Predicting Atmospheric Ionization and Excitation by Precipitating SEP and Solar Wind Protons Measured By MAVEN

Science.gov (United States)

Jolitz, Rebecca; Dong, Chuanfei; Lee, Christina; Lillis, Rob; Brain, David; Curry, Shannon; Halekas, Jasper; Bougher, Stephen W.; Jakosky, Bruce

2017-10-01

Precipitating energetic particles ionize and excite planetary atmospheres, increasing electron content and producing aurora. At Mars, the solar wind and solar energetic particles (SEPs) can precipitate directly into the atmosphere because solar wind protons can charge exchange to become neutral and pass the magnetosheath, and SEPs are sufficiently energetic to cross the magnetosheath unchanged. We will compare ionization and Lyman alpha emission rates for solar wind and SEP protons during nominal solar activity and a CME shock front impact event on May 16 2016. We will use the Atmospheric Scattering of Protons and Energetic Neutrals (ASPEN) model to compare excitation and ionization rates by SEPs and solar wind protons currently measured by the SWIA (Solar Wind Ion Analyzer) and SEP instruments aboard the MAVEN spacecraft. Results will help quantify how SEP and solar wind protons influence atmospheric energy deposition during solar minimum.

Ayres' bifurcated solar model

International Nuclear Information System (INIS)

Kalkofen, W.

1985-01-01

The assumptions of Ayres' model of the upper solar atmosphere are examined. It is found that the bistable character of his model is postulated - through the assumptions concerning the opacity sources and the effect of mechanical waves, which are allowed to destroy the CO molecules but not to heat the gas. The neglect of cooling by metal lines is based on their reduced local cooling rate, but it ignores the increased depth over which this cooling occurs. Thus, the bifurcated model of the upper solar atmosphere consists of two models, one cold at the temperature minimum, with a kinetic temperature of 2900 K, and the other hot, with a temperature of 4900 K. 8 references

Predicting Ionization Rates from SEP and Solar Wind Proton Precipitation into the Martian Atmosphere

Science.gov (United States)

Jolitz, R.; Dong, C.; Lee, C. O.; Curry, S.; Lillis, R. J.; Brain, D.; Halekas, J. S.; Larson, D. E.; Bougher, S. W.; Jakosky, B. M.

2017-12-01

Precipitating energetic particles ionize planetary atmospheres and increase total electron content. At Mars, the solar wind and solar energetic particles (SEPs) can precipitate directly into the atmosphere because solar wind protons can charge exchange to become neutrals and pass through the magnetosheath, while SEPs are sufficiently energetic to cross the magnetosheath unchanged. In this study we will present predicted ionization rates and resulting electron densities produced by solar wind and SEP proton ionization during nominal solar activity and a CME shock front impact event on May 16 2016. We will use the Atmospheric Scattering of Protons and Energetic Neutrals (ASPEN) model to compare ionization by SEP and solar wind protons currently measured by the SWIA (Solar Wind Ion Analyzer) and SEP instruments aboard the MAVEN spacecraft. Results will help to quantify how the ionosphere responds to extreme solar events during solar minimum.

Toward Improved Modeling of Spectral Solar Irradiance for Solar Energy Applications: Preprint

Energy Technology Data Exchange (ETDEWEB)

Xie, Yu [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sengupta, Manajit [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-10-19

This study introduces the National Renewable Energy Laboratory's (NREL's) recent efforts to extend the capability of the Fast All-sky Radiation Model for Solar applications (FARMS) by computing spectral solar irradiances over both horizontal and inclined surfaces. A new model is developed by computing the optical thickness of the atmosphere using a spectral irradiance model for clear-sky conditions, SMARTS2. A comprehensive lookup table (LUT) of cloud bidirectional transmittance distribution functions (BTDFs) is precomputed for 2002 wavelength bands using an atmospheric radiative transfer model, libRadtran. The solar radiation transmitted through the atmosphere is given by considering all possible paths of photon transmission and the relevent scattering and absorption attenuation. Our results indicate that this new model has an accuracy that is similar to that of state-of-the-art radiative transfer models, but it is significantly more efficient.

Sensitivity of upper atmospheric emissions calculations to solar/stellar UV flux

Directory of Open Access Journals (Sweden)

Barthelemy Mathieu

2014-01-01

Full Text Available The solar UV (UltraViolet flux, especially the EUV (Extreme UltraViolet and FUV (Far UltraViolet components, is one of the main energetic inputs for planetary upper atmospheres. It drives various processes such as ionization, or dissociation which give rise to upper atmospheric emissions, especially in the UV and visible. These emissions are one of the main ways to investigate the upper atmospheres of planets. However, the uncertainties in the flux measurement or modeling can lead to biased estimates of fundamental atmospheric parameters, such as concentrations or temperatures in the atmospheres. We explore the various problems that can be identified regarding the uncertainties in solar/stellar UV flux by considering three examples. The worst case appears when the solar reflection component is dominant in the recorded spectrum as is seen for outer solar system measurements from HST (Hubble Space Telescope. We also show that the estimation of some particular line parameters (intensity and shape, especially Lyman α, is crucial, and that both total intensity and line profile are useful. In the case of exoplanets, the problem is quite critical since the UV flux of their parent stars is often very poorly known.

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.

Sensitivity of a soil-plant-atmosphere model to changes in air temperature, dew point temperature, and solar radiation

Energy Technology Data Exchange (ETDEWEB)

Luxmoore, R.J. (Oak Ridge National Lab.,TN); Stolzy, J.L.; Holdeman, J.T.

1981-01-01

Air temperature, dew point temperature and solar radiation were independently varied in an hourly soil-plant-atmosphere model in a sensitivity analysis of these parameters. Results suggested that evapotranspiration in eastern Tennessee is limited more by meteorological conditions that determine the vapor-pressure gradient than by the necessary energy to vaporize water within foliage. Transpiration and soil water drainage were very sensitive to changes in air and dew point temperature and to solar radiation under low atmospheric vapor-pressure deficit conditions associated with reduced air temperature. Leaf water potential and stomatal conductance were reduced under conditions having high evapotranspiration. Representative air and dew point temperature input data for a particular application are necessary for satisfactory results, whereas irradiation may be less well characterized for applications with high atmospheric vapor-pressure deficit. The effects of a general rise in atmospheric temperature on forest water budgets are discussed.

The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere VII. Further Insights into the Chromosphere and Corona

Directory of Open Access Journals (Sweden)

Robitaille P.-M.

2013-07-01

Full Text Available In the liquid metallic hydrogen model of the Sun, the chromosphere is responsible for the capture of atomic hydrogen in the solar atmosphere and its eventual re-entry onto the photospheric surface (P.M. Robitaille. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere IV. On the Nature of the Chromosphere. Prog. Phys., 2013, v. 3, L15–L21. As for the corona, it represents a diffuse region containing both gaseous plasma and condensed matter with elevated electron affinity (P.M. Robitaille. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere V. On the Nature of the Corona. Prog. Phys., 2013, v. 3, L22–L25. Metallic hydrogen in the corona is thought to enable the continual harvest of electrons from the outer reaches of the Sun, thereby preserving the neutrality of the solar body. The rigid rotation of the corona is offered as the thirty-third line of evidence that the Sun is comprised of condensed matter. Within the context of the gaseous models of the Sun, a 100 km thick transition zone has been hypothesized to exist wherein temperatures increase dramatically from 104–106 K. Such extreme transitional temperatures are not reasonable given the trivial physical scale of the proposed transition zone, a region adopted to account for the ultra-violet emission lines of ions such as C IV, O IV, and Si IV. In this work, it will be argued that the transition zone does not exist. Rather, the intermediate ionization states observed in the solar atmosphere should be viewed as the result of the simultaneous transfer of protons and electrons onto condensed hydrogen structures, CHS. Line emissions from ions such as C IV, O IV, and Si IV are likely to be the result of condensation reactions, manifesting the involvement of species such as CH4, SiH4, H3O+ in the synthesis of CHS in the chromosphere. In addition, given the presence of a true solar surface at the level of the photosphere in the liquid metallic hydrogen model

Diagnosing transient plasma status: from solar atmosphere to tokamak divertor

International Nuclear Information System (INIS)

Giunta, A.S.; Henderson, S.; O'Mullane, M.; Summers, H.P.; Harrison, J.; Doyle, J.G.

2016-01-01

This work strongly exploits the interdisciplinary links between astrophysical (such as the solar upper atmosphere) and laboratory plasmas (such as tokamak devices) by sharing the development of a common modelling for time-dependent ionisation. This is applied to the interpretation of solar flare data observed by the UVSP (Ultraviolet Spectrometer and Polarimeter), on-board the Solar Maximum Mission and the IRIS (Interface Region Imaging Spectrograph), and also to data from B2-SOLPS (Scrape Off Layer Plasma Simulations) for MAST (Mega Ampère Spherical Tokamak) Super-X divertor upgrade. The derived atomic data, calculated in the framework of the ADAS (Atomic Data and Analysis Structure) project, allow equivalent prediction in non-stationary transport regimes and transients of both the solar atmosphere and tokamak divertors, except that the tokamak evolution is about one thousand times faster.

Solar Atmosphere to Earth's Surface: Long Lead Time dB/dt Predictions with the Space Weather Modeling Framework

Science.gov (United States)

Welling, D. T.; Manchester, W.; Savani, N.; Sokolov, I.; van der Holst, B.; Jin, M.; Toth, G.; Liemohn, M. W.; Gombosi, T. I.

2017-12-01

The future of space weather prediction depends on the community's ability to predict L1 values from observations of the solar atmosphere, which can yield hours of lead time. While both empirical and physics-based L1 forecast methods exist, it is not yet known if this nascent capability can translate to skilled dB/dt forecasts at the Earth's surface. This paper shows results for the first forecast-quality, solar-atmosphere-to-Earth's-surface dB/dt predictions. Two methods are used to predict solar wind and IMF conditions at L1 for several real-world coronal mass ejection events. The first method is an empirical and observationally based system to estimate the plasma characteristics. The magnetic field predictions are based on the Bz4Cast system which assumes that the CME has a cylindrical flux rope geometry locally around Earth's trajectory. The remaining plasma parameters of density, temperature and velocity are estimated from white-light coronagraphs via a variety of triangulation methods and forward based modelling. The second is a first-principles-based approach that combines the Eruptive Event Generator using Gibson-Low configuration (EEGGL) model with the Alfven Wave Solar Model (AWSoM). EEGGL specifies parameters for the Gibson-Low flux rope such that it erupts, driving a CME in the coronal model that reproduces coronagraph observations and propagates to 1AU. The resulting solar wind predictions are used to drive the operational Space Weather Modeling Framework (SWMF) for geospace. Following the configuration used by NOAA's Space Weather Prediction Center, this setup couples the BATS-R-US global magnetohydromagnetic model to the Rice Convection Model (RCM) ring current model and a height-integrated ionosphere electrodynamics model. The long lead time predictions of dB/dt are compared to model results that are driven by L1 solar wind observations. Both are compared to real-world observations from surface magnetometers at a variety of geomagnetic latitudes

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.

Elemental composition and ionization state of the solar atmosphere and solar wind

International Nuclear Information System (INIS)

Joselyn, J.A.C.

1978-01-01

Abundance measurements have always proved useful in generating and refining astrophysical theories. Some of the classical problems of astrophysics involve determining the relative abundances of elements in the atmosphere of a star from observations of its line spectrum, and then synthesizing the physical processes which would produce such abundances. Theories of the formation of the solar system are critically tested by their ability to explain observed abundances, and, elemental abundances can serve as tracers, helping to determine the origin and transport of ions. Since the solar wind originates at the sun, it can act as a diagnostic probe of solar conditions. In particular, measurements of the composition of the solar wind should be related to the solar composition. And, assuming ionization equilibrium, measurements of the relative abundances of the ionization states in the solar wind should infer coronal temperatures and temperature gradients. However, most spherically symmetric models of the solar wind are unable to explain the relationship between the composition estimated from solar observations and as measured at 1 AU; and, recent observations of significant flow speeds in the transition region raise doubts about the validity of the assumption of ionization equilibrium

Statistical equilibrium of copper in the solar atmosphere

International Nuclear Information System (INIS)

Shi, J. R.; Mashonkina, L.; Zhao, G.; Gehren, T.; Zeng, J. L.

2014-01-01

Non-local thermodynamic equilibrium (NLTE) line formation for neutral copper in the one-dimensional solar atmospheres is presented for the atomic model, including 96 terms of Cu I and the ground state of Cu II. The accurate oscillator strengths for all the line transitions in model atom and photoionization cross sections were calculated using the R-matrix method in the Russell-Saunders coupling scheme. The main NLTE mechanism for Cu I is the ultraviolet overionization. We find that NLTE leads to systematically depleted total absorption in the Cu I lines and, accordingly, positive abundance corrections. Inelastic collisions with neutral hydrogen atoms produce minor effects on the statistical equilibrium of Cu I in the solar atmosphere. For the solar Cu I lines, the departures from LTE are found to be small, the mean NLTE abundance correction of ∼0.01 dex. It was found that the six low-excitation lines, with excitation energy of the lower level E exc ≤ 1.64 eV, give a 0.14 dex lower mean solar abundance compared to that from the six E exc > 3.7 eV lines, when applying experimental gf-values of Kock and Richter. Without the two strong resonance transitions, the solar mean NLTE abundance from 10 lines of Cu I is log ε ☉ (Cu) = 4.19 ± 0.10, which is consistent within the error bars with the meteoritic value 4.25 ± 0.05 of Lodders et al. The discrepancy between E exc = 1.39-1.64 eV and E exc > 3.7 eV lines can be removed when the calculated gf-values are adopted and a mean solar abundance of log ε ☉ (Cu) = 4.24 ± 0.08 is derived.

Automated Detection of Oscillating Regions in the Solar Atmosphere

Science.gov (United States)

Ireland, J.; Marsh, M. S.; Kucera, T. A.; Young, C. A.

2010-01-01

Recently observed oscillations in the solar atmosphere have been interpreted and modeled as magnetohydrodynamic wave modes. This has allowed for the estimation of parameters that are otherwise hard to derive, such as the coronal magnetic-field strength. This work crucially relies on the initial detection of the oscillations, which is commonly done manually. The volume of Solar Dynamics Observatory (SDO) data will make manual detection inefficient for detecting all of the oscillating regions. An algorithm is presented that automates the detection of areas of the solar atmosphere that support spatially extended oscillations. The algorithm identifies areas in the solar atmosphere whose oscillation content is described by a single, dominant oscillation within a user-defined frequency range. The method is based on Bayesian spectral analysis of time series and image filtering. A Bayesian approach sidesteps the need for an a-priori noise estimate to calculate rejection criteria for the observed signal, and it also provides estimates of oscillation frequency, amplitude, and noise, and the error in all of these quantities, in a self-consistent way. The algorithm also introduces the notion of quality measures to those regions for which a positive detection is claimed, allowing for simple post-detection discrimination by the user. The algorithm is demonstrated on two Transition Region and Coronal Explorer (TRACE) datasets, and comments regarding its suitability for oscillation detection in SDO are made.

The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere V. On the Nature of the Corona

Directory of Open Access Journals (Sweden)

Robitaille P.-M.

2013-07-01

Full Text Available The E-corona is the site of numerous emission lines associated with high ionization states (i.e. FeXIV-FeXXV. Modern gaseous models of the Sun require that these states are produced by atomic irradiation, requiring the sequential removal of electrons to infinity, without an associated electron acceptor. This can lead to computed temperatures in the corona which are unrealistic (i.e. ∼30–100 MK contrasted to solar core values of ∼16 MK. In order to understand the emission lines of the E-corona, it is vital to recognize that they are superimposed upon the K-corona, which produces a continuous spectrum, devoid of Fraunhofer lines, arising from this same region of the Sun. It has been advanced that the K-corona harbors self-luminous condensed matter (Robitaille P.M. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere II. Continuous Emission and Condensed Matter Within the Corona. Progr. Phys., 2013, v. 3, L8–L10; Robitaille P.M. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere III. Importance of Continuous Emission Spectra from Flares, Coronal Mass Ejections, Prominences, and Other Coronal Structures. Progr. Phys., 2013, v. 3, L11–L14. Condensed matter can possess elevated electron affinities which may strip nearby atoms of their electrons. Such a scenario accounts for the high ionization states observed in the corona: condensed matter acts to harness electrons, ensuring the electrical neutrality of the Sun, despite the flow of electrons and ions in the solar winds. Elevated ionization states reflect the presence of materials with high electron affinities in the corona, which is likely to be a form of metallic hydrogen, and does not translate into elevated temperatures in this region of the solar atmosphere. As a result, the many mechanisms advanced to account for coronal heating in the gaseous models of the Sun

Fundamental (f) oscillations in a magnetically coupled solar interior-atmosphere system - An analytical approach

Science.gov (United States)

Pintér, Balázs; Erdélyi, R.

2018-01-01

Solar fundamental (f) acoustic mode oscillations are investigated analytically in a magnetohydrodynamic (MHD) model. The model consists of three layers in planar geometry, representing the solar interior, the magnetic atmosphere, and a transitional layer sandwiched between them. Since we focus on the fundamental mode here, we assume the plasma is incompressible. A horizontal, canopy-like, magnetic field is introduced to the atmosphere, in which degenerated slow MHD waves can exist. The global (f-mode) oscillations can couple to local atmospheric Alfvén waves, resulting, e.g., in a frequency shift of the oscillations. The dispersion relation of the global oscillation mode is derived, and is solved analytically for the thin-transitional layer approximation and for the weak-field approximation. Analytical formulae are also provided for the frequency shifts due to the presence of a thin transitional layer and a weak atmospheric magnetic field. The analytical results generally indicate that, compared to the fundamental value (ω =√{ gk }), the mode frequency is reduced by the presence of an atmosphere by a few per cent. A thin transitional layer reduces the eigen-frequencies further by about an additional hundred microhertz. Finally, a weak atmospheric magnetic field can slightly, by a few percent, increase the frequency of the eigen-mode. Stronger magnetic fields, however, can increase the f-mode frequency by even up to ten per cent, which cannot be seen in observed data. The presence of a magnetic atmosphere in the three-layer model also introduces non-permitted propagation windows in the frequency spectrum; here, f-mode oscillations cannot exist with certain values of the harmonic degree. The eigen-frequencies can be sensitive to the background physical parameters, such as an atmospheric density scale-height or the rate of the plasma density drop at the photosphere. Such information, if ever observed with high-resolution instrumentation and inverted, could help to

Atmospheric solar heating rate in the water vapor bands

Science.gov (United States)

Chou, Ming-Dah

1986-01-01

The total absorption of solar radiation by water vapor in clear atmospheres is parameterized as a simple function of the scaled water vapor amount. For applications to cloudy and hazy atmospheres, the flux-weighted k-distribution functions are computed for individual absorption bands and for the total near-infrared region. The parameterization is based upon monochromatic calculations and follows essentially the scaling approximation of Chou and Arking, but the effect of temperature variation with height is taken into account in order to enhance the accuracy. Furthermore, the spectral range is extended to cover the two weak bands centered at 0.72 and 0.82 micron. Comparisons with monochromatic calculations show that the atmospheric heating rate and the surface radiation can be accurately computed from the parameterization. Comparisons are also made with other parameterizations. It is found that the absorption of solar radiation can be computed reasonably well using the Goody band model and the Curtis-Godson approximation.

Simulated solar cycle effects on the middle atmosphere: WACCM3 Versus WACCM4

Science.gov (United States)

Peck, E. D.; Randall, C. E.; Harvey, V. L.; Marsh, D. R.

2015-06-01

The Whole Atmosphere Community Climate Model version 4 (WACCM4) is used to quantify solar cycle impacts, including both irradiance and particle precipitation, on the middle atmosphere. Results are compared to previous work using WACCM version 3 (WACCM3) to estimate the sensitivity of simulated solar cycle effects to model modifications. The residual circulation in WACCM4 is stronger than in WACCM3, leading to larger solar cycle effects from energetic particle precipitation; this impacts polar stratospheric odd nitrogen and ozone, as well as polar mesospheric temperatures. The cold pole problem, which is present in both versions, is exacerbated in WACCM4, leading to more ozone loss in the Antarctic stratosphere. Relative to WACCM3, a westerly shift in the WACCM4 zonal winds in the tropical stratosphere and mesosphere, and a strengthening and poleward shift of the Antarctic polar night jet, are attributed to inclusion of the QBO and changes in the gravity wave parameterization in WACCM4. Solar cycle effects in WACCM3 and WACCM4 are qualitatively similar. However, the EPP-induced increase from solar minimum to solar maximum in polar stratospheric NOy is about twice as large in WACCM4 as in WACCM3; correspondingly, maximum increases in polar O3 loss from solar min to solar max are more than twice as large in WACCM4. This does not cause large differences in the WACCM3 versus WACCM4 solar cycle responses in temperature and wind. Overall, these results provide a framework for future studies using WACCM to analyze the impacts of the solar cycle on the middle atmosphere.

Multi-wavelength imaging of solar plasma. High-beta disruption model of solar flares

International Nuclear Information System (INIS)

Shibasaki, Kiyoto

2007-01-01

Solar atmosphere is filled with plasma and magnetic field. Activities in the atmosphere are due to plasma instabilities in the magnetic field. To understand the physical mechanisms of activities / instabilities, it is necessary to know the physical conditions of magnetized plasma, such as temperature, density, magnetic field, and their spatial structures and temporal developments. Multi-wavelength imaging is essential for this purpose. Imaging observations of the Sun at microwave, X-ray, EUV and optical ranges are routinely going on. Due to free exchange of original data among solar physics and related field communities, we can easily combine images covering wide range of spectrum. Even under such circumstances, we still do not understand the cause of activities in the solar atmosphere well. The current standard model of solar activities is based on magnetic reconnection: release of stored magnetic energy by reconnection is the cause of solar activities on the Sun such as solar flares. However, recent X-ray, EUV and microwave observations with high spatial and temporal resolution show that dense plasma is involved in activities from the beginning. Based on these observations, I propose a high-beta model of solar activities, which is very similar to high-beta disruptions in magnetically confined fusion experiments. (author)

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.

The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. I. Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29

Energy Technology Data Exchange (ETDEWEB)

Kowalski, Adam F. [Department of Astrophysical and Planetary Sciences, University of Colorado Boulder, 2000 Colorado Ave, Boulder, CO 80305 (United States); Allred, Joel C.; Daw, Adrian [NASA/Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States); Cauzzi, Gianna [INAF-Osservatorio Astrofisico di Arcetri, I-50125 Firenze (Italy); Carlsson, Mats, E-mail: Adam.Kowalski@lasp.colorado.edu [Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, NO-0315 Oslo (Norway)

2017-02-10

The 2014 March 29 X1 solar flare (SOL20140329T17:48) produced bright continuum emission in the far- and near-ultraviolet (NUV) and highly asymmetric chromospheric emission lines, providing long-sought constraints on the heating mechanisms of the lower atmosphere in solar flares. We analyze the continuum and emission line data from the Interface Region Imaging Spectrograph (IRIS) of the brightest flaring magnetic footpoints in this flare. We compare the NUV spectra of the brightest pixels to new radiative-hydrodynamic predictions calculated with the RADYN code using constraints on a nonthermal electron beam inferred from the collisional thick-target modeling of hard X-ray data from Reuven Ramaty High Energy Solar Spectroscopic Imager . We show that the atmospheric response to a high beam flux density satisfactorily achieves the observed continuum brightness in the NUV. The NUV continuum emission in this flare is consistent with hydrogen (Balmer) recombination radiation that originates from low optical depth in a dense chromospheric condensation and from the stationary beam-heated layers just below the condensation. A model producing two flaring regions (a condensation and stationary layers) in the lower atmosphere is also consistent with the asymmetric Fe ii chromospheric emission line profiles observed in the impulsive phase.

Solar energy and the abatement of atmospheric emissions

International Nuclear Information System (INIS)

Mirasgedis, S.; Diakoulaki, D.; Assimacopoulos, D.

1996-01-01

In spite of the fact that solar energy is a ''clean'' energy form, gaseous pollutants are emitted during the manufacturing of the systems necessary for its utilisation. An attempt is made in this paper to estimate the level of atmospheric pollutants emitted during the successive stages which make up the manufacture process for solar water heating (SWH) systems, and to evaluate these results in comparison with the respective pollutant emission levels attributed to the generation of electricity in Greece's conventional power plants. As energy consumption is recognised as the main source of atmospheric pollution, a Life Cycle Analysis (LCA) method was applied, focusing on the most energy-consuming stages of the SWH system production process. The conclusions of the analysis indicate that the emissions of gaseous pollutants associated with the utilisation of solar energy are considerably lower than those caused by the production of electricity in conventional systems, thereby substantiating that solar energy utilisation can make a notable contribution to the abatement of atmospheric pollution. (author)

Solar dynamics influence on the atmospheric ozone

International Nuclear Information System (INIS)

Gogosheva, T.; Grigorieva, V.; Mendeva, B.; Krastev, D.; Petkov, B.

2007-01-01

A response of the atmospheric ozone to the solar dynamics has been studied using the total ozone content data, taken from the satellite experiments GOME on ERS-2 and TOMS-EP together with data obtained from the ground-based spectrophotometer Photon operating in Stara Zagora, Bulgaria during the period 1999-2005. We also use data from surface ozone observations performed in Sofia, Bulgaria. The solar activity was characterized by the sunspot daily numbers W, the solar radio flux at 10.7 cm (F10.7) and the MgII wing-to-core ratio solar index. The impact of the solar activity on the total ozone has been investigated analysing the ozone response to sharp changes of these parameters. Some of the examined cases showed a positive correlation between the ozone and the solar parameters, however, a negative correlation in other cases was found. There were some cases when the sharp increases of the solar activity did not provoke any ozone changes. The solar radiation changes during an eclipse can be considered a particular case of the solar dynamics as this event causes a sharp change of irradiance within a comparatively short time interval. The results of both - the total and surface ozone measurements carried out during the eclipses on 11 August 1999, 31 May 2003 and 29 March 2006 are presented. It was found that the atmospheric ozone behavior shows strong response to the fast solar radiation changes which take place during solar eclipse. (authors)

Proceedings of the workshop: the solar constant and the Earth's atmosphere

International Nuclear Information System (INIS)

Zirin, H.; Moore, R.L.; Walter, J.

1976-01-01

The solar constant has long been a fundamental quantity in astrophysics, but as with many fundamental quantities, interest in its exact value or its variation has not been great over the last decade. This was particularly due to the fact that most models of stars indicated that their luminosity should be quite constant, varying only over nuclear burning times of hundreds of millions of years. Thus, after the pioneering work of Abbott, it has been more a subject of interest for atmospheric scientists who needed to know the exact inputs to the Earth's atmosphere. In recent years however, the celebrated problem of the missing solar neutrinos has brought into question the theories of stellar structure, and the solar constant is again being thought about. Standard solar models predict a lower solar constant in the past, 75% of the present, 4x10 9 years ago and a virtually constant value over short time scales (10 7 years). However, the lack of observed neutrinos predicted by this model suggests that the interior of the Sun is not really understood, which means that solar constant variations cannot be ruled out on the basis of the theory of stellar interiors. Measurement of the planets, the old Smithsonian measurements, and other data suggest that the Sun cannot have varied more than a few percent over the past hundred years, but some of the measurements even suggest small variation of the order of a percent. On the other hand, in the important near ultraviolet region, there is evidence for some variation in the 2700-3100 A region and up to 50% variation below 1600 A, dependent on solar activity. (Auth.)

Is tropospheric weather influenced by solar wind through atmospheric vertical coupling downward control?

Science.gov (United States)

Prikryl, Paul; Tsukijihara, Takumi; Iwao, Koki; Muldrew, Donald B.; Bruntz, Robert; Rušin, Vojto; Rybanský, Milan; Turňa, Maroš; Šťastný, Pavel; Pastirčák, Vladimír

2017-04-01

More than four decades have passed since a link between solar wind magnetic sector boundary structure and mid-latitude upper tropospheric vorticity was discovered (Wilcox et al., Science, 180, 185-186, 1973). The link has been later confirmed and various physical mechanisms proposed but apart from controversy, little attention has been drawn to these results. To further emphasize their importance we investigate the occurrence of mid-latitude severe weather in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system. It is observed that significant snowstorms, windstorms and heavy rain, particularly if caused by low pressure systems in winter, tend to follow arrivals of high-speed solar wind. Previously published statistical evidence that explosive extratropical cyclones in the northern hemisphere tend to occur after arrivals of high-speed solar wind streams from coronal holes (Prikryl et al., Ann. Geophys., 27, 1-30, 2009; Prikryl et al., J. Atmos. Sol.-Terr. Phys., 149, 219-231, 2016) is corroborated for the southern hemisphere. A physical mechanism to explain these observations is proposed. The leading edge of high-speed solar wind streams is a locus of large-amplitude magneto-hydrodynamic waves that modulate Joule heating and/or Lorentz forcing of the high-latitude lower thermosphere generating medium-scale atmospheric gravity waves that propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (Mayr et al., Space Sci. Rev., 54, 297-375, 1990) show that propagating waves originating in the thermosphere can excite a spectrum of gravity waves in the lower atmosphere. In spite of significantly reduced amplitudes but subject to amplification upon reflection in the upper troposphere, these gravity waves can provide a lift of unstable air to release instabilities in the troposphere thus initiating convection to form cloud/precipitation bands

A radiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-J v7.5

Science.gov (United States)

Hsu, Juno; Prather, Michael J.; Cameron-Smith, Philip; Veidenbaum, Alex; Nicolau, Alex

2017-07-01

Solar-J is a comprehensive radiative transfer model for the solar spectrum that addresses the needs of both solar heating and photochemistry in Earth system models. Solar-J is a spectral extension of Cloud-J, a standard in many chemical models that calculates photolysis rates in the 0.18-0.8 µm region. The Cloud-J core consists of an eight-stream scattering, plane-parallel radiative transfer solver with corrections for sphericity. Cloud-J uses cloud quadrature to accurately average over correlated cloud layers. It uses the scattering phase function of aerosols and clouds expanded to eighth order and thus avoids isotropic-equivalent approximations prevalent in most solar heating codes. The spectral extension from 0.8 to 12 µm enables calculation of both scattered and absorbed sunlight and thus aerosol direct radiative effects and heating rates throughout the Earth's atmosphere.The Solar-J extension adopts the correlated-k gas absorption bins, primarily water vapor, from the shortwave Rapid Radiative Transfer Model for general circulation model (GCM) applications (RRTMG-SW). Solar-J successfully matches RRTMG-SW's tropospheric heating profile in a clear-sky, aerosol-free, tropical atmosphere. We compare both codes in cloudy atmospheres with a liquid-water stratus cloud and an ice-crystal cirrus cloud. For the stratus cloud, both models use the same physical properties, and we find a systematic low bias of about 3 % in planetary albedo across all solar zenith angles caused by RRTMG-SW's two-stream scattering. Discrepancies with the cirrus cloud using any of RRTMG-SW's three different parameterizations are as large as about 20-40 % depending on the solar zenith angles and occur throughout the atmosphere.Effectively, Solar-J has combined the best components of RRTMG-SW and Cloud-J to build a high-fidelity module for the scattering and absorption of sunlight in the Earth's atmosphere, for which the three major components - wavelength integration, scattering, and

Modeling the atmospheric chemistry of TICs

Science.gov (United States)

Henley, Michael V.; Burns, Douglas S.; Chynwat, Veeradej; Moore, William; Plitz, Angela; Rottmann, Shawn; Hearn, John

2009-05-01

An atmospheric chemistry model that describes the behavior and disposition of environmentally hazardous compounds discharged into the atmosphere was coupled with the transport and diffusion model, SCIPUFF. The atmospheric chemistry model was developed by reducing a detailed atmospheric chemistry mechanism to a simple empirical effective degradation rate term (keff) that is a function of important meteorological parameters such as solar flux, temperature, and cloud cover. Empirically derived keff functions that describe the degradation of target toxic industrial chemicals (TICs) were derived by statistically analyzing data generated from the detailed chemistry mechanism run over a wide range of (typical) atmospheric conditions. To assess and identify areas to improve the developed atmospheric chemistry model, sensitivity and uncertainty analyses were performed to (1) quantify the sensitivity of the model output (TIC concentrations) with respect to changes in the input parameters and (2) improve, where necessary, the quality of the input data based on sensitivity results. The model predictions were evaluated against experimental data. Chamber data were used to remove the complexities of dispersion in the atmosphere.

Effects in atmospheric electricity daily variation controlled by solar wind

International Nuclear Information System (INIS)

Ptitsyna, N.G.; Tyasto, M.I.; Levitin, A.E.; Gromova, L.A.; Tuomi, T.; AN SSSR, Moscow

1995-01-01

An analysis of fair weather atmospheric electricity, one of the environmental factors which affects the biosphere, is conducted. A distinct difference in the diurnal variation of atmospheric electric field at Helsinki is found between disturbed and extremely quiet conditions in the magnetosphere in winter before midnight. The comparison with the numerical model of the ionospheric electric field based on the solar wind parameters reveals that the maximum contribution of the magnetospheric-ionospheric generator to atmospheric electric field is about 100-150 v/m which assumes values of about 30% of the surface field. 8 refs.; 2 figs

The Long-term Middle Atmospheric Influence of Very Large Solar Proton Events

Science.gov (United States)

Jackman, Charles H.; Marsh, Daniel R.; Vitt, Francis M.; Garcia, Rolando R.; Randall, Cora E.; Fleming, Eric L.; Frith, Stacey M.

2008-01-01

Long-term variations in ozone have been caused by both natural and humankind related processes. The humankind or anthropogenic influence on ozone originates from the chlorofluorocarbons and halons (chlorine and bromine) and has led to international regulations greatly limiting the release of these substances. Certain natural ozone influences are also important in polar regions and are caused by the impact of solar charged particles on the atmosphere. Such natural variations have been studied in order to better quantify the human influence on polar ozone. Large-scale explosions on the Sun near solar maximum lead to emissions of charged particles (mainly protons and electrons), some of which enter the Earth's magnetosphere and rain down on the polar regions. "Solar proton events" have been used to describe these phenomena since the protons associated with these solar events sometimes create a significant atmospheric disturbance. We have used the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM) to study the long-term (> few months) influences of solar proton events from 1963 through 2004 on stratospheric ozone and temperature. There were extremely large solar proton events in 1972, 1989,2000,2001, and 2003. These events caused very distinctive polar changes in layers of the Earth's atmosphere known as the stratosphere (12-50 km; -7-30 miles) and mesosphere (50-90 km; 30-55 miles). The solar protons connected with these events created hydrogen- and nitrogen-containing compounds, which led to the polar ozone destruction. The nitrogen-containing compounds, called odd nitrogen, lasted much longer than the hydrogen-containing compounds and led to long-lived stratospheric impacts. An extremely active period for these events occurred in the five-year period, 2000- 2004, and caused increases in odd nitrogen which lasted for several months after individual events. Associated stratospheric ozone decreases of >lo% were calculated

Short- and Medium-term Atmospheric Effects of Very Large Solar Proton Events

Science.gov (United States)

Jackman, Charles H.; Marsh, Daniel R.; Vitt, Francis M.; Garcia, Rolando R.; Fleming, Eric L.; Labow, Gordon J.; Randall, Cora E.; Lopez-Puertas, Manuel; Funke, Bernd

2007-01-01

Long-term variations in ozone have been caused by both natural and humankind related processes. In particular, the humankind or anthropogenic influence on ozone from chlorofluorocarbons and halons (chlorine and bromine) has led to international regulations greatly limiting the release of these substances. These anthropogenic effects on ozone are most important in polar regions and have been significant since the 1970s. Certain natural ozone influences are also important in polar regions and are caused by the impact of solar charged particles on the atmosphere. Such natural variations have been studied in order to better quantify the human influence on polar ozone. Large-scale explosions on the Sun near solar maximum lead to emissions of charged particles (mainly protons and electrons), some of which enter the Earth's magnetosphere and rain down on the polar regions. "Solar proton events" have been used to describe these phenomena since the protons associated with these solar events sometimes create a significant atmospheric disturbance. We have used the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM) to study the short- and medium-term (days to a few months) influences of solar proton events between 1963 and 2005 on stratospheric ozone. The four largest events in the past 45 years (August 1972; October 1989; July 2000; and October-November 2003) caused very distinctive polar changes in layers of the Earth's atmosphere known as the stratosphere (12-50 km; -7-30 miles) and mesosphere (50-90 km; 30-55 miles). The solar protons connected with these events created hydrogen- and nitrogen- containing compounds, which led to the polar ozone destruction. The hydrogen-containing compounds have very short lifetimes and lasted for only a few days (typically the duration of the solar proton event). On the other hand, the nitrogen-containing compounds lasted much longer, especially in the Winter. The nitrogen oxides were predicted

A radiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-J v7.5

Directory of Open Access Journals (Sweden)

J. Hsu

2017-07-01

Full Text Available Solar-J is a comprehensive radiative transfer model for the solar spectrum that addresses the needs of both solar heating and photochemistry in Earth system models. Solar-J is a spectral extension of Cloud-J, a standard in many chemical models that calculates photolysis rates in the 0.18–0.8 µm region. The Cloud-J core consists of an eight-stream scattering, plane-parallel radiative transfer solver with corrections for sphericity. Cloud-J uses cloud quadrature to accurately average over correlated cloud layers. It uses the scattering phase function of aerosols and clouds expanded to eighth order and thus avoids isotropic-equivalent approximations prevalent in most solar heating codes. The spectral extension from 0.8 to 12 µm enables calculation of both scattered and absorbed sunlight and thus aerosol direct radiative effects and heating rates throughout the Earth's atmosphere.The Solar-J extension adopts the correlated-k gas absorption bins, primarily water vapor, from the shortwave Rapid Radiative Transfer Model for general circulation model (GCM applications (RRTMG-SW. Solar-J successfully matches RRTMG-SW's tropospheric heating profile in a clear-sky, aerosol-free, tropical atmosphere. We compare both codes in cloudy atmospheres with a liquid-water stratus cloud and an ice-crystal cirrus cloud. For the stratus cloud, both models use the same physical properties, and we find a systematic low bias of about 3 % in planetary albedo across all solar zenith angles caused by RRTMG-SW's two-stream scattering. Discrepancies with the cirrus cloud using any of RRTMG-SW's three different parameterizations are as large as about 20–40 % depending on the solar zenith angles and occur throughout the atmosphere.Effectively, Solar-J has combined the best components of RRTMG-SW and Cloud-J to build a high-fidelity module for the scattering and absorption of sunlight in the Earth's atmosphere, for which the three major components – wavelength

Parameterization models for solar radiation and solar technology applications

Energy Technology Data Exchange (ETDEWEB)

Khalil, Samy A. [National Research Institute of Astronomy and Geophysics, Solar and Space Department, Marsed Street, Helwan, 11421 Cairo (Egypt)

2008-08-15

Solar radiation is very important for the evaluation and wide use of solar renewable energy systems. The development of calibration procedures for broadband solar radiation photometric instrumentation and the improvement of broadband solar radiation measurement accuracy have been done. An improved diffuse sky reference and photometric calibration and characterization software for outdoor pyranometer calibrations are outlined. Parameterizations for direct beam, total hemispherical and diffuse sky radiation and solar radiation technology are briefly reviewed. The uncertainties for various broadband solar radiations of solar energy and atmospheric effects are discussed. The varying responsivities of solar radiation with meteorological, statistical and climatological parameters and possibility atmospheric conditions was examined. (author)

Parameterization models for solar radiation and solar technology applications

International Nuclear Information System (INIS)

Khalil, Samy A.

2008-01-01

Solar radiation is very important for the evaluation and wide use of solar renewable energy systems. The development of calibration procedures for broadband solar radiation photometric instrumentation and the improvement of broadband solar radiation measurement accuracy have been done. An improved diffuse sky reference and photometric calibration and characterization software for outdoor pyranometer calibrations are outlined. Parameterizations for direct beam, total hemispherical and diffuse sky radiation and solar radiation technology are briefly reviewed. The uncertainties for various broadband solar radiations of solar energy and atmospheric effects are discussed. The varying responsivities of solar radiation with meteorological, statistical and climatological parameters and possibility atmospheric conditions was examined

Role of solar influences on geomagnetosphere and upper atmosphere

Science.gov (United States)

Kumar Tripathi, Arvind

The Earth's magnetosphere and upper atmosphere can be greatly perturbed by variations in the solar luminosity caused by disturbances on the solar surface. The state of near-Earth space environment is governed by the Sun and is very dynamic on all spatial and temporal scale. The geomagnetic field which protects the Earth from solar wind and cosmic rays is also essential to the evolution of life; its variations can have either direct or indirect effect on human physiology and health state even if the magnitude of the disturbance is small. Geomagnetic disturbances are seen at the surface of the Earth as perturbations in the components of the geomagnetic field, caused by electric currents flowing in the magnetosphere and upper atmosphere. Ionospheric and thermospheric storms also result from the redistribution of particles and fields. Global thermospheric storm winds and composition changes are driven by energy injection at high latitudes. These storm effects may penetrate downwards to the lower thermosphere and may even perturb the mesosphere. Many of the ionospheric changes at mid-latitude can be understood as a response to thermospheric perturbations. The transient bursts of solar energetic particles, often associated with large solar transients, have been observed to have effects on the Earth's middle and lower atmosphere, including the large-scale destruction of polar stratospheric and tropospheric ozone. In the present, we have discussed effect of solar influences on earth's magnetosphere and upper atmosphere that are useful to space weather and global warming, on the basis of various latest studies.

Modeling Climate Responses to Spectral Solar Forcing on Centennial and Decadal Time Scales

Science.gov (United States)

Wen, G.; Cahalan, R.; Rind, D.; Jonas, J.; Pilewskie, P.; Harder, J.

2012-01-01

We report a series of experiments to explore clima responses to two types of solar spectral forcing on decadal and centennial time scales - one based on prior reconstructions, and another implied by recent observations from the SORCE (Solar Radiation and Climate Experiment) SIM (Spectral 1rradiance Monitor). We apply these forcings to the Goddard Institute for Space Studies (GISS) Global/Middle Atmosphere Model (GCMAM). that couples atmosphere with ocean, and has a model top near the mesopause, allowing us to examine the full response to the two solar forcing scenarios. We show different climate responses to the two solar forCing scenarios on decadal time scales and also trends on centennial time scales. Differences between solar maximum and solar minimum conditions are highlighted, including impacts of the time lagged reSponse of the lower atmosphere and ocean. This contrasts with studies that assume separate equilibrium conditions at solar maximum and minimum. We discuss model feedback mechanisms involved in the solar forced climate variations.

TITAN’S UPPER ATMOSPHERE FROM CASSINI/UVIS SOLAR OCCULTATIONS

Energy Technology Data Exchange (ETDEWEB)

Capalbo, Fernando J.; Bénilan, Yves [Laboratoire Inter-Universitaire des Systèmes Atmosphériques (LISA), UMR 7583 du CNRS, Universités Paris Est Créteil (UPEC) and Paris Diderot - UPD, 61 avenue du Général de Gaulle, F-94010, Créteil Cédex (France); Yelle, Roger V.; Koskinen, Tommi T., E-mail: fernando.capalbo@lisa.u-pec.fr [Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721 (United States)

2015-12-01

Titan’s atmosphere is composed mainly of molecular nitrogen, methane being the principal trace gas. From the analysis of 8 solar occultations measured by the Extreme Ultraviolet channel of the Ultraviolet Imaging Spectrograph (UVIS) on board Cassini, we derived vertical profiles of N{sub 2} in the range 1100–1600 km and vertical profiles of CH{sub 4} in the range 850–1300 km. The correction of instrument effects and observational effects applied to the data are described. We present CH{sub 4} mole fractions, and average temperatures for the upper atmosphere obtained from the N{sub 2} profiles. The occultations correspond to different times and locations, and an analysis of variability of density and temperature is presented. The temperatures were analyzed as a function of geographical and temporal variables, without finding a clear correlation with any of them, although a trend of decreasing temperature toward the north pole was observed. The globally averaged temperature obtained is (150 ± 1) K. We compared our results from solar occultations with those derived from other UVIS observations, as well as studies performed with other instruments. The observational data we present confirm the atmospheric variability previously observed, add new information to the global picture of Titan’s upper atmosphere composition, variability, and dynamics, and provide new constraints to photochemical models.

Solar Flux Deposition And Heating Rates In Jupiter's Atmosphere

Science.gov (United States)

Perez-Hoyos, Santiago; Sánchez-Lavega, A.

2009-09-01

We discuss here the solar downward net flux in the 0.25 - 2.5 µm range in the atmosphere of Jupiter and the associated heating rates under a number of vertical cloud structure scenarios focusing in the effect of clouds and hazes. Our numerical model is based in the doubling-adding technique to solve the radiative transfer equation and it includes gas absorption by CH4, NH3 and H2, in addition to Rayleigh scattering by a mixture of H2 plus He. Four paradigmatic Jovian regions have been considered (hot-spots, belts, zones and Polar Regions). The hot-spots are the most transparent regions with downward net fluxes of 2.5±0.5 Wm-2 at the 6 bar level. The maximum solar heating is 0.04±0.01 K/day and occurs above 1 bar. Belts and zones characterization result in a maximum net downward flux of 0.5 Wm-2 at 2 bar and 0.015 Wm-2 at 6 bar. Heating is concentrated in the stratospheric and tropospheric hazes. Finally, Polar Regions are also explored and the results point to a considerable stratospheric heating of 0.04±0.02 K/day. In all, these calculations suggest that the role of the direct solar forcing in the Jovian atmospheric dynamics is limited to the upper 1 - 2 bar of the atmosphere except in the hot-spot areas. Acknowledgments: This work has been funded by Spanish MEC AYA2006-07735 with FEDER support and Grupos Gobierno Vasco IT-464-07.

Models of the quiet and active solar atmosphere from Harvard OSO data.

Science.gov (United States)

Noyes, R. W.

1971-01-01

Review of some Harvard Observatory programs aimed at defining the physical conditions in quiet and active solar regions on the basis of data obtained from the OSO-IV and OSO-VI spacecraft. The spectral range covered is from 300 A to 1400 A. This spectral range consists of emission lines and continua from abundant elements such as hydrogen, helium, carbon, nitrogen, oxygen, silicon, magnesium, aluminum, neon, iron, and calcium in various ionization states ranging from neutral to 15 times ionized. The structure is discussed of the quiet solar atmosphere as deduced from center-to-limb behavior of spectral lines and continua formed in the chromosphere and corona. In reviewing investigations of solar active regions, it is shown that the structure of these regions varies in a complicated manner from point to point. The local structure is influenced by factors such as the magnetic field configuration within the active region and the age or evolutionary state of the region.

A model for calculating hourly global solar radiation from satellite data in the tropics

International Nuclear Information System (INIS)

Janjai, S.; Pankaew, P.; Laksanaboonsong, J.

