressure profiles and emergent spectra from an atmosphere in radiative-convective equilibrium. We can then compare our predicted spectra to observations and retrieval results to aid in their predictions and influence future missions and telescopic observations. In our poster we briefly describe our modeling methodology and present our progress on model grid construction, spanning solar and subsolar C/O and metallicity.

  17. Discovery of Scattering Polarization in the Hydrogen Ly α Line of the Solar Disk Radiation

    International Nuclear Information System (INIS)

    Kano, R.; Narukage, N.; Ishikawa, R.; Bando, T.; Katsukawa, Y.; Kubo, M.; Giono, G.; Hara, H.; Suematsu, Y.; Bueno, J. Trujillo; Winebarger, A.; Kobayashi, K.; Auchère, F.; Ishikawa, S.; Shimizu, T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.; Goto, M.; Belluzzi, L.

    2017-01-01

    There is a thin transition region (TR) in the solar atmosphere where the temperature rises from 10,000 K in the chromosphere to millions of degrees in the corona. Little is known about the mechanisms that dominate this enigmatic region other than the magnetic field plays a key role. The magnetism of the TR can only be detected by polarimetric measurements of a few ultraviolet (UV) spectral lines, the Ly α line of neutral hydrogen at 121.6 nm (the strongest line of the solar UV spectrum) being of particular interest given its sensitivity to the Hanle effect (the magnetic-field-induced modification of the scattering line polarization). We report the discovery of linear polarization produced by scattering processes in the Ly α line, obtained with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) rocket experiment. The Stokes profiles observed by CLASP in quiet regions of the solar disk show that the Q / I and U / I linear polarization signals are of the order of 0.1% in the line core and up to a few percent in the nearby wings, and that both have conspicuous spatial variations with scales of ∼10 arcsec. These observations help constrain theoretical models of the chromosphere–corona TR and extrapolations of the magnetic field from photospheric magnetograms. In fact, the observed spatial variation from disk to limb of polarization at the line core and wings already challenge the predictions from three-dimensional magnetohydrodynamical models of the upper solar chromosphere.

  18. Discovery of Scattering Polarization in the Hydrogen Ly α Line of the Solar Disk Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kano, R.; Narukage, N.; Ishikawa, R.; Bando, T.; Katsukawa, Y.; Kubo, M.; Giono, G.; Hara, H.; Suematsu, Y. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Bueno, J. Trujillo [Instituto de Astrofísica de Canarias, La Laguna, Tenerife, E-38205 (Spain); Winebarger, A.; Kobayashi, K. [Marshall Space Flight Center, National Aeronautics and Space Administration (NASA), Huntsville, AL 35812 (United States); Auchère, F. [Institut d’Astrophysique Spatiale, Université Paris Sud, Batiment 121, F-91405 Orsay (France); Ishikawa, S.; Shimizu, T.; Sakao, T.; Tsuneta, S. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Ichimoto, K. [Hida Observatory, Kyoto University, Takayama, Gifu 506-1314 (Japan); Goto, M. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Belluzzi, L., E-mail: ryouhei.kano@nao.ac.jp [Istituto Ricerche Solari Locarno, CH-6605 Locarno Monti (Switzerland); and others

    2017-04-10

    There is a thin transition region (TR) in the solar atmosphere where the temperature rises from 10,000 K in the chromosphere to millions of degrees in the corona. Little is known about the mechanisms that dominate this enigmatic region other than the magnetic field plays a key role. The magnetism of the TR can only be detected by polarimetric measurements of a few ultraviolet (UV) spectral lines, the Ly α line of neutral hydrogen at 121.6 nm (the strongest line of the solar UV spectrum) being of particular interest given its sensitivity to the Hanle effect (the magnetic-field-induced modification of the scattering line polarization). We report the discovery of linear polarization produced by scattering processes in the Ly α line, obtained with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) rocket experiment. The Stokes profiles observed by CLASP in quiet regions of the solar disk show that the Q / I and U / I linear polarization signals are of the order of 0.1% in the line core and up to a few percent in the nearby wings, and that both have conspicuous spatial variations with scales of ∼10 arcsec. These observations help constrain theoretical models of the chromosphere–corona TR and extrapolations of the magnetic field from photospheric magnetograms. In fact, the observed spatial variation from disk to limb of polarization at the line core and wings already challenge the predictions from three-dimensional magnetohydrodynamical models of the upper solar chromosphere.