2009-01-01

A model for calculating global solar radiation from geostationary satellite data is presented. The model is designed to calculate the monthly average hourly global radiation in the tropics with high aerosol load. This model represents a physical relation between the earth-atmospheric albedo derived from GMS5 satellite data and the absorption and scattering coefficients of various atmospheric constituents. The absorption of solar radiation by water vapour which is important for the tropics, was calculated from ambient temperature and relative humidity. The relationship between the visibility and solar radiation depletion due to aerosols was developed for a high aerosol load environment. This relationship was used to calculate solar radiation depletion by aerosols in the model. The total column ozone from TOMS/EP satellite was employed for the determination of solar radiation absorbed by ozone. Solar radiation from four pyranometer stations was used to formulate the relationship between the satellite band earth-atmospheric albedo and broadband earth-atmospheric albedo required by the model. To test its performance, the model was used to compute the monthly average hourly global radiation at 25 solar radiation monitoring stations in tropical areas in Thailand. It was found that the values of monthly average of hourly global radiations calculated from the model were in good agreement with those obtained from the measurements, with the root mean square difference of 10%. After the validation the model was employed to generate hourly solar radiation maps of Thailand. These maps reveal the diurnal and season variation of solar radiation over the country.

A model for calculating hourly global solar radiation from satellite data in the tropics

Energy Technology Data Exchange (ETDEWEB)

Janjai, S.; Pankaew, P.; Laksanaboonsong, J. [Solar Energy Research Laboratory, Department of Physics, Faculty of Science, Silpakorn University, Nakhon Pathom 73000 (Thailand)

2009-09-15

A model for calculating global solar radiation from geostationary satellite data is presented. The model is designed to calculate the monthly average hourly global radiation in the tropics with high aerosol load. This model represents a physical relation between the earth-atmospheric albedo derived from GMS5 satellite data and the absorption and scattering coefficients of various atmospheric constituents. The absorption of solar radiation by water vapour which is important for the tropics, was calculated from ambient temperature and relative humidity. The relationship between the visibility and solar radiation depletion due to aerosols was developed for a high aerosol load environment. This relationship was used to calculate solar radiation depletion by aerosols in the model. The total column ozone from TOMS/EP satellite was employed for the determination of solar radiation absorbed by ozone. Solar radiation from four pyranometer stations was used to formulate the relationship between the satellite band earth-atmospheric albedo and broadband earth-atmospheric albedo required by the model. To test its performance, the model was used to compute the monthly average hourly global radiation at 25 solar radiation monitoring stations in tropical areas in Thailand. It was found that the values of monthly average of hourly global radiations calculated from the model were in good agreement with those obtained from the measurements, with the root mean square difference of 10%. After the validation the model was employed to generate hourly solar radiation maps of Thailand. These maps reveal the diurnal and season variation of solar radiation over the country. (author)

Wave heating of the solar atmosphere

Science.gov (United States)

Arregui, Iñigo

2015-04-01

Magnetic waves are a relevant component in the dynamics of the solar atmosphere. Their significance has increased because of their potential as a remote diagnostic tool and their presumed contribution to plasma heating processes. We discuss our current understanding of coronal heating by magnetic waves, based on recent observational evidence and theoretical advances. The discussion starts with a selection of observational discoveries that have brought magnetic waves to the forefront of the coronal heating discussion. Then, our theoretical understanding of the nature and properties of the observed waves and the physical processes that have been proposed to explain observations are described. Particular attention is given to the sequence of processes that link observed wave characteristics with concealed energy transport, dissipation and heat conversion. We conclude with a commentary on how the combination of theory and observations should help us to understand and quantify magnetic wave heating of the solar atmosphere.

Fourier analysis of Solar atmospheric numerical simulations accelerated with GPUs (CUDA).

Science.gov (United States)

Marur, A.

2015-12-01

Solar dynamics from the convection zone creates a variety of waves that may propagate through the solar atmosphere. These waves are important in facilitating the energy transfer between the sun's surface and the corona as well as propagating energy throughout the solar system. How and where these waves are dissipated remains an open question. Advanced 3D numerical simulations have furthered our understanding of the processes involved. Fourier transforms to understand the nature of the waves by finding the frequency and wavelength of these waves through the simulated atmosphere, as well as the nature of their propagation and where they get dissipated. In order to analyze the different waves produced by the aforementioned simulations and models, Fast Fourier Transform algorithms will be applied. Since the processing of the multitude of different layers of the simulations (of the order of several 100^3 grid points) would be time intensive and inefficient on a CPU, CUDA, a computing architecture that harnesses the power of the GPU, will be used to accelerate the calculations.

Atmospheric transmittance model for photosynthetically active radiation

International Nuclear Information System (INIS)

Paulescu, Marius; Stefu, Nicoleta; Gravila, Paul; Paulescu, Eugenia; Boata, Remus; Pacurar, Angel; Mares, Oana; Pop, Nicolina; Calinoiu, Delia

2013-01-01

A parametric model of the atmospheric transmittance in the PAR band is presented. The model can be straightforwardly applied for calculating the beam, diffuse and global components of the PAR solar irradiance. The required inputs are: air pressure, ozone, water vapor and nitrogen dioxide column content, Ångström's turbidity coefficient and single scattering albedo. Comparison with other models and ground measured data shows a reasonable level of accuracy for this model, making it suitable for practical applications. From the computational point of view the calculus is condensed into simple algebra which is a noticeable advantage. For users interested in speed-intensive computation of the effective PAR solar irradiance, a PC program based on the parametric equations along with a user guide are available online at http://solar.physics.uvt.ro/srms

On disturbances in the atmosphere produced by solar heating and by earth rotation

International Nuclear Information System (INIS)

Somsikov, V.M.

1980-01-01

Using solar terminator as an example analyzed are the problems connected with generation of various disturbances in atmosphere resulted from solar heating and earth rotation. An equation for atmosphere pressure disturbance in the spherical system of coordinates is obtained. The Green function of this equation is found for isothermal atmosphere. A spectrum of space harmonics of disturbances is found and its diagram is presented. It is shown that disturbances of large and small scales can arize in atmosphere simultaneously. They can be refferred to acoustic, gravitational and tidal waves. It is noted that the obtained equation solution permits to obtain a full spectrum of atmosphere vibrations, conditioned by its solar heating

Response of the upper atmosphere to variations in the solar soft x-ray irradiance. Ph.D. Thesis

Science.gov (United States)

Bailey, Scott Martin

1995-01-01

Terrestrial far ultraviolet (FUV) airglow emissions have been suggested as a means for remote sensing the structure of the upper atmosphere. The energy which leads to the excitation of FUV airglow emissions is solar irradiance at extreme ultraviolet (EUV) and soft x-ray wavelengths. Solar irradiance at these wavelengths is known to be highly variable; studies of nitric oxide (NO) in the lower thermosphere have suggested a variability of more than an order of magnitude in the solar soft x-ray irradiance. To properly interpret the FUV airflow, the magnitude of the solar energy deposition must be known. Previous analyses have used the electron impact excited Lyman-Birge-Hopfield (LBH) bands of N2 to infer the flux of photoelectrons in the atmosphere and thus to infer the magnitude of the solar irradiance. This dissertation presents the first simultaneous measurements of the FUV airglow, the major atmospheric constituent densities, and the solar EUV and soft x-ray irradiances. The measurements were made on three flights of an identical sounding rocket payload at different levels of solar activity. The linear response in brightness of the LBH bands to variations in solar irradiance is demonstrated. In addition to the N2 LBH bands, atomic oxygen lines at 135.6 and 130.4 nm are also studied. Unlike the LBH bands, these emissions undergo radiative transfer effects in the atmosphere. The OI emission at 135.6 nm is found to be well modeled using a radiative transfer calculation and the known excitation processes. Unfortunately, the assumed processes leading to OI 130.4 nm excitation are found to be insufficient to reproduce the observed variability of this emission. Production of NO in the atmosphere is examined; it is shown that a lower than previously reported variability in the solar soft x-ray irradiance is required to explain the variability of NO.

Measurement and modeling of shortwave irradiance components in cloud-free atmospheres

Energy Technology Data Exchange (ETDEWEB)

Halthore, R.N.

1999-08-04

Atmosphere scatters and absorbs incident solar radiation modifying its spectral content and decreasing its intensity at the surface. It is very useful to classify the earth-atmospheric solar radiation into several components--direct solar surface irradiance (E{sub direct}), diffuse-sky downward surface irradiance (E{sub diffuse}), total surface irradiance, and upwelling flux at the surface and at the top-of-the atmosphere. E{sub direct} depends only on the extinction properties of the atmosphere without regard to details of extinction, namely scattering or absorption; furthermore it can be accurately measured to high accuracy (0.3%) with the aid of an active cavity radiometer (ACR). E{sub diffuse} has relatively larger uncertainties both in its measurement using shaded pyranometers and in model estimates, owing to the difficulty in accurately characterizing pyranometers and in measuring model inputs such as surface reflectance, aerosol single scattering albedo, and phase function. Radiative transfer model simulations of the above surface radiation components in cloud-free skies using measured atmospheric properties show that while E{sub direct} estimates are closer to measurements, E{sub diffuse} is overestimated by an amount larger than the combined uncertainties in model inputs and measurements, illustrating a fundamental gap in the understanding of the magnitude of atmospheric absorption in cloud-free skies. The excess continuum type absorption required to reduce the E{sub diffuse} model overestimate ({approximately}3--8% absorptance) would significantly impact climate prediction and remote sensing. It is not clear at present what the source for this continuum absorption is. Here issues related to measurements and modeling of the surface irradiance components are discussed.

Fast and Accurate Hybrid Stream PCRTMSOLAR Radiative Transfer Model for Reflected Solar Spectrum Simulation in the Cloudy Atmosphere

Science.gov (United States)

Yang, Qiguang; Liu, Xu; Wu, Wan; Kizer, Susan; Baize, Rosemary R.

2016-01-01

A hybrid stream PCRTM-SOLAR model has been proposed for fast and accurate radiative transfer simulation. It calculates the reflected solar (RS) radiances with a fast coarse way and then, with the help of a pre-saved matrix, transforms the results to obtain the desired high accurate RS spectrum. The methodology has been demonstrated with the hybrid stream discrete ordinate (HSDO) radiative transfer (RT) model. The HSDO method calculates the monochromatic radiances using a 4-stream discrete ordinate method, where only a small number of monochromatic radiances are simulated with both 4-stream and a larger N-stream (N = 16) discrete ordinate RT algorithm. The accuracy of the obtained channel radiance is comparable to the result from N-stream moderate resolution atmospheric transmission version 5 (MODTRAN5). The root-mean-square errors are usually less than 5x10(exp -4) mW/sq cm/sr/cm. The computational speed is three to four-orders of magnitude faster than the medium speed correlated-k option MODTRAN5. This method is very efficient to simulate thousands of RS spectra under multi-layer clouds/aerosols and solar radiation conditions for climate change study and numerical weather prediction applications.

Cometary X-rays : solar wind charge exchange in cometary atmospheres

NARCIS (Netherlands)

Bodewits, Dennis

2007-01-01

The interaction of the solar wind with the planets and the interstellar medium is of key importance for the evolution of our solar system. The interaction with Earth's atmosphere is best known for the northern light. In case of Mars, the interaction with the solar wind might have lead to the erosion

Estimativa de radiação solar via modelagem atmosférica de mesoescala aplicada à região nordeste do Brasil Estimation of solar radiation by mesoscale atmospheric modeling applied to the northeast Brazil region

Directory of Open Access Journals (Sweden)

Otacilio Leandro De Menezes Neto

2009-09-01

Full Text Available A utilização de fontes alternativas de energias, como a solar, a eólica e a biomassa, vem crescendo significativamente nos últimos anos, sendo a energia solar, em particular, uma fonte abundante na região Nordeste do Brasil. O conhecimento preciso da radiação solar incidente é, assim, de grande importância para o planejamento energético brasileiro, servindo de base para o desenvolvimento de futuros projetos de plantas fotovoltaicas e de aproveitamento da energia solar. Este trabalho apresenta uma metodologia para o mapeamento da energia solar incidente ao nível do solo para a região Nordeste do Brasil, utilizando um modelo atmosférico de mesoescala (Regional Atmospheric Modeling System - RAMS, validado e ajustado por meio dos dados medidos pela rede de plataformas de coleta de dados (PCDs da Fundação Cearense de Meteorologia e Recursos Hídricos (FUNCEME. Os resultados mostraram que o modelo apresenta erros sistemáticos, sobreestimando a radiação na superfície, porém após as devidas correções estatísticas, utilizando-se uma relação entre a fração de cobertura de nuvens prevista pelo modelo e a radiação observada na superfície e estimada no topo da atmosfera, encontram-se correlações de 0,92 com intervalos de confiança de 13,5 W/m² para dados com base mensal. Usando essa metodologia, a estimativa do valor médio anual (após ajustes da radiação solar incidente no estado do Ceará é de 215 W/m² (máximo em outubro: 260 W/m².The use of renewable energy sources, like solar, wind and biomass is rapidly increasing in recent years, with solar radiation being a particularly abundant energy source over Northeast Brazil. Thus, the proper quantitative knowledge of the incoming solar radiation is of great importance for energy generation planning in Brazil, serving as basis for developing future projects of photovoltaic power plants and solar energy exploration. This work presents a methodology for mapping the

Atmosphere-soil-vegetation model including CO2 exchange processes: SOLVEG2

International Nuclear Information System (INIS)

Nagai, Haruyasu

2004-11-01

A new atmosphere-soil-vegetation model named SOLVEG2 (SOLVEG version 2) was developed to study the heat, water, and CO 2 exchanges between the atmosphere and land-surface. The model consists of one-dimensional multilayer sub-models for the atmosphere, soil, and vegetation. It also includes sophisticated processes for solar and long-wave radiation transmission in vegetation canopy and CO 2 exchanges among the atmosphere, soil, and vegetation. Although the model usually simulates only vertical variation of variables in the surface-layer atmosphere, soil, and vegetation canopy by using meteorological data as top boundary conditions, it can be used by coupling with a three-dimensional atmosphere model. In this paper, details of SOLVEG2, which includes the function of coupling with atmosphere model MM5, are described. (author)

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.

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

INSTRUMENTATION FOR MEASURING AND TRANSMISSION THE SOLAR RADIATION THROUGH EARTH’S ATMOSPHERE

Directory of Open Access Journals (Sweden)

Alexandru Dan Toma

2013-07-01

Full Text Available The Sun's energy is distributed over a broad range of the electromagnetic spectrum and Sun behaves approximately like a "blackbody" radiating at a temperature of about 5800 K with maximum output in the green-yellow part of the visible spectrum, around 500 nm. Not all solar radiation reaching the top of the atmosphere reaches Earth's surface due to a various optical phenomena in regard to solar radiation crossing the Earth’s atmosphere. In order to investigate them, there are two general categories of instruments used to measure the transmission of solar radiation through Earth's atmosphere: instruments that measure radiation from the entire sky and instruments that measure only direct solar radiation. Within each of these categories, instruments can be further subdivided into those that measure radiation over a broad range of wavelengths and those that measure only specific wavelengths.

Composition changes after the "Halloween" solar proton event: the High Energy Particle Precipitation in the Atmosphere (HEPPA model versus MIPAS data intercomparison study

Directory of Open Access Journals (Sweden)

B. Funke

2011-09-01

Full Text Available We have compared composition changes of NO, NO₂, H₂O₂, O₃, N₂O, HNO₃, N₂O₅, HNO₄, ClO, HOCl, and ClONO₂ as observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS on Envisat in the aftermath of the "Halloween" solar proton event (SPE in late October 2003 at 25–0.01 hPa in the Northern Hemisphere (40–90° N and simulations performed by the following atmospheric models: the Bremen 2-D model (B2dM and Bremen 3-D Chemical Transport Model (B3dCTM, the Central Aerological Observatory (CAO model, FinROSE, the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA, the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA, the ECHAM5/MESSy Atmospheric Chemistry (EMAC model, the modeling tool for SOlar Climate Ozone Links studies (SOCOL and SOCOLi, and the Whole Atmosphere Community Climate Model (WACCM4. The large number of participating models allowed for an evaluation of the overall ability of atmospheric models to reproduce observed atmospheric perturbations generated by SPEs, particularly with respect to NO_y and ozone changes. We have further assessed the meteorological conditions and their implications for the chemical response to the SPE in both the models and observations by comparing temperature and tracer (CH₄ and CO fields.

Simulated SPE-induced ozone losses agree on average within 5 % with the observations. Simulated NO_y enhancements around 1 hPa, however, are typically 30 % higher than indicated by the observations which are likely to be related to deficiencies in the used ionization rates, though other error sources related to the models' atmospheric background state and/or transport schemes cannot be excluded. The analysis of the observed and modeled NO_y partitioning in the aftermath of the SPE has demonstrated the need to implement

Instrument development for atmospheric radiation measurement (ARM): Status of the Atmospheric Emitted Radiance Interferometer - extended Resolution (AERI-X), the Solar Radiance Transmission Interferometer (SORTI), and the Absolute Solar Transmission Inferometer (ASTI)

Energy Technology Data Exchange (ETDEWEB)

Murcray, F.; Stephen, T.; Kosters, J. [Univ. of Denver, CO (United States)

1996-04-01

This paper describes three instruments currently under developemnt for the Atmospheric Radiation Measurement (ARM) Program at the University of Denver: the AERI-X (Atmospheric Emitted Radiance Interferometer-Extended Resolution) and the SORTI (Solar R adiance Transmission Interferometer), and ASTI (Absolute Solar transmission Interferometer).

Solar system astrophysics planetary atmospheres and the outer solar system

CERN Document Server

Milone, Eugene F

2008-01-01

Solar System Astrophysics opens with coverage of the atmospheres, ionospheres and magnetospheres of the Earth, Venus and Mars and the magnetosphere of Mercury. The book then provides an introduction to meteorology and treating the physics and chemistry of these areas in considerable detail. What follows are the structure, composition, particle environments, satellites, and rings of Jupiter, Saturn, Uranus and Neptune, making abundant use of results from space probes. Solar System Astrophysics follows the history, orbits, structure, origin and demise of comets and the physics of meteors and provides a thorough treatment of meteorites, the asteroids and, in the outer solar system, the Kuiper Belt objects. The methods and results of extrasolar planet searches, the distinctions between stars, brown dwarfs, and planets, and the origins of planetary systems are examined. Historical introductions precede the development and discussion in most chapters. A series of challenges, useful as homework assignments or as foc...

Atmospheric effects on the photovoltaic performance of hybrid perovskite solar cells

KAUST Repository

Sheikh, Arif D.

2015-06-01

Organometal trihalide perovskite solar cells have recently attracted lots of attention in the photovoltaic community due to their escalating efficiency and solution processability. The most efficient organometallic mixed-halide sensitized solar cells often employ 2,2′7,7′-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9′-spirobifluorene (spiro-MeOTAD) as the hole-transporting material. In this work, we investigated the effect of different atmospheric storage conditions, particularly vacuum, dry nitrogen, and dry air, on the photovoltaic performance of TiO2-CH3NH3PbI3-xClx-spiro-MeOTAD solar cells. We found that spin coating of spiro-MeOTAD in an oxygen atmosphere alone was not adequate to functionalize its hole-transport property completely, and our systematic experiments revealed that the device efficiency depends on the ambient atmospheric conditions during the drying process of spiro-MeOTAD. Complementary incident photon to current conversion efficiency (IPCE), light absorption and photoluminescence quenching measurements allowed us to attribute the atmosphere-dependent efficiency to the improved electronic characteristics of the solar cells. Furthermore, our Fourier transform infrared and electrical impedance measurements unambiguously detected modifications in the spiro-MeOTAD after the drying processes in different gas environments. Our findings demonstrate that proper oxidization and p-doping in functionalizing spiro-MeOTAD play a very critical role in determining device performance. These findings will facilitate the search for alternative hole-transporting materials in high-performance perovskite solar cells with long-term stability.

NON-EQUILIBRIUM HELIUM IONIZATION IN AN MHD SIMULATION OF THE SOLAR ATMOSPHERE

International Nuclear Information System (INIS)

Golding, Thomas Peter; Carlsson, Mats; Leenaarts, Jorrit

2016-01-01

The ionization state of the gas in the dynamic solar chromosphere can depart strongly from the instantaneous statistical equilibrium commonly assumed in numerical modeling. We improve on earlier simulations of the solar atmosphere that only included non-equilibrium hydrogen ionization by performing a 2D radiation-magnetohydrodynamics simulation featuring non-equilibrium ionization of both hydrogen and helium. The simulation includes the effect of hydrogen Lyα and the EUV radiation from the corona on the ionization and heating of the atmosphere. Details on code implementation are given. We obtain helium ion fractions that are far from their equilibrium values. Comparison with models with local thermodynamic equilibrium (LTE) ionization shows that non-equilibrium helium ionization leads to higher temperatures in wavefronts and lower temperatures in the gas between shocks. Assuming LTE ionization results in a thermostat-like behavior with matter accumulating around the temperatures where the LTE ionization fractions change rapidly. Comparison of DEM curves computed from our models shows that non-equilibrium ionization leads to more radiating material in the temperature range 11–18 kK, compared to models with LTE helium ionization. We conclude that non-equilibrium helium ionization is important for the dynamics and thermal structure of the upper chromosphere and transition region. It might also help resolve the problem that intensities of chromospheric lines computed from current models are smaller than those observed

Modelling of atmospheric effects on the angular distribution of a backscattering peak

International Nuclear Information System (INIS)

Powers, B.J.; Gerstl, S.A.W.

1987-01-01

If off-nadir satellite sensing of vegetative surfaces is considered, understanding the angular distribution of the radiance exiting the atmosphere in all upward directions is of interest. Of particular interest is the discovery of those reflectance features which are invariant to atmospheric perturbations. When mono-directional radiation is incident on a vegetative scene a characteristic angular signature called the hot-spot is produced in the solar retro-direction. The remotely sensed hot-spot is modified by atmospheric extinction of the direct and reflected solar radiation, atmospheric backscattering, and the diffuse sky irradiance incident on the surface. It is demonstrated, however, by radiative transfer calculations through model atmospheres that at least one parameter which characterizes the canopy hot-spot, namely its angular half width, is invariant to atmospheric perturbations. 7 refs., 4 figs., 1 tab

Waves and Magnetism in the Solar Atmosphere (WAMIS)

Energy Technology Data Exchange (ETDEWEB)

Ko, Yuan-Kuen [Space Science Division, Naval Research Laboratory, Washington, DC (United States); Moses, John D. [Heliophysics Division, Science Mission Directorate, NASA, Washington, DC (United States); Laming, John M.; Strachan, Leonard; Tun Beltran, Samuel [Space Science Division, Naval Research Laboratory, Washington, DC (United States); Tomczyk, Steven; Gibson, Sarah E. [High Altitude Observatory, Boulder, CO (United States); Auchère, Frédéric [Institut d' Astrophysique Spatiale, CNRS Université Paris-Sud, Orsay (France); Casini, Roberto [High Altitude Observatory, Boulder, CO (United States); Fineschi, Silvano [INAF - National Institute for Astrophysics, Astrophysical Observatory of Torino, Pino Torinese (Italy); Knoelker, Michael [High Altitude Observatory, Boulder, CO (United States); Korendyke, Clarence [Space Science Division, Naval Research Laboratory, Washington, DC (United States); McIntosh, Scott W. [High Altitude Observatory, Boulder, CO (United States); Romoli, Marco [Department of Physics and Astronomy, University of Florence, Florence (Italy); Rybak, Jan [Astronomical Institute, Slovak Academy of Sciences, Tatranska Lomnica (Slovakia); Socker, Dennis G. [Space Science Division, Naval Research Laboratory, Washington, DC (United States); Vourlidas, Angelos [Applied Physics Laboratory, Johns Hopkins University, Laurel, MD (United States); Wu, Qian, E-mail: yuan-kuen.ko@nrl.navy.mil [High Altitude Observatory, Boulder, CO (United States)

2016-02-16

Comprehensive measurements of magnetic fields in the solar corona have a long history as an important scientific goal. Besides being crucial to understanding coronal structures and the Sun's generation of space weather, direct measurements of their strength and direction are also crucial steps in understanding observed wave motions. In this regard, the remote sensing instrumentation used to make coronal magnetic field measurements is well suited to measuring the Doppler signature of waves in the solar structures. In this paper, we describe the design and scientific values of the Waves and Magnetism in the Solar Atmosphere (WAMIS) investigation. WAMIS, taking advantage of greatly improved infrared filters and detectors, forward models, advanced diagnostic tools and inversion codes, is a long-duration high-altitude balloon payload designed to obtain a breakthrough in the measurement of coronal magnetic fields and in advancing the understanding of the interaction of these fields with space plasmas. It consists of a 20 cm aperture coronagraph with a visible-IR spectro-polarimeter focal plane assembly. The balloon altitude would provide minimum sky background and atmospheric scattering at the wavelengths in which these observations are made. It would also enable continuous measurements of the strength and direction of coronal magnetic fields without interruptions from the day–night cycle and weather. These measurements will be made over a large field-of-view allowing one to distinguish the magnetic signatures of different coronal structures, and at the spatial and temporal resolutions required to address outstanding problems in coronal physics. Additionally, WAMIS could obtain near simultaneous observations of the electron scattered K-corona for context and to obtain the electron density. These comprehensive observations are not provided by any current single ground-based or space observatory. The fundamental advancements achieved by the near-space observations

Waves and Magnetism in the Solar Atmosphere (WAMIS)

International Nuclear Information System (INIS)

Ko, Yuan-Kuen; Moses, John D.; Laming, John M.; Strachan, Leonard; Tun Beltran, Samuel; Tomczyk, Steven; Gibson, Sarah E.; Auchère, Frédéric; Casini, Roberto; Fineschi, Silvano; Knoelker, Michael; Korendyke, Clarence; McIntosh, Scott W.; Romoli, Marco; Rybak, Jan; Socker, Dennis G.; Vourlidas, Angelos; Wu, Qian

2016-01-01

Comprehensive measurements of magnetic fields in the solar corona have a long history as an important scientific goal. Besides being crucial to understanding coronal structures and the Sun's generation of space weather, direct measurements of their strength and direction are also crucial steps in understanding observed wave motions. In this regard, the remote sensing instrumentation used to make coronal magnetic field measurements is well suited to measuring the Doppler signature of waves in the solar structures. In this paper, we describe the design and scientific values of the Waves and Magnetism in the Solar Atmosphere (WAMIS) investigation. WAMIS, taking advantage of greatly improved infrared filters and detectors, forward models, advanced diagnostic tools and inversion codes, is a long-duration high-altitude balloon payload designed to obtain a breakthrough in the measurement of coronal magnetic fields and in advancing the understanding of the interaction of these fields with space plasmas. It consists of a 20 cm aperture coronagraph with a visible-IR spectro-polarimeter focal plane assembly. The balloon altitude would provide minimum sky background and atmospheric scattering at the wavelengths in which these observations are made. It would also enable continuous measurements of the strength and direction of coronal magnetic fields without interruptions from the day–night cycle and weather. These measurements will be made over a large field-of-view allowing one to distinguish the magnetic signatures of different coronal structures, and at the spatial and temporal resolutions required to address outstanding problems in coronal physics. Additionally, WAMIS could obtain near simultaneous observations of the electron scattered K-corona for context and to obtain the electron density. These comprehensive observations are not provided by any current single ground-based or space observatory. The fundamental advancements achieved by the near-space observations

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.

Solar Wind Interaction and Impact on the Venus Atmosphere

Science.gov (United States)

Futaana, Yoshifumi; Stenberg Wieser, Gabriella; Barabash, Stas; Luhmann, Janet G.

2017-11-01

Venus has intrigued planetary scientists for decades because of its huge contrasts to Earth, in spite of its nickname of "Earth's Twin". Its invisible upper atmosphere and space environment are also part of the larger story of Venus and its evolution. In 60s to 70s, several missions (Venera and Mariner series) explored Venus-solar wind interaction regions. They identified the basic structure of the near-Venus space environment, for example, existence of the bow shock, magnetotail, ionosphere, as well as the lack of the intrinsic magnetic field. A huge leap in knowledge about the solar wind interaction with Venus was made possible by the 14-year long mission, Pioneer Venus Orbiter (PVO), launched in 1978. More recently, ESA's probe, Venus Express (VEX), was inserted into orbit in 2006, operated for 8 years. Owing to its different orbit from that of PVO, VEX made unique measurements in the polar and terminator regions, and probed the near-Venus tail for the first time. The near-tail hosts dynamic processes that lead to plasma energization. These processes in turn lead to the loss of ionospheric ions to space, slowly eroding the Venusian atmosphere. VEX carried an ion spectrometer with a moderate mass-separation capability and the observed ratio of the escaping hydrogen and oxygen ions in the wake indicates the stoichiometric loss of water from Venus. The structure and dynamics of the induced magnetosphere depends on the prevailing solar wind conditions. VEX studied the response of the magnetospheric system on different time scales. A plethora of waves was identified by the magnetometer on VEX; some of them were not previously observed by PVO. Proton cyclotron waves were seen far upstream of the bow shock, mirror mode waves were observed in magnetosheath and whistler mode waves, possibly generated by lightning discharges were frequently seen. VEX also encouraged renewed numerical modeling efforts, including fluid-type of models and particle-fluid hybrid type of models

Phase space representation of neutron monitor count rate and atmospheric electric field in relation to solar activity in cycles 21 and 22.

Science.gov (United States)

Silva, H G; Lopes, I

Heliospheric modulation of galactic cosmic rays links solar cycle activity with neutron monitor count rate on earth. A less direct relation holds between neutron monitor count rate and atmospheric electric field because different atmospheric processes, including fluctuations in the ionosphere, are involved. Although a full quantitative model is still lacking, this link is supported by solid statistical evidence. Thus, a connection between the solar cycle activity and atmospheric electric field is expected. To gain a deeper insight into these relations, sunspot area (NOAA, USA), neutron monitor count rate (Climax, Colorado, USA), and atmospheric electric field (Lisbon, Portugal) are presented here in a phase space representation. The period considered covers two solar cycles (21, 22) and extends from 1978 to 1990. Two solar maxima were observed in this dataset, one in 1979 and another in 1989, as well as one solar minimum in 1986. Two main observations of the present study were: (1) similar short-term topological features of the phase space representations of the three variables, (2) a long-term phase space radius synchronization between the solar cycle activity, neutron monitor count rate, and potential gradient (confirmed by absolute correlation values above ~0.8). Finally, the methodology proposed here can be used for obtaining the relations between other atmospheric parameters (e.g., solar radiation) and solar cycle activity.

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.

Modeling Atmospheric Activity of Cool Stars

Science.gov (United States)

Schrijver, C. J.

2003-10-01

This review discusses a set of simple models for cool-star activity with which we compute (1) photospheric field patterns on stars of different activity levels, (2) the associated outer-atmospheric field configurations, and (3) the soft X-ray emission that is expected to result from the ensemble of loop atmospheres in the coronae of these stars. The model is based on empirically-determined properties of solar activity. It allows us to extrapolate to stars of significantly higher and lower activity than seen on the present-day Sun through its cycle. With it, we can, for example, gain insight into stellar field patterns (including a possible formation mechanism for polar starspots), as well as in the properties of coronal heating (helpful in the identification of the quiescent coronal heating mechanism). Lacking comprehensive theoretical understanding, the model's reliance on empirical solar data means that the multitude of processes involved are approximated to be independent of rotation rate, activity level, and fundamental stellar parameters, or -- where unavoidably necessary -- assumed to simply scale with activity. An evaluation of the most important processes involved guides a discussion of the limits of the model, of the limitations in our knowledge, and of future needs. "I propose to adopt such rules as will ensure the testability of scientific statements; which is to say, their falsifiability." Karl Popper (1902-1994)

A Model for Straight and Helical Solar Jets: II. Parametric Study of the Plasma Beta

Science.gov (United States)

Pariat, E.; Dalmasse, K.; DeVore, C. R.; Antiochos, S. K.; Karpen, J. T.

2016-01-01

Context. Jets are dynamic, impulsive, well-collimated plasma events that develop at many different scales and in different layers of the solar atmosphere. Aims. Jets are believed to be induced by magnetic reconnection, a process central to many astrophysical phenomena. Within the solar atmosphere, jet-like events develop in many different environments, e.g. in the vicinity of active regions as well as in coronal holes, and at various scales, from small photospheric spicules to large coronal jets. In all these events, signatures of helical structure and/or twisting/rotating motions are regularly observed. The present study aims to establish that a single model can generally reproduce the observed properties of these jet-like events. Methods. In this study, using our state-of-the-art numerical solver ARMS, we present a parametric study of a numerical tridimensional magnetohydrodynamic (MHD) model of solar jet-like events. Within the MHD paradigm, we study the impact of varying the atmospheric plasma beta on the generation and properties of solar-like jets. Results. The parametric study validates our model of jets for plasma beta ranging from 10(sup 3) to 1, typical of the different layers and magnetic environments of the solar atmosphere. Our model of jets can robustly explain the generation of helical solar jet-like events at various beta less than or equal to 1. We show that the plasma beta modifies the morphology of the helical jet, explaining the different observed shapes of jets at different scales and in different layers of the solar atmosphere. Conclusions. Our results allow us to understand the energisation, triggering, and driving processes of jet-like events. Our model allows us to make predictions of the impulsiveness and energetics of jets as determined by the surrounding environment, as well as the morphological properties of the resulting jets.

Acoustic waves in the solar atmosphere. VII - Non-grey, non-LTE H(-) models

Science.gov (United States)

Schmitz, F.; Ulmschneider, P.; Kalkofen, W.

1985-01-01

The propagation and shock formation of radiatively damped acoustic waves in the solar chromosphere are studied under the assumption that H(-) is the only absorber; the opacity is non-grey. Deviations from local thermodynamic equilibrium (LTE) are permitted. The results of numerical simulations show the depth dependence of the heating by the acoustic waves to be insensitive to the mean state of the atmosphere. After the waves have developed into shocks, their energy flux decays exponentially with a constant damping length of about 1.4 times the pressure scale height, independent of initial flux and wave period. Departures from LTE have a strong influence on the mean temperature structure in dynamical chromosphere models; this is even more pronounced in models with reduced particle density - simulating conditions in magnetic flux tubes - which show significantly increased temperatures in response to mechanical heating. When the energy dissipation of the waves is sufficiently large to dissociate most of the H(-) ions, a strong temperature rise is found that is reminiscent of the temperature structure in the transition zone between chromosphere and corona; the energy flux remaining in the waves then drives mass motions.

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

Experimental investigation of simple solar radiation spectral model performances under a Mediterranean Algerian's climate

International Nuclear Information System (INIS)

Koussa, Mustapha; Saheb-Koussa, Djohra; Hadji, Seddik

2017-01-01

In this work, models are presented that, under cloudless atmosphere conditions, calculate solar spectral normal direct and horizontal diffuse irradiance. Based on different monochromatic transmission factors related to the main constituents of the atmosphere, the models evaluate the spectral irradiance between 0.29 and 4.0 μm. Absorption by water vapor, uniformly mixed gas, and ozone are considered as well as scattering by the atmospheric aerosols. Based on the equations relative to each one of the two retained models, a MATLAB program is developed to evaluate the spectral distribution of each solar irradiance component. Hence, the geographical coordinates of the site, and the monochromatic distribution of the extraterrestrial irradiance are used as input data. From three-year data measurement records made in Bouzareah site (temperate climate), thirty eight days characterized by a clear sky state have been selected from over different months of the year and the corresponding main meteorological parameters used as input parameters. So, because only the five-minute broadband data measurements are available, the modified numerical trapeze method is used to integrate the monochromatic curve values related to each solar irradiance component. Consequently, the precipitable water vapor amount, the Angstrom and Linke turbidity factors are evaluated and a multi-linear correlation relating the Linke turbidity factor to the precipitable water vapor and the Angstrom turbidity coefficient is established. Hence, according to the mean values of Linke and Angstrom turbidity factors and those of the precipitable water vapor, the site of Bouzareah is classified as a rural site. So, the effect of the main constituents of the atmosphere on the spectral distribution of solar irradiance is discussed and, it is also observed that the aerosol amount contained in the atmosphere affects most both of the diffuse and direct solar irradiance amount than that of the horizontal and inclined

Improved Statistical Model Of 10.7-cm Solar Radiation

Science.gov (United States)

Vedder, John D.; Tabor, Jill L.

1993-01-01

Improved mathematical model simulates short-term fluctuations of flux of 10.7-cm-wavelength solar radiation during 91-day averaging period. Called "F10.7 flux", important as measure of solar activity and because it is highly correlated with ultraviolet radiation causing fluctuations in heating and density of upper atmosphere. F10.7 flux easily measureable at surface of Earth.

Energy loss of solar p modes due to the excitation of magnetic sausage tube waves: Importance of coupling the upper atmosphere

International Nuclear Information System (INIS)

Gascoyne, A.; Jain, R.; Hindman, B. W.

2014-01-01

We consider damping and absorption of solar p modes due to their energy loss to magnetic tube waves that can freely carry energy out of the acoustic cavity. The coupling of p modes and sausage tube waves is studied in a model atmosphere composed of a polytropic interior above which lies an isothermal upper atmosphere. The sausage tube waves, excited by p modes, propagate along a magnetic fibril which is assumed to be a vertically aligned, stratified, thin magnetic flux tube. The deficit of p-mode energy is quantified through the damping rate, Γ, and absorption coefficient, α. The variation of Γ and α as a function of frequency and the tube's plasma properties is studied in detail. Previous similar studies have considered only a subphotospheric layer, modeled as a polytrope that has been truncated at the photosphere. Such studies have found that the resulting energy loss by the p modes is very sensitive to the upper boundary condition, which, due to the lack of an upper atmosphere, have been imposed in a somewhat ad hoc manner. The model presented here avoids such problems by using an isothermal layer to model the overlying atmosphere (chromosphere, and, consequently, allows us to analyze the propagation of p-mode-driven sausage waves above the photosphere. In this paper, we restrict our attention to frequencies below the acoustic cut off frequency. We demonstrate the importance of coupling all waves (acoustic, magnetic) in the subsurface solar atmosphere with the overlying atmosphere in order to accurately model the interaction of solar f and p modes with sausage tube waves. In calculating the absorption and damping of p modes, we find that for low frequencies, below ≈3.5 mHz, the isothermal atmosphere, for the two-region model, behaves like a stress-free boundary condition applied at the interface (z = –z 0 ).

Energy loss of solar p modes due to the excitation of magnetic sausage tube waves: Importance of coupling the upper atmosphere

Energy Technology Data Exchange (ETDEWEB)

Gascoyne, A.; Jain, R. [Applied Mathematics Department, University of Sheffield, Sheffield S3 7RH (United Kingdom); Hindman, B. W., E-mail: a.d.gascoyne@sheffield.ac.uk, E-mail: r.jain@sheffield.ac.uk [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado at Boulder, Boulder, CO 80309-0440 (United States)

2014-07-10

We consider damping and absorption of solar p modes due to their energy loss to magnetic tube waves that can freely carry energy out of the acoustic cavity. The coupling of p modes and sausage tube waves is studied in a model atmosphere composed of a polytropic interior above which lies an isothermal upper atmosphere. The sausage tube waves, excited by p modes, propagate along a magnetic fibril which is assumed to be a vertically aligned, stratified, thin magnetic flux tube. The deficit of p-mode energy is quantified through the damping rate, Γ, and absorption coefficient, α. The variation of Γ and α as a function of frequency and the tube's plasma properties is studied in detail. Previous similar studies have considered only a subphotospheric layer, modeled as a polytrope that has been truncated at the photosphere. Such studies have found that the resulting energy loss by the p modes is very sensitive to the upper boundary condition, which, due to the lack of an upper atmosphere, have been imposed in a somewhat ad hoc manner. The model presented here avoids such problems by using an isothermal layer to model the overlying atmosphere (chromosphere, and, consequently, allows us to analyze the propagation of p-mode-driven sausage waves above the photosphere. In this paper, we restrict our attention to frequencies below the acoustic cut off frequency. We demonstrate the importance of coupling all waves (acoustic, magnetic) in the subsurface solar atmosphere with the overlying atmosphere in order to accurately model the interaction of solar f and p modes with sausage tube waves. In calculating the absorption and damping of p modes, we find that for low frequencies, below ≈3.5 mHz, the isothermal atmosphere, for the two-region model, behaves like a stress-free boundary condition applied at the interface (z = –z{sub 0}).

Modelization and numerical simulation of atmospheric aerosols dynamics

International Nuclear Information System (INIS)

Debry, Edouard

2004-01-01

Chemical-transport models are now able to describe in a realistic way gaseous pollutants behavior in the atmosphere. Nevertheless atmospheric pollution also exists as a fine suspended particles, called aerosols which interact with gaseous phase, solar radiation, and have their own dynamic behavior. The goal of this thesis is the modelization and numerical simulation of the General Dynamic Equation of aerosols (GDE). Part I deals with some theoretical aspects of aerosol modelization. Part II is dedicated to the building of one size resolved aerosol model (SIREAM). In part III we perform the reduction of this model in order to use it in dispersion models as POLAIR3D. Several modelization issues are still opened: organic aerosol matter, externally mixed aerosols, coupling with turbulent mixing, and nano-particles. (author) [fr

Solar and atmospheric neutrinos in three generations with a magnetic moment

International Nuclear Information System (INIS)

Pulido, J.; Tao, Z.

1995-01-01

A solution to the solar and atomospheric neutrino problems in three generations in the joint context of matter oscillations and the magnetic moment is investigated. An appropriate rotation of the evolution Hamiltonian reduces the three generation case to a two generation one. A convenient background for such a scenario with small neutrino masses and large magnetic moments is given by the Zee-type models, in which the mass generation mechanism leads to a pair of separate orders of magnitude for the mass square differences between neutrino species. We obtain a ratio var-epsilon congruent 10 -2 --10 -3 between these orders of magnitude, so that one of them [(0.3--3)x10 -2 eV 2 ] is suitable for the atmospheric neutrino solution and the other (∼10 -5 eV 2 ) for the solar neutrino solution. The magnetic moment leads to a decrease of the survival probability with solar neutrino energy. Such a decrease is consistent with the experimental situation

Some studies relating to solar-terrestrial physics and the middle atmosphere

International Nuclear Information System (INIS)

Theobald, A.G.

1977-12-01

A review is given of observed variations in the Earth's rotation rate, and mechanisms by which the Sun might affect the length of day are discussed. Solar activity and means by which the planets might influence this activity are considered. Observed solar activity - weather correlations, in particular in relation to the sun-based, interplanetary magnetic sector structure and some of the suggested mechanisms for producing these correlations are discussed. The simple photochemical production of ozone in the middle atmosphere and the manner in which cosmic rays, through the production of nitrogen compounds, alter the ozone concentration at high altitudes is described. A computer model is developed which calculates ozone concentrations and energy absorption at any altitude, latitude, longitude and time of year and used to predict ozone and temperature change profiles over a 14-day cycle of ultra-violet changes. The existence of a solar magnetic sector linked variation of the high latitude, high altitude NO concentration is postulated and this is incorporated into the computer model to predict a temperature oscillation over a 14-day cycle which varies with geographic latitude and longitude. This effect is investigated in detail. (UK)

Changes in atmospheric circulation between solar maximum and minimum conditions in winter and summer

Science.gov (United States)

Lee, Jae Nyung

2008-10-01

Statistically significant climate responses to the solar variability are found in Northern Annular Mode (NAM) and in the tropical circulation. This study is based on the statistical analysis of numerical simulations with ModelE version of the chemistry coupled Goddard Institute for Space Studies (GISS) general circulation model (GCM) and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis. The low frequency large scale variability of the winter and summer circulation is described by the NAM, the leading Empirical Orthogonal Function (EOF) of geopotential heights. The newly defined seasonal annular modes and its dynamical significance in the stratosphere and troposphere in the GISS ModelE is shown and compared with those in the NCEP/NCAR reanalysis. In the stratosphere, the summer NAM obtained from NCEP/NCAR reanalysis as well as from the ModelE simulations has the same sign throughout the northern hemisphere, but shows greater variability at low latitudes. The patterns in both analyses are consistent with the interpretation that low NAM conditions represent an enhancement of the seasonal difference between the summer and the annual averages of geopotential height, temperature and velocity distributions, while the reverse holds for high NAM conditions. Composite analysis of high and low NAM cases in both the model and observation suggests that the summer stratosphere is more "summer-like" when the solar activity is near a maximum. This means that the zonal easterly wind flow is stronger and the temperature is higher than normal. Thus increased irradiance favors a low summer NAM. A quantitative comparison of the anti-correlation between the NAM and the solar forcing is presented in the model and in the observation, both of which show lower/higher NAM index in solar maximum/minimum conditions. The summer NAM in the troposphere obtained from NCEP/NCAR reanalysis has a dipolar zonal structure with maximum

A parameterization for the absorption of solar radiation by water vapor in the earth's atmosphere

Science.gov (United States)

Wang, W.-C.

1976-01-01

A parameterization for the absorption of solar radiation as a function of the amount of water vapor in the earth's atmosphere is obtained. Absorption computations are based on the Goody band model and the near-infrared absorption band data of Ludwig et al. A two-parameter Curtis-Godson approximation is used to treat the inhomogeneous atmosphere. Heating rates based on a frequently used one-parameter pressure-scaling approximation are also discussed and compared with the present parameterization.

Mid-latitude summer response of the middle atmosphere to short-term solar UV changes

Directory of Open Access Journals (Sweden)

P. Keckhut

1995-06-01

Full Text Available Temperature and wind data obtained with Rayleigh lidar since 1979 and Russian rockets since 1964 are analyzed to deduce the summer response of the middle atmosphere to short-term solar UV changes. The equivalent width of the 1083 nm He I line is used as a proxy to monitor the short-term UV flux changes. Spectral analyses are performed on 108-day windows to extract the 27-day component from temperature, wind and solar data sets. Linear regressions between these spectral harmonics show some significant correlations around 45 km at mid-latitudes. For large 27-day solar cycles, amplitudes of 2 K and 6 m s-1 are calculated for temperature data series over the south of France (44°N, and on wind data series over Volgograd (49°N, respectively. Cross-spectrum analyses have indicated correlations between these atmospheric parameters and the solar proxy with a phase lag of less than 2 days. These statistically correlative results, which provide good qualitative agreement with numerical simulations, are both obtained at mid-latitude. However, the observed amplitudes are larger than expected, with numerical models suggesting that dynamical processes such as equatorial or gravity waves may be responsible.

Mid-latitude summer response of the middle atmosphere to short-term solar UV changes

Directory of Open Access Journals (Sweden)

P. Keckhut

Full Text Available Temperature and wind data obtained with Rayleigh lidar since 1979 and Russian rockets since 1964 are analyzed to deduce the summer response of the middle atmosphere to short-term solar UV changes. The equivalent width of the 1083 nm He I line is used as a proxy to monitor the short-term UV flux changes. Spectral analyses are performed on 108-day windows to extract the 27-day component from temperature, wind and solar data sets. Linear regressions between these spectral harmonics show some significant correlations around 45 km at mid-latitudes. For large 27-day solar cycles, amplitudes of 2 K and 6 m s^-1 are calculated for temperature data series over the south of France (44°N, and on wind data series over Volgograd (49°N, respectively. Cross-spectrum analyses have indicated correlations between these atmospheric parameters and the solar proxy with a phase lag of less than 2 days. These statistically correlative results, which provide good qualitative agreement with numerical simulations, are both obtained at mid-latitude. However, the observed amplitudes are larger than expected, with numerical models suggesting that dynamical processes such as equatorial or gravity waves may be responsible.