  19. Evolution and dynamics of orphan penumbrae in the solar photosphere: Analysis from multi-instrument observations

    International Nuclear Information System (INIS)

    Zuccarello, Francesca; Guglielmino, Salvo L.; Romano, Paolo

    2014-01-01

    We investigate the dynamics and magnetic properties of orphan penumbrae observed in the solar photosphere to understand the formation process of such structures. We observed two orphan penumbrae in active region NOAA 11089 during a coordinated observing campaign carried out in 2010 July, involving the Hinode/Solar Optical Telescope (SOT) and Dutch Open Telescope (DOT), benefiting also from continuous observations acquired by the SDO satellite. We follow their evolution during about three days. The two structures form in different ways: one seems to break off the penumbra of a nearby sunspot, the other is formed through the emergence of new flux. Then they fragment while evolving. The SDO Helioseismic and Magnetic Imager measurements indicate the presence of strong line-of-sight motions in the regions occupied by these orphan penumbrae, lasting for several hours and decreasing with time. This is confirmed by SOT spectro-polarimetric measurements of the Fe I 630.2 nm pair. The latter also show that Stokes parameters exhibit significant asymmetries in the orphan penumbral regions, typical of an uncombed filamentary structure. The orphan penumbrae lie above polarity inversion lines, where peculiar plasma motions take place with velocities larger than ±3 km s –1 . The vector magnetic field in these regions is highly inclined, with the average magnetic field strength decreasing with time. The DOT observations in the Hα line and SDO Atmospheric Imaging Assembly measurements in the He II 30.4 nm line indicate that there is no counterpart for the orphan penumbrae at midchromospheric heights or above. Our findings suggest that in at least one of the features investigated the emerging flux may be trapped in the low atmospheric layers by the overlying pre-existing fields, forming these filamentary structures.

  20. Evolution and dynamics of orphan penumbrae in the solar photosphere: Analysis from multi-instrument observations

    Energy Technology Data Exchange (ETDEWEB)

    Zuccarello, Francesca [Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 78, I-95123 Catania (Italy); Guglielmino, Salvo L.; Romano, Paolo, E-mail: fzu@oact.inaf.it [INAF-Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania (Italy)

    2014-05-20

    We investigate the dynamics and magnetic properties of orphan penumbrae observed in the solar photosphere to understand the formation process of such structures. We observed two orphan penumbrae in active region NOAA 11089 during a coordinated observing campaign carried out in 2010 July, involving the Hinode/Solar Optical Telescope (SOT) and Dutch Open Telescope (DOT), benefiting also from continuous observations acquired by the SDO satellite. We follow their evolution during about three days. The two structures form in different ways: one seems to break off the penumbra of a nearby sunspot, the other is formed through the emergence of new flux. Then they fragment while evolving. The SDO Helioseismic and Magnetic Imager measurements indicate the presence of strong line-of-sight motions in the regions occupied by these orphan penumbrae, lasting for several hours and decreasing with time. This is confirmed by SOT spectro-polarimetric measurements of the Fe I 630.2 nm pair. The latter also show that Stokes parameters exhibit significant asymmetries in the orphan penumbral regions, typical of an uncombed filamentary structure. The orphan penumbrae lie above polarity inversion lines, where peculiar plasma motions take place with velocities larger than ±3 km s{sup –1}. The vector magnetic field in these regions is highly inclined, with the average magnetic field strength decreasing with time. The DOT observations in the Hα line and SDO Atmospheric Imaging Assembly measurements in the He II 30.4 nm line indicate that there is no counterpart for the orphan penumbrae at midchromospheric heights or above. Our findings suggest that in at least one of the features investigated the emerging flux may be trapped in the low atmospheric layers by the overlying pre-existing fields, forming these filamentary structures.

  1. Evolution and Dynamics of Orphan Penumbrae in the Solar Photosphere: Analysis from Multi-instrument Observations

    Science.gov (United States)

    Zuccarello, Francesca; Guglielmino, Salvo L.; Romano, Paolo

    2014-05-01

    We investigate the dynamics and magnetic properties of orphan penumbrae observed in the solar photosphere to understand the formation process of such structures. We observed two orphan penumbrae in active region NOAA 11089 during a coordinated observing campaign carried out in 2010 July, involving the Hinode/Solar Optical Telescope (SOT) and Dutch Open Telescope (DOT), benefiting also from continuous observations acquired by the SDO satellite. We follow their evolution during about three days. The two structures form in different ways: one seems to break off the penumbra of a nearby sunspot, the other is formed through the emergence of new flux. Then they fragment while evolving. The SDO Helioseismic and Magnetic Imager measurements indicate the presence of strong line-of-sight motions in the regions occupied by these orphan penumbrae, lasting for several hours and decreasing with time. This is confirmed by SOT spectro-polarimetric measurements of the Fe I 630.2 nm pair. The latter also show that Stokes parameters exhibit significant asymmetries in the orphan penumbral regions, typical of an uncombed filamentary structure. The orphan penumbrae lie above polarity inversion lines, where peculiar plasma motions take place with velocities larger than ±3 km s-1. The vector magnetic field in these regions is highly inclined, with the average magnetic field strength decreasing with time. The DOT observations in the Hα line and SDO Atmospheric Imaging Assembly measurements in the He II 30.4 nm line indicate that there is no counterpart for the orphan penumbrae at midchromospheric heights or above. Our findings suggest that in at least one of the features investigated the emerging flux may be trapped in the low atmospheric layers by the overlying pre-existing fields, forming these filamentary structures.

  2. A long XMM-Newton observation of an extreme narrow-line Seyfert 1: PG 1244+026

    NARCIS (Netherlands)

    Jin, C.; Done, C.; Middleton, M.; Ward, M.

    2013-01-01

    We explore the origin of the strong soft X-ray excess in narrow-line Seyfert 1 galaxies using spectral-timing information from a 120 ks XMM-Newton observation of PG 1244+026. Spectral fitting alone cannot distinguish between a true additional soft X-ray continuum component and strongly

  3. Columbia River ESI: FISHL (Fish Lines)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for anadromous fish species in Columbia River. Vector lines in this data set represent locations of...

  4. Western Alaska ESI: FISHL (Fish Lines)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for anadromous fish species in Western Alaska. Vector lines in this data set represent species occurrences...

  5. The Formation of IRIS Diagnostics. IX. The Formation of the C i 135.58 NM Line in the Solar Atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Hsiao-Hsuan; Carlsson, Mats; Leenaarts, Jorrit, E-mail: mats.carlsson@astro.uio.no, E-mail: jorrit.leenaarts@astro.su.se [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway)

    2017-09-01

    The C i 135.58 nm line is located in the wavelength range of NASA’s Interface Region Imaging Spectrograph ( IRIS ) small explorer mission. We study the formation and diagnostic potential of this line by means of non local-thermodynamic-equilibrium modeling, employing both 1D and 3D radiation-magnetohydrodynamic models. The C i/C ii ionization balance is strongly influenced by photoionization by Ly α emission. The emission in the C i 135.58 nm line is dominated by a recombination cascade and the line forming region is optically thick. The Doppler shift of the line correlates strongly with the vertical velocity in its line forming region, which is typically located at 1.5 Mm height. With IRIS , the C i 135.58 nm line is usually observed together with the O i 135.56 nm line, and from the Doppler shift of both lines, we obtain the velocity difference between the line forming regions of the two lines. From the ratio of the C i/O i line core intensity, we can determine the distance between the C i and the O i forming layers. Combined with the velocity difference, the velocity gradient at mid-chromospheric heights can be derived. The C i/O i total intensity line ratio is correlated with the inverse of the electron density in the mid-chromosphere. We conclude that the C i 135.58 nm line is an excellent probe of the middle chromosphere by itself, and together with the O i 135.56 nm line the two lines provide even more information, which complements other powerful chromospheric diagnostics of IRIS such as the Mg ii h and k lines and the C ii lines around 133.5 nm.

  6. Void growth suppression by dislocation impurity atmospheres

    International Nuclear Information System (INIS)

    Weertman, J.; Green, W.V.

    1976-01-01

    A detailed calculation is given of the effect of an impurity atmosphere on void growth under irradiation damage conditions. Norris has proposed that such an atmosphere can suppress void growth. The hydrostatic stress field of a dislocation that is surrounded by an impurity atmosphere was found and used to calculate the change in the effective radius of a dislocation line as a sink for interstitials and vacancies. The calculation of the impurity concentration in a Cottrell cloud takes into account the change in hydrostatic pressure produced by the presence of the cloud itself. It is found that void growth is eliminated whenever dislocations are surrounded by a condensed atmosphere of either oversized substitutional impurity atoms or interstitial impurity atoms. A condensed atmosphere will form whenever the average impurity concentration is larger than a critical concentration

  7. A retrieved upper limit of CS in Neptune's atmosphere

    Science.gov (United States)

    Iino, T.; Mizuno, A.; Nagahama, T.; Hirota, A.; Nakajima, T.