Investigation of solar photovoltaic module power output by various models

International Nuclear Information System (INIS)

Jakhrani, A.Q.; Othman, A.K.; Rigit, A.R.H.; Baini, R.

2012-01-01

This paper aims to investigate the power output of a solar photovoltaic module by various models and to formulate a suitable model for predicting the performance of solar photovoltaic modules. The model was used to correct the configurations of solar photovoltaic systems for sustainable power supply. Different types of models namely the efficiency, power, fill factor and current-voltage characteristic curve models have been reviewed. It was found that the examined models predicted a 40% yield of the rated power in cloudy weather conditions and up to 80% in clear skies. The models performed well in terms of electrical efficiency in cloudy days if the influence of low irradiance were incorporated. Both analytical and numerical methods were employed in the formulation of improved model which gave +- 2% error when compared with the rated power output of solar photovoltaic module. The proposed model is more practical in terms of number of variables used and acceptable performance in humid atmospheres. Therefore, it could be useful for the estimation of power output of the solar photovoltaic systems in Sarawak region. (author)

Heating of the outer solar atmosphere

International Nuclear Information System (INIS)

Parker, E.N.

1983-01-01

The author discusses the idea that there must be a source of magnetic fields somewhere below the solar surface. He starts by considering present day ideas about the sun's internal structure. The sun has a radius of approximately 700,000 km, of which the outer 100,000 km or so is the convective zone, according to mixing-length models. The dynamo is believed to operate in the convective zone, across which there may be a 5-10% variation in the angular velocity. There are the stretched east-west fields similar to the ones in the earth's core. Associated with these are poloidal fields which contribute to a net dipole moment of the sun and are generated by a dynamo. The author shows that essentially no magnetic field configuration has an equilibrium; they dissipate quickly in spite of the high conductivity in fluid motions and heating. This is probably the major part of the heating of the sun's outer atmosphere. (Auth.)

Millimeter radiation from a 3D model of the solar atmosphere. II. Chromospheric magnetic field

Science.gov (United States)

Loukitcheva, M.; White, S. M.; Solanki, S. K.; Fleishman, G. D.; Carlsson, M.

2017-05-01

Aims: We use state-of-the-art, three-dimensional non-local thermodynamic equilibrium (non-LTE) radiative magnetohydrodynamic simulations of the quiet solar atmosphere to carry out detailed tests of chromospheric magnetic field diagnostics from free-free radiation at millimeter and submillimeter wavelengths (mm/submm). Methods: The vertical component of the magnetic field was deduced from the mm/submm brightness spectra and the degree of circular polarization synthesized at millimeter frequencies. We used the frequency bands observed by the Atacama Large Millimeter/Submillimeter Array (ALMA) as a convenient reference. The magnetic field maps obtained describe the longitudinal magnetic field at the effective formation heights of the relevant wavelengths in the solar chromosphere. Results: The comparison of the deduced and model chromospheric magnetic fields at the spatial resolution of both the model and current observations demonstrates a good correlation, but has a tendency to underestimate the model field. The systematic discrepancy of about 10% is probably due to averaging of the restored field over the heights contributing to the radiation, weighted by the strength of the contribution. On the whole, the method of probing the longitudinal component of the magnetic field with free-free emission at mm/submm wavelengths is found to be applicable to measurements of the weak quiet-Sun magnetic fields. However, successful exploitation of this technique requires very accurate measurements of the polarization properties (primary beam and receiver polarization response) of the antennas, which will be the principal factor that determines the level to which chromospheric magnetic fields can be measured. Conclusions: Consequently, high-resolution and high-precision observations of circularly polarized radiation at millimeter wavelengths can be a powerful tool for producing chromospheric longitudinal magnetograms.

Solar signals detected within neutral atmospheric and ionospheric parameters

Czech Academy of Sciences Publication Activity Database

Koucká Knížová, Petra; Georgieva, K.; Mošna, Zbyšek; Kozubek, Michal; Kouba, Daniel; Kirov, B.; Potužníková, Kateřina; Boška, Josef

2018-01-01

Roč. 171, June (2018), s. 147-156 ISSN 1364-6826 R&D Projects: GA ČR(CZ) GA15-24688S Grant - others:AV ČR(CZ) BAS-17-06 Program:Bilaterální spolupráce Institutional support: RVO:68378289 Keywords : solar energy * upper atmosphere Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 1.326, year: 2016 http://www.sciencedirect.com/science/article/pii/S1364682617302365

Integrating Solar Power onto the Electric Grid - Bridging the Gap between Atmospheric Science, Engineering and Economics

Science.gov (United States)

Ghonima, M. S.; Yang, H.; Zhong, X.; Ozge, B.; Sahu, D. K.; Kim, C. K.; Babacan, O.; Hanna, R.; Kurtz, B.; Mejia, F. A.; Nguyen, A.; Urquhart, B.; Chow, C. W.; Mathiesen, P.; Bosch, J.; Wang, G.

2015-12-01

One of the main obstacles to high penetrations of solar power is the variable nature of solar power generation. To mitigate variability, grid operators have to schedule additional reliability resources, at considerable expense, to ensure that load requirements are met by generation. Thus despite the cost of solar PV decreasing, the cost of integrating solar power will increase as penetration of solar resources onto the electric grid increases. There are three principal tools currently available to mitigate variability impacts: (i) flexible generation, (ii) storage, either virtual (demand response) or physical devices and (iii) solar forecasting. Storage devices are a powerful tool capable of ensuring smooth power output from renewable resources. However, the high cost of storage is prohibitive and markets are still being designed to leverage their full potential and mitigate their limitation (e.g. empty storage). Solar forecasting provides valuable information on the daily net load profile and upcoming ramps (increasing or decreasing solar power output) thereby providing the grid advance warning to schedule ancillary generation more accurately, or curtail solar power output. In order to develop solar forecasting as a tool that can be utilized by the grid operators we identified two focus areas: (i) develop solar forecast technology and improve solar forecast accuracy and (ii) develop forecasts that can be incorporated within existing grid planning and operation infrastructure. The first issue required atmospheric science and engineering research, while the second required detailed knowledge of energy markets, and power engineering. Motivated by this background we will emphasize area (i) in this talk and provide an overview of recent advancements in solar forecasting especially in two areas: (a) Numerical modeling tools for coastal stratocumulus to improve scheduling in the day-ahead California energy market. (b) Development of a sky imager to provide short term

Waves and Magnetism in the Solar Atmosphere (WAMIS

Directory of Open Access Journals (Sweden)

Yuan-Kuen eKo

2016-02-01

Full Text Available Comprehensive measurements of magnetic fields in the solar corona have a long history as an important scientific goal. Besides being crucial to understanding coronal structures and the Sun’s generation of space weather, direct measurements of their strength and direction are also crucial steps in understanding observed wave motions. In this regard, the remote sensing instrumentation used to make coronal magnetic field measurements is well suited to measuring the Doppler signature of waves in the solar structures. In this paper, we describe the design and scientific values of the Waves and Magnetism in the Solar Atmosphere (WAMIS investigation. WAMIS, taking advantage of greatly improved infrared filters and detectors, forward models, advanced diagnostic tools and inversion codes, is a long-duration high-altitude balloon payload designed to obtain a breakthrough in the measurement of coronal magnetic fields and in advancing the understanding of the interaction of these fields with space plasmas. It consists of a 20 cm aperture coronagraph with a visible-IR spectro-polarimeter focal plane assembly. The balloon altitude would provide minimum sky background and atmospheric scattering at the wavelengths in which these observations are made. It would also enable continuous measurements of the strength and direction of coronal magnetic fields without interruptions from the day-night cycle and weather. These measurements will be made over a large field-of-view allowing one to distinguish the magnetic signatures of different coronal structures, and at the spatial and temporal resolutions required to address outstanding problems in coronal physics. Additionally, WAMIS could obtain near simultaneous observations of the electron scattered K-corona for context and to obtain the electron density. These comprehensive observations are not provided by any current single ground-based or space observatory. The fundamental advancements achieved by the near

Newtonian CAFE: a new ideal MHD code to study the solar atmosphere

Science.gov (United States)

González-Avilés, J. J.; Cruz-Osorio, A.; Lora-Clavijo, F. D.; Guzmán, F. S.

2015-12-01

We present a new code designed to solve the equations of classical ideal magnetohydrodynamics (MHD) in three dimensions, submitted to a constant gravitational field. The purpose of the code centres on the analysis of solar phenomena within the photosphere-corona region. We present 1D and 2D standard tests to demonstrate the quality of the numerical results obtained with our code. As solar tests we present the transverse oscillations of Alfvénic pulses in coronal loops using a 2.5D model, and as 3D tests we present the propagation of impulsively generated MHD-gravity waves and vortices in the solar atmosphere. The code is based on high-resolution shock-capturing methods, uses the Harten-Lax-van Leer-Einfeldt (HLLE) flux formula combined with Minmod, MC, and WENO5 reconstructors. The divergence free magnetic field constraint is controlled using the Flux Constrained Transport method.

Atmospheric Mining in the Outer Solar System: Resource Capturing, Storage, and Utilization

Science.gov (United States)

Palaszewski, Bryan

2014-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as helium 3 and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and hydrogen (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate for hydrogen helium 4 and helium 3, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues.

A model for radio emission from solar coronal shocks

Energy Technology Data Exchange (ETDEWEB)

Zhao, G. Q.; Chen, L.; Wu, D. J., E-mail: djwu@pmo.ac.cn [Purple Mountain Observatory, CAS, Nanjing 210008 (China)

2014-05-01

Solar coronal shocks are very common phenomena in the solar atmosphere and are believed to be the drivers of solar type II radio bursts. However, the microphysical nature of these emissions is still an open question. This paper proposes that electron cyclotron maser (ECM) emission is responsible for the generation of radiation from the coronal shocks. In the present model, an energetic ion beam accelerated by the shock first excites the Alfvén wave (AW), then the excited AW leads to the formation of a density-depleted duct along the foreshock boundary of the shock. In this density-depleted duct, the energetic electron beam produced via the shock acceleration can effectively excite radio emission by ECM instability. Our results show that this model may potentially be applied to solar type II radio bursts.

A model for radio emission from solar coronal shocks

International Nuclear Information System (INIS)

Zhao, G. Q.; Chen, L.; Wu, D. J.

2014-01-01

Solar coronal shocks are very common phenomena in the solar atmosphere and are believed to be the drivers of solar type II radio bursts. However, the microphysical nature of these emissions is still an open question. This paper proposes that electron cyclotron maser (ECM) emission is responsible for the generation of radiation from the coronal shocks. In the present model, an energetic ion beam accelerated by the shock first excites the Alfvén wave (AW), then the excited AW leads to the formation of a density-depleted duct along the foreshock boundary of the shock. In this density-depleted duct, the energetic electron beam produced via the shock acceleration can effectively excite radio emission by ECM instability. Our results show that this model may potentially be applied to solar type II radio bursts.

Stellar Atmospheric Modelling for the ACCESS Program

Science.gov (United States)

Morris, Matthew; Kaiser, Mary Elizabeth; Bohlin, Ralph; Kurucz, Robert; ACCESS Team

2018-01-01

A goal of the ACCESS program (Absolute Color Calibration Experiment for Standard Stars) is to enable greater discrimination between theoretical astrophysical models and observations, where the comparison is limited by systematic errors associated with the relative flux calibration of the targets. To achieve these goals, ACCESS has been designed as a sub-orbital rocket borne payload and ground calibration program, to establish absolute flux calibration of stellar targets at flight candidates, as well as a selection of A and G stars from the CALSPEC database. Stellar atmosphere models were generated using Atlas 9 and Atlas 12 Kurucz stellar atmosphere software. The effective temperature, log(g), metallicity, and redenning were varied and the chi-squared statistic was minimized to obtain a best-fit model. A comparison of these models and the results from interpolation between grids of existing models will be presented. The impact of the flexibility of the Atlas 12 input parameters (e.g. solar metallicity fraction, abundances, microturbulent velocity) is being explored.

Structure and dynamics of solar atmosphere: the reign of SOHO

International Nuclear Information System (INIS)

Bocchialini, Karine

2004-01-01

In this report for Accreditation to Supervise Research (HDR), the author proposes an overview of his research works which particularly addressed the study of the solar atmosphere, notably based on observations made by the SOHO (Solar and Heliospheric Observatory) satellite. After a recall of his curriculum, he presents and comments results obtained in various areas: Corona heating and origin of solar wind, heating by waves, heating by quasi-steady mechanisms, regions which are sources of fast solar wind, sources of Coronal matter ejections. He also presents the different adopted approaches and methods (multi-wavelength analysis, oscillation measurement, statistical analysis) and the various observed structures (chromospheric network, shiny points, Coronal holes, and protuberances)

Coupled atmosphere-ocean models of Titan's past

Science.gov (United States)

Mckay, Christopher P.; Pollack, James B.; Lunine, Jonathan I.; Courtin, Regis

1993-01-01

The behavior and possible past evolution of fully coupled atmosphere and ocean model of Titan are investigated. It is found that Titan's surface temperature was about 20 K cooler at 4 Gyr ago and will be about 5 K warmer 0.5 Gyr in the future. The change in solar luminosity and the conversion of oceanic CH4 to C2H6 drive the evolution of the ocean and atmosphere over time. Titan appears to have experienced a frozen epoch about 3 Gyr ago independent of whether an ocean is present or not. This finding may have important implications for understanding the inventory of Titan's volatile compounds.

The induced electric field distribution in the solar atmosphere

International Nuclear Information System (INIS)

Chen Rong; Yang Zhi-Liang; Deng Yuan-Yong

2013-01-01

A method of calculating the induced electric field is presented. The induced electric field in the solar atmosphere is derived by the time variation of the magnetic field when the accumulation of charged particles is neglected. In order to derive the spatial distribution of the magnetic field, several extrapolation methods are introduced. With observational data from the Helioseismic and Magnetic Imager aboard NASA's Solar Dynamics Observatory taken on 2010 May 20, we extrapolate the magnetic field from the photosphere to the upper atmosphere. By calculating the time variation of the magnetic field, we can get the induced electric field. The derived induced electric field can reach a value of 10 2 V cm −1 and the average electric field has a maximum point at the layer 360 km above the photosphere. The Monte Carlo method is used to compute the triple integration of the induced electric field.

Spectral solar irradiance and some optical properties for various polluted atmospheres

International Nuclear Information System (INIS)

Jacovides, Constantinos P.; Asimakopoulos, Demosthenis N.; Steven, Michael D.

2000-01-01

Using ground-based spectroradiometric measurements taken over the Athens atmosphere during May 1995, the influence of gaseous pollutants and aerosol on the spectral radiant energy distribution was investigated. It was found that spectral measurements exhibited variations based on various polluted urban atmospheric conditions as determined via gaseous pollutants record analysis. The relative attenuations cause by gaseous pollutants and aerosol can exceed 27%, 17% and 16% in the global ultraviolet, visible and near-infrared portions of the solar spectrum respectively, as compared to 'background' values. In contrast, an enhancement of the near-infrared diffuse component by 66%, was observed, while in visible and ultraviolet bands the relative increases reached 54% and 21% respectively. Experimental total Rayleigh-corrected and spectral aerosol optical depths were retrieved, representing differences in polluted air over the Athens atmosphere. The diffuse component accounts for more than 80% of the total radiation field under high polluted atmosphere. The observed differences of solar radiation between the Athens center and at a nearby suburban site are a manifestation of contrasting air properties provided mainly by automotive traffic. (Author)

Sonora: A New Generation Model Atmosphere Grid for Brown Dwarfs and Young Extrasolar Giant Planets

Science.gov (United States)

Marley, Mark S.; Saumon, Didier; Fortney, Jonathan J.; Morley, Caroline; Lupu, Roxana Elena; Freedman, Richard; Visscher, Channon

2017-01-01

Brown dwarf and giant planet atmospheric structure and composition has been studied both by forward models and, increasingly so, by retrieval methods. While indisputably informative, retrieval methods are of greatest value when judged in the context of grid model predictions. Meanwhile retrieval models can test the assumptions inherent in the forward modeling procedure. In order to provide a new, systematic survey of brown dwarf atmospheric structure, emergent spectra, and evolution, we have constructed a new grid of brown dwarf model atmospheres. We ultimately aim for our grid to span substantial ranges of atmospheric metallilcity, C/O ratios, cloud properties, atmospheric mixing, and other parameters. Spectra predicted by our modeling grid can be compared to both observations and retrieval results to aid in the interpretation and planning of future telescopic observations. We thus present Sonora, a new generation of substellar atmosphere models, appropriate for application to studies of L, T, and Y-type brown dwarfs and young extrasolar giant planets. The models describe the expected temperature-pressure profile and emergent spectra of an atmosphere in radiative-convective equilibrium for ranges of effective temperatures and gravities encompassing 200 less than or equal to T(sub eff) less than or equal to 2400 K and 2.5 less than or equal to log g less than or equal to 5.5. In our poster we briefly describe our modeling methodology, enumerate various updates since our group's previous models, and present our initial tranche of models for cloudless, solar metallicity, and solar carbon-to-oxygen ratio, chemical equilibrium atmospheres. These models will be available online and will be updated as opacities and cloud modeling methods continue to improve.

Atmospheric scattering corrections to solar radiometry

International Nuclear Information System (INIS)

Box, M.A.; Deepak, A.

1979-01-01

Whenever a solar radiometer is used to measure direct solar radiation, some diffuse sky radiation invariably enters the detector's field of view along with the direct beam. Therefore, the atmospheric optical depth obtained by the use of Bouguer's transmission law (also called Beer-Lambert's law), that is valid only for direct radiation, needs to be corrected by taking account of the scattered radiation. In this paper we shall discuss the correction factors needed to account for the diffuse (i.e., singly and multiply scattered) radiation and the algorithms developed for retrieving aerosol size distribution from such measurements. For a radiometer with a small field of view (half-cone angle 0 ) and relatively clear skies (optical depths <0.4), it is shown that the total diffuse contributions represents approximately l% of the total intensity. It is assumed here that the main contributions to the diffuse radiation within the detector's view cone are due to single scattering by molecules and aerosols and multiple scattering by molecules alone, aerosol multiple scattering contributions being treated as negligibly small. The theory and the numerical results discussed in this paper will be helpful not only in making corrections to the measured optical depth data but also in designing improved solar radiometers

THE ROLE OF NITROGEN IN TITAN’S UPPER ATMOSPHERIC HYDROCARBON CHEMISTRY OVER THE SOLAR CYCLE

Energy Technology Data Exchange (ETDEWEB)

Luspay-Kuti, A.; Mandt, K. E.; Greathouse, T. K. [Department of Space Research, Southwest Research Institute, San Antonio, TX 78228 (United States); Westlake, J. H. [Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States); Plessis, S., E-mail: aluspaykuti@swri.edu [Fund Kis, F-92160 Antony (France)

2016-06-01

Titan’s thermospheric photochemistry is primarily driven by solar radiation. Similarly to other planetary atmospheres, such as Mars’, Titan’s atmospheric structure is also directly affected by variations in the solar extreme-UV/UV output in response to the 11-year-long solar cycle. Here, we investigate the influence of nitrogen on the vertical production, loss, and abundance profiles of hydrocarbons as a function of the solar cycle. Our results show that changes in the atmospheric nitrogen atomic density (primarily in its ground state N({sup 4}S)) as a result of photon flux variations have important implications for the production of several minor hydrocarbons. The solar minimum enhancement of CH{sub 3}, C{sub 2}H{sub 6}, and C{sub 3}H{sub 8}, despite the lower CH{sub 4} photodissociation rates compared with solar maximum conditions, is explained by the role of N({sup 4}S). N({sup 4}S) indirectly controls the altitude of termolecular versus bimolecular chemical regimes through its relationship with CH{sub 3}. When in higher abundance during solar maximum at lower altitudes, N({sup 4}S) increases the importance of bimolecular CH{sub 3} + N({sup 4}S) reactions producing HCN and H{sub 2}CN. The subsequent remarkable CH{sub 3} loss and decrease in the CH{sub 3} abundance at lower altitudes during solar maximum affects the overall hydrocarbon chemistry.

Solar flares and radiocarbon abundance in the atmosphere of the Earth

International Nuclear Information System (INIS)

Metskhvarishvili, R.Ya.; Imedadze, T.Sh.; Tleugaliev, S.Kh.; Tsinamdzgvrishvili, T.Sh.; Tsereteli, S.L.

1978-01-01

The correlation between the radiocarbon ( 14 C) content in the atmosphere of the Earth and the solar activity is studied. Annual measurements of the 14 C content in the tree rings for the last 120 years have been made. Relations of the radiocarbon content in dendrochronologically dated tree rings and the Wolf numbers for the period from 1850 to 1940 are presented. The spectroscopic and Borg methods have been used to ascertain the periodicities in the radiocarbon series. It is shown that well-defined periods of approximately 11 and approximately 65 years are observed in the radiocarbon series. The former is associated with an 11-year and the latter with a secular cycle of the 14 C content in the earth atmosphere. To study the relation of the solar activity to the level of radiocarbon in the earth atmosphere a mutual correlation function was calculated for various values of the time lags of 14 C with respect to the processes on the Sun. It follows from the data obtained that a positive correlation takes place for time lags smaller than three years. The detected positive correlation has revealed that the effect of solar flares in the 11-year cycle is prevalent

Mathematical model of solar radiation based on climatological data from NASA SSE

Science.gov (United States)

Obukhov, S. G.; Plotnikov, I. A.; Masolov, V. G.

2018-05-01

An original model of solar radiation arriving at the arbitrarily oriented surface has been developed. The peculiarity of the model is that it uses numerical values of the atmospheric transparency index and the surface albedo from the NASA SSE database as initial data. The model is developed in the MatLab/Simulink environment to predict the main characteristics of solar radiation for any geographical point in Russia, including those for territories with no regular actinometric observations.

Self-consistent atmosphere modeling with cloud formation for low-mass stars and exoplanets

Science.gov (United States)

Juncher, Diana; Jørgensen, Uffe G.; Helling, Christiane

2017-12-01

Context. Low-mass stars and extrasolar planets have ultra-cool atmospheres where a rich chemistry occurs and clouds form. The increasing amount of spectroscopic observations for extrasolar planets requires self-consistent model atmosphere simulations to consistently include the formation processes that determine cloud formation and their feedback onto the atmosphere. Aims: Our aim is to complement the MARCS model atmosphere suit with simulations applicable to low-mass stars and exoplanets in preparation of E-ELT, JWST, PLATO and other upcoming facilities. Methods: The MARCS code calculates stellar atmosphere models, providing self-consistent solutions of the radiative transfer and the atmospheric structure and chemistry. We combine MARCS with a kinetic model that describes cloud formation in ultra-cool atmospheres (seed formation, growth/evaporation, gravitational settling, convective mixing, element depletion). Results: We present a small grid of self-consistently calculated atmosphere models for Teff = 2000-3000 K with solar initial abundances and log (g) = 4.5. Cloud formation in stellar and sub-stellar atmospheres appears for Teff day-night energy transport and no temperature inversion.

The Whole Atmosphere Community Climate Model

Science.gov (United States)

Boville, B. A.; Garcia, R. R.; Sassi, F.; Kinnison, D.; Roble, R. G.

The Whole Atmosphere Community Climate Model (WACCM) is an upward exten- sion of the National Center for Atmospheric Research Community Climate System Model. WACCM simulates the atmosphere from the surface to the lower thermosphere (140 km) and includes both dynamical and chemical components. The salient points of the model formulation will be summarized and several aspects of its performance will be discussed. Comparison with observations indicates that WACCM produces re- alistic temperature and zonal wind distributions. Both the mean state and interannual variability will be summarized. Temperature inversions in the midlatitude mesosphere have been reported by several authors and are also found in WACCM. These inver- sions are formed primarily by planetary wave forcing, but the background state on which they form also requires gravity wave forcing. The response to sea surface temperature (SST) anomalies will be examined by com- paring simulations with observed SSTs for 1950-1998 to a simulation with clima- tological annual cycle of SSTs. The response to ENSO events is found to extend though the winter stratosphere and mesosphere and a signal is also found at the sum- mer mesopause. The experimental framework allows the ENSO signal to be isolated, because no other forcings are included (e.g. solar variability and volcanic eruptions) which complicate the observational record. The temperature and wind variations asso- ciated with ENSO are large enough to generate significant perturbations in the chem- ical composition of the middle atmosphere, which will also be discussed.

Composition Changes After the "Halloween" Solar Proton Event: The High-Energy Particle Precipitation in the Atmosphere (HEPPA) Model Versus MIPAS Data Intercomparison Study

Science.gov (United States)

Funke, B.; Baumgaertner, A.; Calisto, M.; Egorova, T.; Jackman, C. H.; Kieser, J.; Krivolutsky, A.; Lopez-Puertas, M.; Marsh. D. R.; Reddmann, T.;

Reading The Sun: A Three Dimensional Visual Model of The Solar Environment During Solar Cycle 24

Science.gov (United States)

Carranza-fulmer, T. L.; Moldwin, M.

2014-12-01

The sun is a powerful force that has proven to our society that it has a large impact on our lives. Unfortunately, there is still a lack of awareness on how the sun is capable of affecting Earth. The over all idea of "Reading The Sun" installation is to help demonstrate how the sun impacts the Earth, by compiling various data sources from satellites (SOHO, SDO, and STERO) with solar and solar wind models (MAS and ENLIL) to create a comprehensive three dimensional display of the solar environment. It focuses on the current solar maximum of solar cycle 24 and a CME that impacted Earth's magnetic field on February 27, 2014, which triggered geomagnetic storms around the Earth's poles. The CME was an after-effect of a class X4.9 solar flare, which was released from the sun on February 25, 2014. "Reading The Sun" is a 48" x 48" x 48" hanging model of the sun with color coded open opposing magnetic field lines along with various layers of the solar atmosphere, the heliospheric current sheet, and the inner planets. At the center of the xyz axis is the sun with the open magnetic field lines and the heliospheric current sheet permeating inner planetary space. The xyz axes are color coded to represent various types of information with corresponding visual images for the viewer to be able to read the model. Along the z-axis are three colors (yellow, orange, and green) that represent the different layers of the solar atmosphere (photosphere, chromosphere, and corona) that correspond to three satellite images in various spectrums related to a CME and Solar Flare and the xy-plane shows where the inner planets are in relation to the sun. The exhibit in which "Reading The Sun "is being displayed is called, The Rotation of Language at the Wheather Again Gallery in Rockaway, New York. The intent of the exhibit is to both celebrate as well as present a cautionary tale on the ability of human language to spark and ignite the individual and collective imagination towards an experience

Non-LTE H2+ as the source of missing opacity in the solar atmosphere

Science.gov (United States)

Swamy, K. S. K.; Stecher, T. P.

1974-01-01

The population of the various vibrational levels of the H2+ molecule has been calculated from the consideration of formation and destruction mechanisms. The resulting population is used in calculating the total absorption due to H2+ and is compared with the other known sources of opacity at several optical depths of the solar atmosphere. It is shown that the absorption due to H2+ can probably account for the missing ultraviolet opacity in the solar atmosphere.

An Atmospheric Variability Model for Venus Aerobraking Missions

Science.gov (United States)

Tolson, Robert T.; Prince, Jill L. H.; Konopliv, Alexander A.

2013-01-01

Aerobraking has proven to be an enabling technology for planetary missions to Mars and has been proposed to enable low cost missions to Venus. Aerobraking saves a significant amount of propulsion fuel mass by exploiting atmospheric drag to reduce the eccentricity of the initial orbit. The solar arrays have been used as the primary drag surface and only minor modifications have been made in the vehicle design to accommodate the relatively modest aerothermal loads. However, if atmospheric density is highly variable from orbit to orbit, the mission must either accept higher aerothermal risk, a slower pace for aerobraking, or a tighter corridor likely with increased propulsive cost. Hence, knowledge of atmospheric variability is of great interest for the design of aerobraking missions. The first planetary aerobraking was at Venus during the Magellan mission. After the primary Magellan science mission was completed, aerobraking was used to provide a more circular orbit to enhance gravity field recovery. Magellan aerobraking took place between local solar times of 1100 and 1800 hrs, and it was found that the Venusian atmospheric density during the aerobraking phase had less than 10% 1 sigma orbit to orbit variability. On the other hand, at some latitudes and seasons, Martian variability can be as high as 40% 1 sigmaFrom both the MGN and PVO mission it was known that the atmosphere, above aerobraking altitudes, showed greater variability at night, but this variability was never quantified in a systematic manner. This paper proposes a model for atmospheric variability that can be used for aerobraking mission design until more complete data sets become available.

A model to calculate solar radiation fluxes on the Martian surface

Directory of Open Access Journals (Sweden)

Vicente-Retortillo Álvaro

2015-01-01

Full Text Available We present a new comprehensive radiative transfer model to study the solar irradiance that reaches the surface of Mars in the spectral range covered by MetSIS, a sensor aboard the Mars MetNet mission that will measure solar irradiance in several bands from the ultraviolet (UV to the near infrared (NIR. The model includes up-to-date wavelength-dependent radiative properties of dust, water ice clouds, and gas molecules. It enables the characterization of the radiative environment in different spectral regions under different scenarios. Comparisons between the model results and MetSIS observations will allow for the characterization of the temporal variability of atmospheric optical depth and dust size distribution, enhancing the scientific return of the mission. The radiative environment at the Martian surface has important implications for the habitability of Mars as well as a strong impact on its atmospheric dynamics and climate.

ON THE COMBINATION OF IMAGING-POLARIMETRY WITH SPECTROPOLARIMETRY OF UPPER SOLAR ATMOSPHERES DURING SOLAR ECLIPSES

International Nuclear Information System (INIS)

Qu, Z. Q.; Deng, L. H.; Dun, G. T.; Chang, L.; Zhang, X. Y.; Cheng, X. M.; Qu, Z. N.; Xue, Z. K.; Ma, L.; Allington-Smith, J.; Murray, G.

2013-01-01

We present results from imaging polarimetry (IP) of upper solar atmospheres during a total solar eclipse on 2012 November 13 and spectropolarimetry of an annular solar eclipse on 2010 January 15. This combination of techniques provides both the synoptic spatial distribution of polarization above the solar limb and spectral information on the physical mechanism producing the polarization. Using these techniques together we demonstrate that even in the transition region, the linear polarization increases with height and can exceed 20%. IP shows a relatively smooth background distribution in terms of the amplitude and direction modified by solar structures above the limb. A map of a new quantity that reflects direction departure from the background polarization supplies an effective technique to improve the contrast of this fine structure. Spectral polarimetry shows that the relative contribution to the integrated polarization over the observed passband from the spectral lines decreases with height while the contribution from the continuum increases as a general trend. We conclude that both imaging and spectral polarimetry obtained simultaneously over matched spatial and spectral domains will be fruitful for future eclipse observations

Theoretical oscillation frequencies for solar-type dwarfs from stellar models with <3D >-atmospheres

DEFF Research Database (Denmark)

Jørgensen, Andreas Christ Sølvsten; Weiss, Achim; Mosumgaard, Jakob Rorsted

2017-01-01

We present a new method for replacing the outermost layers of stellar models with interpolated atmospheres based on results from 3D simulations, in order to correct for structural inadequacies of these layers. This replacement is known as patching. Tests, based on 3D atmospheres from three......, and the mismatch in T-eff and log g between the un-patched model and patched 3D atmosphere. We find the eigen frequencies to be unaltered by the patching depth deep within the adiabatic region, while changing the patching quantity or the employed atmosphere grid leads to frequency shifts that may exceed 1 mu Hz....... Likewise, the eigen frequencies are sensitive to mismatches in T-eff or log g. A thorough investigation of the accuracy of a new scheme, for interpolating mean 3D stratifications within the atmosphere grids, is furthermore performed. Throughout large parts of the atmosphere grids, our interpolation scheme...

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.

The upper atmosphere and solar-terrestrial relations - An introduction to the aerospace environment

International Nuclear Information System (INIS)

Hargreaves, J.K.

1979-01-01

A theoretical and observational overview of earth's aerospace environment is presented in this book. Emphasis is placed on the principles and observed phenomena of the neutral upper atmosphere, particularly in relation to solar activity. Topics include the structure of the ionosphere and magnetosphere, waves in the magnetosphere, solar flares and solar protons, and storms and other disturbance phenomena, while applications to communications, navigation and space technology are also discussed

Estimate of the atmospheric turbidity from three broad-band solar radiation algorithms. A comparative study

Directory of Open Access Journals (Sweden)

G. López

2004-09-01

Full Text Available Atmospheric turbidity is an important parameter for assessing the air pollution in local areas, as well as being the main parameter controlling the attenuation of solar radiation reaching the Earth's surface under cloudless sky conditions. Among the different turbidity indices, the Ångström turbidity coefficient β is frequently used. In this work, we analyse the performance of three methods based on broad-band solar irradiance measurements in the estimation of β. The evaluation of the performance of the models was undertaken by graphical and statistical (root mean square errors and mean bias errors means. The data sets used in this study comprise measurements of broad-band solar irradiance obtained at eight radiometric stations and aerosol optical thickness measurements obtained at one co-located radiometric station. Since all three methods require estimates of precipitable water content, three common methods for calculating atmospheric precipitable water content from surface air temperature and relative humidity are evaluated. Results show that these methods exhibit significant differences for low values of precipitable water. The effect of these differences in precipitable water estimates on turbidity algorithms is discussed. Differences in hourly turbidity estimates are later examined. The effects of random errors in pyranometer measurements and cloud interferences on the performance of the models are also presented. Examination of the annual cycle of monthly mean values of β for each location has shown that all three turbidity algorithms are suitable for analysing long-term trends and seasonal patterns.

Estimate of the atmospheric turbidity from three broad-band solar radiation algorithms. A comparative study

Directory of Open Access Journals (Sweden)

G. López

2004-09-01

Full Text Available Atmospheric turbidity is an important parameter for assessing the air pollution in local areas, as well as being the main parameter controlling the attenuation of solar radiation reaching the Earth's surface under cloudless sky conditions. Among the different turbidity indices, the Ångström turbidity coefficient β is frequently used. In this work, we analyse the performance of three methods based on broad-band solar irradiance measurements in the estimation of β. The evaluation of the performance of the models was undertaken by graphical and statistical (root mean square errors and mean bias errors means. The data sets used in this study comprise measurements of broad-band solar irradiance obtained at eight radiometric stations and aerosol optical thickness measurements obtained at one co-located radiometric station. Since all three methods require estimates of precipitable water content, three common methods for calculating atmospheric precipitable water content from surface air temperature and relative humidity are evaluated. Results show that these methods exhibit significant differences for low values of precipitable water. The effect of these differences in precipitable water estimates on turbidity algorithms is discussed. Differences in hourly turbidity estimates are later examined. The effects of random errors in pyranometer measurements and cloud interferences on the performance of the models are also presented. Examination of the annual cycle of monthly mean values of β for each location has shown that all three turbidity algorithms are suitable for analysing long-term trends and seasonal patterns.

Estimate of the atmospheric turbidity from three broad-band solar radiation algorithms. A comparative study

Energy Technology Data Exchange (ETDEWEB)

Lopez, G.; Batlles, F.J. [Dept. de Ingenieria Electrica y Termica, EPS La Rabida, Univ. de Huelva, Huelva (Spain)

2004-07-01

Atmospheric turbidity is an important parameter for assessing the air pollution in local areas, as well as being the main parameter controlling the attenuation of solar radiation reaching the Earth's surface under cloudless sky conditions. Among the different turbidity indices, the Aangstroem turbidity coefficient {beta} is frequently used. In this work, we analyse the performance of three methods based on broadband solar irradiance measurements in the estimation of {beta}. The evaluation of the performance of the models was undertaken by graphical and statistical (root mean square errors and mean bias errors) means. The data sets used in this study comprise measurements of broad-band solar irradiance obtained at eight radiometric stations and aerosol optical thickness measurements obtained at one co-located radiometric station. Since all three methods require estimates of precipitable water content, three common methods for calculating atmospheric precipitable water content from surface air temperature and relative humidity are evaluated. Results show that these methods exhibit significant differences for low values of precipitable water. The effect of these differences in precipitable water estimates on turbidity algorithms is discussed. Differences in hourly turbidity estimates are later examined. The effects of random errors in pyranometer measurements and cloud interferences on the performance of the models are also presented. Examination of the annual cycle of monthly mean values of {beta} for each location has shown that all three turbidity algorithms are suitable for analysing long-term trends and seasonal patterns. (orig.)

Cosmogenic radionuclide 7Be in atmospheric fallouts, weather factors and solar activity

International Nuclear Information System (INIS)

Kungurov, F.R.

2011-11-01

Key words: 7 Be activity, atmospheric fallouts, solar activity, gamma spectroscopy. Subjects of research: cosmogenic radionuclide 7 Be in atmospheric fallouts and surrounding objects of environment, its migrational distribution connected to solar activity and weather meteorologic parameters of the region studied. Purpose of work: Defining correlation between atmospheric humidity and solar activity with concentration and distribution of cosmogenic radionuclide 7 Be. Methods of research: gamma-spectrometry method of activity measurements. The results obtained and their novelty: Cycle of research works on definition of concentration and migrational distribution of CRN 7 Be in Samarkand region during 2002-2005 was carried out for the first time. Volumetric activity of 7 Be in squat air layer of Samarkand was determined. Average density of 7 Be fallouts for the four years of studies was determined. Qualitative correlation bet ween 7 Be fallouts density variations and solar activity, expressed through Wolf number has been found. Qualitative correlation between 7 Be fallouts density variations and amount of precipitations has been found. Regularity in 7 Be concentration decrease towards north latitudes has been detected. Practical value: Developed scintillation method of 7 Be activity detection in atmospheric fallouts was used in works performed in the framework of republican grants 2F-No 1.2.3, CNT RUz PFNI 2F-No 2.1.39 and ITD-7-024. Methodology was used for the estimation of the velocity of erosion processes in the soils of different regions of Uzbekistan. Methodology is used in the works on 7 Be radioactivity measurements. Degree of embed and economic effectivity: Gained results replenish database on 7 Be isotope distribution on Earth regions and its role in formation of some processes, connected with meteorology, agronomy and radioecology of Samarkand region. Field of application: meteorology, agronomy and radioecology. (author)

The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere I. Continuous Emission and Condensed Matter Within the Chromosphere

Directory of Open Access Journals (Sweden)

Robitaille P.-M.

2013-07-01

Full Text Available The continuous spectrum of the solar photosphere stands as the paramount observation with regard to the condensed nature of the solar body. Studies relative to Kirchhoff’s law of thermal emission (e.g. Robitaille P.-M. Kirchhoff’s law of thermal emission: 150 years. Progr. Phys., 2009, v. 4, 3–13. and a detailed analysis of the stellar opacity problem (Robitaille P.M. Stellar opacity: The Achilles’ heel of the gaseous Sun. Progr. Phys., 2011, v. 3, 93–99 have revealed that gaseous models remain unable to properly account for the generation of this spectrum. Therefore, it can be stated with certainty that the photosphere is comprised of condensed matter. Beyond the solar surface, the chromospheric layer of the Sun also generates a weak continuous spectrum in the visible region. This emission exposes the presence of material in the condensed state. As a result, above the level of the photosphere, matter exists in both gaseous and condensed forms, much like within the atmosphere of the Earth. The continuous visible spectrum associated with the chromosphere provides the twenty-sixth line of evidence that the Sun is condensed matter.

Bridging the Radiative Transfer Models for Meteorology and Solar Energy Applications

Science.gov (United States)

Xie, Y.; Sengupta, M.

2017-12-01

Radiative transfer models are used to compute solar radiation reaching the earth surface and play an important role in both meteorology and solar energy studies. Therefore, they are designed to meet the needs of specialized applications. For instance, radiative transfer models for meteorology seek to provide more accurate cloudy-sky radiation compared to models used in solar energy that are geared towards accuracy in clear-sky conditions associated with the maximum solar resource. However, models for solar energy applications are often computationally faster, as the complex solution of the radiative transfer equation is parameterized by atmospheric properties that can be acquired from surface- or satellite-based observations. This study introduces the National Renewable Energy Laboratory's (NREL's) recent efforts to combine the advantages of radiative transfer models designed for meteorology and solar energy applictions. A fast all-sky radiation model, FARMS-NIT, was developed to efficiently compute narrowband all-sky irradiances over inclined photovoltaic (PV) panels. This new model utilizes the optical preperties from a solar energy model, SMARTS, to computes surface radiation by considering all possible paths of photon transmission and the relevent scattering and absorption attenuation. For cloudy-sky conditions, cloud bidirectional transmittance functions (BTDFs) are provided by a precomputed lookup table (LUT) by LibRadtran. Our initial results indicate that FARMS-NIT has an accuracy that is similar to LibRadtran, a highly accurate multi-stream model, but is significantly more efficient. The development and validation of this model will be presented.

Response of earth's atmosphere to increases in solar flux and implications for loss of water from Venus

International Nuclear Information System (INIS)

Kasting, J.F.; Pollack, J.B.; Ackerman, T.P.

1984-01-01

A one-dimensional radiative-convective model is used to compute temperature and water vapor profiles as functions of solar flux for an earthlike atmosphere. The troposphere is assumed to be fully saturated, with a moist adiabatic lapse rate, and changes in cloudiness are neglected. Predicted surface temperatures increase monotonically from -1 to 111 C as the solar flux is increased from 0.81 to 1.45 times its present value. The results imply that the surface temperature of a primitive water-rich Venus should have been at least 80-100 C and may have been much higher. Water vapor should have been a major atmospheric constituent at all altitudes, leading to the rapid hydrodynamic escape of hydrogen. The oxygen left behind by this process was presumably consumed by reactions with reduced minerals in the crust. 43 references

Motions and magnetic fields in the solar atmosphere

Energy Technology Data Exchange (ETDEWEB)

Krat, V A [AN SSSR, Leningrad. Glavnaya Astronomicheskaya Observatoriya

1977-09-01

The measured magnetic fields generally cannot be regarded as ''mean'' values of the magnetic field intensity H due to depolarization effects in the sum of the Zeeman components of small elements. A picture of smallest magnetic elements in the photosphere can be identified with the photospheric network of the granulation. A relatively long lifetime of the elements of this network and characteristics of its evolution show that a magnetic field of H > or approximately = 10/sup 2/ Oe is concentrated in the dark network between granules near to the solar disc center. Direct measurements of H in solar prominences give values of H ranging from 10 to 10/sup 2/ Oe. At their boundary they cannot be smaller than 10/sup 2/ Oe. The chromospheric elements seen in the center of H/sub a/ (spectrograms obtained on the solar stratospheric observatory (SSO) in 1970-1973) are about four times wider than photospheric elements. The growth in size of the structure elements from the photosphere to the chromosphere results from the magnetic expansion of elements floating up in the atmosphere. On the basis of the stratospheric and best filter observations it is shown that typical configurations of the field are magnetic arcs. Sunspots are considered as stationary processes dissipating due to magnetohydrodynamic instabilities. They have (observations on the SSO) considerable regions of a homogeneous magnetic field inside the umbra. The complicated system of twisted magnetic ropes in outer parts of the umbra and penumbra results from the dissipation of the main configuration. The most plausible model of a sunspot seems to be a twisted toroid with a steady magnetic field directed along the axis of symmetry inside the toroid. This model explains the fact of appearance of a secondary sunspot group inside the primary main group. The axis of the sunspot toroid always remains in the photosphere. Some properties of ''super-granules'' and ''giant granules'' are discussed.

An estimation of impact of anthropogenic aerosols in atmosphere of Tirana on solar insolation. Part II: Modification of solar energy potential

Energy Technology Data Exchange (ETDEWEB)

Buzra, Urim, E-mail: rimibuzra@yahoo.com; Berberi, Pellumb; Mitrushi, Driada; Muda, Valbona [Department of Engineering Physics, FIMIF, PUT, Tirana (Albania); Halili, Daniela [Department of physics, FNS, AXHU, Elbasan (Albania); Berdufi, Irma [Institute of Nuclear Physics, INP, TU, Tirana (Albania)

2016-03-25

Change of irradiative properties of the atmosphere during clear days is an indicator, among others, of existence of atmospheric aerosols and can be used as an indicator for assessment both air pollution and local modifications of solar energy potentials. The main objective of this study is estimation of influence of anthropogenic aerosols on solar energy falling in a horizontal surface during a cloudless day. We have analyzed and quantified the effect of aerosols on reducing the amount of solar energy that falls on the horizontal ground surface in cloudless sky conditions, estimating temporal evolution, both in daily and hour scale, considering also, side effects caused by relative humidity of the air wind speed and geometric factor. As an indicator of concentration of aerosols in atmosphere, we agreed to use the attenuation of solar radiation after the last rainy day. All data were corrected by factors such as, variations of relative humidity, wind speed and daily change of incident angle of solar radiation. We studied the change of solar insolation in three sites with different traffic intensity, one in city of Shkodra and two in city of Tirana. Fifteen days after last rainy day, approximate time needed to achieve saturation, the insolation drops only 3.1% in the city of Shkodra, while in two sites in city of Tirana are 8.5 % and 18.4%. These data show that reduction of solar insolation is closely related with anthropogenic activity, mainly traffic around the site of the meteorological station. The day to day difference tends to decrease with increasing of number of days passed from the last rainy day, which is an evidence of a trend toward a dynamic equilibrium between decantation process of aerosols during the night and their generation during the day.

Electrifying atmospheres charging, ionisation and lightning in the solar system and beyond

CERN Document Server

Aplin, Karen L

2013-01-01

Electrical processes take place in all planetary atmospheres. There is evidence for lightning on Venus, Jupiter, Saturn, Uranus and Neptune, it is possible on Mars and Titan, and cosmic rays ionise every atmosphere, leading to charged droplets and particles. Controversy surrounds the role of atmospheric electricity in physical climate processes on Earth; here, a comparative approach is employed to review the role of electrification in the atmospheres of other planets and their moons. This book reviews the theory, and, where available, measurements, of planetary atmospheric electricity, taken to include ion production and ion-aerosol interactions. The conditions necessary for a global atmospheric electric circuit similar to Earth’s, and the likelihood of meeting these conditions in other planetary atmospheres, are briefly discussed. Atmospheric electrification is more important at planets receiving little solar radiation, increasing the relative significance of electrical forces. Nucleation onto atmospheric ...

Climate response to changes in atmospheric carbon dioxide and solar irradiance on the time scale of days to weeks

International Nuclear Information System (INIS)

Cao Long; Bala, Govindasamy; Caldeira, Ken

2012-01-01

Recent studies show that fast climate response on time scales of less than a month can have important implications for long-term climate change. In this study, we investigate climate response on the time scale of days to weeks to a step-function quadrupling of atmospheric CO 2 and contrast this with the response to a 4% increase in solar irradiance. Our simulations show that significant climate effects occur within days of a stepwise increase in both atmospheric CO 2 content and solar irradiance. Over ocean, increased atmospheric CO 2 warms the lower troposphere more than the surface, increasing atmospheric stability, moistening the boundary layer, and suppressing evaporation and precipitation. In contrast, over ocean, increased solar irradiance warms the lower troposphere to a much lesser extent, causing a much smaller change in evaporation and precipitation. Over land, both increased CO 2 and increased solar irradiance cause rapid surface warming that tends to increase both evaporation and precipitation. However, the physiological effect of increased atmospheric CO 2 on plant stomata reduces plant transpiration, drying the boundary layer and decreasing precipitation. This effect does not occur with increased solar irradiance. Therefore, differences in climatic effects from CO 2 versus solar forcing are manifested within days after the forcing is imposed. (letter)

Solar magnetism eXplorer (SolmeX). Exploring the magnetic field in the upper atmosphere of our closest star

Science.gov (United States)

Peter, Hardi; Abbo, L.; Andretta, V.; Auchère, F.; Bemporad, A.; Berrilli, F.; Bommier, V.; Braukhane, A.; Casini, R.; Curdt, W.; Davila, J.; Dittus, H.; Fineschi, S.; Fludra, A.; Gandorfer, A.; Griffin, D.; Inhester, B.; Lagg, A.; Landi Degl'Innocenti, E.; Maiwald, V.; Sainz, R. Manso; Martínez Pillet, V; Matthews, S.; Moses, D.; Parenti, S.; Pietarila, A.; Quantius, D.; Raouafi, N.-E.; Raymond, J.; Rochus, P.; Romberg, O.; Schlotterer, M.; Schühle, U.; Solanki, S.; Spadaro, D.; Teriaca, L.; Tomczyk, S.; Trujillo Bueno, J.; Vial, J.-C.

2012-04-01

The magnetic field plays a pivotal role in many fields of Astrophysics. This is especially true for the physics of the solar atmosphere. Measuring the magnetic field in the upper solar atmosphere is crucial to understand the nature of the underlying physical processes that drive the violent dynamics of the solar corona—that can also affect life on Earth. SolmeX, a fully equipped solar space observatory for remote-sensing observations, will provide the first comprehensive measurements of the strength and direction of the magnetic field in the upper solar atmosphere. The mission consists of two spacecraft, one carrying the instruments, and another one in formation flight at a distance of about 200 m carrying the occulter to provide an artificial total solar eclipse. This will ensure high-quality coronagraphic observations above the solar limb. SolmeX integrates two spectro-polarimetric coronagraphs for off-limb observations, one in the EUV and one in the IR, and three instruments for observations on the disk. The latter comprises one imaging polarimeter in the EUV for coronal studies, a spectro-polarimeter in the EUV to investigate the low corona, and an imaging spectro-polarimeter in the UV for chromospheric studies. SOHO and other existing missions have investigated the emission of the upper atmosphere in detail (not considering polarization), and as this will be the case also for missions planned for the near future. Therefore it is timely that SolmeX provides the final piece of the observational quest by measuring the magnetic field in the upper atmosphere through polarimetric observations.

A solar neutrino loophole: standard solar models

Energy Technology Data Exchange (ETDEWEB)

Rouse, C A [General Atomic Co., San Diego, Calif. (USA)

1975-11-01

The salient aspects of the existence theorem for a unique solution to a system of linear of nonlinear first-order, ordinary differential equations are given and applied to the equilibrium stellar structure equations. It is shown that values of pressure, temperature, mass and luminosity are needed at one point - and for the sun, the logical point is the solar radius. It is concluded that since standard solar model calculations use split boundary conditions, a solar neutrino loophole still remains: solar model calculations that seek to satisfy the necessary condition for a unique solution to the solar structure equations suggest a solar interior quite different from that deduced in standard models. This, in turn, suggests a theory of formation and solar evolution significantly different from the standard theory.

Solar and atmospheric forcing on mountain lakes.

Science.gov (United States)

Luoto, Tomi P; Nevalainen, Liisa

2016-10-01

We investigated the influence of long-term external forcing on aquatic communities in Alpine lakes. Fossil microcrustacean (Cladocera) and macrobenthos (Chironomidae) community variability in four Austrian high-altitude lakes, determined as ultra-sensitive to climate change, were compared against records of air temperature, North Atlantic Oscillation (NAO) and solar forcing over the past ~400years. Summer temperature variability affected both aquatic invertebrate groups in all study sites. The influence of NAO and solar forcing on aquatic invertebrates was also significant in the lakes except in the less transparent lake known to have remained uniformly cold during the past centuries due to summertime snowmelt input. The results suggest that external forcing plays an important role in these pristine ecosystems through their impacts on limnology of the lakes. Not only does the air temperature variability influence the communities but also larger-scale external factors related to atmospheric circulation patterns and solar activity cause long-term changes in high-altitude aquatic ecosystems, through their connections to hydroclimatic conditions and light environment. These findings are important in the assessment of climate change impacts on aquatic ecosystems and in greater understanding of the consequences of external forcing on lake ontogeny. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of a Fast and Accurate PCRTM Radiative Transfer Model in the Solar Spectral Region

Science.gov (United States)

Liu, Xu; Yang, Qiguang; Li, Hui; Jin, Zhonghai; Wu, Wan; Kizer, Susan; Zhou, Daniel K.; Yang, Ping

2016-01-01

A fast and accurate principal component-based radiative transfer model in the solar spectral region (PCRTMSOLAR) has been developed. The algorithm is capable of simulating reflected solar spectra in both clear sky and cloudy atmospheric conditions. Multiple scattering of the solar beam by the multilayer clouds and aerosols are calculated using a discrete ordinate radiative transfer scheme. The PCRTM-SOLAR model can be trained to simulate top-of-atmosphere radiance or reflectance spectra with spectral resolution ranging from 1 cm(exp -1) resolution to a few nanometers. Broadband radiances or reflectance can also be calculated if desired. The current version of the PCRTM-SOLAR covers a spectral range from 300 to 2500 nm. The model is valid for solar zenith angles ranging from 0 to 80 deg, the instrument view zenith angles ranging from 0 to 70 deg, and the relative azimuthal angles ranging from 0 to 360 deg. Depending on the number of spectral channels, the speed of the current version of PCRTM-SOLAR is a few hundred to over one thousand times faster than the medium speed correlated-k option MODTRAN5. The absolute RMS error in channel radiance is smaller than 10(exp -3) mW/cm)exp 2)/sr/cm(exp -1) and the relative error is typically less than 0.2%.

A MODEL OF MAGNETIC BRAKING OF SOLAR ROTATION THAT SATISFIES OBSERVATIONAL CONSTRAINTS

International Nuclear Information System (INIS)

Denissenkov, Pavel A.

2010-01-01

The model of magnetic braking of solar rotation considered by Charbonneau and MacGregor has been modified so that it is able to reproduce for the first time the rotational evolution of both the fastest and slowest rotators among solar-type stars in open clusters of different ages, without coming into conflict with other observational constraints, such as the time evolution of the atmospheric Li abundance in solar twins and the thinness of the solar tachocline. This new model assumes that rotation-driven turbulent diffusion, which is thought to amplify the viscosity and magnetic diffusivity in stellar radiative zones, is strongly anisotropic with the horizontal components of the transport coefficients strongly dominating over those in the vertical direction. Also taken into account is the poloidal field decay that helps to confine the width of the tachocline at the solar age. The model's properties are investigated by numerically solving the azimuthal components of the coupled momentum and magnetic induction equations in two dimensions using a finite element method.

ANNEALING OF POLYCRYSTALLINE THIN FILM SILICON SOLAR CELLS IN WATER VAPOUR AT SUB-ATMOSPHERIC PRESSURES

Directory of Open Access Journals (Sweden)

Peter Pikna

2014-10-01

Full Text Available Thin film polycrystalline silicon (poly-Si solar cells were annealed in water vapour at pressures below atmospheric pressure. PN junction of the sample was contacted by measuring probes directly in the pressure chamber filled with steam during passivation. Suns-VOC method and a Lock-in detector were used to monitor an effect of water vapour to VOC of the solar cell during whole passivation process (in-situ. Tested temperature of the sample (55°C – 110°C was constant during the procedure. Open-circuit voltage of a solar cell at these temperatures is lower than at room temperature. Nevertheless, voltage response of the solar cell to the light flash used during Suns-VOC measurements was good observable. Temperature dependences for multicrystalline wafer-based and polycrystalline thin film solar cells were measured and compared. While no significant improvement of thin film poly-Si solar cell parameters by annealing in water vapour at under-atmospheric pressures was observed up to now, in-situ observation proved required sensitivity to changing VOC at elevated temperatures during the process.

Empirical Models for the Estimation of Global Solar Radiation in ...

African Journals Online (AJOL)

Empirical Models for the Estimation of Global Solar Radiation in Yola, Nigeria. ... and average daily wind speed (WS) for the interval of three years (2010 – 2012) measured using various instruments for Yola of recorded data collected from the Center for Atmospheric Research (CAR), Anyigba are presented and analyzed.

Internal Gravity Waves in the Magnetized Solar Atmosphere. I. Magnetic Field Effects

Energy Technology Data Exchange (ETDEWEB)

Vigeesh, G.; Steiner, O. [Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, D-79104 Freiburg (Germany); Jackiewicz, J., E-mail: vigeesh@leibniz-kis.de [New Mexico State University, Department of Astronomy, P.O. Box 30001, MSC 4500, Las Cruces, NM 88003 (United States)

2017-02-01

Observations of the solar atmosphere show that internal gravity waves are generated by overshooting convection, but are suppressed at locations of magnetic flux, which is thought to be the result of mode conversion into magnetoacoustic waves. Here, we present a study of the acoustic-gravity wave spectrum emerging from a realistic, self-consistent simulation of solar (magneto)convection. A magnetic field free, hydrodynamic simulation and a magnetohydrodynamic (MHD) simulation with an initial, vertical, homogeneous field of 50 G flux density were carried out and compared with each other to highlight the effect of magnetic fields on the internal gravity wave propagation in the Sun’s atmosphere. We find that the internal gravity waves are absent or partially reflected back into the lower layers in the presence of magnetic fields and argue that the suppression is due to the coupling of internal gravity waves to slow magnetoacoustic waves still within the high- β region of the upper photosphere. The conversion to Alfvén waves is highly unlikely in our model because there is no strongly inclined magnetic field present. We argue that the suppression of internal waves observed within magnetic flux concentrations may also be due to nonlinear breaking of internal waves due to vortex flows that are ubiquitously present in the upper photosphere and the chromosphere.

Development of a three-dimensional local scale atmospheric model with turbulence closure model

International Nuclear Information System (INIS)

Yamazawa, Hiromi

1989-05-01

Through the study to improve SPEEDI's capability, a three-dimensional numerical atmospheric model PHYSIC (Prognostic HYdroStatic model Including turbulence Closure model) was developed to apply it to the transport and diffusion evaluation over complex terrains. The detailed description of the atmospheric model was given. This model consists of five prognostic equations; the momentum equations of horizontal components with the so-called Boussinesq and hydrostatic assumptions, the conservation equations of heat, turbulence kinetic energy and turbulence length scale. The coordinate system used is the terrain following z * coordinate system which allows the existence of complex terrain. The minute formula of the turbulence closure calculation, the surface layer process, the ground surface heat budget, and the atmospheric and solar radiation were also presented. The time integration method used in this model is the Alternating Direction Implicit (A.D.I.) method with a vertically and horizontally staggered grid system. The memory storage needed to execute this model with 31 x 31 x 16 grid points, five layers in soil and double precision variables is about 5.3 MBytes. The CPU time is about 2.2 x 10 -5 s per one step per one grid point with a vector processor FACOM VP-100. (author)

Chemical effects in 11-year solar cycle simulations with the Freie Universität Berlin Climate Middle Atmosphere Model with online chemistry (FUB-CMAM-CHEM)

OpenAIRE

U. Langematz; J. Grenfell; K. Matthes; P. Mieth; M. Kunze; B. Steil; C. Brühl;  

2005-01-01

The impact of 11-year solar cycle variations on stratospheric ozone (O3) is studied with the Freie Universität Berlin Climate Middle Atmosphere Model with interactive chemistry (FUB-CMAM-CHEM). To consider the effect of variations in charged particle precipitation we included an idealized NO x source in the upper mesosphere representing relativistic electron precipitation (REP). Our results suggest that the NO x source by particles and its transport from the mesosphere to the stratosphe...

Short- and medium-term atmospheric constituent effects of very large solar proton events

Directory of Open Access Journals (Sweden)

C. H. Jackman

2008-02-01

Full Text Available Solar eruptions sometimes produce protons, which impact the Earth's atmosphere. These solar proton events (SPEs generally last a few days and produce high energy particles that precipitate into the Earth's atmosphere. The protons cause ionization and dissociation processes that ultimately lead to an enhancement of odd-hydrogen and odd-nitrogen in the polar cap regions (>60° geomagnetic latitude. We have used the Whole Atmosphere Community Climate Model (WACCM3 to study the atmospheric impact of SPEs over the period 1963–2005. The very largest SPEs were found to be the most important and caused atmospheric effects that lasted several months after the events. We present the short- and medium-term (days to a few months atmospheric influence of the four largest SPEs in the past 45 years (August 1972; October 1989; July 2000; and October–November 2003 as computed by WACCM3 and observed by satellite instruments. Polar mesospheric NO_x (NO+NO₂ increased by over 50 ppbv and mesospheric ozone decreased by over 30% during these very large SPEs. Changes in HNO₃, N₂O₅, ClONO₂, HOCl, and ClO were indirectly caused by the very large SPEs in October–November 2003, were simulated by WACCM3, and previously measured by Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS. WACCM3 output was also represented by sampling with the MIPAS averaging kernel for a more valid comparison. Although qualitatively similar, there are discrepancies between the model and measurement with WACCM3 predicted HNO₃ and ClONO₂ enhancements being smaller than measured and N₂O₅ enhancements being larger than measured. The HOCl enhancements were fairly similar in amounts and temporal variation in WACCM3 and MIPAS. WACCM3 simulated ClO decreases below 50 km, whereas MIPAS mainly observed increases, a very perplexing difference. Upper stratospheric

Modeling and Control of DC/DC Boost Converter using K-Factor Control for MPPT of Solar PV System

DEFF Research Database (Denmark)

Vangari, Adithya; Haribabu, Divyanagalakshmi; Sakamuri, Jayachandra N.

2015-01-01

This paper is focused on the design of a controller for the DC/DC boost converter using K factor control, which is based on modified PI control method, for maximum power point tracking (MPPT) of solar PV system. A mathematical model for boost converter based on small signal averaging approach...... is presented. Design of the passive elements of the boost converter as per the system specifications is also illustrated. The performance of the proposed K factor control method is verified with the simulations for MPPT on solar PV system at different atmospheric conditions. A new circuit based model for solar...... PV array, which includes the effect of solar insolation and temperature on PV array output, for the application in power system transient simulations, is also presented. The performance of the PV array model is verified with simulations at different atmospheric conditions. A 160W PV module from BP...

Non-LTE models of Titan's upper atmosphere

Science.gov (United States)

Yelle, Roger V.

1991-01-01

Models for the thermal structure of Titan's upper atmosphere, between 0.1 mbar and 0.01 nbar are presented. The calculations include non-LTE heating/cooling in the rotation-vibration bands of CH4, C2H2, and C2H6, absorption of solar IR radiation in the near-IR bands of CH4 and subsequent cascading to the nu-4 band of CH4, absorption of solar EUV and UV radiation, thermal conduction and cooling by HCN rotational lines. Unlike earlier models, the calculated exospheric temperature agrees well with observations, because of the importance of HCN cooling. The calculations predict a well-developed mesopause with a temperature of 135-140 K at an altitude of approximately 600 km and pressure of about 0.1 microbar. The mesopause is at a higher pressure than predicted by earlier calculations because non-LTE radiative transfer in the rotation-vibration bands of CH4, C2H2, and C2H6 is treated in an accurate manner. The accuracy of the LTE approximation for source functions and heating rates is discussed.

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

Chemical kinetics and modeling of planetary atmospheres

Science.gov (United States)

Yung, Yuk L.

1990-01-01

A unified overview is presented for chemical kinetics and chemical modeling in planetary atmospheres. The recent major advances in the understanding of the chemistry of the terrestrial atmosphere make the study of planets more interesting and relevant. A deeper understanding suggests that the important chemical cycles have a universal character that connects the different planets and ultimately link together the origin and evolution of the solar system. The completeness (or incompleteness) of the data base for chemical kinetics in planetary atmospheres will always be judged by comparison with that for the terrestrial atmosphere. In the latter case, the chemistry of H, O, N, and Cl species is well understood. S chemistry is poorly understood. In the atmospheres of Jovian planets and Titan, the C-H chemistry of simple species (containing 2 or less C atoms) is fairly well understood. The chemistry of higher hydrocarbons and the C-N, P-N chemistry is much less understood. In the atmosphere of Venus, the dominant chemistry is that of chlorine and sulfur, and very little is known about C1-S coupled chemistry. A new frontier for chemical kinetics both in the Earth and planetary atmospheres is the study of heterogeneous reactions. The formation of the ozone hole on Earth, the ubiquitous photochemical haze on Venus and in the Jovian planets and Titan all testify to the importance of heterogeneous reactions. It remains a challenge to connect the gas phase chemistry to the production of aerosols.

Solar system sputtering

Science.gov (United States)

Tombrello, T. A.

1982-01-01

The sites and materials involved in solar system sputtering of planetary surfaces are reviewed, together with existing models for the processes of sputtering. Attention is given to the interaction of the solar wind with planetary atmospheres in terms of the role played by the solar wind in affecting the He-4 budget in the Venus atmosphere, and the erosion and differentiation of the Mars atmosphere by solar wind sputtering. The study is extended to the production of isotopic fractionation and anomalies in interplanetary grains by irradiation, and to erosion effects on planetary satellites with frozen volatile surfaces, such as with Io, Europa, and Ganymede. Further measurements are recommended of the molecular form of the ejected material, the yields and energy spectra of the sputtered products, the iosotopic fractionation sputtering causes, and the possibility of electronic sputtering enhancement with materials such as silicates.

Atmospheric Mining in the Outer Solar System:. [Aerial Vehicle Reconnaissance and Exploration Options

Science.gov (United States)

Palaszewski, Bryan A.

2014-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and hydrogen (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues. While capturing 3He, large amounts of hydrogen and 4He are produced. With these two additional gases, the potential for fueling small and large fleets of additional exploration and exploitation vehicles exists. Additional aerospacecraft or other aerial vehicles (UAVs, balloons, rockets, etc.) could fly through the outer planet atmospheres, for global weather observations, localized storm or other disturbance investigations, wind speed measurements, polar observations, etc. Deep-diving aircraft (built with the strength to withstand many atmospheres of pressure) powered by the excess hydrogen or helium 4 may be designed to probe the higher density regions of the gas giants. Outer planet atmospheric properties, atmospheric storm data, and mission planning for future outer planet UAVs are presented.

Evaluation of different models to estimate the global solar radiation on inclined surface

Science.gov (United States)

Demain, C.; Journée, M.; Bertrand, C.

2012-04-01

Global and diffuse solar radiation intensities are, in general, measured on horizontal surfaces, whereas stationary solar conversion systems (both flat plate solar collector and solar photovoltaic) are mounted on inclined surface to maximize the amount of solar radiation incident on the collector surface. Consequently, the solar radiation incident measured on a tilted surface has to be determined by converting solar radiation from horizontal surface to tilted surface of interest. This study evaluates the performance of 14 models transposing 10 minutes, hourly and daily diffuse solar irradiation from horizontal to inclined surface. Solar radiation data from 8 months (April to November 2011) which include diverse atmospheric conditions and solar altitudes, measured on the roof of the radiation tower of the Royal Meteorological Institute of Belgium in Uccle (Longitude 4.35°, Latitude 50.79°) were used for validation purposes. The individual model performance is assessed by an inter-comparison between the calculated and measured solar global radiation on the south-oriented surface tilted at 50.79° using statistical methods. The relative performance of the different models under different sky conditions has been studied. Comparison of the statistical errors between the different radiation models in function of the clearness index shows that some models perform better under one type of sky condition. Putting together different models acting under different sky conditions can lead to a diminution of the statistical error between global measured solar radiation and global estimated solar radiation. As models described in this paper have been developed for hourly data inputs, statistical error indexes are minimum for hourly data and increase for 10 minutes and one day frequency data.

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.

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.

Origin and structures of solar eruptions II: Magnetic modeling

Science.gov (United States)

Guo, Yang; Cheng, Xin; Ding, MingDe

2017-07-01

The topology and dynamics of the three-dimensional magnetic field in the solar atmosphere govern various solar eruptive phenomena and activities, such as flares, coronal mass ejections, and filaments/prominences. We have to observe and model the vector magnetic field to understand the structures and physical mechanisms of these solar activities. Vector magnetic fields on the photosphere are routinely observed via the polarized light, and inferred with the inversion of Stokes profiles. To analyze these vector magnetic fields, we need first to remove the 180° ambiguity of the transverse components and correct the projection effect. Then, the vector magnetic field can be served as the boundary conditions for a force-free field modeling after a proper preprocessing. The photospheric velocity field can also be derived from a time sequence of vector magnetic fields. Three-dimensional magnetic field could be derived and studied with theoretical force-free field models, numerical nonlinear force-free field models, magnetohydrostatic models, and magnetohydrodynamic models. Magnetic energy can be computed with three-dimensional magnetic field models or a time series of vector magnetic field. The magnetic topology is analyzed by pinpointing the positions of magnetic null points, bald patches, and quasi-separatrix layers. As a well conserved physical quantity, magnetic helicity can be computed with various methods, such as the finite volume method, discrete flux tube method, and helicity flux integration method. This quantity serves as a promising parameter characterizing the activity level of solar active regions.

Atmospheric turbidity and transmittance of solar radiation in Riyadh, Saudi Arabia

Science.gov (United States)

El-Shobokshy, Mohammad S.; Al-Saedi, Yaseen G.

During the last two decades, the urban areas in the city of Riyadh—the capital of Saudi Arabia—were increasing at an exceptionally high rate through a series of development plans. The major plans had been completed by the end of 1982. Some other big utility projects were started and completed during 1987. As a consequence, the air quality has deteriorated markedly and air pollution episodes recorded during these activities showed that particulates were present in the atmosphere at high concentrations. Later in January 1991 the Gulf war started and the firing of the oil fields in Kuwait soon followed. It was estimated that soot particulates were emitted at a rate of 600 ton d -1 along with high rates of other gases. This event has led to significant air quality and visibility problems. Direct normal solar radiation has been measured during the summer months of July and August which were characterized by very dry and cloudless weather for the period between 1982 and 1992. A year-to-year trend of the transmittance of direct normal solar irradiance was then determined. The atmospheric fine aerosol (oil field fires in Kuwait were passing over Riyadh are presented. The reduction in solar irradiation reflects the intensity of dark smoke at a distance of 500 km from Kuwait.

Global response to solar radiation absorbed by phytoplankton in a coupled climate model

Energy Technology Data Exchange (ETDEWEB)

Patara, Lavinia [Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC), Bologna (Italy); Helmholtz Centre for Ocean Research Kiel (GEOMAR), Kiel (Germany); Vichi, Marcello; Masina, Simona [Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC), Bologna (Italy); Istituto Nazionale di Geofisica e Vulcanologia (INGV), Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC), Bologna (Italy); Fogli, Pier Giuseppe [Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC), Bologna (Italy); Manzini, Elisa [Centro Euro-Mediterraneo per i Cambiamenti Climatici (CMCC), Bologna (Italy); Max-Planck-Institut fuer Meteorologie, Hamburg (Germany)

2012-10-15

The global climate response to solar radiation absorbed by phytoplankton is investigated by performing multi-century simulations with a coupled ocean-atmosphere-biogeochemistry model. The absorption of solar radiation by phytoplankton increases radiative heating in the near-surface ocean and raises sea surface temperature (SST) by overall {approx}0.5 C. The resulting increase in evaporation enhances specific atmospheric humidity by 2-5%, thereby increasing the Earth's greenhouse effect and the atmospheric temperatures. The Hadley Cell exhibits a weakening and poleward expansion, therefore reducing cloudiness at subtropical-middle latitudes and increasing it at tropical latitudes except near the Equator. Higher SST at polar latitudes reduces sea ice cover and albedo, thereby increasing the high-latitude ocean absorption of solar radiation. Changes in the atmospheric baroclinicity cause a poleward intensification of mid-latitude westerly winds in both hemispheres. As a result, the North Atlantic Ocean meridional overturning circulation extends more northward, and the equatorward Ekman transport is enhanced in the Southern Ocean. The combination of local and dynamical processes decreases upper-ocean heat content in the Tropics and in the subpolar Southern Ocean, and increases it at middle latitudes. This study highlights the relevance of coupled ocean-atmosphere processes in the global climate response to phytoplankton solar absorption. Given that simulated impacts of phytoplankton on physical climate are within the range of natural climate variability, this study suggests the importance of phytoplankton as an internal constituent of the Earth's climate and its potential role in participating in its long-term climate adjustments. (orig.)

Global response to solar radiation absorbed by phytoplankton in a coupled climate model

International Nuclear Information System (INIS)

Patara, Lavinia; Vichi, Marcello; Masina, Simona; Fogli, Pier Giuseppe; Manzini, Elisa

2012-01-01

The global climate response to solar radiation absorbed by phytoplankton is investigated by performing multi-century simulations with a coupled ocean-atmosphere-biogeochemistry model. The absorption of solar radiation by phytoplankton increases radiative heating in the near-surface ocean and raises sea surface temperature (SST) by overall ∼0.5 C. The resulting increase in evaporation enhances specific atmospheric humidity by 2-5%, thereby increasing the Earth's greenhouse effect and the atmospheric temperatures. The Hadley Cell exhibits a weakening and poleward expansion, therefore reducing cloudiness at subtropical-middle latitudes and increasing it at tropical latitudes except near the Equator. Higher SST at polar latitudes reduces sea ice cover and albedo, thereby increasing the high-latitude ocean absorption of solar radiation. Changes in the atmospheric baroclinicity cause a poleward intensification of mid-latitude westerly winds in both hemispheres. As a result, the North Atlantic Ocean meridional overturning circulation extends more northward, and the equatorward Ekman transport is enhanced in the Southern Ocean. The combination of local and dynamical processes decreases upper-ocean heat content in the Tropics and in the subpolar Southern Ocean, and increases it at middle latitudes. This study highlights the relevance of coupled ocean-atmosphere processes in the global climate response to phytoplankton solar absorption. Given that simulated impacts of phytoplankton on physical climate are within the range of natural climate variability, this study suggests the importance of phytoplankton as an internal constituent of the Earth's climate and its potential role in participating in its long-term climate adjustments. (orig.)

Atmospheric effects of nuclar war aerosols in general circulation model simulations: Influence of smoke optical properties

International Nuclear Information System (INIS)

Thompson, S.L.; Ramaswamy, V.; Covey, C.

1987-01-01

A global atmospheric general circulation model (GCM) is modified to include radiative transfer parameterizations for the absorption and scattering of solar radiation and the absorption of thermal infrared (IR) radiation by smoke aerosols. The solar scattering modifications include a parameterization for diagnosing smoke optical properties as a function of the time- and space-dependent smoke particle radii. The aerosol IR modifications allow for both the ''grey'' absorber approximation and a broadband approximation that resolves the aerosol absorption in four spectral intervals. We examine the sensitivity of some GCM-simulated atmospheric and climatic effects to the optical properties and radiative transfer parameterizations used in studies of massive injections of smoke. Specifically, we test the model response to solar scattering versus nonscattering smoke, variations in prescribed smoke single scattering albedo and IR specific absorption, and interactive versus fixed smoke optical properties. Hypothetical nuclear war created smoke scenarios assume the July injection of 60 or 180 Tg of smoke over portions of the mid-latitude land areas of the northern hemisphere. Atmospheric transport and scavenging of the smoke are included. Nonscattering smoke cases produce roughly 40 Wm/sup -2/ more Earth-atmosphere solar irradiance absorption over the northern hemisphere, when compared to scattering smoke cases having equivalent specific absorption efficiencies. Varying the elemental carbon content of smoke over a plausible range produces a 4 0 --6 0 C change in average mid-latitude land surface temperature, and a variation of about 0.1 in zonally averaged planetary albedo in the northern hemisphere

The northern annular mode in summer and its relation to solar activity variations in the GISS ModelE

Science.gov (United States)

Lee, Jae N.; Hameed, Sultan; Shindell, Drew T.

2008-03-01

The northern annular mode (NAM) has been successfully used in several studies to understand the variability of the winter atmosphere and its modulation by solar activity. The variability of summer circulation can also be described by the leading empirical orthogonal function (EOF) of geopotential heights. We compare the annular modes of the summer geopotential heights in the northern hemisphere stratosphere and troposphere in the Goddard Institute for Space Studies (GISS) ModelE with those in the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis. In the stratosphere, the summer NAM obtained from NCEP/NCAR reanalysis as well as from the ModelE simulations has the same sign throughout the northern hemisphere, but shows greater variability at low latitudes. The patterns in both analyses are consistent with the interpretation that low NAM conditions represent an enhancement of the seasonal difference between the summer and the annual averages of geopotential height, temperature and velocity distributions, while the reverse holds for high NAM conditions. Composite analysis of high and low NAM cases in both model and observation suggests that the summer stratosphere is more "summer-like" when the solar activity is near a maximum. This means that the zonal easterly wind flow is stronger and the temperature is higher than normal. Thus increased irradiance favors a low summer NAM. A quantitative comparison of the anti-correlation between the NAM and the solar forcing is presented in the model and in the observation, both of which show lower/higher NAM index in solar maximum/minimum conditions. The temperature fluctuations in simulated solar minimum conditions are greater than in solar maximum throughout the summer stratosphere. The summer NAM in the troposphere obtained from NCEP/NCAR reanalysis has a dipolar zonal structure with maximum variability over the Asian monsoon region. The corresponding EOF in ModelE has

Divergence of sun-rays by atmospheric refraction at large solar zenith angles

Directory of Open Access Journals (Sweden)

R. Uhl

2004-01-01

Full Text Available For the determination of photolysis rates at large zenith angles it has been demonstrated that refraction by the earth's atmosphere must be taken into account. In fact, due to the modified optical path the optical transmittance is thereby increased in most instances. Here we show that in addition the divergence of sun-rays, which is also caused by refraction but which reduces the direct solar irradiance, should not be neglected. Our calculations are based on a spherically symmetric atmosphere and include extinction by Rayleigh scattering, ozone, and background aerosol. For rays with 10km tangent altitude the divergence yields a reduction of about 10% to 40% at solar zenith angles of 91° to 96°. Moreover, we find that the divergence effect can completely cancel the relative enhancement caused by the increase of transmittance.

THERMAL DIAGNOSTICS WITH THE ATMOSPHERIC IMAGING ASSEMBLY ON BOARD THE SOLAR DYNAMICS OBSERVATORY: A VALIDATED METHOD FOR DIFFERENTIAL EMISSION MEASURE INVERSIONS

Energy Technology Data Exchange (ETDEWEB)

Cheung, Mark C. M.; Boerner, P.; Schrijver, C. J.; Malanushenko, A. [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street Bldg. 252, Palo Alto, CA 94304 (United States); Testa, P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Chen, F.; Peter, H., E-mail: cheung@lmsal.com [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

2015-07-10

We present a new method for performing differential emission measure (DEM) inversions on narrow-band EUV images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. The method yields positive definite DEM solutions by solving a linear program. This method has been validated against a diverse set of thermal models of varying complexity and realism. These include (1) idealized Gaussian DEM distributions, (2) 3D models of NOAA Active Region 11158 comprising quasi-steady loop atmospheres in a nonlinear force-free field, and (3) thermodynamic models from a fully compressible, 3D MHD simulation of active region (AR) corona formation following magnetic flux emergence. We then present results from the application of the method to AIA observations of Active Region 11158, comparing the region's thermal structure on two successive solar rotations. Additionally, we show how the DEM inversion method can be adapted to simultaneously invert AIA and Hinode X-ray Telescope data, and how supplementing AIA data with the latter improves the inversion result. The speed of the method allows for routine production of DEM maps, thus facilitating science studies that require tracking of the thermal structure of the solar corona in time and space.

Different atmospheric parameters influence on spectral UV radiation (measurements and modelling)

Energy Technology Data Exchange (ETDEWEB)

Chubarova, N Y [Moscow State Univ. (Russian Federation). Meteorological Observatory; Krotkov, N A [Maryland Univ., MD (United States). JCESS/Meteorology Dept.; Geogdzhaev, I V; Bushnev, S V; Kondranin, T V [SUMGF/MIPT, Dolgoprudny (Russian Federation); Khattatov, V U [Central Aerological Observatory, Dolgoprudny (Russian Federation)

1996-12-31

The ultraviolet (UV) radiation plays a vital role in the biophysical processes despite its small portion in the total solar flux. UV radiation is subject to large variations at the Earth surface depending greatly on solar elevation, ozone and cloud amount, aerosols and surface albedo. The analysis of atmospheric parameters influence is based on the spectral archive data of three spectral instruments: NSF spectroradiometer (Barrow network) (NSF Polar Programs UV Spectroradiometer Network 1991-1992,1992), spectrophotometer (SUVS-M) of Central Aerological Observatory CAO, spectroradiometer of Meteorological Observatory of the Moscow State University (MO MSU) and model simulations based on delta-Eddington approximation

Different atmospheric parameters influence on spectral UV radiation (measurements and modelling)

Energy Technology Data Exchange (ETDEWEB)

Chubarova, N.Y. [Moscow State Univ. (Russian Federation). Meteorological Observatory; Krotkov, N.A. [Maryland Univ., MD (United States). JCESS/Meteorology Dept.; Geogdzhaev, I.V.; Bushnev, S.V.; Kondranin, T.V. [SUMGF/MIPT, Dolgoprudny (Russian Federation); Khattatov, V.U. [Central Aerological Observatory, Dolgoprudny (Russian Federation)

1995-12-31

The ultraviolet (UV) radiation plays a vital role in the biophysical processes despite its small portion in the total solar flux. UV radiation is subject to large variations at the Earth surface depending greatly on solar elevation, ozone and cloud amount, aerosols and surface albedo. The analysis of atmospheric parameters influence is based on the spectral archive data of three spectral instruments: NSF spectroradiometer (Barrow network) (NSF Polar Programs UV Spectroradiometer Network 1991-1992,1992), spectrophotometer (SUVS-M) of Central Aerological Observatory CAO, spectroradiometer of Meteorological Observatory of the Moscow State University (MO MSU) and model simulations based on delta-Eddington approximation

Periodicities common to the solar atmosphere rotation and the functioning of human organism

International Nuclear Information System (INIS)

Tyagun, N.F.

1995-01-01

The study is made of the occurrence rates of menstrual cycle periods for ∼ 2000 women. Peaks on the distribution histogram, corresponding to 21, 25, 28 and 30 days, coincide with a set of axial rotation periods of the solar atmosphere. It is proposed that the functioning of human organism is determined not only by the Moon bu by the rithmics of solar system. 10 refs., 1 fig

Organic chemistry in the atmosphere. [laboratory modeling of Titan atmosphere

Science.gov (United States)

Sagan, C.

1974-01-01

The existence of an at least moderately complex organic chemistry on Titan is stipulated based on clear evidence of methane, and at least presumptive evidence of hydrogen in its atmosphere. The ratio of methane to hydrogen is the highest of any atmosphere in the solar system. Irradiation of hydrogen/methane mixtures produces aromatic and aliphatic hydrocarbons. A very reasonable hypothesis assumes that the red cloud cover of Titan is made of organic chemicals. Two-carbon hydrocarbons experimentally produced from irradiated mixtures of methane, ammonia, water, and hydrogen bear out the possible organic chemistry of the Titanian environment.

Impact of cosmic rays and solar energetic particles on the Earth’s ionosphere and atmosphere

Czech Academy of Sciences Publication Activity Database

Velinov, P. I. Y.; Asenovski, S.; Kudela, K.; Laštovička, Jan; Mateev, L.; Mishev, A.; Tonev, P.

2013-01-01

Roč. 3, 26 March (2013), A14/1-A14/17 ISSN 2115-7251 Grant - others:European COST Action(XE) ES0803 Institutional support: RVO:68378289 Keywords : cosmic rays * solar energetic particles * ionization * ionosphere * atmosphere * solar activity * solar-terrestrial relationships Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.519, year: 2013 http://www.swsc-journal.org/articles/swsc/abs/2013/01/swsc120040/swsc120040.html

Climate responses to SATIRE and SIM-based spectral solar forcing in a 3D atmosphere-ocean coupled GCM

Directory of Open Access Journals (Sweden)

Wen Guoyong

2017-01-01

Full Text Available We apply two reconstructed spectral solar forcing scenarios, one SIM (Spectral Irradiance Monitor based, the other the SATIRE (Spectral And Total Irradiance REconstruction modeled, as inputs to the GISS (Goddard Institute for Space Studies GCMAM (Global Climate Middle Atmosphere Model to examine climate responses on decadal to centennial time scales, focusing on quantifying the difference of climate response between the two solar forcing scenarios. We run the GCMAM for about 400 years with present day trace gas and aerosol for the two solar forcing inputs. We find that the SIM-based solar forcing induces much larger long-term response and 11-year variation in global averaged stratospheric temperature and column ozone. We find significant decreasing trends of planetary albedo for both forcing scenarios in the 400-year model runs. However the mechanisms for the decrease are very different. For SATIRE solar forcing, the decreasing trend of planetary albedo is associated with changes in cloud cover. For SIM-based solar forcing, without significant change in cloud cover on centennial and longer time scales, the apparent decreasing trend of planetary albedo is mainly due to out-of-phase variation in shortwave radiative forcing proxy (downwelling flux for wavelength >330 nm and total solar irradiance (TSI. From the Maunder Minimum to present, global averaged annual mean surface air temperature has a response of ~0.1 °C to SATIRE solar forcing compared to ~0.04 °C to SIM-based solar forcing. For 11-year solar cycle, the global surface air temperature response has 3-year lagged response to either forcing scenario. The global surface air 11-year temperature response to SATIRE forcing is about 0.12 °C, similar to recent multi-model estimates, and comparable to the observational-based evidence. However, the global surface air temperature response to 11-year SIM-based solar forcing is insignificant and inconsistent with observation-based evidence.

The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere II. Continuous Emission and Condensed Matter Within the Corona

Directory of Open Access Journals (Sweden)

Robitaille P.-M.

2013-07-01

Full Text Available The K-corona, a significant portion of the solar atmosphere, displays a continuous spectrum which closely parallels photospheric emission, though without the presence of overlying Fraunhofer lines. The E-corona exists in the same region and is characterized by weak emission lines from highly ionized atoms. For instance, the famous green emission line from coronium (FeXIV is part of the E-corona. The F-corona exists beyond the K/E-corona and, like the photospheric spectrum, is characterized by Fraunhofer lines. The F-corona represents photospheric light scattered by dust particles in the interplanetary medium. Within the gaseous models of the Sun, the K-corona is viewed as photospheric radiation which has been scattered by relativistic electrons. This scattering is thought to broaden the Fraunhofer lines of the solar spectrum such that they can no longer be detected in the K-corona. Thus, the gaseous models of the Sun account for the appearance of the K-corona by distorting photospheric light, since they are unable to have recourse to condensed matter to directly produce such radiation. Conversely, it is now advanced that the continuous emission of the K-corona and associated emission lines from the E-corona must be interpreted as manifestations of the same phenomenon: condensed matter exists in the corona. It is well-known that the Sun expels large amounts of material from its surface in the form of flares and coronal mass ejections. Given a liquid metallic hydrogen model of the Sun, it is logical to assume that such matter, which exists in the condensed state on the solar surface, continues to manifest its nature once expelled into the corona. Therefore, the continuous spectrum of the K-corona provides the twenty-seventh line of evidence that the Sun is composed of condensed matter.

Atmospheric effects on the photovoltaic performance of hybrid perovskite solar cells

KAUST Repository

Sheikh, Arif D.; Bera, Ashok; Haque, Mohammed; Baby, Rakhi Raghavan; Del Gobbo, Silvano; Alshareef, Husam N.; Wu, Tao

2015-01-01

nitrogen, and dry air, on the photovoltaic performance of TiO2-CH3NH3PbI3-xClx-spiro-MeOTAD solar cells. We found that spin coating of spiro-MeOTAD in an oxygen atmosphere alone was not adequate to functionalize its hole-transport property completely

Long-period fading in atmospherics during severe meteorological activity and associated solar geophysical phenomena at low latitudes

Directory of Open Access Journals (Sweden)

A. B. Bhattacharya

1998-02-01

Full Text Available The records of VLF atmospherics over Calcutta and then over Kalyani (West Bengal during the torrential rainfall, caused by violent monsoon and post-monsoon depressions, exhibit distinct long-period fadings both at day and night. Interesting results obtained from an analysis of round-the-clock atmospherics data and associated meteorological parameters are reported in this paper. A possible correlation between the severe meteorological activity with the solar geophysical phenomena was studied. The results are indicative of an interesting sequence of solar-terrestrial events. A tentative conclusion is reached, suggesting an origin of the fading from atmospheric gravity waves generated in the centre of activity of the depressions concerned.Key words. Meteorology and atmospheric dynamics · Lightning · Precipitation

Abundance analysis of neodymium in the solar atmosphere

Science.gov (United States)

Abdelkawy, Ali G. A.; Shaltout, Abdelrazek M. K.; Beheary, M. M.; Bakry, A.

2017-10-01

Based on non-local thermodynamical equilibrium (NLTE) calculations, the solar neodymium (Nd) content was found based on a model atom of singly ionized neodymium (Nd II) containing 153 energy levels and 42 line transitions plus the ground state of Nd III. Here, we re-derive the solar Nd abundance using the model of the solar photosphere of Holweger & Müller.We succeed in selecting a good sample line list, relying on 20 Nd II solar lines together with the most accurate transition probabilities measured experimentally and available observational data. With damping parameters obtained from the literature, we find a mean NLTE solar photospheric Nd abundance of log ɛNd(1D) = 1.43 ± 0.16, which is in excellent agreement with the meteoritic value (log ɛNd = 1.45 ± 0.02). For a set of selected Nd II lines, the NLTE abundance correction is found to be +0.01 dex compared with the standard LTE effect. The influence of collisional interactions with electrons and neutral hydrogen atoms is investigated in detail.

Atmospheric Mining in the Outer Solar System: Aerial Vehicle Mission and Design Issues

Science.gov (United States)

Palaszewski, Bryan

2015-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and deuterium can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and deuterium were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. While capturing 3He, large amounts of hydrogen and 4He are produced. With these two additional gases, the potential for fueling small and large fleets of additional exploration and exploitation vehicles exists. The mining aerospacecraft (ASC) could fly through the outer planet atmospheres, for global weather observations, localized storm or other disturbance investigations, wind speed measurements, polar observations, etc. Analyses of orbital transfer vehicles (OTVs), landers, and in-situ resource utilization (ISRU) mining factories are included. Preliminary observations are presented on near-optimal selections of moon base orbital locations, OTV power levels, and OTV and lander rendezvous points.

Whole Atmosphere Simulation of Anthropogenic Climate Change

Science.gov (United States)

Solomon, Stanley C.; Liu, Han-Li; Marsh, Daniel R.; McInerney, Joseph M.; Qian, Liying; Vitt, Francis M.

2018-02-01

We simulated anthropogenic global change through the entire atmosphere, including the thermosphere and ionosphere, using the Whole Atmosphere Community Climate Model-eXtended. The basic result was that even as the lower atmosphere gradually warms, the upper atmosphere rapidly cools. The simulations employed constant low solar activity conditions, to remove the effects of variable solar and geomagnetic activity. Global mean annual mean temperature increased at a rate of +0.2 K/decade at the surface and +0.4 K/decade in the upper troposphere but decreased by about -1 K/decade in the stratosphere-mesosphere and -2.8 K/decade in the thermosphere. Near the mesopause, temperature decreases were small compared to the interannual variation, so trends in that region are uncertain. Results were similar to previous modeling confined to specific atmospheric levels and compared favorably with available measurements. These simulations demonstrate the ability of a single comprehensive numerical model to characterize global change throughout the atmosphere.

The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere VI. Helium in the Chromosphere

Directory of Open Access Journals (Sweden)

Robitaille P.-M.

2013-07-01

Full Text Available Molecular hydrogen and hydrides have recently been advanced as vital agents in the generation of emission spectra in the chromosphere. This is a result of the role they play in the formation of condensed hydrogen structures (CHS within the chromosphere (P.M. Robitaille. The Liquid Metallic Hydrogen Model of the Sun and the Solar Atmosphere IV. On the Nature of the Chromosphere. Progr. Phys., 2013, v. 3, 15–21. Next to hydrogen, helium is perhaps the most intriguing component in this region of the Sun. Much like other elements, which combine with hydrogen to produce hydrides, helium can form the well-known helium hydride molecular ion, HeH+, and the excited neutral helium hydride molecule, HeH∗. While HeH+ is hypothesized to be a key cosmologicalmolecule, its possible presence in the Sun, and that of its excited neutral counterpart, has not been considered. Still, these hydrides are likely to play a role in the synthesis of CHS, as the He I and He II emission lines strongly suggest. In this regard, the study of helium emission spectra can provide insight into the condensed nature of the Sun, especially when considering the 10830 Å line associated with the 23P→2 3S triplet state transition. This line is strong in solar prominences and can be seen clearly on the disk. The excessive population of helium triplet states cannot be adequately explained using the gaseous models, since these states should be depopulated by collisional processes. Conversely, when He-based molecules are used to build CHS in a liquid metallic hydrogen model, an ever increasing population of the 23S and 23P states might be expected. The overpopulation of these triplet states leads to the conclusion that these emission lines are unlikely to be produced through random collisional or photon excitation, as required by the gaseous models. This provides a significant hurdle for these models. Thus, the strong 23P→2 3S lines and the overpopulation of the helium triplet

Atmospheric turbidity parameters affecting the incident solar solar radiation for two different areas in (Eg))

International Nuclear Information System (INIS)

Tadros, M.T.Y.; Mosalam, M.A.; El-metwally, M.