    2012-12-01

    We present our new result of CS(J=7-6), CO(J=3-2) observations of Neptune's atmosphere carried out with 10-m ASTE sub-mm waveband telescope on August 2010. As a result, while CS line was not detected with 6.4 mK 1-sigma r.m.s. noise level, CO line was detected as 282 mK with 9.7 mK noise level in antenna temperature scale. All of the observations were carried out with 512 MHz bandwidth and 500 kHz resolution, the total integration time for CS and CO were 23 m 40 s and 11 m 00 s, respectively. Abundances have been obtained from the comparison between the intensity and the synthesis spectra modeled by plane parallel 1-D radiative transfer code assuming various mixing ratio of each gas. The retrieved upper limit of CS mixing ratio was 0.03 ppb throughout tropopause to stratosphere. CO mixing ratio have been retrieved 1.0 ppm with errors +0.3 and -0.2 ppm, and the result was consistent with previous observation [1]. The origin of abundant CO in Neptune's atmosphere has been long discussed since its mixing ratio is 30 - 500 times higher than the value of other gas giants [2][3][4]. Assuming that all of CO is produced by thermochemical equilibrium process in deep interior of Neptune, required O/H value in interior is 440 times higher than the solar value [5]. For this reason, it is claimed that the external CO supply source, such as the impact of comet or asteroid, is also the possible candidates of the origin of CO along with the internal supply source [6]. In this observation, we searched the remnant gas of cometary impact in Neptune's atmosphere. Along with CO and HCN, CS could be one of the possible candidate of the remnant gas of cometary impact since CS was largely produced after the impact of comet SL/9 on Jupiter while many other major sulfur compounds have not been detected. Actually, derived L37-40. [7]Moreno et al., 2003. Planetary and Space Sciences 51, 591-611 [8]Zahnle et al.,1995. GRL 22, 1593-1596 [9]Feuchtgruber et al., 1999. Proceeding of the conference

  8. Atmospheric benzene observations from oil and gas production in the Denver-Julesburg Basin in July and August 2014

    Science.gov (United States)

    Halliday, Hannah S.; Thompson, Anne M.; Wisthaler, Armin; Blake, Donald R.; Hornbrook, Rebecca S.; Mikoviny, Tomas; Müller, Markus; Eichler, Philipp; Apel, Eric C.; Hills, Alan J.

    2016-09-01

    High time resolution measurements of volatile organic compounds (VOCs) were collected using a proton-transfer-reaction quadrupole mass spectrometry (PTR-QMS) instrument at the Platteville Atmospheric Observatory (PAO) in Colorado to investigate how oil and natural gas (O&NG) development impacts air quality within the Wattenburg Gas Field (WGF) in the Denver-Julesburg Basin. The measurements were carried out in July and August 2014 as part of NASA's "Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality" (DISCOVER-AQ) field campaign. The PTR-QMS data were supported by pressurized whole air canister samples and airborne vertical and horizontal surveys of VOCs. Unexpectedly high benzene mixing ratios were observed at PAO at ground level (mean benzene = 0.53 ppbv, maximum benzene = 29.3 ppbv), primarily at night (mean nighttime benzene = 0.73 ppbv). These high benzene levels were associated with southwesterly winds. The airborne measurements indicate that benzene originated from within the WGF, and typical source signatures detected in the canister samples implicate emissions from O&NG activities rather than urban vehicular emissions as primary benzene source. This conclusion is backed by a regional toluene-to-benzene ratio analysis which associated southerly flow with vehicular emissions from the Denver area. Weak benzene-to-CO correlations confirmed that traffic emissions were not responsible for the observed high benzene levels. Previous measurements at the Boulder Atmospheric Observatory (BAO) and our data obtained at PAO allow us to locate the source of benzene enhancements between the two atmospheric observatories. Fugitive emissions of benzene from O&NG operations in the Platteville area are discussed as the most likely causes of enhanced benzene levels at PAO.