1999-01-01

Atmospheric turbidity parameters such as Linke turbidity (L-0) and true Angstrom parameters (Bita o , Alpha 0 ) have been determined from the measurements of direct solar radiation for entire spectrum and for specified spectral bands during one year starting from june 1992 to may 1993. Comparison between the industrial area in Helwan (south Cairo) with that of the agricultural area in Mansoura, in (Eg), was done. Analysis of data revealed that the atmospheric turbidity parameters (L Beta) in Helwan is higher than that in Mansoura, except for hot wet months. The increase of L in Mansoura, in summer, is due to the increase of water vapor content. The wavelength exponent Alpha shows that the size the size of particles in Helwan is larger than that in Mansoura

Formation of a hybrid-type proto-atmosphere on Mars accreting in the solar nebula

Science.gov (United States)

Saito, Hiroaki; Kuramoto, Kiyoshi

2018-03-01

Recent studies of the chronology of Martian meteorites suggest that the growth of Mars was almost complete within a few Myr after the birth of the Solar system. During such rapid accretion, proto-Mars likely gravitationally maintained both the solar nebula component and the impact degassing component, containing H2O vapour and reduced gas species, as a proto-atmosphere to be called a hybrid-type proto-atmosphere. Here we numerically analyse the mass and composition of the degassed component and the atmospheric thermal structure sustained by accretional heating. Our results predict that a growing Mars possibly acquired a massive and hot hybrid-type proto-atmosphere with surface pressure and temperature greater than several kbar and 2000 K, respectively, which is sufficient to produce a deep magma ocean. In such a high-temperature and high-pressure environment, a significant amount of H2O, CH4, CO, and H2 is expected to be partitioned into the planetary interior, although this would strongly depend on the dynamics of the magma ocean and mantle solidification. The dissolved H2O may explain the wet Martian mantle implied from basaltic Martian meteorites. Along with the remnant reduced atmosphere after the hydrodynamic atmospheric escape, dissolved reduced gas species may have maintained an earliest Martian surface environment that allowed prebiotic chemical evolution and liquid H2O activities.

Water vapor measurements at ALOMAR over a solar cycle compared with model calculations by LIMA

Science.gov (United States)

Hartogh, P.; Sonnemann, G. R.; Grygalashvyly, M.; Song, Li; Berger, U.; Lübken, F.-J.

2010-01-01

Microwave water vapor measurements between 40 and 80 km altitude over a solar cycle (1996-2006) were carried out in high latitudes at Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) (69.29°N, 16.03°E), Norway. Some smaller gaps and three interruptions of monitoring in the winters 1996/1997 and 2005/2006 and from spring 2001 to spring 2002 occurred during this period. The observations show a distinct year-to-year variability not directly related to solar Lyman-α radiation. In winter the water vapor mixing ratios in the upper domain were anticorrelated to the solar activity, whereas in summer, minima occurred in the years after the solar maximum in 2000/2001. In winter, sudden stratospheric warmings (SSWs) modulated the water vapor mixing ratios. Within the stratopause region a middle atmospheric water vapor maximum was observed, which results from the methane oxidation and is a regular feature there. The altitude of the maximum increased by approximately 5 km as summer approached. The largest mixing ratios were monitored in autumn. During the summer season a secondary water vapor maximum also occurred above 65 km most pronounced in late summer. The solar Lyman-α radiation impacts the water vapor mixing ratio particularly in winter above 65 km. In summer the correlation is positive below 70 km. The correlation is also positive in the lower mesosphere/stratopause region in winter due to the action of sudden stratospheric warmings, which occur more frequently under the condition of high solar activity and the enhancing the humidity. A strong day-to-day variability connected with planetary wave activity was found throughout the entire year. Model calculations by means of Leibniz-Institute Middle Atmosphere model (LIMA) reflect the essential patterns of the water vapor variation, but the results also show differences from the observations, indicating that exchange processes between the troposphere and stratosphere not modeled by LIMA could have

CORRELATION BETWEEN THE 22-YEAR SOLAR MAGNETIC CYCLE AND THE 22-YEAR QUASICYCLE IN THE EARTH'S ATMOSPHERIC TEMPERATURE

International Nuclear Information System (INIS)

Qu Weizheng; Zhao Jinping; Huang Fei; Deng Shenggui

2012-01-01

According to the variation pattern of the solar magnetic field polarity and its relation to the relative sunspot number, we established the time series of the sunspot magnetic field polarity index and analyzed the strength and polarity cycle characteristics of the solar magnetic field. The analysis showed the existence of a cycle with about a 22-year periodicity in the strength and polarity of the solar magnetic field, which proved the Hale proposition that the 11-year sunspot cycle is one-half of the 22-year solar magnetic cycle. By analyzing the atmospheric temperature field, we found that the troposphere and the stratosphere in the middle latitude of both the northern and southern hemispheres exhibited a common 22-year quasicycle in the atmospheric temperature, which is believed to be attributable to the 22-year solar magnetic cycle.

ENERGY CONTENT AND PROPAGATION IN TRANSVERSE SOLAR ATMOSPHERIC WAVES

Energy Technology Data Exchange (ETDEWEB)

Goossens, M.; Van Doorsselaere, T. [Centre for mathematical Plasma Astrophysics, Mathematics Department, Celestijnenlaan 200B bus 2400, B-3001 Heverlee (Belgium); Soler, R. [Solar Physics Group, Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Verth, G., E-mail: tom.vandoorsselaere@wis.kuleuven.be [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, University of Sheffield, Hounsfield Road, Hicks Building, Sheffield S3 7RH (United Kingdom)

2013-05-10

Recently, a significant amount of transverse wave energy has been estimated propagating along solar atmospheric magnetic fields. However, these estimates have been made with the classic bulk Alfven wave model which assumes a homogeneous plasma. In this paper, the kinetic, magnetic, and total energy densities and the flux of energy are computed for transverse MHD waves in one-dimensional cylindrical flux tube models with a piecewise constant or continuous radial density profile. There are fundamental deviations from the properties for classic bulk Alfven waves. (1) There is no local equipartition between kinetic and magnetic energy. (2) The flux of energy and the velocity of energy transfer have, in addition to a component parallel to the magnetic field, components in the planes normal to the magnetic field. (3) The energy densities and the flux of energy vary spatially, contrary to the case of classic bulk Alfven waves. This last property has the important consequence that the energy flux computed with the well known expression for bulk Alfven waves could overestimate the real flux by a factor in the range 10-50, depending on the flux tube equilibrium properties.

Solar nuclear energy

International Nuclear Information System (INIS)

Tlalka, R.

1977-01-01

Brief characteristics are given of solar radiation and of its spectral range. The relation is derived for the gas pressure in the centre of the Sun and the mechanism is described of particle interactions in the Sun. Using the Eddington model the basic nuclear reactions in the Sun are described, namely the proton-proton chain and the C-N cycle. The energy transfer is discussed from the Sun to the boundaries of the Earth atmosphere and inside the atmosphere. The measurement of solar energy is conducted with actinometers, i.e., pyrheliometers, pyranometers and combinations thereof. The results of solar radiation measurement in different weather conditions are graphically represented. (J.B.)

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

THE RESPONSE OF A THREE-DIMENSIONAL SOLAR ATMOSPHERE TO WAVE-DRIVEN JETS

Energy Technology Data Exchange (ETDEWEB)

Scullion, E. [Institute of Theoretical Astrophysics, University of Oslo (Norway); Erdelyi, R.; Fedun, V. [Solar Physics and Space Plasma Research Centre (SP2RC), Department of Applied Mathematics, University of Sheffield, Sheffield S3 7RH (United Kingdom); Doyle, J. G., E-mail: eamonms@astro.uio.no, E-mail: robertus@sheffield.ac.uk, E-mail: v.fedun@sheffield.ac.uk, E-mail: jgd@arm.ac.uk [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom)

2011-12-10

Global oscillations from the solar interior are, mainly, pressure-driven (p-modes) oscillations with a peak power of a five-minute period. These oscillations are considered to manifest in many phenomena in the lower solar atmosphere, most notably, in spicules. These small-scale jets may provide the key to understanding the powering mechanisms of the transition region (TR) and lower corona. Here, we simulate the formation of wave-driven (type-I) spicule phenomena in three dimensions and the transmission of acoustic waves from the lower chromosphere and into the corona. The outer atmosphere oscillates in response to the jet formation, and in turn, we reveal the formation of a circular seismic surface wave, which we name as a Transition Region Quake (TRQ). The TRQ forms as a consequence of an upward propelling spicular wave train that repeatedly punctures and energizes the TR. The steep density gradient enables the TRQ to develop and radially fan outward from the location where the spicular plasma column impinges the TR. We suggest the TRQ formation as a formidable mechanism in continuously sustaining part of the energy budget of the TR. We present a supporting numerical model which allow us to determine the level of energy dumping at the TR by upward-propagating p-modes. Upon applying a wavelet analysis on our simulations we identify the presence of a chromospheric cavity which resonates with the jet propagation and leaves behind an oscillatory wake with a distinctive periodicity. Through our numerical analysis we also discover type-I spicule turbulence leading to a convection-based motion in the low corona.

A theoretical analysis of the impact of atmospheric parameters on the spectral, electrical and thermal performance of a concentrating III–V triple-junction solar cell

International Nuclear Information System (INIS)

Theristis, Marios; Fernández, Eduardo F.; Stark, Cameron; O’Donovan, Tadhg S.

2016-01-01

Highlights: • An integrated spectral dependent electrical–thermal model has been developed. • The effect of atmospheric parameters on system’s performance is evaluated. • The HCPV cooling requirements under “hot & dry” conditions are quantified. • Case studies show the impact of heat transfer coefficient on annual energy yield. • The integrated modelling allows the system’s optimisation. - Abstract: The spectral sensitivity of a concentrating triple-junction (3J) solar cell has been investigated. The atmospheric parameters such as the air mass (AM), aerosol optical depth (AOD) and precipitable water (PW) change the distribution of the solar spectrum in a way that the spectral, electrical and thermal performance of a 3J solar cell is affected. In this paper, the influence of the spectral changes on the performance of each subcell and whole cell has been analysed. It has been shown that increasing the AM and AOD have a negative impact on the spectral and electrical performance of 3J solar cells while increasing the PW has a positive effect, although, to a lesser degree. A three-dimensional finite element analysis model is used to quantify the effect of each atmospheric parameter on the thermal performance for a range of heat transfer coefficients from the back-plate to the ambient air and also ambient temperature. It is shown that a heat transfer coefficient greater than 1300 W/(m"2 K) is required to keep the solar cell under 100 °C at all times. In order to get a more realistic assessment and also to investigate the effect of heat transfer coefficient on the annual energy yield, the methodology is applied for four US locations using data from a typical meteorological year (TMY3).

An Overview of Modeling Middle Atmospheric Odd Nitrogen

Science.gov (United States)

Jackman, Charles H.; Kawa, S. Randolph; Einaudi, Franco (Technical Monitor)

2001-01-01

Odd nitrogen (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, and BrONO2) constituents are important components in the control of middle atmospheric ozone. Several processes lead to the production of odd nitrogen (NO(sub y)) in the middle atmosphere (stratosphere and mesosphere) including the oxidation of nitrous oxide (N2O), lightning, downflux from the thermosphere, and energetic charged particles (e.g., galactic cosmic rays, solar proton events, and energetic electron precipitation). The dominant production mechanism of NO(sub y) in the stratosphere is N2O oxidation, although other processes contribute. Mesospheric NO(sub y) is influenced by N2O oxidation, downflux from the thermosphere, and energetic charged particles. NO(sub y) is destroyed in the middle atmosphere primarily via two processes: 1) dissociation of NO to form N and O followed by N + NO yielding N2 + O to reform even nitrogen; and 2) transport to the troposphere where HNO3 can be rapidly scavenged in water droplets and rained out of the atmosphere. There are fairly significant differences among global models that predict NO(sub y). NO(sub y) has a fairly long lifetime in the stratosphere (months to years), thus disparate transport in the models probably contributes to many of these differences. Satellite and aircraft measurement provide modeling tests of the various components of NO(sub y). Although some recent reaction rate measurements have led to improvements in model/measurement agreement, significant differences do remain. This presentation will provide an overview of several proposed sources and sinks of NO(sub y) and their regions of importance. Multi-dimensional modeling results for NO(sub y) and its components with comparisons to observations will also be presented.

Measurement of atmospheric precipitable water using a solar radiometer. [water vapor absorption effects

Science.gov (United States)

Pitts, D. E.; Dillinger, A. E.; Mcallum, W. E.

1974-01-01

A technique is described and tested that allows the determination of atmospheric precipitable water from two measurements of solar intensity: one in a water-vapor absorption band and another in a nearby spectral region unaffected by water vapor.

Non-equilibrium hydrogen ionization in 2D simulations of the solar atmosphere

Science.gov (United States)

Leenaarts, J.; Carlsson, M.; Hansteen, V.; Rutten, R. J.

2007-10-01

Context: The ionization of hydrogen in the solar chromosphere and transition region does not obey LTE or instantaneous statistical equilibrium because the timescale is long compared with important hydrodynamical timescales, especially of magneto-acoustic shocks. Since the pressure, temperature, and electron density depend sensitively on hydrogen ionization, numerical simulation of the solar atmosphere requires non-equilibrium treatment of all pertinent hydrogen transitions. The same holds for any diagnostic application employing hydrogen lines. Aims: To demonstrate the importance and to quantify the effects of non-equilibrium hydrogen ionization, both on the dynamical structure of the solar atmosphere and on hydrogen line formation, in particular Hα. Methods: We implement an algorithm to compute non-equilibrium hydrogen ionization and its coupling into the MHD equations within an existing radiation MHD code, and perform a two-dimensional simulation of the solar atmosphere from the convection zone to the corona. Results: Analysis of the simulation results and comparison to a companion simulation assuming LTE shows that: a) non-equilibrium computation delivers much smaller variations of the chromospheric hydrogen ionization than for LTE. The ionization is smaller within shocks but subsequently remains high in the cool intershock phases. As a result, the chromospheric temperature variations are much larger than for LTE because in non-equilibrium, hydrogen ionization is a less effective internal energy buffer. The actual shock temperatures are therefore higher and the intershock temperatures lower. b) The chromospheric populations of the hydrogen n = 2 level, which governs the opacity of Hα, are coupled to the ion populations. They are set by the high temperature in shocks and subsequently remain high in the cool intershock phases. c) The temperature structure and the hydrogen level populations differ much between the chromosphere above photospheric magnetic elements

A method for daily global solar radiation estimation from two instantaneous values using MODIS atmospheric products

International Nuclear Information System (INIS)

Xu, Xiaojun; Du, Huaqiang; Zhou, Guomo; Mao, Fangjie; Li, Pingheng; Fan, Weiliang; Zhu, Dien

2016-01-01

Accurate information on the temporal and spatial distributions of solar radiation is very important in many scientific fields. In this study, instantaneous solar irradiances on a horizontal surface at 10:30 and 13:30 local time (LT) were calculated from Moderate Resolution Imaging Spectroradiometer (MODIS) atmospheric data products with relatively high spatial resolution using a solar radiation model. These solar irradiances were combined to derive half-hourly averages of solar irradiance (HASI) and daily global solar radiation (GSR) on a horizontal surface using linear interpolation, piecewise linear regression, and quadratic polynomial regression. Compared with field observations, the HASI were estimated accurately when the total cloud fraction (TCF) was 0.6. Overall, the daily GSR estimated in this study was better than that estimated by the Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis of NASA. The daily GSR estimated in this study was underestimated, whereas it was overestimated by MERRA. The combination of the daily GSR estimates of this study and MERRA offers a simple and feasible technique for reducing uncertainty in daily GSR estimates. - Highlights: • Daily GSR is integrated from two observations from the MODIS products. • Daily GSR from the MODIS products is underestimated. • Biases were attributed primarily to variations in the total cloud percent. • Combining daily GSR estimates from the MODIS and the MERRA increases accuracy.

A Linear Regression Model for Global Solar Radiation on Horizontal Surfaces at Warri, Nigeria

Directory of Open Access Journals (Sweden)

Michael S. Okundamiya

2013-10-01

Full Text Available The growing anxiety on the negative effects of fossil fuels on the environment and the global emission reduction targets call for a more extensive use of renewable energy alternatives. Efficient solar energy utilization is an essential solution to the high atmospheric pollution caused by fossil fuel combustion. Global solar radiation (GSR data, which are useful for the design and evaluation of solar energy conversion system, are not measured at the forty-five meteorological stations in Nigeria. The dearth of the measured solar radiation data calls for accurate estimation. This study proposed a temperature-based linear regression, for predicting the monthly average daily GSR on horizontal surfaces, at Warri (latitude 5.020N and longitude 7.880E an oil city located in the south-south geopolitical zone, in Nigeria. The proposed model is analyzed based on five statistical indicators (coefficient of correlation, coefficient of determination, mean bias error, root mean square error, and t-statistic, and compared with the existing sunshine-based model for the same study. The results indicate that the proposed temperature-based linear regression model could replace the existing sunshine-based model for generating global solar radiation data. Keywords: air temperature; empirical model; global solar radiation; regression analysis; renewable energy; Warri

Thermal structure and dynamics of the Martian upper atmosphere at solar minimum from global circulation model simulations

Directory of Open Access Journals (Sweden)

T. Moffat-Griffin

2007-11-01

Full Text Available Simulations of the Martian upper atmosphere have been produced from a self-consistent three-dimensional numerical model of the Martian thermosphere and ionosphere, called MarTIM. It covers an altitude range of 60 km to the upper thermosphere, usually at least 250 km altitude. A radiation scheme is included that allows the main sources of energy input, EUV/UV and IR absorption by CO2 and CO, to be calculated. CO2, N2 and O are treated as the major gases in MarTIM, and are mutually diffused (though neutral chemistry is ignored. The densities of other species (the minor gases, CO, Ar, O2 and NO, are based on diffusive equilibrium above the turbopause. The ionosphere is calculated from a simple photoionisation and charge exchange routine though in this paper we will only consider the thermal and dynamic structure of the neutral atmosphere at solar minimum conditions. The semi-diurnal (2,2 migrating tide, introduced at MarTIM's lower boundary, affects the dynamics up to 130 km. The Mars Climate Database (Lewis et al., 2001 can be used as a lower boundary in MarTIM. The effect of this is to increase wind speeds in the thermosphere and to produce small-scale structures throughout the thermosphere. Temperature profiles are in good agreement with Pathfinder results. Wind velocities are slightly lower compared to analysis of MGS accelerometer data (Withers, 2003. The novel step-by-step approach of adding in new features to MarTIM has resulted in further understanding of the drivers of the Martian thermosphere.

KNOW YOUR NEIGHBORHOOD: A DETAILED MODEL ATMOSPHERE ANALYSIS OF NEARBY WHITE DWARFS

Energy Technology Data Exchange (ETDEWEB)

Giammichele, N.; Bergeron, P. [Kitt Peak National Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation (United States); Dufour, P., E-mail: noemi.giammichele@astro.umontreal.ca, E-mail: pierre.bergeron@astro.umontreal.ca, E-mail: patrick.dufour@astro.umontreal.ca [Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, Quebec H3C 3J7 (Canada)

2012-04-01

We present improved atmospheric parameters of nearby white dwarfs lying within 20 pc of the Sun. The aim of the current study is to obtain the best statistical model of the least-biased sample of the white dwarf population. A homogeneous analysis of the local population is performed combining detailed spectroscopic and photometric analyses based on improved model atmosphere calculations for various spectral types including DA, DB, DC, DQ, and DZ stars. The spectroscopic technique is applied to all stars in our sample for which optical spectra are available. Photometric energy distributions, when available, are also combined to trigonometric parallax measurements to derive effective temperatures, stellar radii, as well as atmospheric compositions. A revised catalog of white dwarfs in the solar neighborhood is presented. We provide, for the first time, a comprehensive analysis of the mass distribution and the chemical distribution of white dwarf stars in a volume-limited sample.

A 3D Multi-fluid MHD Study of the Interaction of the Solar Wind with the Ionosphere/Atmosphere System of Venus.

Science.gov (United States)

Najib, D.; Nagy, A.; Toth, G.; Ma, Y.-J.

2011-10-01

We use the latest version of our four species multifluid model to study the interaction of the solar wind with Venus. The model solves simultaneously the continuity, momentum and energy equations of the different ions. The lower boundary of our model is at 100 km, below the main ionospheric peak, and the radial resolution is about 10 km in the ionosphere, thus the model does a very good job in reproducing the ionosphere and the associated processes. We carry out calculations for high and low solar activity conditions and establish the importance of mass loading by the extended exosphere of Venus. We demonstrate the importance of using the multi-fluid rather than a single fluid model. We also calculate the atmospheric escape of the ionospheric species and compare our model results with the observed parameters from Pioneer Venus and Venus Express.

Solar Radiation Received by Slopes Using COMS Imagery, a Physically Based Radiation Model, and GLOBE

Directory of Open Access Journals (Sweden)

Jong-Min Yeom

2016-01-01

Full Text Available This study mapped the solar radiation received by slopes for all of Korea, including areas that are not measured by ground station measurements, through using satellites and topographical data. When estimating insolation with satellite, we used a physical model to measure the amount of hourly based solar surface insolation. Furthermore, we also considered the effects of topography using the Global Land One-Kilometer Base Elevation (GLOBE digital elevation model (DEM for the actual amount of incident solar radiation according to solar geometry. The surface insolation mapping, by integrating a physical model with the Communication, Ocean, and Meteorological Satellite (COMS Meteorological Imager (MI image, was performed through a comparative analysis with ground-based observation data (pyranometer. Original and topographically corrected solar radiation maps were created and their characteristics analyzed. Both the original and the topographically corrected solar energy resource maps captured the temporal variations in atmospheric conditions, such as the movement of seasonal rain fronts during summer. In contrast, although the original solar radiation map had a low insolation value over mountain areas with a high rate of cloudiness, the topographically corrected solar radiation map provided a better description of the actual surface geometric characteristics.

Solar energy prediction and verification using operational model forecasts and ground-based solar measurements

International Nuclear Information System (INIS)

Kosmopoulos, P.G.; Kazadzis, S.; Lagouvardos, K.; Kotroni, V.; Bais, A.

2015-01-01

The present study focuses on the predictions and verification of these predictions of solar energy using ground-based solar measurements from the Hellenic Network for Solar Energy and the National Observatory of Athens network, as well as solar radiation operational forecasts provided by the MM5 mesoscale model. The evaluation was carried out independently for the different networks, for two forecast horizons (1 and 2 days ahead), for the seasons of the year, for varying solar elevation, for the indicative energy potential of the area, and for four classes of cloud cover based on the calculated clearness index (k_t): CS (clear sky), SC (scattered clouds), BC (broken clouds) and OC (overcast). The seasonal dependence presented relative rRMSE (Root Mean Square Error) values ranging from 15% (summer) to 60% (winter), while the solar elevation dependence revealed a high effectiveness and reliability near local noon (rRMSE ∼30%). An increment of the errors with cloudiness was also observed. For CS with mean GHI (global horizontal irradiance) ∼ 650 W/m"2 the errors are 8%, for SC 20% and for BC and OC the errors were greater (>40%) but correspond to much lower radiation levels (<120 W/m"2) of consequently lower energy potential impact. The total energy potential for each ground station ranges from 1.5 to 1.9 MWh/m"2, while the mean monthly forecast error was found to be consistently below 10%. - Highlights: • Long term measurements at different atmospheric cases are needed for energy forecasting model evaluations. • The total energy potential at the Greek sites presented ranges from 1.5 to 1.9 MWh/m"2. • Mean monthly energy forecast errors are within 10% for all cases analyzed. • Cloud presence results of an additional forecast error that varies with the cloud cover.

Solar Irradiance Variability is Caused by the Magnetic Activity on the Solar Surface.

Science.gov (United States)

Yeo, Kok Leng; Solanki, Sami K; Norris, Charlotte M; Beeck, Benjamin; Unruh, Yvonne C; Krivova, Natalie A

2017-09-01

The variation in the radiative output of the Sun, described in terms of solar irradiance, is important to climatology. A common assumption is that solar irradiance variability is driven by its surface magnetism. Verifying this assumption has, however, been hampered by the fact that models of solar irradiance variability based on solar surface magnetism have to be calibrated to observed variability. Making use of realistic three-dimensional magnetohydrodynamic simulations of the solar atmosphere and state-of-the-art solar magnetograms from the Solar Dynamics Observatory, we present a model of total solar irradiance (TSI) that does not require any such calibration. In doing so, the modeled irradiance variability is entirely independent of the observational record. (The absolute level is calibrated to the TSI record from the Total Irradiance Monitor.) The model replicates 95% of the observed variability between April 2010 and July 2016, leaving little scope for alternative drivers of solar irradiance variability at least over the time scales examined (days to years).

Parameterizations of Chromospheric Condensations in dG and dMe Model Flare Atmospheres

Science.gov (United States)

Kowalski, Adam F.; Allred, Joel C.

2018-01-01

The origin of the near-ultraviolet and optical continuum radiation in flares is critical for understanding particle acceleration and impulsive heating in stellar atmospheres. Radiative-hydrodynamic (RHD) simulations in 1D have shown that high energy deposition rates from electron beams produce two flaring layers at T ∼ 104 K that develop in the chromosphere: a cooling condensation (downflowing compression) and heated non-moving (stationary) flare layers just below the condensation. These atmospheres reproduce several observed phenomena in flare spectra, such as the red-wing asymmetry of the emission lines in solar flares and a small Balmer jump ratio in M dwarf flares. The high beam flux simulations are computationally expensive in 1D, and the (human) timescales for completing NLTE models with adaptive grids in 3D will likely be unwieldy for some time to come. We have developed a prescription for predicting the approximate evolved states, continuum optical depth, and emergent continuum flux spectra of RHD model flare atmospheres. These approximate prescriptions are based on an important atmospheric parameter: the column mass ({m}{ref}) at which hydrogen becomes nearly completely ionized at the depths that are approximately in steady state with the electron beam heating. Using this new modeling approach, we find that high energy flux density (>F11) electron beams are needed to reproduce the brightest observed continuum intensity in IRIS data of the 2014 March 29 X1 solar flare, and that variation in {m}{ref} from 0.001 to 0.02 g cm‑2 reproduces most of the observed range of the optical continuum flux ratios at the peak of M dwarf flares.

Solar-stellar Coffee: A Model For Informal Interdisciplinary Professional Development

Science.gov (United States)

Metcalfe, Travis S.

2007-12-01

Initiated at NCAR more than two years ago, solar-stellar coffee is a weekly informal discussion of recent papers that are relevant to solar and stellar physics. The purpose is to generate awareness of new papers, to discuss their connections to past and current work, and to encourage a broader and more interdisciplinary view of solar physics. The discussion is local, but traffic to the website (http://coffee.solar-stellar.org/) is global -- suggesting that solar and stellar astronomers around the world find value in this intelligent pre-filter for astro-ph and other sources (papers are selected by local participants). In addition to enhancing the preprint posting and reading habits of solar physicists (with the associated boost in citation rates), the weekly discussion also provides an interdisciplinary professional development opportunity for graduate students, postdocs, and early career scientists. The web page is driven by a simple set of scripts (available on request), so this interaction model can easily be replicated at other institutions for topics of local interest. The concept of solar-stellar coffee began with support from an NSF Astronomy & Astrophysics Postdoctoral Fellowship under award AST-0401441. The National Center for Atmospheric Research is a federally funded research and development center sponsored by the National Science Foundation.

WFIRST: Exoplanet Data Challenge. Atmospheric retrieval results

Science.gov (United States)

Hildebrandt, Sergi; Turnbull, Margaret; Exoplanet Data Challenge Team

2018-01-01

We present the results of the Exoplanet Data Challenge for its first 2016/17 cycle and the current cycle 2. Some input spectra for extra-solar systems are processed through the WFIRST IFS instrument model, producing simulated data representative of the flight data. Atmospheric properties are then recovered using complex atmospheric models and multidimensional optimization. The results inform about WFIRST CGI ability to characterize exo-planetray atmospheres.

Correlation of trace element content in air particulates with solar meteorological data in the atmosphere of Athens

International Nuclear Information System (INIS)

Kanias, G.D.; Grimanis, A.P.; Viras, L.G.

2003-01-01

Relation between the trace element content in air particulates and solar meteorological data in the atmospheric environment of Athens, Greece, was studied. For this purpose, Sm, Br, As, Na, K, La, Ce, Cr, Ag, Sc, Fe, Zn, Co, Sb, Th were determined by INAA in respirable aerosols collected during winter 1993-1994. The results showed that the average cloudiness, sunshine, and the total solar radiation (sun and sky) on a horizontal surface, (3 variables) have no relation with trace element variation. However, diffuse solar radiation (sun and sky) on a horizontal surface seems to have statistically significant relationship with some of the trace element variation. It forms a single component with some trace elements after the application of the factor analysis. The increase of the same solar variable in the Athens City center, is one of the factors which cannot permit the emission of trace elements in the atmospheric environment from dust soil and car tires. (author)

A Solar Radiation Parameterization for Atmospheric Studies. Volume 15

Science.gov (United States)

Chou, Ming-Dah; Suarez, Max J. (Editor)

1999-01-01

The solar radiation parameterization (CLIRAD-SW) developed at the Goddard Climate and Radiation Branch for application to atmospheric models are described. It includes the absorption by water vapor, O3, O2, CO2, clouds, and aerosols and the scattering by clouds, aerosols, and gases. Depending upon the nature of absorption, different approaches are applied to different absorbers. In the ultraviolet and visible regions, the spectrum is divided into 8 bands, and single O3 absorption coefficient and Rayleigh scattering coefficient are used for each band. In the infrared, the spectrum is divided into 3 bands, and the k-distribution method is applied for water vapor absorption. The flux reduction due to O2 is derived from a simple function, while the flux reduction due to CO2 is derived from precomputed tables. Cloud single-scattering properties are parameterized, separately for liquid drops and ice, as functions of water amount and effective particle size. A maximum-random approximation is adopted for the overlapping of clouds at different heights. Fluxes are computed using the Delta-Eddington approximation.

Modelling solar-like oscillators

Energy Technology Data Exchange (ETDEWEB)

Eggenberger, P; Miglio, A [Institut d' Astrophysique et de Geophysique de l' Universite de Liege, 17 Allee du 6 Aout, B-4000 Liege (Belgium); Carrier, F [Institute of Astronomy, University of Leuven, Celestijnenlaan 200 D, B-3001 Leuven (Belgium); Mathis, S [CEA/DSM/DAPNIA/Service d' Astrophysique, CEA/Saclay, AIM-Unite Mixte de Recherche CEA-CNRS-Universite Paris VII, UMR 7158, 91191 Gif-sur-Yvette Cedex (France)], E-mail: eggenberger@Qastro.ulg.ac.be

2008-10-15

The computation of models of stars for which solar-like oscillations have been observed is discussed. After a brief intoduction on the observations of solar-like oscillations, the modelling of isolated stars and of stars belonging to a binary system is presented with specific examples of recent theoretical calibrations. Finally the input physics introduced in stellar evolution codes for the computation of solar-type stars is discussed with a peculiar emphasis on the modelling of rotation for these stars.

Solar Coronal Jets: Observations, Theory, and Modeling

Science.gov (United States)

Raouafi, N. E.; Patsourakos, S.; Pariat, E.; Young, P. R.; Sterling, A.; Savcheva, A.; Shimojo, M.; Moreno-Insertis, F.; Devore, C. R.; Archontis, V.;

An Analytic Approach to Modeling Land-Atmosphere Interaction: 1. Construct and Equilibrium Behavior

Science.gov (United States)

Brubaker, Kaye L.; Entekhabi, Dara

1995-03-01

A four-variable land-atmosphere model is developed to investigate the coupled exchanges of water and energy between the land surface and atmosphere and the role of these exchanges in the statistical behavior of continental climates. The land-atmosphere system is substantially simplified and formulated as a set of ordinary differential equations that, with the addition of random noise, are suitable for analysis in the form of the multivariate Îto equation. The model treats the soil layer and the near-surface atmosphere as reservoirs with storage capacities for heat and water. The transfers between these reservoirs are regulated by four states: soil saturation, soil temperature, air specific humidity, and air potential temperature. The atmospheric reservoir is treated as a turbulently mixed boundary layer of fixed depth. Heat and moisture advection, precipitation, and layer-top air entrainment are parameterized. The system is forced externally by solar radiation and the lateral advection of air and water mass. The remaining energy and water mass exchanges are expressed in terms of the state variables. The model development and equilibrium solutions are presented. Although comparisons between observed data and steady state model results re inexact, the model appears to do a reasonable job of partitioning net radiation into sensible and latent heat flux in appropriate proportions for bare-soil midlatitude summer conditions. Subsequent work will introduce randomness into the forcing terms to investigate the effect of water-energy coupling and land-atmosphere interaction on variability and persistence in the climatic system.

Impacts of the January 2005 solar particle events on middle atmospheric chlorine species

Science.gov (United States)

Winkler, Holger; Sinnhuber, Miriam; Notholt, Justus; Maik Wissing, Jan; Kallenrode, May-Britt; Santee, Michelle

It is well established that solar particle events (SPEs) are sources of significant chemical dis-turbances in the Earth's polar atmosphere. The observed SPE effects on nitrogen, hydrogen and oxygen compounds have been investigated in some detail in recent years, and they can be reproduced by atmospheric models using basic parametrizations for NOx and HOx produc-tion as a funtion of the particle impact ionisation. However, there are considerable differences between model predictions and measurements concerning several other trace gases including chlorine species. Two major SPEs occurred on January 17, and January 20, 2005. The latter had an exceptionally hard energy spectrum which caused maximum particle impact ionization at stratospheric altitudes. The Microwave Limb Sounder (MLS) instrument on-board the Aura satellite has measured a short-term decrease of HCl in the northern polar region corresponding to January 2005 SPEs. The peak HCl depletion is ˜300 ppt at 35-40 km. This is comparable to the depletion of messopheric HCl observed by the HALOE instrument during the July 2000 SPE. We will present simulation results of the University of Bremen Ion Chemistry (UBIC) model for the SPEs in January 2005 focusing on chlorine species. The simulations indicate that the observed short-term decrease of middle atmospheric HCl is due to a conversion into active chlorine species such as Cl, ClO and HOCl. The magnitude of the observed HCl loss can only be reproduced if reactions of negative chlorine species and the production of O(1 D) from the reaction N(2 D) + O2 are taken into account. The model results will be compared to MLS/Aura data of HCl, HOCl and ClO. Additionally, the impacts of the observed chlorine activation, e.g. on ozone, will be assessed.

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.

SOLAR WIND IMPLANTATION MODEL FOR 10Be IN CALCIUM-ALUMINUM INCLUSIONS

International Nuclear Information System (INIS)

Bricker, Glynn E.; Caffee, Marc W.

2010-01-01

We propose a model for the incorporation of 10 Be within calcium-aluminum inclusions (CAIs) in primitive carbonaceous meteorites. In this model, 10 Be is produced by energetic particle reactions in the proto-solar atmosphere of a more active proto-Sun characterized by energetic particle fluxes higher than contemporary particle fluxes. This 10 Be is incorporated into the solar wind that is then implanted into CAI precursor material. This production mechanism is operational in the contemporary solar system implanting 10 Be in lunar materials. The contemporary production rate of 10 Be at the surface of the Sun is ∼0.1 10 Be cm -2 s -1 . Scaling up the contemporary 10 Be production in the proto-Sun by a factor of 10 5 would increase the production rate to 10 410 Be cm -2 s -1 . Using this enhanced production value in conjunction with refractory mass inflow rates at 0.06 AU from the proto-Sun we model 10 Be concentrations in CAI precursors. We calculate the content of solar-wind-implanted 10 Be would have been of the order of 10 1210 Be g -1 in CAIs, consistent with initial 10 Be content found from boron-beryllium isotopic systematics in CAIs.

DNDO Report: Predicting Solar Modulation Potentials for Modeling Cosmic Background Radiation

Energy Technology Data Exchange (ETDEWEB)

Behne, Patrick Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-08-08

The modeling of the detectability of special nuclear material (SNM) at ports and border crossings requires accurate knowledge of the background radiation at those locations. Background radiation originates from two main sources, cosmic and terrestrial. Cosmic background is produced by high-energy galactic cosmic rays (GCR) entering the atmosphere and inducing a cascade of particles that eventually impact the earth’s surface. The solar modulation potential represents one of the primary inputs to modeling cosmic background radiation. Usosokin et al. formally define solar modulation potential as “the mean energy loss [per unit charge] of a cosmic ray particle inside the heliosphere…” Modulation potential, a function of elevation, location, and time, shares an inverse relationship with cosmic background radiation. As a result, radiation detector thresholds require adjustment to account for differing background levels, caused partly by differing solar modulations. Failure to do so can result in higher rates of false positives and failed detection of SNM for low and high levels of solar modulation potential, respectively. This study focuses on solar modulation’s time dependence, and seeks the best method to predict modulation for future dates using Python. To address the task of predicting future solar modulation, we utilize both non-linear least squares sinusoidal curve fitting and cubic spline interpolation. This material will be published in transactions of the ANS winter meeting of November, 2016.

A Parameter Study for Modeling Mg ii h and k Emission during Solar Flares

Energy Technology Data Exchange (ETDEWEB)

Rubio da Costa, Fatima [Department of Physics, Stanford University, Stanford, CA 94305 (United States); Kleint, Lucia, E-mail: frubio@stanford.edu [University of Applied Sciences and Arts Northwestern Switzerland, 5210, Windisch (Switzerland)

2017-06-20

Solar flares show highly unusual spectra in which the thermodynamic conditions of the solar atmosphere are encoded. Current models are unable to fully reproduce the spectroscopic flare observations, especially the single-peaked spectral profiles of the Mg ii h and k lines. We aim to understand the formation of the chromospheric and optically thick Mg ii h and k lines in flares through radiative transfer calculations. We take a flare atmosphere obtained from a simulation with the radiative hydrodynamic code RADYN as input for a radiative transfer modeling with the RH code. By iteratively changing this model atmosphere and varying thermodynamic parameters such as temperature, electron density, and velocity, we study their effects on the emergent intensity spectra. We reproduce the typical single-peaked Mg ii h and k flare spectral shape and approximate the intensity ratios to the subordinate Mg ii lines by increasing either densities, temperatures, or velocities at the line core formation height range. Additionally, by combining unresolved upflows and downflows up to ∼250 km s{sup −1} within one resolution element, we reproduce the widely broadened line wings. While we cannot unambiguously determine which mechanism dominates in flares, future modeling efforts should investigate unresolved components, additional heat dissipation, larger velocities, and higher densities and combine the analysis of multiple spectral lines.

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).

Solar Extreme UV radiation and quark nugget dark matter model

Energy Technology Data Exchange (ETDEWEB)

Zhitnitsky, Ariel, E-mail: arz@phas.ubc.ca [Department of Physics and Astronomy, University of British Columbia, Vancouver, B.C. V6T 1Z1 (Canada)

2017-10-01

We advocate the idea that the surprising emission of extreme ultra violet (EUV) radiation and soft x-rays from the Sun are powered externally by incident dark matter (DM) particles. The energy and the spectral shape of this otherwise unexpected solar irradiation is estimated within the quark nugget dark matter model. This model was originally invented as a natural explanation of the observed ratio Ω{sub dark} ∼ Ω{sub visible} when the DM and visible matter densities assume the same order of magnitude values. This generic consequence of the model is a result of the common origin of both types of matter which are formed during the same QCD transition and both proportional to the same fundamental dimensional parameter Λ{sub QCD}. We also present arguments suggesting that the transient brightening-like 'nanoflares' in the Sun may be related to the annihilation events which inevitably occur in the solar atmosphere within this dark matter scenario.

Solar Extreme UV radiation and quark nugget dark matter model

Science.gov (United States)

Zhitnitsky, Ariel

2017-10-01

We advocate the idea that the surprising emission of extreme ultra violet (EUV) radiation and soft x-rays from the Sun are powered externally by incident dark matter (DM) particles. The energy and the spectral shape of this otherwise unexpected solar irradiation is estimated within the quark nugget dark matter model. This model was originally invented as a natural explanation of the observed ratio Ωdark ~ Ωvisible when the DM and visible matter densities assume the same order of magnitude values. This generic consequence of the model is a result of the common origin of both types of matter which are formed during the same QCD transition and both proportional to the same fundamental dimensional parameter ΛQCD. We also present arguments suggesting that the transient brightening-like "nanoflares" in the Sun may be related to the annihilation events which inevitably occur in the solar atmosphere within this dark matter scenario.

3D General Circulation Model of the Middle Atmosphere of Jupiter

Science.gov (United States)

Zube, Nicholas Gerard; Zhang, Xi; Li, Cheng; Le, Tianhao

2017-10-01

The characteristics of Jupiter’s large-scale stratospheric circulation remain largely unknown. Detailed distributions of temperature and photochemical species have been provided by recent observations [1], but have not yet been accurately reproduced by middle atmosphere general circulation models (GCM). Jupiter’s stratosphere and upper troposphere are influenced by radiative forcing from solar insolation and infrared cooling from hydrogen and hydrocarbons, as well as waves propagating from the underlying troposphere [2]. The relative significance of radiative and mechanical forcing on stratospheric circulation is still being debated [3]. Here we present a 3D GCM of Jupiter’s atmosphere with a correlated-k radiative transfer scheme. The simulation results are compared with observations. We analyze the impact of model parameters on the stratospheric temperature distribution and dynamical features. Finally, we discuss future tracer transport and gravity wave parameterization schemes that may be able to accurately simulate the middle atmosphere dynamics of Jupiter and other giant planets.[1] Kunde et al. 2004, Science 305, 1582.[2] Zhang et al. 2013a, EGU General Assembly, EGU2013-5797-2.[3] Conrath 1990, Icarus, 83, 255-281.

Examining Model Atmospheric Particles Inside and Out

Science.gov (United States)

Wingen, L. M.; Zhao, Y.; Fairhurst, M. C.; Perraud, V. M.; Ezell, M. J.; Finlayson-Pitts, B. J.

2017-12-01

Atmospheric particles scatter incoming solar radiation and act as cloud condensation nuclei (CCN), thereby directly and indirectly affecting the earth's radiative balance and reducing visibility. These atmospheric particles may not be uniform in composition. Differences in the composition of a particle's outer surface from its core can arise during particle growth, (photo)chemical aging, and exchange of species with the gas phase. The nature of the surface on a molecular level is expected to impact growth mechanisms as well as their ability to act as CCN. Model laboratory particle systems are explored using direct analysis in real time-mass spectrometry (DART-MS), which is sensitive to surface composition, and contrasted with average composition measurements using high resolution, time-of-flight aerosol mass spectrometry (HR-ToF-AMS). Results include studies of the heterogeneous reactions of amines with solid dicarboxylic acid particles, which are shown to generate aminium dicarboxylate salts at the particle surface, leaving an unreacted core. Combination of both mass spectrometric techniques reveals a trend in reactivity of C3-C7 dicarboxylic acids with amines and allows calculation of the DART probe depth into the particles. The results of studies on additional model systems that are currently being explored will also be reported.

Thermal structure and dynamics of the Martian upper atmosphere at solar minimum from global circulation model simulations

Directory of Open Access Journals (Sweden)

T. Moffat-Griffin

2007-11-01

Full Text Available Simulations of the Martian upper atmosphere have been produced from a self-consistent three-dimensional numerical model of the Martian thermosphere and ionosphere, called MarTIM. It covers an altitude range of 60 km to the upper thermosphere, usually at least 250 km altitude. A radiation scheme is included that allows the main sources of energy input, EUV/UV and IR absorption by CO₂ and CO, to be calculated. CO₂, N₂ and O are treated as the major gases in MarTIM, and are mutually diffused (though neutral chemistry is ignored. The densities of other species (the minor gases, CO, Ar, O₂ and NO, are based on diffusive equilibrium above the turbopause. The ionosphere is calculated from a simple photoionisation and charge exchange routine though in this paper we will only consider the thermal and dynamic structure of the neutral atmosphere at solar minimum conditions. The semi-diurnal (2,2 migrating tide, introduced at MarTIM's lower boundary, affects the dynamics up to 130 km. The Mars Climate Database (Lewis et al., 2001 can be used as a lower boundary in MarTIM. The effect of this is to increase wind speeds in the thermosphere and to produce small-scale structures throughout the thermosphere. Temperature profiles are in good agreement with Pathfinder results. Wind velocities are slightly lower compared to analysis of MGS accelerometer data (Withers, 2003. The novel step-by-step approach of adding in new features to MarTIM has resulted in further understanding of the drivers of the Martian thermosphere.

The lower solar atmosphere

NARCIS (Netherlands)

Rutten, R.J.

1998-01-01

This "rapporteur" report discusses the solar photosphere and low chromosphere in the context of chemical composition studies. The highly dynamical nature of the photosphere does not seem to jeopardize precise determination of solar abundances in classical fashion. It is still an open question how

CORRELATION BETWEEN THE 22-YEAR SOLAR MAGNETIC CYCLE AND THE 22-YEAR QUASICYCLE IN THE EARTH'S ATMOSPHERIC TEMPERATURE

Energy Technology Data Exchange (ETDEWEB)

Qu Weizheng; Zhao Jinping; Huang Fei; Deng Shenggui, E-mail: quweizhe@ouc.edu.cn [College of Environment Oceanography, Ocean University of China, Qingdao 266100 (China)

2012-07-15

According to the variation pattern of the solar magnetic field polarity and its relation to the relative sunspot number, we established the time series of the sunspot magnetic field polarity index and analyzed the strength and polarity cycle characteristics of the solar magnetic field. The analysis showed the existence of a cycle with about a 22-year periodicity in the strength and polarity of the solar magnetic field, which proved the Hale proposition that the 11-year sunspot cycle is one-half of the 22-year solar magnetic cycle. By analyzing the atmospheric temperature field, we found that the troposphere and the stratosphere in the middle latitude of both the northern and southern hemispheres exhibited a common 22-year quasicycle in the atmospheric temperature, which is believed to be attributable to the 22-year solar magnetic cycle.

Ionization rates and profiles of electron concentration in Martian atmosphere

International Nuclear Information System (INIS)

Komitov, B.; Spasov, S.; Gogoshev, M.

1981-01-01

The ionization and vertical profiles of electron concentration in the Martian atmosphere are calculated as functions of the solar zenith angles varying from O deg to 90 deg. A neutral atmospheric model based on direct mass-spectometric measurements from the Viking-1 landing modul is employed in the calculation. The Earth data of the ionization solar flux at the same level of the solar activity and for the month of the Viking-1 measurements reduced for the Mars orbit are used. The numerical result for the photoionization rates and quasi-equilibrium electron-concentration profiles in the upper Martian atmosphere at different solar zenith angles from 0 deg to 100 deg are presented. It is shown that the maxima of both quantities decrease and move towards the upper atmosphere regions. The calculated electron density at the zenith solar angle of 40 deg are compared to Viking-1 experimental data and a good agreement is achieved

An electrodynamic model of the solar wind interaction with the ionospheres of Mars and Venus

International Nuclear Information System (INIS)

Cloutier, P.A.; Daniell, R.E. Jr.