  9. Observations of far-infrared line profiles in the Orion-KL region

    International Nuclear Information System (INIS)

    Crawford, M.K.; Lugten, J.B.; Fitelson, W.; Genzel, R.; Melnick, G.; Harvard-Smithsonian Center for Astrophysics, Cambridge, MA)

    1986-01-01

    Measurements of several far-infrared emission line profiles in the Orion-KL region are reported. The emission from the CO, OH, and forbidden O I emission lines toward the BN-KL and H2 peak 1 positions probably comes from dense, hot molecular gas in the Orion-KL shock. The CO and forbidden O I lines have similar profiles, suggesting that the high-velocity forbidden O I emission also arises in magnetohydrodynamic cloud shocks. The velocity centroids of the lines are somewhat blueshifted. The far-infrared data thus support the interpretation that the blue asymmetry of the H2 2 micron lines is not mainly due to differential dust extinction, but rather to the kinematics and geometry of the shocked gas in the Orion-KL outflow. The forbidden O I and CO lines, however, have significantly less extreme blueshifted emission than the H2 lines. Both the forbidden O I 63 micron and forbidden C II 158 micron lines have features strongly supporting a common origin near the surface of the Orion molecular cloud. 28 references

  10. Instrument Design of the Large Aperture Solar UV Visible and IR Observing Telescope (SUVIT) for the SOLAR-C Mission

    Science.gov (United States)

    Suematsu, Y.; Katsukawa, Y.; Shimizu, T.; Ichimoto, K.; Takeyama, N.

    2012-12-01

    We present an instrumental design of one major solar observation payload planned for the SOLAR-C mission: the Solar Ultra-violet Visible and near IR observing Telescope (SUVIT). The SUVIT is designed to provide high-angular-resolution investigation of the lower solar atmosphere, from the photosphere to the uppermost chromosphere, with enhanced spectroscopic and spectro-polarimetric capability in wide wavelength regions from 280 nm (Mg II h&k lines) to 1100 nm (He I 1083 nm line) with 1.5 m class aperture and filtergraphic and spectrographic instruments.

  11. Derivation of Color Confusion Lines for Pseudo-Dichromat Observers from Color Discrimination Thresholds

    Directory of Open Access Journals (Sweden)

    Kahiro Matsudaira

    2011-05-01

    Full Text Available The objective is to develop a method of defining color confusion lines in the display RGB color space through color discrimination tasks. In the experiment, reference and test square patches were presented side by side on a CRT display. The subject's task is to set the test color where the color difference from the reference is just noticeable to him/her. In a single trial, the test color was only adjustable along one of 26 directions around the reference. Thus 26 colors with just noticeable difference (JND were obtained and made up a tube-like or an ellipsoidal shape around each reference. With color-anomalous subjects, the major axes of these shapes should be parallel to color confusion lines that have a common orientation vector corresponding to one of the cone excitation axes L, M, or S. In our method, the orientation vector was determined by minimizing the sum of the squares of the distances from JND colors to each confusion line. To assess the performance the method, the orientation vectors obtained by pseudo-dichromats (color normal observers with a dichromat simulator were compared to those theoretically calculated from the color vision model used in the simulator.

  12. Slit shaped microwave induced atmospheric pressure plasma based on a parallel plate transmission line resonator

    Science.gov (United States)

    Kang, S. K.; Seo, Y. S.; Lee, H. Wk; Aman-ur-Rehman; Kim, G. C.; Lee, J. K.

    2011-11-01

    A new type of microwave-excited atmospheric pressure plasma source, based on the principle of parallel plate transmission line resonator, is developed for the treatment of large areas in biomedical applications such as skin treatment and wound healing. A stable plasma of 20 mm width is sustained by a small microwave power source operated at a frequency of 700 MHz and a gas flow rate of 0.9 slm. Plasma impedance and plasma density of this plasma source are estimated by fitting the calculated reflection coefficient to the measured one. The estimated plasma impedance shows a decreasing trend while estimated plasma density shows an increasing trend with the increase in the input power. Plasma uniformity is confirmed by temperature and optical emission distribution measurements. Plasma temperature is sustained at less than 40 °C and abundant amounts of reactive species, which are important agents for bacteria inactivation, are detected over the entire plasma region. Large area treatment ability of this newly developed device is verified through bacteria inactivation experiment using E. coli. Sterilization experiment shows a large bacterial killing mark of 25 mm for a plasma treatment time of 10 s.