1979-01-01

the electrodynamic model for the solar wind interaction with non-magnetic planets (Cloutier and Daniell, Planet. Space Sci. 21, 463, 1973; Daniell and Cloutier, Planet. Space Sci. 25, 621, 1977) is modified to include the effects of non-ohmic currents in the upper ionosphere. The model is then used to calculate convection patterns induced by the solar wind in the ionospheres of Mars and Venus. For Mars the observations of the neutral mass spectrometer or Vikings 1 and 2 provided the neutral atmosphere. Model calculations reproduced the retarding potential analyzer data and indicate that the ionosphere above about 200 km is probably controlled by convection rather than chemistry or diffusion. For Venus a model atmosphere based on Dickenson and Ridley, J. Atmos. Sci. 32, 1219 (1975) and Mayr et al., J. Geophys. Res. 83, 4411 (1978) was used. The resulting model calculations were compared to radio occultation data from Mariners 5 and 10 and Venera 9 which represent extremes in the variability of the upper Cytherean ionosphere. The model calculations are shown to fall within this variation. These results represent the state of the theory immediately prior to the Pioneer-Venus encounter. (author)

Solar cycle variations of stratospheric ozone and temperature in simulations of a coupled chemistry-climate model

Directory of Open Access Journals (Sweden)

J. Austin

2007-01-01

Full Text Available The results from three 45-year simulations of a coupled chemistry climate model are analysed for solar cycle influences on ozone and temperature. The simulations include UV forcing at the top of the atmosphere, which includes a generic 27-day solar rotation effect as well as the observed monthly values of the solar fluxes. The results are analysed for the 27-day and 11-year cycles in temperature and ozone. In accordance with previous results, the 27-day cycle results are in good qualitative agreement with observations, particularly for ozone. However, the results show significant variations, typically a factor of two or more in sensitivity to solar flux, depending on the solar cycle. In the lower and middle stratosphere we show good agreement also between the modelled and observed 11-year cycle results for the ozone vertical profile averaged over low latitudes. In particular, the minimum in solar response near 20 hPa is well simulated. In comparison, experiments of the model with fixed solar phase (solar maximum/solar mean and climatological sea surface temperatures lead to a poorer simulation of the solar response in the ozone vertical profile, indicating the need for variable phase simulations in solar sensitivity experiments. The role of sea surface temperatures and tropical upwelling in simulating the ozone minimum response are also discussed.

Model for forecasting of monthly average insulation at ground level taking into account the radiation absorption losses crossing atmosphere in the thermal solar applications; Modelo de previsao da insolacao media mensal ao nivel do solo levando em conta a perda por absorcao na atmosfera em aplicacoes solares termicas

Energy Technology Data Exchange (ETDEWEB)

Camargo, J.C.; Apolinario, F.R.; Silva, E.P. da [Universidade Estadual de Campinas, SP (Brazil). Lab. de Hidrogenio]. E-mails: joaoc@fem.unicamp.br; rezende@ifi.unicamp.br; lh2ennio@ifi.unicamp.br

2000-07-01

The use of the solar energy, for thermal or photovoltaic ends, depends basically on the amount of radiation that reaches the ground in the place where desires to carry through this use, defining the necessary area of the collectors, or panels, that in turn are the main components of the final cost of the system and, therefore, of the viability or not on its use. The incident radiation in the terrestrial surface is minor that one reaches the top of the atmosphere due to the absorption and dispersion factors. The objective of this work is to present a model of forecast the monthly average radiation for ends of use in systems of flat solar collectors for heating water, in the city of Campinas - Sao Paulo, Brazil. This work has been developed by the Hydrogen Laboratory of the Institute of Physics of the UNICAMP, being also used for other applications with solar energy. Based in the radiation data, taken from a local station, a theoretical study was developed to calculate a parameter of loss of radiation when this cross the atmosphere. This Kt loss factor, has basic importance for the knowledge of the effective available energy for use. With this data it is possible to determine, on the basis of the incident radiation in the top of the atmosphere, the value of the radiation on a surface. (author)

Solar Deployment System (SolarDS) Model: Documentation and Sample Results

Energy Technology Data Exchange (ETDEWEB)

Denholm, P.; Drury, E.; Margolis, R.

2009-09-01

The Solar Deployment System (SolarDS) model is a bottom-up, market penetration model that simulates the potential adoption of photovoltaics (PV) on residential and commercial rooftops in the continental United States through 2030. NREL developed SolarDS to examine the market competitiveness of PV based on regional solar resources, capital costs, electricity prices, utility rate structures, and federal and local incentives. The model uses the projected financial performance of PV systems to simulate PV adoption for building types and regions then aggregates adoption to state and national levels. The main components of SolarDS include a PV performance simulator, a PV annual revenue calculator, a PV financial performance calculator, a PV market share calculator, and a regional aggregator. The model simulates a variety of installed PV capacity for a range of user-specified input parameters. PV market penetration levels from 15 to 193 GW by 2030 were simulated in preliminary model runs. SolarDS results are primarily driven by three model assumptions: (1) future PV cost reductions, (2) the maximum PV market share assumed for systems with given financial performance, and (3) PV financing parameters and policy-driven assumptions, such as the possible future cost of carbon emissions.

Extended neutral atmosphere effect on solar wind interaction with nonmagnetic bodies of the solar system

International Nuclear Information System (INIS)

Breus, T.K.; Krymskij, A.M.; Mitnitskij, V.Ya.

1987-01-01

Numeric modelling of the Venus flow-around by the solar wind with regard to stream loading by heavy ions, produced under photoionization of the Venus neutral oxygen corona, is conducted. It is shown, that this effect can account for a whole number of peculiarities related to the solar wind interaction with the planet which have not been clearly explained yet, namely, shock wave position, solar wind stream and magnetic field characteristics behind the front

Ellerman bombs observed with the new vacuum solar telescope and the atmospheric imaging assembly onboard the solar dynamics observatory

Science.gov (United States)

Chen, Yajie; Tian, Hui; Xu, Zhi; Xiang, Yongyuan; Fang, Yuliang; Yang, Zihao

2017-12-01

Ellerman bombs (EBs) are believed to be small-scale reconnection events occurring around the temperature minimum region in the solar atmosphere. They are often identified as significant enhancements in the extended Hα wings without obvious signatures in the Hα core. Here we explore the possibility of using the 1700 Å images taken by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) to study EBs. From the Hα wing images obtained with the New Vacuum Solar Telescope (NVST) on 2015 May 2, we have identified 145 EBs and 51% of them clearly correspond to the bright points (BPs) in the AIA 1700 Å images. If we resize the NVST images using a linear interpolation to make the pixel sizes of the AIA and NVST images the same, some previously identified EBs disappear and about 71% of the remaining EBs are associated with BPs. Meanwhile, 66% of the compact brightenings in the AIA 1700 Å images can be identified as EBs in the Hα wings. The intensity enhancements of the EBs in the Hα wing images reveal a linear correlation with those of the BPs in the AIA 1700 Å images. Our study suggests that a significant fraction of EBs can be observed with the AIA 1700 Å filter, which is promising for large-sample statistical study of EBs as the seeing-free and full-disk SDO/AIA data are routinely available.

Annual reconstruction of the solar cycle from atmospheric 14C variations

International Nuclear Information System (INIS)

Murphy, J.O.

1990-01-01

Initially, the rise and fall components of the 11-year solar sunspot cycle are approximated by separate least-squares polynomials for four cycle classifications, which are determined by the magnitude of the average of the annual sunspot numbers per cycle. Following a method is formulated to generate detailed reconstruction of the annual variation of a solar cycle based on this cycle average, and the results obtained for cycles -4 through to 21 are compared with the annual Zurich values. This procedure is then employed to establish annual sunspot numbers using published average cycle values obtained from atmospheric carbon 14 variations, which have been derived from the chemical analysis of tree ring sections. The reconstructed sequences are correlated with the observed cycle values and with tree ring width index chronologies which exhibit a significant 11-year periodicity. It is anticipated that the long carbon 14 records and parallel dendrochronological data could be employed to obtain a more detailed portrayal of previous periods of strong solar activity than that given by current estimates based on historical records. 17 refs., 2 tabs., 9 figs

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.

Atmospheric radiative transfer modeling: a summary of the AER codes

Energy Technology Data Exchange (ETDEWEB)

Clough, S.A. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States); Shephard, M.W. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States)]. E-mail: mshephar@aer.com; Mlawer, E.J. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States); Delamere, J.S. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States); Iacono, M.J. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States); Cady-Pereira, K. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States); Boukabara, S. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States); Brown, P.D. [Atmospheric and Environmental Research (AER) Inc., 131 Hartwell Avenue, Lexington, MA 02421-3126 (United States)

2005-03-01

The radiative transfer models developed at AER are being used extensively for a wide range of applications in the atmospheric sciences. This communication is intended to provide a coherent summary of the various radiative transfer models and associated databases publicly available from AER (http://www.rtweb.aer.com). Among the communities using the models are the remote sensing community (e.g. TES, IASI), the numerical weather prediction community (e.g. ECMWF, NCEP GFS, WRF, MM5), and the climate community (e.g. ECHAM5). Included in this communication is a description of the central features and recent updates for the following models: the line-by-line radiative transfer model (LBLRTM); the line file creation program (LNFL); the longwave and shortwave rapid radiative transfer models, RRTM{sub L}W and RRTM{sub S}W; the Monochromatic Radiative Transfer Model (MonoRTM); the MT{sub C}KD Continuum; and the Kurucz Solar Source Function. LBLRTM and the associated line parameter database (e.g. HITRAN 2000 with 2001 updates) play a central role in the suite of models. The physics adopted for LBLRTM has been extensively analyzed in the context of closure experiments involving the evaluation of the model inputs (e.g. atmospheric state), spectral radiative measurements and the spectral model output. The rapid radiative transfer models are then developed and evaluated using the validated LBLRTM model.

Response of the middle atmosphere to anthropogenic and natural forcings in the CMIP5 simulations with the Max Planck Institute Earth system model

KAUST Repository

Schmidt, H.; Rast, S.; Bunzel, F.; Esch, M.; Giorgetta, M.; Kinne, S.; Krismer, T.; Stenchikov, Georgiy L.; Timmreck, C.; Tomassini, L.; Walz, M.

2013-01-01

The ECHAM6 atmospheric general circulation model is the atmosphere component of the Max Planck Institute Earth System Model (MPI-ESM) that is used in the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations. As ECHAM6 has its uppermost layer centered at 0.01 hPa in the upper mesosphere, these simulations offer the opportunity to study the middle atmosphere climate change and its relation to the troposphere on the basis of a very comprehensive set of state-of-the-art model simulations. The goals of this paper are (a) to introduce those new features of ECHAM6 particularly relevant for the middle atmosphere, including external forcing data, and (b) to evaluate the simulated middle atmosphere and describe the simulated response to natural and anthropogenic forcings. New features in ECHAM6 with respect to ECHAM5 include a new short-wave radiation scheme, the option to vary spectral irradiance independent of total solar irradiance, and a latitude-dependent gravity-wave source strength. The description of external forcing data focuses on solar irradiance and ozone. Stratospheric temperature trends simulated with the MPI-ESM for the last decades of the 20th century agree well with observations. The future projections depend strongly on the scenario. Under the high emission scenario RCP8.5, simulated temperatures are locally lower by more than 20 K than preindustrial values. Many of the simulated patterns of the responses to natural forcings as provided by solar variability, volcanic aerosols, and El Nino-Southern Oscillation, largely agree with the observations. 2013. American Geophysical Union. All Rights Reserved.

Response of the middle atmosphere to anthropogenic and natural forcings in the CMIP5 simulations with the Max Planck Institute Earth system model

KAUST Repository

Schmidt, H.

2013-03-06

The ECHAM6 atmospheric general circulation model is the atmosphere component of the Max Planck Institute Earth System Model (MPI-ESM) that is used in the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations. As ECHAM6 has its uppermost layer centered at 0.01 hPa in the upper mesosphere, these simulations offer the opportunity to study the middle atmosphere climate change and its relation to the troposphere on the basis of a very comprehensive set of state-of-the-art model simulations. The goals of this paper are (a) to introduce those new features of ECHAM6 particularly relevant for the middle atmosphere, including external forcing data, and (b) to evaluate the simulated middle atmosphere and describe the simulated response to natural and anthropogenic forcings. New features in ECHAM6 with respect to ECHAM5 include a new short-wave radiation scheme, the option to vary spectral irradiance independent of total solar irradiance, and a latitude-dependent gravity-wave source strength. The description of external forcing data focuses on solar irradiance and ozone. Stratospheric temperature trends simulated with the MPI-ESM for the last decades of the 20th century agree well with observations. The future projections depend strongly on the scenario. Under the high emission scenario RCP8.5, simulated temperatures are locally lower by more than 20 K than preindustrial values. Many of the simulated patterns of the responses to natural forcings as provided by solar variability, volcanic aerosols, and El Nino-Southern Oscillation, largely agree with the observations. 2013. American Geophysical Union. All Rights Reserved.

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

A comparative Thermal Analysis of conventional parabolic receiver tube and Cavity model tube in a Solar Parabolic Concentrator

Science.gov (United States)

Arumugam, S.; Ramakrishna, P.; Sangavi, S.

2018-02-01

Improvements in heating technology with solar energy is gaining focus, especially solar parabolic collectors. Solar heating in conventional parabolic collectors is done with the help of radiation concentration on receiver tubes. Conventional receiver tubes are open to atmosphere and loose heat by ambient air currents. In order to reduce the convection losses and also to improve the aperture area, we designed a tube with cavity. This study is a comparative performance behaviour of conventional tube and cavity model tube. The performance formulae were derived for the cavity model based on conventional model. Reduction in overall heat loss coefficient was observed for cavity model, though collector heat removal factor and collector efficiency were nearly same for both models. Improvement in efficiency was also observed in the cavity model’s performance. The approach towards the design of a cavity model tube as the receiver tube in solar parabolic collectors gave improved results and proved as a good consideration.

Development of a Greek solar map based on solar model estimations

Science.gov (United States)

Kambezidis, H. D.; Psiloglou, B. E.; Kavadias, K. A.; Paliatsos, A. G.; Bartzokas, A.

2016-05-01

The realization of Renewable Energy Sources (RES) for power generation as the only environmentally friendly solution, moved solar systems to the forefront of the energy market in the last decade. The capacity of the solar power doubles almost every two years in many European countries, including Greece. This rise has brought the need for reliable predictions of meteorological data that can easily be utilized for proper RES-site allocation. The absence of solar measurements has, therefore, raised the demand for deploying a suitable model in order to create a solar map. The generation of a solar map for Greece, could provide solid foundations on the prediction of the energy production of a solar power plant that is installed in the area, by providing an estimation of the solar energy acquired at each longitude and latitude of the map. In the present work, the well-known Meteorological Radiation Model (MRM), a broadband solar radiation model, is engaged. This model utilizes common meteorological data, such as air temperature, relative humidity, barometric pressure and sunshine duration, in order to calculate solar radiation through MRM for areas where such data are not available. Hourly values of the above meteorological parameters are acquired from 39 meteorological stations, evenly dispersed around Greece; hourly values of solar radiation are calculated from MRM. Then, by using an integrated spatial interpolation method, a Greek solar energy map is generated, providing annual solar energy values all over Greece.

A Two-Dimensional Gridded Solar Forecasting System using Situation-Dependent Blending of Multiple Weather Models

Science.gov (United States)

Lu, S.; Hwang, Y.; Shao, X.; Hamann, H.

2015-12-01

Previously, we reported the application of a "weather situation" dependent multi-model blending approach to improve the forecast accuracy of solar irradiance and other atmospheric parameters. The approach uses machine-learning techniques to classify "weather situations" by a set of atmospheric parameters. The "weather situation" classification is location-dependent and each "weather situation" has characteristic forecast errors from a set of individual input numerical weather prediction (NWP) models. The input models are thus corrected or combined differently for different "weather situations" to minimize the overall forecast error. While the original implementation of the model-blending is applicable to only point-like locations having historical data of both measurements and forecasts, here we extend the approach to provide two-dimensional (2D) gridded forecasts. An experimental 2D forecasting system has been set up to provide gridded forecasts of solar irradiance (global horizontal irradiance), temperature, wind speed, and humidity for the contiguous United States (CONUS). Validation results show around 30% enhancement of 0 to 48 hour ahead solar irradiance forecast accuracy compared to the best input NWP model. The forecasting system may be leveraged by other site- or region-specific solar energy forecast products. To enable the 2D forecasting system, historical solar irradiance measurements from around 1,600 selected sites of the remote automated weather stations (RAWS) network have been employed. The CONUS was divided into smaller sub-regions, each containing a group of 10 to 20 RAWS sites. A group of sites, as classified by statistical analysis, have similar "weather patterns", i.e. the NWPs have similar "weather situation" dependent forecast errors for all sites in a group. The model-blending trained by the historical data from a group of sites is then applied for all locations in the corresponding sub-region. We discuss some key techniques developed for

HEATING MECHANISMS IN THE LOW SOLAR ATMOSPHERE THROUGH MAGNETIC RECONNECTION IN CURRENT SHEETS

Energy Technology Data Exchange (ETDEWEB)

Ni, Lei; Lin, Jun [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Roussev, Ilia I. [Division of Geosciences, National Science Foundation Arlington, Virginia (United States); Schmieder, Brigitte, E-mail: leini@ynao.ac.cn [Observatoire de Paris, LESIA, Meudon (France)

2016-12-01

We simulate several magnetic reconnection processes in the low solar chromosphere/photosphere; the radiation cooling, heat conduction and ambipolar diffusion are all included. Our numerical results indicate that both the high temperature (≳8 × 10{sup 4} K) and low temperature (∼10{sup 4} K) magnetic reconnection events can happen in the low solar atmosphere (100–600 km above the solar surface). The plasma β controlled by plasma density and magnetic fields is one important factor to decide how much the plasma can be heated up. The low temperature event is formed in a high β magnetic reconnection process, Joule heating is the main mechanism to heat plasma and the maximum temperature increase is only several thousand Kelvin. The high temperature explosions can be generated in a low β magnetic reconnection process, slow and fast-mode shocks attached at the edges of the well developed plasmoids are the main physical mechanisms to heat the plasma from several thousand Kelvin to over 8 × 10{sup 4} K. Gravity in the low chromosphere can strongly hinder the plasmoid instability and the formation of slow-mode shocks in a vertical current sheet. Only small secondary islands are formed; these islands, however, are not as well developed as those in the horizontal current sheets. This work can be applied to understand the heating mechanism in the low solar atmosphere and could possibly be extended to explain the formation of common low temperature Ellerman bombs (∼10{sup 4} K) and the high temperature Interface Region Imaging Spectrograph (IRIS) bombs (≳8 × 10{sup 4}) in the future.

Five-minute oscillation power within magnetic elements in the solar atmosphere

International Nuclear Information System (INIS)

Jain, Rekha; Gascoyne, Andrew; Hindman, Bradley W.; Greer, Benjamin

2014-01-01

It has long been known that magnetic plage and sunspots are regions in which the power of acoustic waves is reduced within the photospheric layers. Recent observations now suggest that this suppression of power extends into the low chromosphere and is also present in small magnetic elements far from active regions. In this paper we investigate the observed power suppression in plage and magnetic elements, by modeling each as a collection of vertically aligned magnetic fibrils and presuming that the velocity within each fibril is the response to buffeting by incident p modes in the surrounding field-free atmosphere. We restrict our attention to modeling observations made near the solar disk center, where the line-of-sight velocity is nearly vertical and hence, only the longitudinal component of the motion within the fibril contributes. Therefore, we only consider the excitation of axisymmetric sausage waves and ignore kink oscillations as their motions are primarily horizontal. We compare the vertical motion within the fibril with the vertical motion of the incident p mode by constructing the ratio of their powers. In agreement with observational measurements we find that the total power is suppressed within strong magnetic elements for frequencies below the acoustic cut-off frequency. However, further physical effects need to be examined for understanding the observed power ratios for stronger magnetic field strengths and higher frequencies. We also find that the magnitude of the power deficit increases with the height above the photosphere at which the measurement is made. Furthermore, we argue that the area of the solar disk over which the power suppression extends increases as a function of height.

Solar and terrestrial physics. [effects of solar activities on earth environment

Science.gov (United States)

1975-01-01

The effects of solar radiation on the near space and biomental earth, the upper atmosphere, and the magnetosphere are discussed. Data obtained from the OSO satellites pertaining to the solar cycle variation of extreme ultraviolet (EUV) radiation are analyzed. The effects of solar cycle variation of the characteristics of the solar wind are examined. The fluid mechanics of shock waves and the specific relationship to the characteristics of solar shock waves are investigated. The solar and corpuscular heating of the upper atmosphere is reported based on the findings of the AEROS and NATE experiments. Seasonal variations of the upper atmosphere composition are plotted based on OGO-6 mass spectrometer data.

Modeling Martian Atmospheric Losses over Time: Implications for Exoplanetary Climate Evolution and Habitability

Science.gov (United States)

Dong, Chuanfei; Lee, Yuni; Ma, Yingjuan; Lingam, Manasvi; Bougher, Stephen; Luhmann, Janet; Curry, Shannon; Toth, Gabor; Nagy, Andrew; Tenishev, Valeriy; Fang, Xiaohua; Mitchell, David; Brain, David; Jakosky, Bruce

2018-05-01

In this Letter, we make use of sophisticated 3D numerical simulations to assess the extent of atmospheric ion and photochemical losses from Mars over time. We demonstrate that the atmospheric ion escape rates were significantly higher (by more than two orders of magnitude) in the past at ∼4 Ga compared to the present-day value owing to the stronger solar wind and higher ultraviolet fluxes from the young Sun. We found that the photochemical loss of atomic hot oxygen dominates over the total ion loss at the current epoch, while the atmospheric ion loss is likely much more important at ancient times. We briefly discuss the ensuing implications of high atmospheric ion escape rates in the context of ancient Mars, and exoplanets with similar atmospheric compositions around young solar-type stars and M-dwarfs.

Early solar physics

CERN Document Server

Meadows, A J

1970-01-01

Early Solar Physics reviews developments in solar physics, particularly the advent of solar spectroscopy and the discovery of relationships between the various layers of the solar atmosphere and between the different forms of solar activity. Topics covered include solar observations during 1843; chemical analysis of the solar atmosphere; the spectrum of a solar prominence; and the solar eclipse of December 12, 1871. Spectroscopic observations of the sun are also presented. This book is comprised of 30 chapters and begins with an overview of ideas about the sun in the mid-nineteenth century, fo

Atmospheric chemistry and transport modeling in the outer solar system

Science.gov (United States)

Lee, Yuan-Tai (Anthony)

2001-11-01

This thesis consists of 1-D and 2-D photochemical- dynamical modeling in the upper atmospheres of outer planets. For 1-D modeling, a unified hydrocarbon photochemical model has been studied in Jupiter, Saturn, Uranus, Neptune, and Titan, by comparing with the Voyager observations, and the recent measurements of methyl radicals by ISO in Saturn and Neptune. The CH3 observation implies a kinetically sensitive test to the measured and estimated hydrocarbon rate constants at low temperatures. We identify the key reactions that control the concentrations of CH3 in the model, such as the three-body recombination reaction, CH3 + CH3 + M --> C 2H6 + M, and the recycling reaction H + CH3 + M --> CH4 + M. The results show reasonable agreement with ISO values. In Chapter 4, the detection of PH3 in the lower stratosphere and upper troposphere of Jupiter has provided a photochemical- dynamical coupling model to derive the eddy diffusion coefficient in the upper troposphere of Jupiter. Using a two-layers photochemical model with updated photodissociation cross-sections and chemical rate constants for NH3 and PH 3, we find that the upper tropospheric eddy diffusion coefficient 106 cm2 sec-1, are required to match the derived PH3 vertical profile by the observation. The best-fit functional form derivation of eddy diffusion coefficient in the upper troposphere of Jupiter above 400 mbar is K = 2.0 × 104 (n/2.2 × 1019)-0.5 cm 2 sec-1. On the other hand, Chapter 5 demonstrates a dynamical-only 2-D model of C2H6 providing a complete test for the current 2-D transport models in Jovian lower stratosphere and upper troposphere (270 to 0.1 mbar pressure levels). Different combinations of residual advection, horizontal eddy dispersion, and vertical eddy mixing are examined at different latitudes.

Modeling pN2 through Geological Time: Implications for Planetary Climates and Atmospheric Biosignatures.

Science.gov (United States)

Stüeken, E E; Kipp, M A; Koehler, M C; Schwieterman, E W; Johnson, B; Buick, R

2016-12-01

Nitrogen is a major nutrient for all life on Earth and could plausibly play a similar role in extraterrestrial biospheres. The major reservoir of nitrogen at Earth's surface is atmospheric N 2 , but recent studies have proposed that the size of this reservoir may have fluctuated significantly over the course of Earth's history with particularly low levels in the Neoarchean-presumably as a result of biological activity. We used a biogeochemical box model to test which conditions are necessary to cause large swings in atmospheric N 2 pressure. Parameters for our model are constrained by observations of modern Earth and reconstructions of biomass burial and oxidative weathering in deep time. A 1-D climate model was used to model potential effects on atmospheric climate. In a second set of tests, we perturbed our box model to investigate which parameters have the greatest impact on the evolution of atmospheric pN 2 and consider possible implications for nitrogen cycling on other planets. Our results suggest that (a) a high rate of biomass burial would have been needed in the Archean to draw down atmospheric pN 2 to less than half modern levels, (b) the resulting effect on temperature could probably have been compensated by increasing solar luminosity and a mild increase in pCO 2 , and (c) atmospheric oxygenation could have initiated a stepwise pN 2 rebound through oxidative weathering. In general, life appears to be necessary for significant atmospheric pN 2 swings on Earth-like planets. Our results further support the idea that an exoplanetary atmosphere rich in both N 2 and O 2 is a signature of an oxygen-producing biosphere. Key Words: Biosignatures-Early Earth-Planetary atmospheres. Astrobiology 16, 949-963.

Remote Thermal IR Spectroscopy of our Solar System

Science.gov (United States)

Kostiuk, Theodor; Hewagama, Tilak; Goldstein, Jeffrey; Livengood, Timothy; Fast, Kelly

1999-01-01

Indirect methods to detect extrasolar planets have been successful in identifying a number of stars with companion planets. No direct detection of an extrasolar planet has yet been reported. Spectroscopy in the thermal infrared region provides a potentially powerful approach to detection and characterization of planets and planetary systems. We can use knowledge of our own solar system, its planets and their atmospheres to model spectral characteristics of planets around other stars. Spectra derived from modeling our own solar system seen from an extrasolar perspective can be used to constrain detection strategies, identification of planetary class (terrestrial vs. gaseous) and retrieval of chemical, thermal and dynamical information. Emission from planets in our solar system peaks in the thermal infrared region, approximately 10 - 30 microns, substantially displaced from the maximum of the much brighter solar emission in the visible near 0.5 microns. This fact provides a relatively good contrast ratio to discriminate between stellar (solar) and planetary emission and optimize the delectability of planetary spectra. Important molecular constituents in planetary atmospheres have rotational-vibrational spectra in the thermal infrared region. Spectra from these molecules have been well characterized in the laboratory and studied in the atmospheres of solar system planets from ground-based and space platforms. The best example of such measurements are the studies with Fourier transform spectrometers, the Infrared Interferometer Spectrometers (IRIS), from spacecraft: Earth observed from NIMBUS 8, Mars observed from Mariner 9, and the outer planets observed from Voyager spacecraft. An Earth-like planet is characterized by atmospheric spectra of ozone, carbon dioxide, and water. Terrestrial planets have oxidizing atmospheres which are easily distinguished from reducing atmospheres of gaseous giant planets which lack oxygen-bearing species and are characterized by spectra

Influence of the atmospheric aerosol and air pollution on solar albedo of the earth. Vol. 4

International Nuclear Information System (INIS)

Mayhoub, A.B.; Mohamed, K.S.

1996-01-01

The effect of increasing atmospheric aerosol and air pollutant concentration on the solar albedo and consequently upon the heat budget near the earth's surface is studied. The magnitude of aerosol absorption coefficient to back-scattering coefficient B ab /B bs is calculated. This study will be used to estimate atmospheric stability categories and other meteorological parameters which are affected by thermal state radiation balance of the atmosphere as mixing and inversion height of Inshas nuclear reactor site. Consequently, concentration distribution of radioactive release from Inshas can be evaluated.. 4 figs., 5 tabs

Influence of the atmospheric aerosol and air pollution on solar albedo of the earth. Vol. 4

Energy Technology Data Exchange (ETDEWEB)

Mayhoub, A B; Mohamed, K S [Mathematics and Theoretical Physics Department, Nuclear Research Center, Atomic Energy Auhtority, Cairo, (Egypt)

1996-03-01

The effect of increasing atmospheric aerosol and air pollutant concentration on the solar albedo and consequently upon the heat budget near the earth`s surface is studied. The magnitude of aerosol absorption coefficient to back-scattering coefficient B{sub ab}/B{sub bs} is calculated. This study will be used to estimate atmospheric stability categories and other meteorological parameters which are affected by thermal state radiation balance of the atmosphere as mixing and inversion height of Inshas nuclear reactor site. Consequently, concentration distribution of radioactive release from Inshas can be evaluated.. 4 figs., 5 tabs.

National Solar Radiation Database (NSRDB) SolarAnywhere 10 km Model Output for 1989 to 2009

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The National Solar Radiation Database (NSRDB) was produced by the National Renewable Energy Laboratory under the U.S. Department of Energy's Office of Energy...

Crosstalk in solar polarization measurements

Science.gov (United States)

West, E. A.; Balasubramaniam, K. S.

1992-01-01

The instrumental crosstalk associated with the Marshall Space Flight Center Vector Magnetograph and the solar crosstalk created by the magnetic field are described and their impact on the reconstruction of the solar vector magnetic field is analyzed. It is pointed out that identifying and correcting the crosstalk is important in the development of realistic models describing the solar atmosphere. Solar crosstalk is spatially dependent on the structure of the magnetic field while instrumental crosstalk is dependent on the position of the analyzer.

Solar Indices - Solar Flares

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

Solar Indices - Solar Ultraviolet

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

Solar Indices - Solar Corona

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

Solar Indices - Solar Irradiance

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

Solar ultraviolet radiation induced variations in the stratosphere and mesosphere

Science.gov (United States)

Hood, L. L.

1987-01-01

The detectability and interpretation of short-term solar UV induced responses of middle atmospheric ozone, temperature, and dynamics are reviewed. The detectability of solar UV induced perturbations in the middle atmosphere is studied in terms of seasonal and endogenic dynamical variations. The interpretation of low-latitude ozone and possible temperature responses on the solar rotation time scale is examined. The use of these data to constrain or test photochemical model predictions is discussed.

Model study of the influence of solar wind parameters on electric currents and fields in middle atmosphere at high latitudes

International Nuclear Information System (INIS)

Tonev, P.; Velinov, P.

2012-01-01

The electric currents and fields in the strato/mesosphere and lower ionosphere are a result mainly of tropospheric electrical generators (thunderstorms and electrified clouds) which principally determine their global distributions and magnitudes. There are, however, additional sources, e.g. the solar wind (SW), whose contribution to these currents and fields is realized by SW-magnetosphere-ionosphere coupling. This last causes creation of large trans-polar electric potential difference VPC in each polar cap of ∼ 30–140 kV and of horizontal scale ∼ 3000 km which is realized through field-aligned currents (FAC) and is controlled by SW parameters. The potential difference VPC forces formation of closure currents in the dynamo-region. Our study by simulation shows that much smaller currents penetrate into the lower atmospheric regions and influence characteristics of the global atmospheric electrical circuit (GEC). Also, the downward mapping of the horizontal electric fields due to the potential difference VPC leads to creation of very small, but non-negligible vertical electric fields at sea level. They have been demonstrated experimentally as significant (up to few tens of per cent) SW-controlled modifications of the GEC electric characteristics at the ground, at polar latitudes. Our model, based on simulation of Maxwell’s equations in the region 0–160 km under steady-state conditions show that similar but relatively much larger SW-dominated modifications of GEC characteristics take place in the strato/mesosphere and lower ionosphere at polar and high latitudes

Northern Hemisphere Atmospheric Influence of the Solar Proton Events and Ground Level Enhancement in January 2005

Science.gov (United States)

Jackman, C. H.; Marsh, D. R.; Vitt, F. M.; Roble, R. G.; Randall, C. E.; Bernath, P. F.; Funke, B.; Lopez-Puertas, M.; Versick, S.; Stiller, G. P.;

The Greenhouse effect within an analytic model of the atmosphere

Energy Technology Data Exchange (ETDEWEB)

Dehnen, Heinz [Konstanz Univ. (Germany). Fachbereich Physik

2009-01-15

Within a simplified atmospheric model the greenhouse effect is treated by analytical methods starting from physical first principles. The influence of solar radiation, absorption cross sections of the greenhouse molecules, and cloud formation on the earth's temperature is shown and discussed explicitly by mathematical formulae in contrast to the climate simulations. The application of our analytical results on the production of 20 .10{sup 9} t of CO{sub 2} per year yields an enlargement of the earth's surface temperature of 2.3 .10{sup -2} C per year in agreement with other estimations. (orig.)

The Effect of Cumulus Cloud Field Anisotropy on Domain-Averaged Solar Fluxes and Atmospheric Heating Rates

Science.gov (United States)

Hinkelman, Laura M.; Evans, K. Franklin; Clothiaux, Eugene E.; Ackerman, Thomas P.; Stackhouse, Paul W., Jr.

2006-01-01

Cumulus clouds can become tilted or elongated in the presence of wind shear. Nevertheless, most studies of the interaction of cumulus clouds and radiation have assumed these clouds to be isotropic. This paper describes an investigation of the effect of fair-weather cumulus cloud field anisotropy on domain-averaged solar fluxes and atmospheric heating rate profiles. A stochastic field generation algorithm was used to produce twenty three-dimensional liquid water content fields based on the statistical properties of cloud scenes from a large eddy simulation. Progressively greater degrees of x-z plane tilting and horizontal stretching were imposed on each of these scenes, so that an ensemble of scenes was produced for each level of distortion. The resulting scenes were used as input to a three-dimensional Monte Carlo radiative transfer model. Domain-average transmission, reflection, and absorption of broadband solar radiation were computed for each scene along with the average heating rate profile. Both tilt and horizontal stretching were found to significantly affect calculated fluxes, with the amount and sign of flux differences depending strongly on sun position relative to cloud distortion geometry. The mechanisms by which anisotropy interacts with solar fluxes were investigated by comparisons to independent pixel approximation and tilted independent pixel approximation computations for the same scenes. Cumulus anisotropy was found to most strongly impact solar radiative transfer by changing the effective cloud fraction, i.e., the cloud fraction when the field is projected on a surface perpendicular to the direction of the incident solar beam.

Improving Soft X-Ray Spectral Irradiance Models for Use Throughout the Solar System

Science.gov (United States)

Eparvier, F. G.; Thiemann, E.; Woods, T. N.

2017-12-01

Understanding the effects of solar variability on planetary atmospheres has been hindered by the lack of accurate models and measurements of the soft x-ray (SXR) spectral irradiance (0-6 nm). Most measurements of the SXR have been broadband and are difficult to interpret due to changing spectral distribution under the pass band of the instruments. Models that use reference spectra for quiet sun, active region, and flaring contributions to irradiance have been made, but with limited success. The recent Miniature X-ray Solar Spectrometer (MinXSS) CubeSat made spectral measurements in the 0.04 - 3 nm range from June 2016 to May 2017, observing the Sun at many different levels of activity. In addition, the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) has observed the Sun since May 2010, in both broad bands (including a band at 0-7 nm) and spectrally resolved (6-105 nm at 0.1 nm resolution). We will present an improved model of the SXR based on new reference spectra from MinXSS and SDO-EVE. The non-flaring portion of the model is driven by broadband SXR measurements for determining activity level and relative contributions of quiet and active sun. Flares are modeled using flare temperatures from the GOES X-Ray Sensors. The improved SXR model can be driven by any sensors that provide a measure of activity level and flare temperature from any vantage point in the solar system. As an example, a version of the model is using the broadband solar irradiance measurements from the MAVEN EUV Monitor at Mars will be presented.

Assessment of satellite and model derived long term solar radiation for spatial crop models: A case study using DSSAT in Andhra Pradesh

Directory of Open Access Journals (Sweden)

Anima Biswal

2014-09-01

Full Text Available Crop Simulation models are mathematical representations of the soil plant-atmosphere system that calculate crop growth and yield, as well as the soil and plant water and nutrient balances, as a function of environmental conditions and crop management practices on daily time scale. Crop simulation models require meteorological data as inputs, but data availability and quality are often problematic particularly in spatialising the model for a regional studies. Among these weather variables, daily total solar radiation and air temperature (Tmax and Tmin have the greatest influence on crop phenology and yield potential. The scarcity of good quality solar radiation data can be a major limitation to the use of crop models. Satellite-sensed weather data have been proposed as an alternative when weather station data are not available. These satellite and modeled based products are global and, in general, contiguous in time and also been shown to be accurate enough to provide reliable solar and meteorological resource data over large regions where surface measurements are sparse or nonexistent. In the present study, an attempt was made to evaluate the satellite and model derived daily solar radiation for simulating groundnut crop growth in the rainfed distrcits of Andhra Pradesh. From our preliminary investigation, we propose that satellite derived daily solar radiation data could be used along with ground observed temperature and rainfall data for regional crop simulation studies where the information on ground observed solar radiation is missing or not available.

Atmospheric Mining in the Outer Solar System: Outer Planet Orbital Transfer and Lander Analyses

Science.gov (United States)

Palaszewski, Bryan

2016-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and deuterium can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and deuterium were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. While capturing 3He, large amounts of hydrogen and 4He are produced. Analyses of orbital transfer vehicles (OTVs), landers, and the issues with in-situ resource utilization (ISRU) mining factories are included. Preliminary observations are presented on near-optimal selections of moon base orbital locations, OTV power levels, and OTV and lander rendezvous points. For analyses of round trip OTV flights from Uranus to Miranda or Titania, a 10- Megawatt electric (MWe) OTV power level and a 200 metricton (MT) lander payload were selected based on a relative short OTV trip time and minimization of the number of lander flights. A similar optimum power level is suggested for OTVs flying from low orbit around Neptune to Thalassa or Triton. Several moon base sites at Uranus and Neptune and the OTV requirements to support them are also addressed.

A model to predict solar heat gains to outside wine tanks

Energy Technology Data Exchange (ETDEWEB)

Delves, T.; Weedon, M.; Louis, J. [Charles Sturt Univ., Wagga Wagga, NSW (Australia). National Wine and Grape Industry Centre

2006-07-01

Although there are many software and simulation tools for calculating solar heat gains to residential and commercial buildings, little information is available to predict the heating effect of products stored in outdoor facilities. In older wineries where wine is stored outdoors in stainless steel tanks, solar heat gains can result in unwanted warming of the wine. This not only ruins the wine quality, but places an additional load on the winery refrigeration system. In this study, experiments were performed to determine the effect of solar radiation and ambient conditions on the heating of wine stored in outside tanks. Trials were conducted on a 25 kL outdoor stainless steel tank at Rutherglen, Australia. In order to incorporate the effect of shading from adjacent tanks, trials were also conducted at Wagga Wagga, Australia, on a group of tanks where mutual shading was present. Each tank was fitted with sensors to study the effect of morning, afternoon and mid-day shading. A mathematical model was developed to predict the amount of solar heat load received by the tank. The model considered the effect of seasonal variations in radiation intensity, day length and sun angle. The model incorporated the size, spacing and orientation of the tanks as well as solar considerations such as time of year and latitude. This paper also presented background information on the solar radiation received by the earth. Solar radiation comprises direct radiation and diffuse radiation. Direct radiation refers to direct sunlight, travelling in parallel rays from the sun, while diffuse radiation refers to radiation which has been scattered by the atmosphere. In most cases, direct radiation is dominant, but both radiations are considered when calculating solar energy gains. The solar heating of the 25 kL tank of wine was calculated by isolating the solar heating from other heat flows. Fermentation was complete and no refrigeration was applied to the tank during the 5 days of the trial. Only

About the standard solar model

International Nuclear Information System (INIS)

Cahen, S.

1986-07-01

A discussion of the still controversial solar helium content is presented, based on a comparison of recent standard solar models. Our last model yields an helium mass fraction ∼0.276, 6.4 SNU on 37 Cl and 126 SNU on 71 Ga

Soil-vegetation-atmosphere transfer modeling

Energy Technology Data Exchange (ETDEWEB)

Ikonen, J P; Sucksdorff, Y [Finnish Environment Agency, Helsinki (Finland)

1997-12-31

In this study the soil/vegetation/atmosphere-model based on the formulation of Deardorff was refined to hour basis and applied to a field in Vihti. The effect of model parameters on model results (energy fluxes, temperatures) was also studied as well as the effect of atmospheric conditions. The estimation of atmospheric conditions on the soil-vegetation system as well as an estimation of the effect of vegetation parameters on the atmospheric climate was estimated. Areal surface fluxes, temperatures and moistures were also modelled for some river basins in southern Finland. Land-use and soil parameterisation was developed to include properties and yearly variation of all vegetation and soil types. One classification was selected to describe the hydrothermal properties of the soils. Evapotranspiration was verified against the water balance method

Soil-vegetation-atmosphere transfer modeling

Energy Technology Data Exchange (ETDEWEB)

Ikonen, J.P.; Sucksdorff, Y. [Finnish Environment Agency, Helsinki (Finland)

1996-12-31

In this study the soil/vegetation/atmosphere-model based on the formulation of Deardorff was refined to hour basis and applied to a field in Vihti. The effect of model parameters on model results (energy fluxes, temperatures) was also studied as well as the effect of atmospheric conditions. The estimation of atmospheric conditions on the soil-vegetation system as well as an estimation of the effect of vegetation parameters on the atmospheric climate was estimated. Areal surface fluxes, temperatures and moistures were also modelled for some river basins in southern Finland. Land-use and soil parameterisation was developed to include properties and yearly variation of all vegetation and soil types. One classification was selected to describe the hydrothermal properties of the soils. Evapotranspiration was verified against the water balance method

Solar Measurement and Modeling | Grid Modernization | NREL

Science.gov (United States)

Measurement and Modeling Solar Measurement and Modeling NREL supports grid integration studies , industry, government, and academia by disseminating solar resource measurements, models, and best practices have continuously gathered basic solar radiation information, and they now gather high-resolution data

Solar UV Variations During the Decline of Cycle 23

Science.gov (United States)

DeLand, Matthew, T.; Cebula, Richard P.

2011-01-01

Characterization of temporal and spectral variations in solar ultraviolet irradiance over a solar cycle is essential for understanding the forcing of Earth's atmosphere and climate. Satellite measurements of solar UV variability for solar cycles 21, 22, and 23 show consistent solar cycle irradiance changes at key wavelengths (e.g. 205 nm, 250 nm) within instrumental uncertainties. All historical data sets also show the same relative spectral dependence for both short-term (rotational) and long-term (solar cycle) variations. Empirical solar irradiance models also produce long-term solar UV variations that agree well with observational data. Recent UV irradiance data from the Solar Radiation and Climate Experiment (SORCE) Spectral Irradiance Monitor (SIM) and Solar Stellar Irradiance Comparison Experiment (SOLSTICE) instruments covering the declining phase of Cycle 23 present a different picture oflong-term solar variations from previous results. Time series of SIM and SOLSTICE spectral irradiance data between 2003 and 2007 show solar variations that greatly exceed both previous measurements and predicted irradiance changes over this period, and the spectral dependence of the SIM and SOLSTICE variations during these years do not show features expected from solar physics theory. The use of SORCE irradiance variations in atmospheric models yields substantially different middle atmosphere ozone responses in both magnitude and vertical structure. However, short-term solar variability derived from SIM and SOLSTICE UV irradiance data is consistent with concurrent solar UV measurements from other instruments, as well as previous results, suggesting no change in solar physics. Our analysis of short-term solar variability is much less sensitive to residual instrument response changes than the observations of long-term variations. The SORCE long-term UV results can be explained by under-correction of instrument response changes during the first few years of measurements

Performance analysis of a parallel Monte Carlo code for simulating solar radiative transfer in cloudy atmospheres using CUDA-enabled NVIDIA GPU

Science.gov (United States)

Russkova, Tatiana V.

2017-11-01

One tool to improve the performance of Monte Carlo methods for numerical simulation of light transport in the Earth's atmosphere is the parallel technology. A new algorithm oriented to parallel execution on the CUDA-enabled NVIDIA graphics processor is discussed. The efficiency of parallelization is analyzed on the basis of calculating the upward and downward fluxes of solar radiation in both a vertically homogeneous and inhomogeneous models of the atmosphere. The results of testing the new code under various atmospheric conditions including continuous singlelayered and multilayered clouds, and selective molecular absorption are presented. The results of testing the code using video cards with different compute capability are analyzed. It is shown that the changeover of computing from conventional PCs to the architecture of graphics processors gives more than a hundredfold increase in performance and fully reveals the capabilities of the technology used.

Solar Indices - Solar Radio Flux

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

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.

Solar Radiation Model for Development and Control of Solar Energy Sources

Directory of Open Access Journals (Sweden)

Dominykas Vasarevičius

2016-06-01

Full Text Available The model of solar radiation, which takes into account direct, diffused and reflected components of solar energy, has been presented. Model is associated with geographical coordinates and local time of every day of the year. It is shown that using analytic equations for modelling the direct component, it is possible to adopt it for embedded systems with low computational power and use in solar tracking applications. Reflected and diffused components are especially useful in determining the performance of photovoltaic modules in certain location and surroundings. The statistical method for cloud layer simulation based on local meteorological data is offered. The presented method can’t be used for prediction of weather conditions but it provides patterns of solar radiation in time comparable to those measured with pyranometer. Cloud layer simulation together with total solar radiation model is a useful tool for development and analysis of maximum power point tracking controllers for PV modules.

Modelling the solar magnetism: from its internal origin to its manifestations at the surface

International Nuclear Information System (INIS)

Jouve, Laurene

2008-01-01

This thesis is part of the general study of dynamical processes involved in stars such as convection, rotation or magnetic fields and of their nonlinear interactions. The results of numerical simulations using the 2D finite element code STELEM and the pseudo-spectral 3D code ASH are presented. The first part of this work focuses on the global modeling of the solar dynamo. Through 2D simulations using mean-field theory, I studied the influence of a complex profile of meridional flow in Babcock-Leighton models. We show that there may be doubts about the ability of such models to reproduce the main characteristics of the solar cycle. In order to better constrain the effects of solar variability on the Earth climate, we present a first application in solar physics of sophisticated prediction methods which are used in meteorology. I also computed the first 3D MHD simulations in spherical geometry of a key step in the solar dynamo: the nonlinear evolution of magnetic structures from the base of the convection zone up to the surface where they produce active regions. Weak fields are likely to be modulated by convective motions, thus creating favored longitudes of emergence. If these structures are sufficiently arched, the orientation of bipolar spots corresponds to Joy's law. The introduction of an atmosphere in these models is a step towards a 3D global vision of our Sun. (author) [fr

Martian Atmospheric and Ionospheric plasma Escape

Science.gov (United States)

Lundin, Rickard

2016-04-01

Solar forcing is responsible for the heating, ionization, photochemistry, and erosion processes in the upper atmosphere throughout the lifetime of the terrestrial planets. Of the four terrestrial planets, the Earth is the only one with a fully developed biosphere, while our kin Venus and Mars have evolved into arid inhabitable planets. As for Mars, there are ample evidences for an early Noachian, water rich period on Mars. The question is, what made Mars evolve so differently compared to the Earth? Various hydrosphere and atmospheric evolution scenarios for Mars have been forwarded based on surface morphology, chemical composition, simulations, semi-empiric (in-situ data) models, and the long-term evolution of the Sun. Progress has been made, but the case is still open regarding the changes that led to the present arid surface and tenuous atmosphere at Mars. This presentation addresses the long-term variability of the Sun, the solar forcing impact on the Martian atmosphere, and its interaction with the space environment - an electromagnetic wave and particle interaction with the upper atmosphere that has implications for its photochemistry, composition, and energization that governs thermal and non-thermal escape. Non-thermal escape implies an electromagnetic upward energization of planetary ions and molecules to velocities above escape velocity, a process governed by a combination of solar EUV radiation (ionization), and energy and momentum transfer by the solar wind. The ion escape issue dates back to the early Soviet and US-missions to Mars, but the first more accurate estimates of escape rates came with the Phobos-2 mission in 1989. Better-quality ion composition measurement results of atmospheric/ionospheric ion escape from Mars, obtained from ESA Mars Express (MEX) instruments, have improved our understanding of the ion escape mechanism. With the NASA MAVEN spacecraft orbiting Mars since Sept. 2014, dual in-situ measurement with plasma instruments are now

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

A Comparison of Satellite Based, Modeled Derived Daily Solar Radiation Data with Observed Data for the Continental US

Science.gov (United States)

White, Jeffrey W.; Hoogenboom, Gerrit; Wilkens, Paul W.; Stackhouse, Paul W., Jr.; Hoell, James M.