  13. Observational and theoretical spectra of supernovae

    Science.gov (United States)

    Wheeler, J. Craig; Swartz, Douglas A.; Harkness, Robert P.

    1993-05-01

    Progress in nuclear astrophysics by means of quantitative supernova spectroscopy is discussed with special concentration on type Ia, Ib and Ic and on SN 1987A. Spectral calculations continue to support an exploding C/O white dwarf as the best model of a SN Ia. Deflagration model W7 produces good maximum light spectra of SN Ia and seems to have a better composition distribution compared to delayed detonation models, but proper treatment of opacity remains a problem and the physical basis of SN Ia explosions is still not completely understood. All models for SN Ia predict large quantities of 56Co in the ejecta, but it is not clear that observations confirm this. Although the evolutionary origin of SN Ia remains uncertain, there is recent evidence that transfer of hydrogen in a binary system may be involved, as long suspected. There has been progress in comparing dynamical models with the optical/IR spectra of SN 1987A. The evolution of the [OI] λλ6300, 6364 feature and the presence of strong persistent HeI λ10 830 indicate that both the envelope and core material contribute substantially to the formation of emission lines in the nebular phase and that neither the core nor the envelope can be neglected. Blending with nearby hydrogen lines may affect both of these spectral features, thereby complicating the analysis of the lines. The effects of continuum transfer and photoionization have been included and are under study. The discrepancies between theoretical and observed spectra are due primarily to the one-dimensional hydrodynamic models. The spectral data are not consistent with the high density ``spike'' (in radial coordinate) of the core material that is predicted by all such models. Analysis of the light curves of SN Ib and SN Ic supernovae implies that there are significant differences in their physical properties. Some SN Ib have considerably more ejecta mass than SN Ic events. SN Ib require He-rich atmospheres to produce the observed strong optical lines of

  14. 200 and 270 GHz SIS receivers development for atmospheric observation

    International Nuclear Information System (INIS)

    Ochiai, S.; Masuko, H.

    1993-01-01

    Superconducting mixers have been developed for observations of atmospheric minor constituents such as ClO and ozone at Communications Research Laboratory. This paper describes the work at development of 200 and 270 GHz SIS mixers. Nb/AlOx/Nb junctions were fabricated at Nobeyama Radio Observatory. The base Nb layer 200 nm, the Al (AlOx) insulation layer, and the counter Nb electrode 150 nm are sputtered. The area outside of a junction defined by etching of the counter electrode is insulated by anodized Nb layer and sputtered SiO 2 . After sputtering thick SiO 2 layer on the whole wafer, a contact hole is made by etching. The thickness of the wiring Nb layer is 500 nm. The junctions are formed on the 250 μm thick fused quartz substrate. After the process of the junction fabrication, the quartz substrate is shaved from the back side until 150 μm thickness. Each junction for 270 GHz mixer has an area of about 1 μm 2 . The normal resistance of the six junctions series array is around 70 Ω. The mixer block has a reduced waveguide (1.2 x 0.1 mm for 200 GHz and 0.98 x 0. 1 mm for 270 GHz). The waveguide has two tuners in addition to a fixed backshort cavity. This configuration can allow to realize the lower embedding impedance, and less sensitive to the position of the tuners. The SIS mixers are cooled in a closed cycle He refrigerator. The LO is optically injected through a Fabry Perot interferometer. The 5--7 GHz IF is fed to a HEMT amplifier cooled at 15 K. The authors have started a preliminary measurement of the noise temperature of the SIS receivers, and comparing with calculated DSB receiver noise temperature assuming 3-port model. They continue to improve the performance of the SIS mixers now. They intend that the receivers shall be utilized for atmospheric monitor from next winter

  15. Microphysical Characteristics of Atmospheric Particulate Matter from NASA’s MODIS, MISR, and AERONET Observations

    International Nuclear Information System (INIS)