2010-01-01

Many applications of simulation models and related decision support tools for agriculture and natural resource management require daily meteorological data as inputs. Availability and quality of such data, however, often constrain research and decision support activities that require use of these tools. Daily solar radiation (SRAD) data are especially problematic because the instruments require electronic integrators, accurate sensors are expensive, and calibration standards are seldom available. The Prediction Of Worldwide Energy Resources (NASA/POWER; power.larc.nasa.gov) project at the NASA Langley Research Center estimates daily solar radiation based on data that are derived from satellite observations of outgoing visible radiances and atmospheric parameters based upon satellite observations and assimilation models. The solar data are available for a global 1 degree x 1 degree coordinate grid. SRAD can also be estimated based on attenuation of extraterrestrial radiation (Q0) using daily temperature and rainfall data to estimate the optical thickness of the atmosphere. This study compares daily solar radiation data from NASA/POWER (SRADNP) with instrument readings from 295 stations (SRADOB), as well as with values that were estimated with the WGENR solar generator. WGENR was used both with daily temperature and precipitation records from the stations reporting solar data and records from the NOAA Cooperative Observer Program (COOP), thus providing two additional sources of solar data, SRADWG and SRADCO. Values of SRADNP for different grid cells consistently showed higher correlations (typically 0.85 to 0.95) with SRADOB data than did SRADWG or SRADCO for sites within the corresponding cells. Mean values of SRADOB, SRADWG and SRADNP for sites within a grid cell usually were within 1 MJm-2d-1 of each other, but NASA/POWER values averaged 1.1 MJm-2d-1 lower than SRADOB. The magnitude of this bias was greater at lower latitudes and during summer months and may be at

Estimation of solar radiation over Cambodia from long-term satellite data

Energy Technology Data Exchange (ETDEWEB)

Janjai, S.; Pankaew, P.; Laksanaboonsong, J. [Solar Energy Research Laboratory, Department of Physics, Faculty of Science, Silpakorn University, Nakhon Pathom 73000 (Thailand); Kitichantaropas, P. [Department of Alternative Energy Development and Efficiency, Ministry of Energy, 17 Rama 1 Road, Patumwan, Bangkok 10330 (Thailand)

2011-04-15

In this work, monthly average daily global solar irradiation over Cambodia was estimated from a long-term satellite data. A 14-year period (1995-2008) of visible channel data from GMS5, GOES9 and MTSAT-1R satellites were used to provide earth-atmospheric reflectivity. A satellite-based solar radiation model developed for a tropical environment was used to estimate surface solar radiation. The model relates the satellite-derived earth-atmospheric reflectivity to absorption and scattering coefficients of various atmospheric constituents. The absorption of solar radiation due to water vapour was calculated from precipitable water derived from ambient relative humidity and temperature. Ozone data from the TOMS and OMI satellite data were employed to compute the solar radiation absorption by ozone. The depletion of radiation due to aerosols was estimated from the visibility data. Five new solar radiation measuring stations were established at Cambodian cities, namely Siem Reap (13.87 N, 103.85 E), Kompong Thom (12.68 N, 104.88 E), Phnom Penh (11.55 N, 104.83 E), Sihanouke Ville (10.67 N, 103.63 E) and Kampot (10.70 N, 104.28 E). Global solar radiation measured at these stations was used to validate the model. The validation was also carried out by using solar radiation measured at four Thai meteorological stations. These stations are situated near the Cambodian border. Monthly average daily global irradiation from these stations was compared with that calculated from the model. The measured and calculated irradiation is in good agreement, with the root mean square difference of 6.3%, with respect to the mean values. After the validation, the model was used to calculate monthly average daily global solar irradiation over Cambodia. Based on this satellite-derived irradiation, solar radiation maps for Cambodia were generated. These maps show that solar radiation climate of this country is strongly influenced by the monsoons. A solar radiation database was also generated

Modeling the Chemical Complexity in Titan's Atmosphere

Science.gov (United States)

Vuitton, Veronique; Yelle, Roger; Klippenstein, Stephen J.; Horst, Sarah; Lavvas, Panayotis

2018-06-01

Titan's atmospheric chemistry is extremely complicated because of the multiplicity of chemical as well as physical processes involved. Chemical processes begin with the dissociation and ionization of the most abundant species, N2 and CH4, by a variety of energy sources, i.e. solar UV and X-ray photons, suprathermal electrons (reactions involving radicals as well as positive and negative ions, all possibly in some excited electronic and vibrational state. Heterogeneous chemistry at the surface of the aerosols could also play a significant role. The efficiency and outcome of these reactions depends strongly on the physical characteristics of the atmosphere, namely pressure and temperature, ranging from 1.5×103 to 10-10 mbar and from 70 to 200 K, respectively. Moreover, the distribution of the species is affected by molecular diffusion and winds as well as escape from the top of the atmosphere and condensation in the lower stratosphere.Photochemical and microphysical models are the keystones of our understanding of Titan's atmospheric chemistry. Their main objective is to compute the distribution and nature of minor chemical species (typically containing up to 6 carbon atoms) and haze particles, respectively. Density profiles are compared to the available observations, allowing to identify important processes and to highlight those that remain to be constrained in the laboratory, experimentally and/or theoretically. We argue that positive ion chemistry is at the origin of complex organic molecules, such as benzene, ammonia and hydrogen isocyanide while neutral-neutral radiative association reactions are a significant source of alkanes. We find that negatively charged macromolecules (m/z ~100) attract the abundant positive ions, which ultimately leads to the formation of the aerosols. We also discuss the possibility that an incoming flux of oxygen from Enceladus, another Saturn's satellite, is responsible for the presence of oxygen-bearing species in Titan's reductive

A solar radiation model for use in climate studies

Science.gov (United States)

Chou, Ming-Dah

1992-01-01

A solar radiation routine is developed for use in climate studies that includes absorption and scattering due to ozone, water vapor, oxygen, carbon dioxide, clouds, and aerosols. Rayleigh scattering is also included. Broadband parameterization is used to compute the absorption by water vapor in a clear atmosphere, and the k-distribution method is applied to compute fluxes in a scattering atmosphere. The reflectivity and transmissivity of a scattering layer are computed analytically using the delta-four-stream discrete-ordinate approximation. The two-stream adding method is then applied to compute fluxes for a composite of clear and scattering layers. Compared to the results of high spectral resolution and detailed multiple-scattering calculations, fluxes and heating rate are accurately computed to within a few percent. The high accuracy of the flux and heating-rate calculations is achieved with a reasonable amount of computing time. With the UV and visible region grouped into four bands, this solar radiation routine is useful not only for climate studies but also for studies on photolysis in the upper atmosphere and photosynthesis in the biosphere.

A contribution to the study of the influence of the energy of solar wind upon the atmospheric processes

Directory of Open Access Journals (Sweden)

Radovanović Milan M.

2003-01-01

Full Text Available According to the satellite observing of solar wind, and as well according the development of certain weather conditions it is realized that their interactive connections could have important role on the development of atmospheric processes. In this paper is given several of such situations. We have tried to point to a very important significance of new methodological approach in understanding development of meteorological conditions. Researching the influence of the solar wind on the changes of conditions in the atmosphere could develop in several ways but in any case for the further steps a multidiscipline approach is needed. Karen Labitske in Germany has done a lot of research in this area. "The physics is still highly speculative at this point though".

Influence of Dust Loading on Atmospheric Ionizing Radiation on Mars

Science.gov (United States)

Norman, Ryan B.; Gronoff, Guillaume; Mertens, Christopher J.

2014-01-01

Measuring the radiation environment at the surface of Mars is the primary goal of the Radiation Assessment Detector on the NASA Mars Science Laboratory's Curiosity rover. One of the conditions that Curiosity will likely encounter is a dust storm. The objective of this paper is to compute the cosmic ray ionization in different conditions, including dust storms, as these various conditions are likely to be encountered by Curiosity at some point. In the present work, the Nowcast of Atmospheric Ionizing Radiation for Aviation Safety model, recently modified for Mars, was used along with the Badhwar & O'Neill 2010 galactic cosmic ray model. In addition to galactic cosmic rays, five different solar energetic particle event spectra were considered. For all input radiation environments, radiation dose throughout the atmosphere and at the surface was investigated as a function of atmospheric dust loading. It is demonstrated that for galactic cosmic rays, the ionization depends strongly on the atmosphere profile. Moreover, it is shown that solar energetic particle events strongly increase the ionization throughout the atmosphere, including ground level, and can account for the radio blackout conditions observed by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument on the Mars Express spacecraft. These results demonstrate that the cosmic rays' influence on the Martian surface chemistry is strongly dependent on solar and atmospheric conditions that should be taken into account for future studies.

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)

Solar Irradiance Variability and Its Impacts on the Earth Climate System

Science.gov (United States)

Harder, J. W.; Woods, T. N.

The Sun plays a vital role in the evolution of the climates of terrestrial planets. Observations of the solar spectrum are now routinely made that span the wavelength range from the X-ray portion of the spectrum (5 nm) into the infrared to about 2400 nm. Over this very broad wavelength range, accounting for about 97% of the total solar irradiance, the intensity varies by more than 6 orders of magnitude, requiring a suite of very different and innovative instruments to determine both the spectral irradiance and its variability. The origins of solar variability are strongly linked to surface magnetic field changes, and analysis of solar images and magnetograms show that the intensity of emitted radiation from solar surface features in active regions has a very strong wavelength and magnetic field strength dependence. These magnetic fields produce observable solar surface features such as sunspots, faculae, and network structures that contribute in different ways to the radiated output. Semi-empirical models of solar spectral irradiance are able to capture much of the Sun's output, but this topic remains an active area of research. Studies of solar structures in both high spectral and spatial resolution are refining this understanding. Advances in Earth observation systems and high-quality three-dimensional chemical climate models provide a sound methodology to study the mechanisms of the interaction between Earth's atmosphere and the incoming solar radiation. Energetic photons have a profound effect on the chemistry and dynamics of the thermosphere and ionosphere, and these processes are now well represented in upper atmospheric models. In the middle and lower atmosphere the effects of solar variability enter the climate system through two nonexclusive pathways referred to as the top-down and bottom-up mechanisms. The top-down mechanism proceeds through the alteration of the photochemical rates that establish the middle atmospheric temperature structure and

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.

Inter-comparison of different models for estimating clear sky solar global radiation for the Negev region of Israel

International Nuclear Information System (INIS)

Ianetz, Amiran; Lyubansky, Vera; Setter, Ilan; Kriheli, Boris; Evseev, Efim G.; Kudish, Avraham I.

2007-01-01

Solar global radiation is a function of solar altitude, site altitude, albedo, atmospheric transparency and cloudiness, whereas solar global radiation on a clear day is defined such that it is a function of all the abovementioned parameters except cloudiness. Consequently, analysis of the relative magnitudes of solar global radiation and solar global radiation on a clear day provides a platform for studying the influence of cloudiness on solar global radiation. The Iqbal filter for determining the day type has been utilized to calculate the monthly average clear day solar global radiation at three sites in the Negev region of Israel. An inter-comparison between four models for estimating clear sky solar global radiation at the three sites was made. The relative accuracy of the four models was determined by comparing the monthly average daily clear sky solar global radiation to that determined using the Iqbal filter. The analysis was performed on databases consisting of measurements made during the time interval of January 1991 to December 2004. The monthly average daily clear sky solar global radiation determined by the Berlynd model was found to give the best agreement with that determined using the Iqbal filter. The Berlynd model was then utilized to calculate a daily clear day index, K c , which is defined as the ratio of the daily solar global radiation to the daily clear day solar global radiation. It is suggested that this index be used as an indication of the degree of cloudiness. Linear regression analysis was performed on the individual monthly databases for each site to determine the correlation between the daily clear day index and the daily clearness index, K T

Isca, v1.0: a framework for the global modelling of the atmospheres of Earth and other planets at varying levels of complexity

Science.gov (United States)

Vallis, Geoffrey K.; Colyer, Greg; Geen, Ruth; Gerber, Edwin; Jucker, Martin; Maher, Penelope; Paterson, Alexander; Pietschnig, Marianne; Penn, James; Thomson, Stephen I.

2018-03-01

Isca is a framework for the idealized modelling of the global circulation of planetary atmospheres at varying levels of complexity and realism. The framework is an outgrowth of models from the Geophysical Fluid Dynamics Laboratory in Princeton, USA, designed for Earth's atmosphere, but it may readily be extended into other planetary regimes. Various forcing and radiation options are available, from dry, time invariant, Newtonian thermal relaxation to moist dynamics with radiative transfer. Options are available in the dry thermal relaxation scheme to account for the effects of obliquity and eccentricity (and so seasonality), different atmospheric optical depths and a surface mixed layer. An idealized grey radiation scheme, a two-band scheme, and a multiband scheme are also available, all with simple moist effects and astronomically based solar forcing. At the complex end of the spectrum the framework provides a direct connection to comprehensive atmospheric general circulation models. For Earth modelling, options include an aquaplanet and configurable continental outlines and topography. Continents may be defined by changing albedo, heat capacity, and evaporative parameters and/or by using a simple bucket hydrology model. Oceanic Q fluxes may be added to reproduce specified sea surface temperatures, with arbitrary continental distributions. Planetary atmospheres may be configured by changing planetary size and mass, solar forcing, atmospheric mass, radiation, and other parameters. Examples are given of various Earth configurations as well as a giant planet simulation, a slowly rotating terrestrial planet simulation, and tidally locked and other orbitally resonant exoplanet simulations. The underlying model is written in Fortran and may largely be configured with Python scripts. Python scripts are also used to run the model on different architectures, to archive the output, and for diagnostics, graphics, and post-processing. All of these features are publicly

Meteorology ans solar physics

Science.gov (United States)

Schwarz, Oliver

When in the second half of the 19th century both solar physics and astrophysics came into existence, various solar phenomena were described by analogies encountered in the terrestrial atmosphere. For a certain time, meteorology played a central role in research on solar processes. At first glance, this may appear as a curious and old-fashioned specialty. However, solar physics owes its first insights into solar structure to various analogies in terrestrial atmospheric studies. The present investigation intends to elucidate this fact, to present details of the historical development, and to demonstrate how our present knowledge in certain fields is based on considerations which were originally taken from the description of the terrestrial atmosphere.

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.

A roll-to-roll process to flexible polymer solar cells: model studies, manufacture and operational stability studies

DEFF Research Database (Denmark)

Krebs, Frederik C; Gevorgyan, Suren; Alstrup, Jan

2009-01-01

An inverted polymer solar cell geometry comprising a total of five layers was optimized using laboratory scale cells and the operational stability was studied under model atmospheres. The device geometry was substrate-ITO-ZnO-(active layer)-PEDOT:PSS-silver with P3HT-PCBM as the active layer. The...

TEMPERATURE GRADIENTS IN THE SOLAR ATMOSPHERE AND THE ORIGIN OF CUTOFF FREQUENCY FOR TORSIONAL TUBE WAVES

International Nuclear Information System (INIS)

Routh, S.; Musielak, Z. E.; Hammer, R.

2010-01-01

Fundamental modes supported by a thin magnetic flux tube embedded in the solar atmosphere are typically classified as longitudinal, transverse, and torsional waves. If the tube is isothermal, then the propagation of longitudinal and transverse tube waves is restricted to frequencies that are higher than the corresponding global cutoff frequency for each wave. However, no such global cutoff frequency exists for torsional tube waves, which means that a thin and isothermal flux tube supports torsional tube waves of any frequency. In this paper, we consider a thin and non-isothermal magnetic flux tube and demonstrate that temperature gradients inside this tube are responsible for the origin of a cutoff frequency for torsional tube waves. The cutoff frequency is used to determine conditions for the wave propagation in the solar atmosphere, and the obtained results are compared to the recent observational data that support the existence of torsional tube waves in the Sun.

DYNAMO: a Mars upper atmosphere package for investigating solar wind interaction and escape processes, and mapping Martian fields

DEFF Research Database (Denmark)

Chassefiere, E.; Nagy, A.; Mandea, M.

2004-01-01

DYNAMO is a small multi-instrument payload aimed at characterizing current atmospheric escape, which is still poorly constrained, and improving gravity and magnetic field representations, in order to better understand the magnetic, geologic and thermal history of Mars. The internal structure...... of periapsis 170 km), and in a lesser extent 2a, offers an unprecedented opportunity to investigate by in situ probing the chemical and dynamical properties of the deep ionosphere, thermosphere, and the interaction between the atmosphere and the solar wind, and therefore the present atmospheric escape rate...

A stochastic post-processing method for solar irradiance forecasts derived from NWPs models

Science.gov (United States)

Lara-Fanego, V.; Pozo-Vazquez, D.; Ruiz-Arias, J. A.; Santos-Alamillos, F. J.; Tovar-Pescador, J.

2010-09-01

Solar irradiance forecast is an important area of research for the future of the solar-based renewable energy systems. Numerical Weather Prediction models (NWPs) have proved to be a valuable tool for solar irradiance forecasting with lead time up to a few days. Nevertheless, these models show low skill in forecasting the solar irradiance under cloudy conditions. Additionally, climatic (averaged over seasons) aerosol loading are usually considered in these models, leading to considerable errors for the Direct Normal Irradiance (DNI) forecasts during high aerosols load conditions. In this work we propose a post-processing method for the Global Irradiance (GHI) and DNI forecasts derived from NWPs. Particularly, the methods is based on the use of Autoregressive Moving Average with External Explanatory Variables (ARMAX) stochastic models. These models are applied to the residuals of the NWPs forecasts and uses as external variables the measured cloud fraction and aerosol loading of the day previous to the forecast. The method is evaluated for a set one-moth length three-days-ahead forecast of the GHI and DNI, obtained based on the WRF mesoscale atmospheric model, for several locations in Andalusia (Southern Spain). The Cloud fraction is derived from MSG satellite estimates and the aerosol loading from the MODIS platform estimates. Both sources of information are readily available at the time of the forecast. Results showed a considerable improvement of the forecasting skill of the WRF model using the proposed post-processing method. Particularly, relative improvement (in terms of the RMSE) for the DNI during summer is about 20%. A similar value is obtained for the GHI during the winter.

Atmospheric Mining in the Outer Solar System: Resource Capturing, Exploration, and Exploitation

Science.gov (United States)

Palaszewski, Bryan

2015-01-01

Atmospheric mining in the outer solar system (AMOSS) has been investigated as a means of fuel production for high-energy propulsion and power. Fusion fuels such as helium 3 (He-3) and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. 3He and hydrogen (deuterium, etc.) were the primary gases of interest, with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of AMOSS. These analyses included the gas capturing rate, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues. While capturing 3He, large amounts of hydrogen and helium 4 (He-4) are produced. With these two additional gases, the potential exists for fueling small and large fleets of additional exploration and exploitation vehicles. Additional aerospacecraft or other aerial vehicles (UAVs, balloons, rockets, etc.) could fly through the outer-planet atmosphere to investigate cloud formation dynamics, global weather, localized storms or other disturbances, wind speeds, the poles, and so forth. Deep-diving aircraft (built with the strength to withstand many atmospheres of pressure) powered by the excess hydrogen or 4He may be designed to probe the higher density regions of the gas giants.

Estimating solar ultraviolet irradiance (290-385 nm by means of the spectral parametric models: SPCTRAL2 and SMARTS2

Directory of Open Access Journals (Sweden)

I. Foyo-Moreno

2000-11-01

Full Text Available Since the discovery of the ozone depletion in Antarctic and the globally declining trend of stratospheric ozone concentration, public and scientific concern has been raised in the last decades. A very important consequence of this fact is the increased broadband and spectral UV radiation in the environment and the biological effects and heath risks that may take place in the near future. The absence of widespread measurements of this radiometric flux has lead to the development and use of alternative estimation procedures such as the parametric approaches. Parametric models compute the radiant energy using available atmospheric parameters. Some parametric models compute the global solar irradiance at surface level by addition of its direct beam and diffuse components. In the present work, we have developed a comparison between two cloudless sky parametrization schemes. Both methods provide an estimation of the solar spectral irradiance that can be integrated spectrally within the limits of interest. For this test we have used data recorded in a radiometric station located at Granada (37.180°N, 3.580°W, 660 m a.m.s.l., an inland location. The database includes hourly values of the relevant variables covering the years 1994-95. The performance of the models has been tested in relation to their predictive capability of global solar irradiance in the UV range (290–385 nm. After our study, it appears that information concerning the aerosol radiative effects is fundamental in order to obtain a good estimation. The original version of SPCTRAL2 provides estimates of the experimental values with negligible mean bias deviation. This suggests not only the appropriateness of the model but also the convenience of the aerosol features fixed in it to Granada conditions. SMARTS2 model offers increased flexibility concerning the selection of different aerosol models included in the code and provides the best results when the selected models are those

Estimating solar ultraviolet irradiance (290-385 nm by means of the spectral parametric models: SPCTRAL2 and SMARTS2

Directory of Open Access Journals (Sweden)

I. Foyo-Moreno

Full Text Available Since the discovery of the ozone depletion in Antarctic and the globally declining trend of stratospheric ozone concentration, public and scientific concern has been raised in the last decades. A very important consequence of this fact is the increased broadband and spectral UV radiation in the environment and the biological effects and heath risks that may take place in the near future. The absence of widespread measurements of this radiometric flux has lead to the development and use of alternative estimation procedures such as the parametric approaches. Parametric models compute the radiant energy using available atmospheric parameters. Some parametric models compute the global solar irradiance at surface level by addition of its direct beam and diffuse components. In the present work, we have developed a comparison between two cloudless sky parametrization schemes. Both methods provide an estimation of the solar spectral irradiance that can be integrated spectrally within the limits of interest. For this test we have used data recorded in a radiometric station located at Granada (37.180°N, 3.580°W, 660 m a.m.s.l., an inland location. The database includes hourly values of the relevant variables covering the years 1994-95. The performance of the models has been tested in relation to their predictive capability of global solar irradiance in the UV range (290–385 nm. After our study, it appears that information concerning the aerosol radiative effects is fundamental in order to obtain a good estimation. The original version of SPCTRAL2 provides estimates of the experimental values with negligible mean bias deviation. This suggests not only the appropriateness of the model but also the convenience of the aerosol features fixed in it to Granada conditions. SMARTS2 model offers increased flexibility concerning the selection of different aerosol models included in the code and provides the best results when the selected models are those

Verification of high-speed solar wind stream forecasts using operational solar wind models

DEFF Research Database (Denmark)

Reiss, Martin A.; Temmer, Manuela; Veronig, Astrid M.

2016-01-01

and the background solar wind conditions. We found that both solar wind models are capable of predicting the large-scale features of the observed solar wind speed (root-mean-square error, RMSE ≈100 km/s) but tend to either overestimate (ESWF) or underestimate (WSA) the number of high-speed solar wind streams (threat......High-speed solar wind streams emanating from coronal holes are frequently impinging on the Earth's magnetosphere causing recurrent, medium-level geomagnetic storm activity. Modeling high-speed solar wind streams is thus an essential element of successful space weather forecasting. Here we evaluate...... high-speed stream forecasts made by the empirical solar wind forecast (ESWF) and the semiempirical Wang-Sheeley-Arge (WSA) model based on the in situ plasma measurements from the Advanced Composition Explorer (ACE) spacecraft for the years 2011 to 2014. While the ESWF makes use of an empirical relation...

A trigger mechanism for the emerging flux model of solar flares

International Nuclear Information System (INIS)

Tur, T.J.; Priest, E.R.

1978-01-01

The energetics of a current sheet that forms between newly emerging flux and an ambient field are considered. As more and more flux emerges, so the sheet rises in the solar atmosphere. The various contributions to the thermal energy balance in the sheet approximated and the resulting equation solved for the internal temperature of the sheet. It is found that, for certain choices of the ambient magnetic field strength and velocity, the internal temperature increases until, when the sheet reaches some critical height, no neighbouring equilibrium state exists. The temperature than increases rapidly, seeking a hotter branch of the solution curve. During this dynamic heating the threshold temperature for the onset of plasma microinstabilities may be attained. It is suggested that this may be a suitable trigger mechanism for the recently proposed 'emerging flux' model of a solar flare. (Auth.)

A rapid radiative transfer model for reflection of solar radiation

Science.gov (United States)

Xiang, X.; Smith, E. A.; Justus, C. G.

1994-01-01

A rapid analytical radiative transfer model for reflection of solar radiation in plane-parallel atmospheres is developed based on the Sobolev approach and the delta function transformation technique. A distinct advantage of this model over alternative two-stream solutions is that in addition to yielding the irradiance components, which turn out to be mathematically equivalent to the delta-Eddington approximation, the radiance field can also be expanded in a mathematically consistent fashion. Tests with the model against a more precise multistream discrete ordinate model over a wide range of input parameters demonstrate that the new approximate method typically produces average radiance differences of less than 5%, with worst average differences of approximately 10%-15%. By the same token, the computational speed of the new model is some tens to thousands times faster than that of the more precise model when its stream resolution is set to generate precise calculations.

Atmospheric solar tides and their electrodynamic effects. I. The global Ssub(q) current system

Energy Technology Data Exchange (ETDEWEB)

Forbes, J M; Lindzen, R S [Harvard Univ., Cambridge, Mass. (USA)

1976-09-01

This paper is Part I of a study dealing with the electrodynamic consequences of solar tides in the E-region of the Earth's atmosphere. The major result to emerge from Part I is that E-region dynamo action of combined diurnal and semidiurnal winds consistent with measurements is found to account for the Ssub(q) variations in ground magnetic data, without having to resort to electric fields of plasmaspheric origin as suggested in the recent literature. Real discrepancies of the order of 20% in amplitude and 1 to 2 h in phase still exist between the data and the present theoretical model. The model couples a global thin-shell dynamo solution which takes into account the vertical structure of the winds with a full three-dimensional model of the equatorial electrojet. Part I is primarily concerned with the classical thin-shell global solution, whereas Part II (Forbes et al., J. Atmos. Terr. Phys.; 38:911 (1976)) deals solely with the equatorial electrojet; however, the equatorial magnetic variations to be presented here are taken from Part II. Previous global dynamo models have utilized winds which are shown to be unrealistic by recent measurements and dissipative tidal theory, and do not include the important effects of vertical current flow at the magnetic equator. Inclusion of vertical current effects, which are discussed in detail in Part II, relaxes the need for E-region diurnal wind speeds as large as those required by previous workers to reproduce the Ssub(q) current system. Computed vertical structures of the Ssub(q) currents explain some puzzling features of the few midlatitude rocket magnetometer measurements that are available. The Joule heating by Ssub(q) currents is comparable to solar EUV heating above 60/sup 0/N, but contribute negligibly to the total heat budget of the thermosphere.

Atmospheric data over a solar cycle: no connection between galactic cosmic rays and new particle formation

Directory of Open Access Journals (Sweden)

M. Kulmala

2010-02-01

Full Text Available Aerosol particles affect the Earth's radiative balance by directly scattering and absorbing solar radiation and, indirectly, through their activation into cloud droplets. Both effects are known with considerable uncertainty only, and translate into even bigger uncertainties in future climate predictions. More than a decade ago, variations in galactic cosmic rays were suggested to closely correlate with variations in atmospheric cloud cover and therefore constitute a driving force behind aerosol-cloud-climate interactions. Later, the enhancement of atmospheric aerosol particle formation by ions generated from cosmic rays was proposed as a physical mechanism explaining this correlation. Here, we report unique observations on atmospheric aerosol formation based on measurements at the SMEAR II station, Finland, over a solar cycle (years 1996–2008 that shed new light on these presumed relationships. Our analysis shows that none of the quantities related to aerosol formation correlates with the cosmic ray-induced ionisation intensity (CRII. We also examined the contribution of ions to new particle formation on the basis of novel ground-based and airborne observations. A consistent result is that ion-induced formation contributes typically significantly less than 10% to the number of new particles, which would explain the missing correlation between CRII and aerosol formation. Our main conclusion is that galactic cosmic rays appear to play a minor role for atmospheric aerosol formation events, and so for the connected aerosol-climate effects as well.

Simulation of atmospheric CO2 over Europe and western Siberia using the regional scale model REMO

International Nuclear Information System (INIS)

Chevillard, A.; Ciais, P.; Lafont, S.

2002-01-01

The spatial distribution and the temporal variability of atmospheric CO 2 over Europe and western Siberia are investigated using the regional atmospheric model, REMO. The model, of typical horizontal resolution 50 km, is part of a nested modelling framework that has been established as a concerted action during the EUROSIBERIAN CARBONFLUX project. In REMO, the transport of CO 2 is simulated together with climate variables, which offers the possibility of calculating at each time step the land atmosphere CO 2 fluxes as driven by the modelled meteorology. The uptake of CO 2 by photosynthesis is calculated using a light use efficiency formulation, where the absorbed photosynthetically active solar radiation is inferred from satellite measurements. The release of CO 2 from plant and soil respiration is driven by the simulated climate and assumed to be in equilibrium with photosynthesis over the course of one year. Fossil CO 2 emissions and air-sea fluxes within the model domain are prescribed, whereas the influence of sources outside the model domain is computed from as a boundary condition CO 2 fields determined a global transport model. The modelling results are compared against pointwise eddy covariance fluxes, and against atmospheric CO 2 records. We show that a necessary condition to simulate realistically the variability of atmospheric CO 2 over continental Europe is to account for the diurnal cycle of biospheric exchange. Overall, for the study period of July 1998, REMO realistically simulates the short-term variability of fluxes and of atmospheric mixing ratios. However, the mean CO 2 gradients from western Europe to western Siberia are not correctly reproduced. This latter deficiency points out the key role of boundary conditions in a limited-area model, as well as the need for using more realistic geographic mean patterns of biospheric carbon fluxes

Models of diffuse solar radiation

Energy Technology Data Exchange (ETDEWEB)

Boland, John; Ridley, Barbara [Centre for Industrial and Applied Mathematics, University of South Australia, Mawson Lakes Boulevard, Mawson Lakes, SA 5095 (Australia); Brown, Bruce [Department of Statistics and Applied Probability, National University of Singapore, Singapore 117546 (Singapore)

2008-04-15

For some locations both global and diffuse solar radiation are measured. However, for many locations, only global is measured, or inferred from satellite data. For modelling solar energy applications, the amount of radiation on a tilted surface is needed. Since only the direct component on a tilted surface can be calculated from trigonometry, we need to have diffuse on the horizontal available. There are regression relationships for estimating the diffuse on a tilted surface from diffuse on the horizontal. Models for estimating the diffuse radiation on the horizontal from horizontal global that have been developed in Europe or North America have proved to be inadequate for Australia [Spencer JW. A comparison of methods for estimating hourly diffuse solar radiation from global solar radiation. Sol Energy 1982; 29(1): 19-32]. Boland et al. [Modelling the diffuse fraction of global solar radiation on a horizontal surface. Environmetrics 2001; 12: 103-16] developed a validated model for Australian conditions. We detail our recent advances in developing the theoretical framework for the approach reported therein, particularly the use of the logistic function instead of piecewise linear or simple nonlinear functions. Additionally, we have also constructed a method, using quadratic programming, for identifying values that are likely to be erroneous. This allows us to eliminate outliers in diffuse radiation values, the data most prone to errors in measurement. (author)

Hawaii Solar Integration Study: Solar Modeling Developments and Study Results; Preprint

Energy Technology Data Exchange (ETDEWEB)

Orwig, K.; Corbus, D.; Piwko, R.; Schuerger, M.; Matsuura, M.; Roose, L.

2012-12-01

The Hawaii Solar Integration Study (HSIS) is a follow-up to the Oahu Wind Integration and Transmission Study completed in 2010. HSIS focuses on the impacts of higher penetrations of solar energy on the electrical grid and on other generation. HSIS goes beyond the island of Oahu and investigates Maui as well. The study examines reserve strategies, impacts on thermal unit commitment and dispatch, utilization of energy storage, renewable energy curtailment, and other aspects of grid reliability and operation. For the study, high-frequency (2-second) solar power profiles were generated using a new combined Numerical Weather Prediction model/ stochastic-kinematic cloud model approach, which represents the 'sharp-edge' effects of clouds passing over solar facilities. As part of the validation process, the solar data was evaluated using a variety of analysis techniques including wavelets, power spectral densities, ramp distributions, extreme values, and cross correlations. This paper provides an overview of the study objectives, results of the solar profile validation, and study results.

A Generalized Approach to Model the Spectra and Radiation Dose Rate of Solar Particle Events on the Surface of Mars

Science.gov (United States)

Guo, Jingnan; Zeitlin, Cary; Wimmer-Schweingruber, Robert F.; McDole, Thoren; Kühl, Patrick; Appel, Jan C.; Matthiä, Daniel; Krauss, Johannes; Köhler, Jan

2018-01-01

For future human missions to Mars, it is important to study the surface radiation environment during extreme and elevated conditions. In the long term, it is mainly galactic cosmic rays (GCRs) modulated by solar activity that contribute to the radiation on the surface of Mars, but intense solar energetic particle (SEP) events may induce acute health effects. Such events may enhance the radiation level significantly and should be detected as immediately as possible to prevent severe damage to humans and equipment. However, the energetic particle environment on the Martian surface is significantly different from that in deep space due to the influence of the Martian atmosphere. Depending on the intensity and shape of the original solar particle spectra, as well as particle types, the surface spectra may induce entirely different radiation effects. In order to give immediate and accurate alerts while avoiding unnecessary ones, it is important to model and well understand the atmospheric effect on the incoming SEPs, including both protons and helium ions. In this paper, we have developed a generalized approach to quickly model the surface response of any given incoming proton/helium ion spectra and have applied it to a set of historical large solar events, thus providing insights into the possible variety of surface radiation environments that may be induced during SEP events. Based on the statistical study of more than 30 significant solar events, we have obtained an empirical model for estimating the surface dose rate directly from the intensities of a power-law SEP spectra.

Metrology of the Solar Spectral Irradiance at the Top Of Atmosphere in the Near Infrared using Ground Based Instruments. Final results of the PYR-ILIOS campaign (Mauna Loa Observatory, June-July 2016).

Science.gov (United States)

Cessateur, G.; Bolsée, D.; Pereira, N.; Sperfeld, P.; Pape, S.

2017-12-01

The availability of reference spectra for the Solar Spectral Irradiance (SSI) is important for the solar physics, the studies of planetary atmospheres and climatology. The near infrared (NIR) part of these spectra is of great interest for its main role for example, in the Earth's radiative budget. Until recently, some large and unsolved discrepancies (up to 10 %) were observed in the 1.6 μm region between space instruments, models and ground-based measurements. We designed a ground-based instrumentation for SSI measurements at the Top Of Atmosphere (TOA) through atmospheric NIR windows using the Bouguer-Langley technique. The main instrument is a double NIR spectroradiometer designed by Bentham (UK), radiometrically characterized at the Royal Belgian Institute for Space Aeronomy. It was absolute calibrated against a high-temperature blackbody as primary standard for spectral irradiance at the Physikalisch-Technische Bundesanstalt (Germany). The PYR-ILIOS campaign was carried out in June to July 2016 at the Mauna Loa Observatory (Hawaii, USA, 3396 m a.s.l.) follows the four-month IRESPERAD campaign which was carried out in the summer 2011 at the Izaña Atmospheric Observatory (Canary Islands, 2367 m a.s.l.). We present here the results of the 3'week PYR-ILIOS campaign and compare them with the ATLAS 3 spectrum as well as from recently reprocessed NIR solar spectra obtained with SOLAR/SOLSPEC on ISS and SCIAMACHY on ENVISAT. The uncertainty budget of the PYR-ILIOS results will be discussed.

Estimating surface solar radiation from upper-air humidity

Energy Technology Data Exchange (ETDEWEB)

Kun Yang [Telecommunications Advancement Organization of Japan, Tokyo (Japan); Koike, Toshio [University of Tokyo (Japan). Dept. of Civil Engineering

2002-07-01

A numerical model is developed to estimate global solar irradiance from upper-air humidity. In this model, solar radiation under clear skies is calculated through a simple model with radiation-damping processes under consideration. A sky clearness indicator is parameterized from relative humidity profiles within three atmospheric sublayers, and the indicator is used to connect global solar radiation under clear skies and that under cloudy skies. Model inter-comparisons at 18 sites in Japan suggest (1) global solar radiation strongly depends on the sky clearness indicator, (2) the new model generally gives better estimation to hourly-mean solar irradiance than the other three methods used in numerical weather predictions, and (3) the new model may be applied to estimate long-term solar radiation. In addition, a study at one site in the Tibetan Plateau shows vigorous convective activities in the region may cause some uncertainties to radiation estimations due to the small-scale and short life of convective systems. (author)

Middle atmospheric thermal structures in Eastern and Western hemispheres over a solar cycle

International Nuclear Information System (INIS)

Mohanakumar, K.; Devanarayanan, S.

1987-01-01

Temperature variations of the 25-60 km region of the atmosphere over stations in the Eastern and Western Hemispheres were compared for an 11-year solar cycle period (1971-1981). The temperature of the two hemispheres did not show similar variations at the same height and time. A cross-correlation analysis between the variations in temperature of the two hemispheres showed insignificant correlation, except at 30 km over the tropics and at 40 km over the midlatitude. Up to 40 km, the temperature changes in the two hemispheres are identical. At higher levels, Western Hemispheric temperatures were higher than those of the Eastern Hemisphere. The diurnal variation of minor constituents and their vertical transport in the middle atmosphere might be responsible for the differences in temperature observed in the two hemispheres. (author)

Modeling the Interaction of Mineral Dust with Solar Radiation: Spherical versus Non-spherical Particles

Science.gov (United States)

Hoshyaripour, A.; Vogel, B.; Vogel, H.

2017-12-01

Mineral dust, emitted from arid and semi-arid regions, is the most dominant atmospheric aerosol by mass. Beside detrimental effect on air quality, airborne dust also influences the atmospheric radiation by absorbing and scattering solar and terrestrial radiation. As a result, while the long-term radiative impacts of dust are important for climate, the short-term effects are significant for the photovoltaic energy production. Therefore, it is a vital requirement to accurately forecast the effects of dust on energy budget of the atmosphere and surface. To this end, a major issue is the fact that dust particles are non-spherical. Thus, the optical properties of such particles cannot be calculated precisely using the conventional methods like Mie theory that are often used in climate and numerical weather forecast models. In this study, T-Matrix method is employed, which is able to treat the non-sphericity of particles. Dust particles are assumed to be prolate spheroids with aspect ratio of 1.5 distributed in three lognormal modes. The wavelength-dependent refractive indices of dust are used in T-Matrix algorithm to calculate the extinction coefficient, single scattering albedo, asymmetry parameter and backscattering ratio at different wavelengths. These parameters are then implemented in ICON-ART model (ICOsahedral Nonhydrostatic model with Aerosols and Reactive Trace gases) to conduct a global simulation with 80 km horizontal resolution and 90 vertical levels. April 2014 is selected as the simulation period during which North African dust plumes reached central Europe and Germany. Results show that treatment of non-sphericity reduces the dust AOD in the range of 10 to 30%/. The impacts on diffuse and direct radiation at global, regional and local scales show strong dependency on the size distribution of the airborne dust. The implications for modeling and remote sensing the dust impacts on solar energy are also discussed.

CAN A NANOFLARE MODEL OF EXTREME-ULTRAVIOLET IRRADIANCES DESCRIBE THE HEATING OF THE SOLAR CORONA?

Energy Technology Data Exchange (ETDEWEB)

Tajfirouze, E.; Safari, H. [Department of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan (Iran, Islamic Republic of)

2012-01-10

Nanoflares, the basic units of impulsive energy release, may produce much of the solar background emission. Extrapolation of the energy frequency distribution of observed microflares, which follows a power law to lower energies, can give an estimation of the importance of nanoflares for heating the solar corona. If the power-law index is greater than 2, then the nanoflare contribution is dominant. We model a time series of extreme-ultraviolet emission radiance as random flares with a power-law exponent of the flare event distribution. The model is based on three key parameters: the flare rate, the flare duration, and the power-law exponent of the flare intensity frequency distribution. We use this model to simulate emission line radiance detected in 171 A, observed by Solar Terrestrial Relation Observatory/Extreme-Ultraviolet Imager and Solar Dynamics Observatory/Atmospheric Imaging Assembly. The observed light curves are matched with simulated light curves using an Artificial Neural Network, and the parameter values are determined across the active region, quiet Sun, and coronal hole. The damping rate of nanoflares is compared with the radiative losses cooling time. The effect of background emission, data cadence, and network sensitivity on the key parameters of the model is studied. Most of the observed light curves have a power-law exponent, {alpha}, greater than the critical value 2. At these sites, nanoflare heating could be significant.

Solar Modulation of Atmospheric Cosmic Radiation:. Comparison Between In-Flight and Ground-Level Measurements

Science.gov (United States)

Iles, R. H. A.; Taylor, G. C.; Jones, J. B. L.

January 2000 saw the start of a collaborative study involving the Mullard Space Science Laboratory, Virgin Atlantic Airways, the Civil Aviation Authority and the National Physical Laboratory in a program to investigate the cosmic radiation exposure to aircrew. The study has been undertaken in view of EU Directive 96/291 (May 2000) which requires the assessment of the level of radiation exposure to aircrew. The project's aims include validation of radiation dose models and evaluation of space weather effects on atmospheric cosmic radiation levels, in particular those effects not accounted for by the models. Ground level measurements are often used as a proxy for variations in cosmic radiation dose levels at aircraft altitudes, especially during Forbush Decreases (FDs) and Solar Energetic Particle (SEP) events. Is this estimation realistic and does the ground level data accurately represent what is happening at altitude? We have investigated the effect of a FD during a flight from Hong Kong to London Heathrow on the 15th July 2000 and compared count rate and dose measurements with simultaneous variations measured at ground level. We have also compared the results with model outputs.

WSA-Enlil Solar Wind Prediction

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — WSA-Enlil is a large-scale, physics-based prediction model of the heliosphere, used by the Space Weather Forecast Office to provide 1-4 day advance warning of solar...

Secular trends and climate drift in coupled ocean-atmosphere general circulation models

Science.gov (United States)

Covey, Curt; Gleckler, Peter J.; Phillips, Thomas J.; Bader, David C.

2006-02-01

Coupled ocean-atmosphere general circulation models (coupled GCMs) with interactive sea ice are the primary tool for investigating possible future global warming and numerous other issues in climate science. A long-standing problem with such models is that when different components of the physical climate system are linked together, the simulated climate can drift away from observation unless constrained by ad hoc adjustments to interface fluxes. However, 11 modern coupled GCMs, including three that do not employ flux adjustments, behave much better in this respect than the older generation of models. Surface temperature trends in control run simulations (with external climate forcing such as solar brightness and atmospheric carbon dioxide held constant) are small compared with observed trends, which include 20th century climate change due to both anthropogenic and natural factors. Sea ice changes in the models are dominated by interannual variations. Deep ocean temperature and salinity trends are small enough for model control runs to extend over 1000 simulated years or more, but trends in some regions, most notably the Arctic, differ substantially among the models and may be problematic. Methods used to initialize coupled GCMs can mitigate climate drift but cannot eliminate it. Lengthy "spin-ups" of models, made possible by increasing computer power, are one reason for the improvements this paper documents.

Training and Validation of the Fast PCRTM_Solar Model

Science.gov (United States)

Yang, Q.; Liu, X.; Wu, W.; Yang, P.; Wang, C.

2015-12-01

Fast and accurate radiative transfer model is the key for satellite data assimilation for remote sensing application. The simulation of the satellite remote sensing radiances is very complicated since many physical processes, such as absorption, emission, and scattering, are involved due to the interactions between electromagnetic radiation and earth surface, water vapor, clouds, aerosols, and gas molecules in the sky. The principal component-based radiative transfer model (PCRTM) has been developed for various passive IR and MW instruments. In this work, we extended PCRTM to including the contribution from solar radiation. The cloud/aerosol bidirectional reflectances have been carefully calculated using the well-known Discrete-Ordinate-Method Radiative Transfer (DISORT) model under over 10 millions of diverse conditions with varying cloud particle size, wavelength, satellite viewing direction, and solar angles. The obtained results were compressed significantly using principal component analysis and used in the mono domain radiance calculation. We used 1352 different atmosphere profiles, each of them has different surface skin temperatures and surface pressures in our training. Different surface emissivity spectra were derived from ASTER database and emissivity models. Some artificially generated emissivity spectra were also used to account for diverse surface types of the earth. Concentrations of sixteen trace gases were varied systematically in the training and the remaining trace gas contributions were accounted for as a fixed gas. Training was done in both clear and cloudy skies conditions. Finally the nonlocal thermal equilibrium (NLTE) induced radiance change was included for daytime conditions. We have updated the PCRTM model for instruments such as IASI, NASTI, CrIS, AIRS, and SHIS. The training results show that the PCRTM model can calculate thousands of channel radiances by computing only a few hundreds of mono radiances. This greatly increased the

Solar Advisor Model User Guide for Version 2.0

Energy Technology Data Exchange (ETDEWEB)

Gilman, P.; Blair, N.; Mehos, M.; Christensen, C.; Janzou, S.; Cameron, C.

2008-08-01

The Solar Advisor Model (SAM) provides a consistent framework for analyzing and comparing power system costs and performance across the range of solar technologies and markets, from photovoltaic systems for residential and commercial markets to concentrating solar power and large photovoltaic systems for utility markets. This manual describes Version 2.0 of the software, which can model photovoltaic and concentrating solar power technologies for electric applications for several markets. The current version of the Solar Advisor Model does not model solar heating and lighting technologies.