    Gad, N; Ibrahim, Alaa; Shokr, M

    2017-01-01

    We present a comparative study of atmospheric particulate matter (also known as aerosols) observed by satellite remote sensing and ground-based observations. We compare satellite measurements obtained by NASA’s Moderate Resolution Imaging Spectro-Radiometer (MODIS) and Multi-angle Imaging Spectro-Radiometer (MISR) instruments against the ground-based aerosol sun-photometer data from the Aerosol Robotic Network (AERONET) station in Cairo, Egypt from 2003 to 2014 to build a long-term database for climatological studies and to improve upon the accuracy and coverage achievable from the satellite data. We deduce microphysical and geometrical properties about the dominant aerosols based on key optical properties including aerosol optical depth (AOD), single scattering albedo (SSA), and Ångström exponent (AE). This has allowed us to place important constraints on the type of aerosols (natural, anthropogenic, and biogenic). (paper)

  16. Temperature retrieval at the southern pole of the Venusian atmosphere

    Science.gov (United States)

    Garate-Lopez, Itziar; Garcia-Munoz, A.; Hueso, R.; Sanchez-Lavega, A.

    2013-10-01

    Venus’ thermal radiation spectrum is punctuated by CO2 bands of various strengths probing into different atmospheric depths. It is thus possible to invert measured spectra of thermal radiation to infer atmospheric temperature profiles. VIRTIS-M observations of Venus in the 3-5 µm range allow us to study the night time thermal structure of the planet’s upper troposphere and lower mesosphere from 50 to 105 km [1, 2]. Building a forward radiative transfer model that solves the radiative transfer equation for the atmosphere on a line-by-line basis, we confirmed that aerosol scattering must be taken into account and we studied the impact of factors such as cloud opacity, and the size, composition and vertical distribution of aerosols [3]. The cloud top altitude and aerosol scale height have a notable impact on the spectrum. However, their weighting function matrices have similar structures contributing to the degeneracy of the temperature retrieval algorithm [2]. Our retrieval code is focused on the strong 4.3µm CO2 band, which enables the determination of the thermal profile above the cloud top, and based on the algorithm proposed by Grassi et al. (2008) in their equation (2). We present temperature maps for the south pole of Venus, where a highly variable vortex is observed. We aim to combine these maps with our previously measured velocity fields from the same VIRTIS-M infrared images [4], in order to infer the potential vorticity distribution for different vortex configurations and to improve the understanding of its unpredictable character and its role in the general atmospheric circulation. Acknowledgements This work was supported by the Spanish MICIIN projects AYA2009-10701 and AYA2012-36666 with FEDER funds, by Grupos Gobierno Vasco IT-765-13 and by Universidad País Vasco UPV/EHU through program UFI11/55. IGL and AGM gratefully acknowledge ESA/RSSD for hospitality and access to ‘The Grid’ computing resources. References [1] Roos-Serote, M., et al

  17. Venus' night side atmospheric dynamics using near infrared observations from VEx/VIRTIS and TNG/NICS

    Science.gov (United States)

    Mota Machado, Pedro; Peralta, Javier; Luz, David; Gonçalves, Ruben; Widemann, Thomas; Oliveira, Joana

    2016-10-01

    We present night side Venus' winds based on coordinated observations carried out with Venus Express' VIRTIS instrument and the Near Infrared Camera (NICS) of the Telescopio Nazionale Galileo (TNG). With NICS camera, we acquired images of the continuum K filter at 2.28 μm, which allows to monitor motions at the Venus' lower cloud level, close to 48 km altitude. We will present final results of cloud tracked winds from ground-based TNG observations and from coordinated space-based VEx/VIRTIS observations.The Venus' lower cloud deck is centred at 48 km of altitude, where fundamental dynamical exchanges that help maintain superrotation are thought to occur. The lower Venusian atmosphere is a strong source of thermal radiation, with the gaseous CO2 component allowing radiation to escape in windows at 1.74 and 2.28 μm. At these wavelengths radiation originates below 35 km and unit opacity is reached at the lower cloud level, close to 48 km. Therefore, it is possible to observe the horizontal cloud structure, with thicker clouds seen silhouetted against the bright thermal background from the low atmosphere. By continuous monitoring of the horizontal cloud structure at 2.28 μm (NICS Kcont filter), it is possible to determine wind fields using the technique of cloud tracking. We acquired a series of short exposures of the Venus disk. Cloud displacements in the night side of Venus were computed taking advantage of a phase correlation semi-automated technique. The Venus apparent diameter at observational dates was greater than 32" allowing a high spatial precision. The 0.13" pixel scale of the NICS narrow field camera allowed to resolve ~3-pixel displacements. The absolute spatial resolution on the disk was ~100 km/px at disk center, and the (0.8-1") seeing-limited resolution was ~400 km/px. By co-adding the best images and cross-correlating regions of clouds the effective resolution was significantly better than the seeing-limited resolution. In order to correct for

  18. Mars: Atmosphere

    Science.gov (United States)

    Moroz, V.; Murdin, P.

    2001-07-01

    The atmosphere of MARS is much thinner than the terrestrial one. However, even the simplest visual telescopic observations show a set of atmospheric events such as seasonal exchange of material between polar caps, temporal appearance of clouds and changes of visibility of dark regions on the disk of the planet. In 1947 the prominent CO2 bands in the near-infrared part of the Martian spectrum were...

  19. Earth as an extrasolar planet: Earth model validation using EPOXI earth observations.

    Science.gov (United States)

    Robinson, Tyler D; Meadows, Victoria S; Crisp, David; Deming, Drake; A'hearn, Michael F; Charbonneau, David; Livengood, Timothy A; Seager, Sara; Barry, Richard K; Hearty, Thomas; Hewagama, Tilak; Lisse, Carey M; McFadden, Lucy A; Wellnitz, Dennis D

    2011-06-01

    The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely detectable extrasolar planet characteristics. We have used these data to upgrade, correct, and validate the NASA Astrobiology Institute's Virtual Planetary Laboratory three-dimensional line-by-line, multiple-scattering spectral Earth model. This comprehensive model now includes specular reflectance from the ocean and explicitly includes atmospheric effects such as Rayleigh scattering, gas absorption, and temperature structure. We have used this model to generate spatially and temporally resolved synthetic spectra and images of Earth for the dates of EPOXI observation. Model parameters were varied to yield an optimum fit to the data. We found that a minimum spatial resolution of ∼100 pixels on the visible disk, and four categories of water clouds, which were defined by using observed cloud positions and optical thicknesses, were needed to yield acceptable fits. The validated model provides a simultaneous fit to Earth's lightcurve, absolute brightness, and spectral data, with a root-mean-square (RMS) error of typically less than 3% for the multiwavelength lightcurves and residuals of ∼10% for the absolute brightness throughout the visible and NIR spectral range. We have extended our validation into the mid-infrared by comparing the model to high spectral resolution observations of Earth from the Atmospheric Infrared Sounder, obtaining a fit with residuals of ∼7% and brightness temperature errors of less than 1 K in the atmospheric window. For the purpose of understanding the observable characteristics of the distant Earth at arbitrary viewing geometry and observing cadence, our validated forward model can be

  20. Two centuries of observed atmospheric variability and change over the North Sea region

    Science.gov (United States)

    Stendel, Martin; van den Besselaar, Else; Hannachi, Abdel; Kent, Elizabeth; Lefebvre, Christiana; Rosenhagen, Gudrun; Schenk, Frederik; van der Schrier, Gerard; Woollings, Tim

    2016-04-01

    In the upcoming North Sea Region Climate Change Assessment (NOSCCA), we present a synthesis of current knowledge about past, present and possible future climate change in the North Sea region. A climate change assessment from published scientific work has been conducted as a kind of regional IPCC report, and a book has been produced that will be published by Springer in 2016. In the framework of the NOSCCA project, we examine past and present studies of variability and changes in atmospheric variables within the North Sea region over the instrumental period, roughly the past 200 years, based on observations and reanalyses. The variables addressed in this presentation are large-scale circulation, pressure and wind, surface air temperature, precipitation and radiative properties (clouds, solar radiation, and sunshine duration). While air temperature over land, not unexpectedly, has increased everywhere in the North Sea region, with strongest trends in spring and in the north of the region, a precipitation increase has been observed in the north and a decrease in the south of the region. This pattern goes along with a north-eastward shift of storm tracks and is in agreement with climate model projections under enhanced greenhouse gas concentrations. For other variables, it is not obvious which part of the observed changes may be due to anthropogenic activities and which is internally forced. It remains also unclear to what extent atmospheric circulation over the North Sea region is influenced by distant factors, in particular Arctic sea-ice decline in recent decades. There are indications of an increase in the number of deep cyclones (but not in the total number of cyclones), while storminess since the late 19th century shows no robust trends. The persistence of circulation types appears to have increased over the last century, and consequently, there is an indication for 'more extreme' extreme events. However, changes in extreme weather events are difficult to assess