Coupled atmosphere-wildland fire modelling

Directory of Open Access Journals (Sweden)

Jacques Henri Balbi

2009-10-01

Full Text Available Simulating the interaction between fire and atmosphere is critical to the estimation of the rate of spread of the fire. Wildfire’s convection (i.e., entire plume can modify the local meteorology throughout the atmospheric boundary layer and consequently affect the fire propagation speed and behaviour. In this study, we use for the first time the Méso-NH meso-scale numerical model coupled to the point functional ForeFire simplified physical front-tracking wildfire model to investigate the differences introduced by the atmospheric feedback in propagation speed and behaviour. Both numerical models have been developed as research tools for operational models and are currently used to forecast localized extreme events. These models have been selected because they can be run coupled and support decisions in wildfire management in France and Europe. The main originalities of this combination reside in the fact that Méso-NH is run in a Large Eddy Simulation (LES configuration and that the rate of spread model used in ForeFire provides a physical formulation to take into account the effect of wind and slope. Simulations of typical experimental configurations show that the numerical atmospheric model is able to reproduce plausible convective effects of the heat produced by the fire. Numerical results are comparable to estimated values for fire-induced winds and present behaviour similar to other existing numerical approaches.

Study of solar radiation prediction and modeling of relationships between solar radiation and meteorological variables

International Nuclear Information System (INIS)

Sun, Huaiwei; Zhao, Na; Zeng, Xiaofan; Yan, Dong

2015-01-01

Highlights: • We investigate relationships between solar radiation and meteorological variables. • A strong relationship exists between solar radiation and sunshine duration. • Daily global radiation can be estimated accurately with ARMAX–GARCH models. • MGARCH model was applied to investigate time-varying relationships. - Abstract: The traditional approaches that employ the correlations between solar radiation and other measured meteorological variables are commonly utilized in studies. It is important to investigate the time-varying relationships between meteorological variables and solar radiation to determine which variables have the strongest correlations with solar radiation. In this study, the nonlinear autoregressive moving average with exogenous variable–generalized autoregressive conditional heteroscedasticity (ARMAX–GARCH) and multivariate GARCH (MGARCH) time-series approaches were applied to investigate the associations between solar radiation and several meteorological variables. For these investigations, the long-term daily global solar radiation series measured at three stations from January 1, 2004 until December 31, 2007 were used in this study. Stronger relationships were observed to exist between global solar radiation and sunshine duration than between solar radiation and temperature difference. The results show that 82–88% of the temporal variations of the global solar radiation were captured by the sunshine-duration-based ARMAX–GARCH models and 55–68% of daily variations were captured by the temperature-difference-based ARMAX–GARCH models. The advantages of the ARMAX–GARCH models were also confirmed by comparison of Auto-Regressive and Moving Average (ARMA) and neutral network (ANN) models in the estimation of daily global solar radiation. The strong heteroscedastic persistency of the global solar radiation series was revealed by the AutoRegressive Conditional Heteroscedasticity (ARCH) and Generalized Auto

Northern Hemisphere atmospheric influence of the solar proton events and ground level enhancement in January 2005

Directory of Open Access Journals (Sweden)

C. H. Jackman

2011-07-01

Full Text Available Solar eruptions in early 2005 led to a substantial barrage of charged particles on the Earth's atmosphere during the 16–21 January period. Proton fluxes were greatly increased during these several days and led to the production of HO_x (H, OH, HO₂ and NO_x (N, NO, NO₂, which then caused the destruction of ozone. We focus on the Northern polar region, where satellite measurements and simulations with the Whole Atmosphere Community Climate Model (WACCM3 showed large enhancements in mesospheric HO_x and NO_x constituents, and associated ozone reductions, due to these solar proton events (SPEs. The WACCM3 simulations show enhanced short-lived OH and HO₂ concentrations throughout the mesosphere in the 60–82.5° N latitude band due to the SPEs for most days in the 16–21 January 2005 period, somewhat higher in abundance than those observed by the Aura Microwave Limb Sounder (MLS. These HO_x enhancements led to huge predicted and MLS-measured ozone decreases of greater than 40 % throughout most of the northern polar mesosphere during the SPE period. Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS measurements of hydrogen peroxide (H₂O₂ show increases throughout the stratosphere with highest enhancements of about 60 pptv in the lowermost mesosphere over the 16–18 January 2005 period due to the solar protons. WACCM3 predictions indicate H₂O₂ enhancements over the same time period of about three times that amount. Measurements of nitric acid (HNO₃ by both MLS and MIPAS show an increase of about 1 ppbv above background levels in the upper stratosphere during 16–29 January 2005. WACCM3 simulations show only minuscule HNO₃ increases (<0.05 ppbv in the upper stratosphere during this time period. Polar mesospheric enhancements of NO_x are computed to be greater than 50

Evaluation of global solar radiation models for Shanghai, China

International Nuclear Information System (INIS)

Yao, Wanxiang; Li, Zhengrong; Wang, Yuyan; Jiang, Fujian; Hu, Lingzhou

2014-01-01

Highlights: • 108 existing models are compared and analyzed by 42 years meteorological data. • Fitting models based on measured data are established according to 42 years data. • All models are compared by recently 10 years meteorological data. • The results show that polynomial models are the most accurate models. - Abstract: In this paper, 89 existing monthly average daily global solar radiation models and 19 existing daily global solar radiation models are compared and analyzed by 42 years meteorological data. The results show that for existing monthly average daily global solar radiation models, linear models and polynomial models have been able to estimate global solar radiation accurately, and complex equation types cannot obviously improve the precision. Considering direct parameters such as latitude, altitude, solar altitude and sunshine duration can help improve the accuracy of the models, but indirect parameters cannot. For existing daily global solar radiation models, multi-parameter models are more accurate than single-parameter models, polynomial models are more accurate than linear models. Then measured data fitting monthly average daily global solar radiation models (MADGSR models) and daily global solar radiation models (DGSR models) are established according to 42 years meteorological data. Finally, existing models and fitting models based on measured data are comparative analysis by recent 10 years meteorological data, and the results show that polynomial models (MADGSR model 2, DGSR model 2 and Maduekwe model 2) are the most accurate models

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

Thermal History and Volatile Partitioning between Proto-Atmosphere and Interior of Mars Accreted in a Solar Nebula

Science.gov (United States)

Saito, Hiroaki; Kuramoto, Kiyoshi

2015-11-01

Recent precise Hf-W chronometry of Martian meteorites reveals that Mars had likely reached the half of its present mass within 3 Myr from the birth of the solar system (Dauphas and Pourmand, 2011). Hence, the accretion is considered to almost proceed within the solar nebula associated with the capture of nebula gas components. At the same time, the impact degassing may inevitably occur because impact velocity increases high enough for such degassing when a proto-planet gets larger than around lunar size. Thus, we can expect the formation of a hybrid-type proto-atmosphere that consists of nebula gas and degassed one.This study analyzes the thermal structure of this proto-atmosphere sustained by accretional heating by building a 1D radiative-convective equilibrium model. Raw materials of Mars are supposed to be volatile-rich on the basis of the geochemical systematics of Mars meteorites (Dreibus and Wanke, 1988). The composition of degassed component comprised of H2, H2O, CH4, and CO is determined by chemical equilibrium with silicate and metal under the physical condition of locally heated region generated by each impact (Kuramoto, 1997). Degassed component lies beneath the nebula gas atmosphere at altitudes below the compositional boundary height that would change depending on the amount of degassed component. The accretion time is taken to be from 1 to 6 Myr.Our model predicts that the surface temperature exceeds the liquidus temperature of rock when a proto Mars grows larger than 0.7 times of its present mass for the longest accretion time case. In this case, the magma ocean mass just after the end of accretion is 0.2 times of its present mass if heat transfer and heat sources such as short-lived radionuclides are neglected in the interior. The corresponding amount of water dissolved into the magma ocean would be around 1.8 times the present Earth ocean mass. These results suggest that the earliest Mars would be hot enough to form deep magma oceans, which

Solar radiation transfer in the inhomogeneous atmosphere; Solarer Strahlungstransport in der inhomogenen Atmosphaere

Energy Technology Data Exchange (ETDEWEB)

Scheirer, R.

2001-07-01

A most profound knowledge about the radiative characteristics of clouds is required for the development of realistic atmospheric circulation models and cloud remote sensing algorithms. At present, cloud fields are treated extremely simplified in both application areas. Cloud radiative flux parameterizations in atmospheric circulation models as well as the correlation between radiance and cloud properties as required for remote sensing algorithm are usually based on the assumption of plane-parallel homogeneous (PPHOM) clouds. Compared to realistically 3D cloud fields, this simplification leads to large systematic errors. In order to quantify these errors a Monte Carlo radiative transfer model has been developed and applied to 3D cloud fields. The latter origin from the non-hydrostatic 3D atmospheric model GESIMA. Absorption and scattering properties of the cloud particles have been calculated by means of Mie-theory for spherical water droplets and a ray-tracing code for non-spherical ice, rain, and snow particles. Line by line calculations have been used to obtain the absorption properties of the relevant atmospheric gases. (orig.) [German] Die Erstellung realistischer Zirkulationsmodelle der Atmosphaere erfordert unter Anderem eine moeglichst genaue Kenntnis der Strahlungseigenschaften von Wolken. Auch fuer Ableitung und Korrektur von Fernerkundungsalgorithmen sind die Einfluesse der Wolken auf die zu messenden Strahldichten von grosser Bedeutung. In den beiden genannten Anwendungen werden Wolkenfelder zur Zeit nur in stark vereinfachter Weise beruecksichtigt. Parameterisierungen der Strahlungsfluesse bei bewoelkter Atmosphaere in atmosphaerischen Zirkulationsmodellen, sowie die Ableitung der Zusammenhaenge zwischen Strahldichten und optischen Wolkeneigenschaften basieren auf der Annahme von planparallelen und horizontal homogenen Wolken (PPHOM). Diese Approximation kann gegenueber der dreidimensionalen Strahlungstransportberechnung (3D) zu erheblichen Fehlern

Combined eye-atmosphere visibility model

Science.gov (United States)

Kaufman, Y. J.

1981-01-01

Existing models of the optical characteristics of the eye are combined with a recent model of optical characteristics of the atmosphere given by its modulation transfer function. This combination results in the combined eye-atmosphere performance given by the product of their modulation transfer functions. An application for the calculation of visibility thresholds in the case of a two-halves field is given.

New enhancement mechanism of the transitions in the Earth of the solar and atmospheric neutrinos crossing the Earth core

International Nuclear Information System (INIS)

Petcov, S.T.

1999-01-01

It is shown that the ν 2 → ν e and ν μ → ν e (ν e → ν μ(τ) ) transitions respectively of the solar and atmospheric neutrinos in the Earth in the case of ν e - ν μ(τ) mixing in vacuum, are strongly enhanced by a new type of resonance when the neutrinos cross the Earth core. The resonance is operative at small mixing angles but differs from the MSW one. It is in many respects similar to the electron paramagnetic resonance taking place in a specific configuration of two magnetic fields. The conditions for existence of the new resonance include, in particular, specific constraints on the neutrino oscillation lengths in the Earth mantle and in the Earth core, thus the resonance is a 'neutrino oscillation length resonance'. It leads also to enhancement of the ν 2 → ν e and ν e → ν s transitions in the case of ν e - ν s mixing and of the ν-bar s (or ν μ → ν s ) transitions at small mixing angles. The presence of the neutrino oscillation length resonance in the transitions of solar and atmospheric neutrinos traversing the Earth core has important implications for current and future solar and atmospheric neutrino experiments, and more specifically, for the interpretation of the results of the Super-Kamiokande experiment

The production of cosmogenic isotopes in the earth's atmosphere and their inventories

International Nuclear Information System (INIS)

O'Brien, K.; de la Zerda Lerner, A.; Shea. M.A.; Smart, D.F.

1991-01-01

In this paper, production rates of cosmogenic isotopes in the Earth's atmosphere and their dependence on solar modulation and geomagnetic field intensity are calculated. Spallation cross sections were also obtained using the Silberberg-Tsao equations and solar modulation effects were calculated using the force-field model. The current geomagnetic field is treated in detail, and past magnetic fields are modeled based on the archeomagnetic record. Radiocarbon and radioberyllium inventories so obtained are in good agreement with current values. The neutrino-emitting radioactivity of the Earth's atmosphere is shown to add a negligible contribution to the flux from the Sun

Hyperspectral material identification on radiance data using single-atmosphere or multiple-atmosphere modeling

Science.gov (United States)

Mariano, Adrian V.; Grossmann, John M.

2010-11-01

Reflectance-domain methods convert hyperspectral data from radiance to reflectance using an atmospheric compensation model. Material detection and identification are performed by comparing the compensated data to target reflectance spectra. We introduce two radiance-domain approaches, Single atmosphere Adaptive Cosine Estimator (SACE) and Multiple atmosphere ACE (MACE) in which the target reflectance spectra are instead converted into sensor-reaching radiance using physics-based models. For SACE, known illumination and atmospheric conditions are incorporated in a single atmospheric model. For MACE the conditions are unknown so the algorithm uses many atmospheric models to cover the range of environmental variability, and it approximates the result using a subspace model. This approach is sometimes called the invariant method, and requires the choice of a subspace dimension for the model. We compare these two radiance-domain approaches to a Reflectance-domain ACE (RACE) approach on a HYDICE image featuring concealed materials. All three algorithms use the ACE detector, and all three techniques are able to detect most of the hidden materials in the imagery. For MACE we observe a strong dependence on the choice of the material subspace dimension. Increasing this value can lead to a decline in performance.

Measurements and modeling of total solar irradiance in X-class solar flares

International Nuclear Information System (INIS)

Moore, Christopher Samuel; Chamberlin, Phillip Clyde; Hock, Rachel

2014-01-01

The Total Irradiance Monitor (TIM) from NASA's SOlar Radiation and Climate Experiment can detect changes in the total solar irradiance (TSI) to a precision of 2 ppm, allowing observations of variations due to the largest X-class solar flares for the first time. Presented here is a robust algorithm for determining the radiative output in the TIM TSI measurements, in both the impulsive and gradual phases, for the four solar flares presented in Woods et al., as well as an additional flare measured on 2006 December 6. The radiative outputs for both phases of these five flares are then compared to the vacuum ultraviolet (VUV) irradiance output from the Flare Irradiance Spectral Model (FISM) in order to derive an empirical relationship between the FISM VUV model and the TIM TSI data output to estimate the TSI radiative output for eight other X-class flares. This model provides the basis for the bolometric energy estimates for the solar flares analyzed in the Emslie et al. study.

Atmospheric dispersion models of radioactivity releases

International Nuclear Information System (INIS)

Oza, R.B.

2016-01-01

In view of the rapid industrialization in recent time, atmospheric dispersion models have become indispensible 'tools' to ensure that the effects of releases are well within the acceptable limits set by the regulatory authority. In the case of radioactive releases from the nuclear facility, though negligible in quantity and many a times not even measurable, it is required to demonstrate the compliance of these releases to the regulatory limits set by the regulatory authority by carrying out radiological impact assessment. During routine operations of nuclear facility, the releases are so low that environmental impact is usually assessed with the help of atmospheric dispersion models as it is difficult to distinguish negligible contribution of nuclear facility to relatively high natural background radiation. The accidental releases from nuclear facility, though with negligible probability of occurrence, cannot be ruled out. In such cases, the atmospheric dispersion models are of great help to emergency planners for deciding the intervention actions to minimize the consequences in public domain and also to workout strategies for the management of situation. In case of accidental conditions, the atmospheric dispersion models are also utilized for the estimation of probable quantities of radionuclides which might have got released to the atmosphere. Thus, atmospheric dispersion models are an essential tool for nuclear facility during routine operation as well as in the case of accidental conditions

Modelling of aircrew radiation exposure during solar particle events

Science.gov (United States)

Al Anid, Hani Khaled

show a very different response during anisotropic events, leading to variations in aircrew radiation doses that may be significant for dose assessment. To estimate the additional exposure due to solar flares, a model was developed using a Monte-Carlo radiation transport code, MCNPX. The model transports an extrapolated particle spectrum based on satellite measurements through the atmosphere using the MCNPX analysis. This code produces the estimated flux at a specific altitude where radiation dose conversion coefficients are applied to convert the particle flux into effective and ambient dose-equivalent rates. A cut-off rigidity model accounts for the shielding effects of the Earth's magnetic field. Comparisons were made between the model predictions and actual flight measurements taken with various types of instruments used to measure the mixed radiation field during Ground Level Enhancements 60 and 65. An anisotropy analysis that uses neutron monitor responses and the pitch angle distribution of energetic solar particles was used to identify particle anisotropy for a solar event in December 2006. In anticipation of future commercial use, a computer code has been developed to implement the radiation dose assessment model for routine analysis. Keywords: Radiation Dosimetry, Radiation Protection, Space Physics.

Analyses of the Photospheric Magnetic Dynamics in Solar Active Region 11117 Using an Advanced CESE-MHD Model

Energy Technology Data Exchange (ETDEWEB)

Jiang, Chaowei [SIGMA Weather Group, State Key Laboratory for Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing (China); Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL (United States); Wu, Shi T. [Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL (United States); Department of Mechanical and Aerospace Engineering, The University of Alabama in Huntsville, AL (United States); Feng, Xueshang, E-mail: cwjiang@spaceweather.ac.cn [SIGMA Weather Group, State Key Laboratory for Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing (China)

2016-05-10

In this study, the photospheric vector magnetograms obtained by Helioseismic and Magnetic Imager on-board the Solar Dynamics Observatory are used as boundary conditions for a CESE-MHD model to investigate some photosphere characteristics around the time of a confined flare in solar active region NOAA AR 11117. We report our attempt of characterizing a more realistic solar atmosphere by including a plasma with temperature stratified from the photosphere to the corona in the CESE-MHD model. The resulted photospheric transverse flow is comparable to the apparent movements of the magnetic flux features that demonstrates shearing and rotations. We calculated the relevant parameters such as the magnetic energy flux and helicity flux, and with analysis of these parameters, we find that magnetic non-potentiality is transported across the photosphere into the corona in the simulated time interval, which might provide a favorable condition for producing the flare.

Modeling of Solar Radiation Management: A Comparison of Simulations Using Reduced Solar Constant and Stratospheric Sulphate Aerosols

Science.gov (United States)

Bala, G.; Kalidindi, S.; Modak, A.; Caldeira, K.

2014-12-01

Several climate modelling studies in the past have used reduction in solar constant to simulate the climatic effects of Solar Radiation Management (SRM) geoengineering. This is most likely valid only for space-based mirrors/reflectors but not for SRM methods that rely on stratospheric aerosols. In this study, we use a climate model to evaluate the differences in climate response to SRM by uniform solar constant reduction and stratospheric aerosols. The experiments are designed such that global mean warming from a doubling of atmospheric CO2 concentration (2xCO2) is nearly cancelled in each case. In such a scenario, the residual climate effects are similar when important surface and tropospheric climate variables such as temperature and precipitation are considered. However, there are significant differences in stratospheric temperature response and diffuse and direct radiation reaching the surface. A difference of 1K in the global mean stratospheric (61-9.8 hPa) temperature is simulated between the two SRM methods, with warming in the aerosol scheme and a slight cooling for sunshades. While the global mean surface diffuse radiation increases by ~23% and direct radiation decreases by about 9% in the case of aerosol SRM method, both direct and diffuse radiation decrease by similar fractional amounts (~1.0%) when solar constant is reduced. When CO2 fertilization effects from elevated CO2 concentration levels are removed, the contribution from shaded leaves to gross primary productivity (GPP) increases by 1.8 % in aerosol SRM because of increased diffuse light. However, this increase is almost offset by a 15.2% decline in sunlit contribution due to reduced direct light. Overall both the SRM simulations show similar decrease in GPP (~ 8%) and NPP (~3%) relative to 2xCO2, indicating the negligible effect of the fractional changes in direct/diffuse radiation on the overall plant productivity. Based on our modelling study, we conclude that the climate states produced by a

Investigating the Impact of a Solar Eclipse on Atmospheric Radiation

Science.gov (United States)

Fender, Josh; Morse, Justin; Ringler, John; Galovich, Cynthia; Kuehn, Charles A.; Semak, Matthew

2018-06-01

We present a project that measured atmospheric muon flux as a function of altitude during a total solar eclipse. An auxiliary goal was to design and build a cost-effective muon detection device that is simple enough for those with minimal training to build. The detector is part of a self-contained autonomous payload that is carried to altitude aboard a weather balloon. The detection system consists of three Geiger counters connected to a coincidence circuit. This system, along with internal and external temperature sensors and an altimeter, are controlled by an onboard Arduino Mega microcontroller. An internal frame was constructed to house and protect the payload components using modular 3D-printed parts. The payload was launched during the 2017 solar eclipse from Guernsey, Wyoming, along the path of totality. Initial data analysis indicates that line-of-sight blockage of the sun due to a total eclipse produces a negligible difference in muon flux when compared to the results of previous daytime flights. The successful performance of the payload, its low overall cost, and its ease of use suggest that this project would be well-suited for individuals or groups such as high school or undergraduate science students to reproduce and enhance.

Determination of daily solar ultraviolet radiation using statistical models and artificial neural networks

Directory of Open Access Journals (Sweden)

F. J. Barbero

2006-09-01

Full Text Available In this study, two different methodologies are used to develop two models for estimating daily solar UV radiation. The first is based on traditional statistical techniques whereas the second is based on artificial neural network methods. Both models use daily solar global broadband radiation as the only measured input. The statistical model is derived from a relationship between the daily UV and the global clearness indices but modulated by the relative optical air mass. The inputs to the neural network model were determined from a large number of radiometric and atmospheric parameters using the automatic relevance determination method, although only the daily solar global irradiation, daily global clearness index and relative optical air mass were shown to be the optimal input variables. Both statistical and neural network models were developed using data measured at Almería (Spain, a semiarid and coastal climate, and tested against data from Table Mountain (Golden, CO, USA, a mountainous and dry environment. Results show that the statistical model performs adequately in both sites for all weather conditions, especially when only snow-free days at Golden were considered (RMSE=4.6%, MBE= –0.1%. The neural network based model provides the best overall estimates in the site where it has been trained, but presents an inadequate performance for the Golden site when snow-covered days are included (RMSE=6.5%, MBE= –3.0%. This result confirms that the neural network model does not adequately respond on those ranges of the input parameters which were not used for its development.

Atmospheric-radiation boundary conditions for high-frequency waves in time-distance helioseismology

Science.gov (United States)

Fournier, D.; Leguèbe, M.; Hanson, C. S.; Gizon, L.; Barucq, H.; Chabassier, J.; Duruflé, M.

2017-12-01

The temporal covariance between seismic waves measured at two locations on the solar surface is the fundamental observable in time-distance helioseismology. Above the acoustic cut-off frequency ( 5.3 mHz), waves are not trapped in the solar interior and the covariance function can be used to probe the upper atmosphere. We wish to implement appropriate radiative boundary conditions for computing the propagation of high-frequency waves in the solar atmosphere. We consider recently developed and published radiative boundary conditions for atmospheres in which sound-speed is constant and density decreases exponentially with radius. We compute the cross-covariance function using a finite element method in spherical geometry and in the frequency domain. The ratio between first- and second-skip amplitudes in the time-distance diagram is used as a diagnostic to compare boundary conditions and to compare with observations. We find that a boundary condition applied 500 km above the photosphere and derived under the approximation of small angles of incidence accurately reproduces the "infinite atmosphere" solution for high-frequency waves. When the radiative boundary condition is applied 2 Mm above the photosphere, we find that the choice of atmospheric model affects the time-distance diagram. In particular, the time-distance diagram exhibits double-ridge structure when using a Vernazza Avrett Loeser atmospheric model.

Solar Physics at Evergreen: Solar Dynamo and Chromospheric MHD

Science.gov (United States)

Zita, E. J.; Maxwell, J.; Song, N.; Dikpati, M.

2006-12-01

We describe our five year old solar physics research program at The Evergreen State College. Famed for its cloudy skies, the Pacific Northwest is an ideal location for theoretical and remote solar physics research activities. Why does the Sun's magnetic field flip polarity every 11 years or so? How does this contribute to the magnetic storms Earth experiences when the Sun's field reverses? Why is the temperature in the Sun's upper atmosphere millions of degrees higher than the Sun's surface temperature? How do magnetic waves transport energy in the Sun’s chromosphere and the Earth’s atmosphere? How does solar variability affect climate change? Faculty and undergraduates investigate questions such as these in collaboration with the High Altitude Observatory (HAO) at the National Center for Atmospheric Research (NCAR) in Boulder. We will describe successful student research projects, logistics of remote computing, and our current physics investigations into (1) the solar dynamo and (2) chromospheric magnetohydrodynamics.

A model for solar constant secular changes

Science.gov (United States)

Schatten, Kenneth H.

1988-01-01

In this paper, contrast models for solar active region and global photospheric features are used to reproduce the observed Active Cavity Radiometer and Earth Radiation Budget secular trends in reasonably good fashion. A prediction for the next decade of solar constant variations is made using the model. Secular trends in the solar constant obtained from the present model support the view that the Maunder Minimum may be related to the Little Ice Age of the 17th century.

Temperature responses to the 11 year solar cycle in the mesosphere from the 31 year (1979-2010) extended Canadian Middle Atmosphere Model simulations and a comparison with the 14 year (2002-2015) TIMED/SABER observations

Science.gov (United States)

Gan, Quan; Du, Jian; Fomichev, Victor I.; Ward, William E.; Beagley, Stephen R.; Zhang, Shaodong; Yue, Jia

2017-04-01

A recent 31 year simulation (1979-2010) by extended Canadian Middle Atmosphere Model (eCMAM30) and the 14 year (2002-2015) observation by the Thermosphere Ionosphere Mesosphere and Dynamics/Sounding of the Atmosphere using Broadband Emssion Radiometry (TIMED/SABER) are utilized to investigate the temperature response to the 11 year solar cycle on the mesosphere. Overall, the zonal mean responses tend to increase with height, and the amplitudes are on the order of 1-2 K/100 solar flux unit (1 sfu = 10-22 W m-2 Hz-1) below 80 km and 2-4 K/100 sfu in the mesopause region (80-100 km) from the eCMAM30, comparatively weaker than those from the SABER except in the midlatitude lower mesosphere. A pretty good consistence takes place at around 75-80 km with a response of 1.5 K/100 sfu within 10°S/N. Also, a symmetric pattern of the responses about the equator agrees reasonably well between the two. It is noteworthy that the eCMAM30 displays an alternate structure with the upper stratospheric cooling and the lower mesospheric warming at midlatitudes of the winter hemisphere, in favor of the long-term Rayleigh lidar observation reported by the previous studies. Through diagnosing multiple dynamical parameters, it is manifested that this localized feature is induced by the anomalous residual circulation as a consequence of the wave-mean flow interaction during the solar maximum year.

Validated TRNSYS Model for Solar Assisted Space Heating System

International Nuclear Information System (INIS)

Abdalla, Nedal

2014-01-01

The present study involves a validated TRNSYS model for solar assisted space heating system as applied to a residential building in Jordan using new detailed radiation models of the TRNSYS 17.1 and geometric building model Trnsys3d for the Google SketchUp 3D drawing program. The annual heating load for a building (Solar House) which is located at the Royal ScientiFIc Society (RS5) in Jordan is estimated under climatological conditions of Amman. The aim of this Paper is to compare measured thermal performance of the Solar House with that modeled using TRNSYS. The results showed that the annual measured space heating load for the building was 6,188 kWh while the heati.ng load for the modeled building was 6,391 kWh. Moreover, the measured solar fraction for the solar system was 50% while the modeled solar fraction was 55%. A comparison of modeled and measured data resulted in percentage mean absolute errors for solar energy for space heating, auxiliary heating and solar fraction of 13%, 7% and 10%, respectively. The validated model will be useful for long-term performance simulation under different weather and operating conditions.(author)

Implementation of Bessel's method for solar eclipses prediction in the WRF-ARW model

Directory of Open Access Journals (Sweden)

A. Montornès

2016-05-01

Full Text Available Solar eclipses are predictable astronomical events that abruptly reduce the incoming solar radiation into the Earth's atmosphere, which frequently results in non-negligible changes in meteorological fields. The meteorological impacts of these events have been analyzed in many studies since the late 1960s. The recent growth in the solar energy industry has greatly increased the interest in providing more detail in the modeling of solar radiation variations in numerical weather prediction (NWP models for the use in solar resource assessment and forecasting applications. The significant impact of the recent partial and total solar eclipses that occurred in the USA (23 October 2014 and Europe (20 March 2015 on solar power generation have provided additional motivation and interest for including these astronomical events in the current solar parameterizations.Although some studies added solar eclipse episodes within NWP codes in the 1990s and 2000s, they used eclipse parameterizations designed for a particular case study. In contrast to these earlier implementations, this paper documents a new package for the Weather Research and Forecasting–Advanced Research WRF (WRF-ARW model that can simulate any partial, total or hybrid solar eclipse for the period 1950 to 2050 and is also extensible to a longer period. The algorithm analytically computes the trajectory of the Moon's shadow and the degree of obscuration of the solar disk at each grid point of the domain based on Bessel's method and the Five Millennium Catalog of Solar Eclipses provided by NASA, with a negligible computational time. Then, the incoming radiation is modified accordingly at each grid point of the domain.This contribution is divided in three parts. First, the implementation of Bessel's method is validated for solar eclipses in the period 1950–2050, by comparing the shadow trajectory with values provided by NASA. Latitude and longitude are determined with a bias lower than 5�

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

Solar radiation modeling and measurements for renewable energy applications: data and model quality

International Nuclear Information System (INIS)

Myers, Daryl R.

2005-01-01

Measurement and modeling of broadband and spectral terrestrial solar radiation is important for the evaluation and deployment of solar renewable energy systems. We discuss recent developments in the calibration of broadband solar radiometric instrumentation and improving broadband solar radiation measurement accuracy. An improved diffuse sky reference and radiometer calibration and characterization software for outdoor pyranometer calibrations are outlined. Several broadband solar radiation model approaches, including some developed at the National Renewable Energy Laboratory, for estimating direct beam, total hemispherical and diffuse sky radiation are briefly reviewed. The latter include the Bird clear sky model for global, direct beam, and diffuse terrestrial solar radiation; the Direct Insolation Simulation Code (DISC) for estimating direct beam radiation from global measurements; and the METSTAT (Meteorological and Statistical) and Climatological Solar Radiation (CSR) models that estimate solar radiation from meteorological data. We conclude that currently the best model uncertainties are representative of the uncertainty in measured data

Solar radiation modeling and measurements for renewable energy applications: data and model quality

Energy Technology Data Exchange (ETDEWEB)

Myers, D.R. [National Renewable Energy Laboratory, Golden, CO (United States)

2005-07-01

Measurement and modeling of broadband and spectral terrestrial solar radiation is important for the evaluation and deployment of solar renewable energy systems. We discuss recent developments in the calibration of broadband solar radiometric instrumentation and improving broadband solar radiation measurement accuracy. An improved diffuse sky reference and radiometer calibration and characterization software for outdoor pyranometer calibrations are outlined. Several broadband solar radiation model approaches, including some developed at the National Renewable Energy Laboratory, for estimating direct beam, total hemispherical and diffuse sky radiation are briefly reviewed. The latter include the Bird clear sky model for global, direct beam, and diffuse terrestrial solar radiation; the Direct Insolation Simulation Code (DISC) for estimating direct beam radiation from global measurements; and the METSTAT (Meteorological and Statistical) and Climatological Solar Radiation (CSR) models that estimate solar radiation from meteorological data. We conclude that currently the best model uncertainties are representative of the uncertainty in measured data. (author)

Hydrodynamic escape from planetary atmospheres

Science.gov (United States)

Tian, Feng

Hydrodynamic escape is an important process in the formation and evolution of planetary atmospheres. Due to the existence of a singularity point near the transonic point, it is difficult to find transonic steady state solutions by solving the time-independent hydrodynamic equations. In addition to that, most previous works assume that all energy driving the escape flow is deposited in one narrow layer. This assumption not only results in less accurate solutions to the hydrodynamic escape problem, but also makes it difficult to include other chemical and physical processes in the hydrodynamic escape models. In this work, a numerical model describing the transonic hydrodynamic escape from planetary atmospheres is developed. A robust solution technique is used to solve the time dependent hydrodynamic equations. The method has been validated in an isothermal atmosphere where an analytical solution is available. The hydrodynamic model is applied to 3 cases: hydrogen escape from small orbit extrasolar planets, hydrogen escape from a hydrogen rich early Earth's atmosphere, and nitrogen/methane escape from Pluto's atmosphere. Results of simulations on extrasolar planets are in good agreement with the observations of the transiting extrasolar planet HD209458b. Hydrodynamic escape of hydrogen from other hypothetical close-in extrasolar planets are simulated and the influence of hydrogen escape on the long-term evolution of these extrasolar planets are discussed. Simulations on early Earth suggest that hydrodynamic escape of hydrogen from a hydrogen rich early Earth's atmosphere is about two orders magnitude slower than the diffusion limited escape rate. A hydrogen rich early Earth's atmosphere could have been maintained by the balance between the hydrogen escape and the supply of hydrogen into the atmosphere by volcanic outgassing. Origin of life may have occurred in the organic soup ocean created by the efficient formation of prebiotic molecules in the hydrogen rich early

Atmospheric Mining in the Outer Solar System: Outer Planet In-Space Bases and Moon Bases for Resource Processing

Science.gov (United States)

Palaszewski, Bryan

2017-01-01

Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and deuterium can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and deuterium were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. While capturing 3He, large amounts of hydrogen and 4He are produced. The propulsion and transportation requirements for all of the major moons of Uranus and Neptune are presented. Analyses of orbital transfer vehicles (OTVs), landers, factories, and the issues with in-situ resource utilization (ISRU) low gravity processing factories are included. Preliminary observations are presented on near-optimal selections of moon base orbital locations, OTV power levels, and OTV and lander rendezvous points. Several artificial gravity in-space base designs and orbital sites at Uranus and Neptune and the OTV requirements to support them are also addressed.

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.

High-Fidelity Solar Power Income Modeling for Solar-Electric UAVs: Development and Flight Test Based Verification

OpenAIRE

Oettershagen, Philipp

2017-01-01

Solar power models are a crucial element of solar-powered UAV design and performance analysis. During the conceptual design phase, their accuracy directly relates to the accuracy of the predicted performance metrics and thus the final design characteristics of the solar-powered UAV. Likewise, during the operations phase of a solar-powered UAV accurate solar power income models are required to predict and assess the solar power system performance. However, the existing literature on solar-powe...

Mechanism of the relations between the changes of the geomagnetic field, solar corpuscular radiation, atmospheric circulation, and climate

International Nuclear Information System (INIS)

Bucha, Vaclav

1980-01-01

The correlations between geomagnetic, climatic, and meteorological phenomena were investigated with the object of demonstrating the function of the geomagnetic pole and changes of its position in controlling the climate and weather. A tentative model has been proposed to enable one to understand the causes of the generation of glacial and interglacial periods, as well as the causes which effect changes of climate (Bucha, 1976a). The analyses of various types of geomagnetic and atmospheric manifestations have disclosed certain associations. The coincidence in the occurrence of increased spectral densities with regard to geomagnetic activity and the variations of atmospheric pressure over the geomagnetic pole shows the relation between their periodicities. The results imply that the changes in the intensity of corpuscular radiation, indicated by geomagnetic activity, affect the temperature and pressure patterns over the geomagnetic pole and polar region significantly, so that a pronounced modification of the general circulation may take place, as shown schematically (Bucha, 1976b). As a result of investigating the relations between the variations of geomagnetic activity and meteorological factors a mechanism of solar-terrestrial relationships and a model of the changes of atmospheric circulation in the Northern Hemisphere are proposed; this provides a probable explanation of the causes of the fluctuation of the climate, of dry and cold periods and of differing vegetation conditions in various years in dependence on the intensity of geomagnetic activity (Bucha, 1976b, 1977a). (author)

SOLAR SOURCES OF 3He-RICH SOLAR ENERGETIC PARTICLE EVENTS IN SOLAR CYCLE 24

International Nuclear Information System (INIS)

Nitta, Nariaki V.; Mason, Glenn M.; Wang, Linghua; Cohen, Christina M. S.; Wiedenbeck, Mark E.

2015-01-01

Using high-cadence EUV images obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we investigate the solar sources of 26 3 He-rich solar energetic particle events at ≲1 MeV nucleon −1 that were well-observed by the Advanced Composition Explorer during solar cycle 24. Identification of the solar sources is based on the association of 3 He-rich events with type III radio bursts and electron events as observed by Wind. The source locations are further verified in EUV images from the Solar and Terrestrial Relations Observatory, which provides information on solar activities in the regions not visible from the Earth. Based on AIA observations, 3 He-rich events are not only associated with coronal jets as emphasized in solar cycle 23 studies, but also with more spatially extended eruptions. The properties of the 3 He-rich events do not appear to be strongly correlated with those of the source regions. As in the previous studies, the magnetic connection between the source region and the observer is not always reproduced adequately by the simple potential field source surface model combined with the Parker spiral. Instead, we find a broad longitudinal distribution of the source regions extending well beyond the west limb, with the longitude deviating significantly from that expected from the observed solar wind speed

Solar Features

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of solar feature datasets contributed by a number of national and private solar observatories located worldwide.

Nb-TiO{sub 2}/polymer hybrid solar cells with photovoltaic response under inert atmosphere conditions

Energy Technology Data Exchange (ETDEWEB)

Lira-Cantu, Monica; Khoda Siddiki, Mahbube; Munoz-Rojas, David; Amade, Roger [Centre d' Investigacio en Nanociencia i Nanotecnologia (CIN2, CSIC), Laboratory of Nanostructured Materials for Photovoltaic Energy, Campus UAB, Barcelona (Spain); Gonzalez-Pech, Natalia I. [Centre d' Investigacio en Nanociencia i Nanotecnologia (CIN2, CSIC), Laboratory of Nanostructured Materials for Photovoltaic Energy, Campus UAB, Barcelona (Spain); Instituto Tecnologico y de Estudios Superiores de Monterrey (ITESM), Ave. Eugenio Garza Sada, 64640 Monterrey, N.L. (Mexico)

2010-07-15

Hybrid Solar Cells (HSC) applying Nb-TiO{sub 2} in direct contact with a conducting organic polymer, MEH-PPV, show higher stability than the bare TiO{sub 2}-based HSC when analyzed under inert atmosphere conditions. IPCE analyses revealed that inert atmospheres affect directly the semiconductor oxide in the first stages of the analyses but photovoltaic performance stabilizes after several hours. A 20 wt% Nb-doped TiO{sub 2} presented the highest stability and photovoltaic properties. The behavior has been attributed to the solubility limit of Nb within the TiO{sub 2} beyond 20 wt% doping level where the co-existence of NbO{sub 2} is observed. The HSCs were analyzed under controlled N{sub 2} atmosphere and 1000 W/m{sup 2} (AM 1.5) irradiation. (author)

Atmospheric Tides in Gale Crater, Mars

Science.gov (United States)

Guzewich, Scott D,; Newman, C. E; de la Torre Juarez, M.; Wilson, R. J.; Lemmon, M.; Smith, M. D.; Kahanpaa, H.; Harri, A.-M.

2015-01-01

Atmospheric tides are the primary source of daily air pressure variation at the surface of Mars. These tides are forced by solar heating of the atmosphere and modulated by the presence of atmospheric dust, topography, and surface albedo and thermal inertia. This results in a complex mix of sun-synchronous and nonsun- synchronous tides propagating both eastward and westward around the planet in periods that are integer fractions of a solar day. The Rover Environmental Monitoring Station on board the Mars Science Laboratory has observed air pressure at a regular cadence for over 1 Mars year and here we analyze and diagnose atmospheric tides in this pressure record. The diurnal tide amplitude varies from 26 to 63 Pa with an average phase of 0424 local true solar time, while the semidiurnal tide amplitude varies from 5 to 20 Pa with an average phase of 0929. We find that both the diurnal and semidiurnal tides in Gale Crater are highly correlated to atmospheric opacity variations at a value of 0.9 and to each other at a value of 0.77, with some key exceptions occurring during regional and local dust storms. We supplement our analysis with MarsWRF general circulation modeling to examine how a local dust storm impacts the diurnal tide in its vicinity. We find that both the diurnal tide amplitude enhancement and regional coverage of notable amplitude enhancement linearly scales with the size of the local dust storm. Our results provide the first long-term record of surface pressure tides near the martian equator.

Polarized Light from the Sun: Unification of the Corona and Analysis of the Second Solar Spectrum — Further Implications of a Liquid Metallic Hydrogen Solar Model

Directory of Open Access Journals (Sweden)

Robitaille P.-M.

2015-07-01

Full Text Available In order to account for the slight polarization of the continuum towards the limb, propo- nents of the Standard Solar Model (SSM must have recourse to electron or hydrogen- based scattering of light, as no other mechanism is possible in a gaseous Sun. Con- versely, acceptance that the solar body is comprised of condensed matter opens up new avenues in the analysis of this problem, even if the photospheric surface itself is viewed as incapable of emitting polarized light. Thus, the increased disk polarization, from the center to the limb, can be explained by invoking the scattering of light by the at- mosphere above the photosphere. The former is reminiscent of mechanisms which are known to account for the polarization of sunlight in the atmosphere of the Earth. Within the context of the Liquid Metallic Hydrogen Solar Model (LMHSM, molecules and small particles, not electrons or hydrogen atoms as required by the SSM, would primarily act as scattering agents in regions also partially comprised of condensed hy- drogen structures (CHS. In addition, the well-known polarization which characterizes the K-corona would become a sign of emission polarization from an anisotropic source, without the need for scattering. In the LMHSM, the K, F, and T- coronas can be viewed as emissive and reflective manifestations of a single corona l entity adopting a radially anisotropic structure, while slowly cooling with altitude above the photosphere. The presence of “dust particles”, advanced by proponents of the SSM, would no longer be required to explain the F and T-corona, as a single cooling structure would account for the properties of the K, F, and T coronas. At the same time, the polarized “Second Solar Spectrum”, characterized by the dominance of certain elemental or ionic spectral lines and an abundance of molecular lines, could be explained in the LMHSM, by first invoking interface polarization and coordination of these species with condensed matter

Modelling of pollution dispersion in atmosphere

International Nuclear Information System (INIS)

Borysiewicz, M.; Stankiewicz, R.

1994-01-01

The paper contains the review of the mathematical foundation of atmospheric dispersion models. The atmospheric phenomena relevant to atmospheric dispersion model are discussed. In particular the parametrization of processes with time and space scales smaller than numerical grid size, limited by available computer power, is presented. The special attention was devoted to similarity theory and parametrization of boundary layer. The numerical methods are analysed and the drawbacks of the method are presented. (author). 99 refs, 15 figs, 3 tabs

Venusian atmospheric and Magellan properties from attitude control data. M.S. Thesis

Science.gov (United States)

Croom, Christopher A.; Tolson, Robert H.

1994-01-01

Results are presented of the study of the Venusian atmosphere, Magellan aerodynamic moment coefficients, moments of inertia, and solar moment coefficients. This investigation is based upon the use of attitude control data in the form of reaction wheel speeds from the Magellan spacecraft. As the spacecraft enters the upper atmosphere of Venus, measurable torques are experienced due to aerodynamic effects. Solar and gravity gradient effects also cause additional torques throughout the orbit. In order to maintain an inertially fixed attitude, the control system counteracts these torques by changing the angular rates of three reaction wheels. Model reaction wheel speeds are compared to observed Magellan reaction wheel speeds through a differential correction procedure. This method determines aerodynamic, atmospheric, solar pressure, and mass moment of inertia parameters. Atmospheric measurements include both base densities and scale heights. Atmospheric base density results confirm natural variability as measured by the standard orbital decay method. Potential inconsistencies in free molecular aerodynamic moment coefficients are identified. Moments of inertia are determined with a precision better than 1 percent of the largest principal moment of inertia.

The thermal structure of Titan's atmosphere

Science.gov (United States)

Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

1989-01-01

The present radiative-convective model of the Titan atmosphere thermal structure obtains the solar and IR radiation in a series of spectral intervals with vertical resolution. Haze properties have been determined with a microphysics model encompassing a minimum of free parameters. It is determined that gas and haze opacity alone, using temperatures established by Voyager observations, yields a model that is within a few percent of the radiative convective balance throughout the Titan atmosphere. Model calculations of the surface temperature are generally colder than the observed value by 5-10 K; better agreement is obtained through adjustment of the model parameters. Sunlight absorption by stratospheric haze and pressure-induced gas opacity in the IR are the most important thermal structure-controlling factors.

Unified fit of solar and atmospheric neutrinos: towards the MNSP matrix

International Nuclear Information System (INIS)

2002-01-01

Present solar and atmospheric neutrino give a strong indication that neutrinos oscillate between the three active species. This is the first step towards the determination of their mass. But we have also to determine the 3 x 3 neutrino mixing matrix (3 angles and one or several phases linked to CP violation), called MNSP (Maki-Nakagawa-Suzuki-Pontecorvo) and similar to the quark mixing matrix, called CKM (Cabibbo-Kobayashi-Maskawa). The purpose of the colloquium (one day) is to give an overview of the present situation and what progresses are expected in the forthcoming years. 3 guidelines: pedagogical approach, critical review of the experimental situation and of the different analyses, lookout to the future. (author)

FIRST NEW SOLAR MODELS WITH OPAS OPACITY TABLES

Energy Technology Data Exchange (ETDEWEB)

Le Pennec, M.; Turck-Chièze, S.; Salmon, S. [CEA/IRFU/Service d’Astrophysique, CE Saclay, F-91191 Gif sur Yvette (France); Blancard, C.; Cossé, P.; Faussurier, G.; Mondet, G. [CEA, DAM, DIF, F-91297 Arpajon (France)

2015-11-10

Stellar seismology appears more and more as a powerful tool for a better determination of the fundamental properties of solar-type stars. However, the particular case of the Sun is still challenging. For about a decade now, the helioseismic sound-speed determination has continued to disagree with the standard solar model (SSM) prediction, questioning the reliability of this model. One of the sources of uncertainty could be in the treatment of the transport of radiation from the solar core to the surface. In this Letter, we use the new OPAS opacity tables, recently available for solar modeling, to address this issue. We discuss first the peculiarities of these tables, then we quantify their impact on the solar sound-speed and density profiles using the reduced OPAS tables taken on the grids of the OPAL ones. We use the two evolution codes, Modules for Experiments in Stellar Astrophysics and Code Liégeois d’Evolution Stellaire, that led to similar conclusions in the solar radiative zone. In comparison to commonly used OPAL opacity tables, the new solar models are computed for the most recent photospheric composition with OPAS tables and present improvements to the location of the base of the convective zone and to the description of the solar radiative zone in comparison to the helioseismic observations, even if the differences in the Rosseland mean opacity do not exceed 6%. We finally carry out a comparison to a solar model computed with the OP opacity tables.

Atmospheric radiative transfer in the UV: special emphasis on photolysis frequencies J(O1D) and J(NO2)