WorldWideScience

Sample records for airglow

  1. Enhanced airglow at Titan

    Science.gov (United States)

    Royer, Emilie; Esposito, Larry; Wahlund, Jan-Erik

    2016-06-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) instrument made thousand of observations of Titan since its arrival in the Saturnian system in 2004, but only few of them have been analyzed yet. Using the imaging capability of UVIS combined to a big data analytics approach, we have been able to uncover an unexpected pattern in this observations: on several occasions the Titan airglow exhibits an enhanced brightness by approximately a factor of 2, generally combined with a lower altitude of the airglow emission peak. These events typically last from 10 to 30 minutes and are followed and preceded by an airglow of regular and expected level of brightness and altitude. Observations made by the Cassini Plasma Spectrometer (CAPS) instrument onboard Cassini allowed us to correlate the enhanced airglow observed on T-32 with an electron burst. The timing of the burst and the level of energetic electrons (1 keV) observed by CAPS correspond to a brighter and lower than typical airglow displayed on the UVIS data. Furthermore, during T-32 Titan was inside the Saturn's magnetosheath and thus more subject to bombardment by energetic particles. However, our analysis demonstrates that the presence of Titan inside the magnetosheath is not a necessary condition for the production of an enhanced airglow, as we detected other similar events while Titan was within Saturn's magnetosphere. The study presented here aims to a better understanding of the interactions of Titan's upper atmosphere with its direct environment.

  2. Byurakan sky night airglow observation

    International Nuclear Information System (INIS)

    The data on sky night airglow are obtained by Byurakan Astrophysical Observatory of the Acadamy of Sciences of the Armenian SSR. (BAO). The picfures of brightness distribution of BAO sky night airglow are presented. The observations were carried out with the help of one-channel electrophotometre placed at the 0.5 metre A 3T-14A telescope in U, B, V bands of the international photometric system in moonless nights of the 1st/2nd October, 1976 and 22nd/23d February, 1977. Presented are also the U, B, V values of BAO sky night airglow brightness from one sguare second in zenith. The ilumination of Erevan and Byurakan is the cause of the increase of airglow brightness of BAO sky night, particularly in the town and village direction

  3. Seasonal hemispherical SWIR airglow imaging

    Science.gov (United States)

    Allen, Jeffrey; Dayton, David C.; Gonglewski, John D.; Myers, Michael M.; Nolasco, Rudolph

    2011-09-01

    Airglow luminescence in the SWIR region due to upper atmospheric recombination of solar excited molecules is a well accepted phenomenon. While the intensity appears broadly uniform over the whole sky hemisphere, we are interested in variations in four areas: 1) fine periodic features known as gravity waves, 2) broad patterns across the whole sky, 3) temporal variations in the hemispheric mean irradiance over the course of the night, and 4) long term seasonal variations in the mean irradiance. An experiment is described and results presented covering a full year of high resolution hemispheric SWIR irradiance images. An automated gimbal views 45 hemispheric positions, using 30 second durations, and repeats approximately every half hour through out the night. The gimbal holds co-mounted and bore-sighted visible and SWIR cameras. Measuring airglow with respect to spatial, temporal, and seasonal variations will facilitate understanding its behavior and possible benefits, such as night vision and predicting upper atmosphere turbulence. The measurements were performed in a tropical marine location on the island of Kauai Hi.

  4. Lyman alpha airglow observations from SORCE SOLSTICE

    Science.gov (United States)

    Dolinar, E.; Snow, M.; Holsclaw, G.; Thomas, G. E.; Woods, T. N.

    2010-12-01

    The Solar Stellar Irradiance Comparison Experiment (SOLSTICE) instrument on board the Solar Radiation Climate Experiment (SORCE) spacecraft in low Earth orbit observes stars every orbit for in-flight calibration. It also observes several star-free regions of the sky near the wavelength of Lyman alpha to correct for airglow emission in the stellar measurements. Although the airglow measurements are only taken during the eclipse portion of the orbit, the look directions cover nearly the entire anti-sunward hemisphere. This seven-year record of Lyman alpha airglow observations (2003-2010) shows the response of the Hydrogen geocorona to changes in the solar Lyman alpha irradiance over the solar cycle.

  5. Solar Irradiance and Thermospheric Airglow Rocket Experiments

    Science.gov (United States)

    Solomon, Stanley C.

    1998-01-01

    This report describes work done in support of the Solar Irradiance and Thermospheric Air-glow Rocket Experiments at the University of Colorado for NASA grant NAG5-5021 under the direction of Dr. Stanley C. Solomon. (The overall rocket program is directed by Dr. Thomas N. Woods, formerly at the National Center for Atmospheric Research, and now also at the University of Colorado, for NASA grant NAG5-5141.) Grant NAG5-5021 provided assistance to the overall program through analysis of airglow and solar data, support of two graduate students, laboratory technical services, and field support. The general goals of the rocket program were to measure the solar extreme ultraviolet spectral irradiance, measure the terrestrial far-ultraviolet airglow, and analyze their relationship at various levels of solar activity, including near solar minimum. These have been met, as shown below. In addition, we have used the attenuation of solar radiation as the rocket descends through the thermosphere to measure density changes. This work demonstrates the maturity of the observational and modeling methods connecting energetic solar photon fluxes and airglow emissions through the processes of photoionization and photoelectron production and loss. Without a simultaneous photoelectron measurement, some aspects of this relationship remain obscure, and there are still questions pertaining to cascade contributions to molecular and atomic airglow emissions. However, by removing the solar irradiance as an "adjustable parameter" in the analysis, significant progress has been made toward understanding the relationship of far-ultraviolet airglow emissions to the solar and atmospheric conditions that control them.

  6. Heater-induced ionization inferred from spectrometric airglow measurements

    Science.gov (United States)

    Hysell, D. L.; Miceli, R. J.; Varney, R. H.; Schlatter, N.; Huba, J. D.

    2013-12-01

    Spectrographic airglow measurements were made during an ionospheric modification experiment at HAARP on March 12, 2013. Artificial airglow enhancements at 427.8, 557.7, 630.0, 777.4, and 844.6 nm were observed. On the basis of these emissions and using a methodology based on the method of Backus and Gilbert [1968, 1970], we estimate the suprathermal electron population and the subsequent equilibrium electron density profile, including contributions from electron impact ionization. We find that the airglow is consistent with significant induced ionization in view of the spatial intermittency of the airglow.

  7. Mesopause region wind, temperature and airglow irradiance above Eureka, Nunavut

    Science.gov (United States)

    Kristoffersen, Samuel; Ward, William E.; Vail, Christopher; Shepherd, Marianna

    2016-07-01

    The PEARL All Sky Imager (PASI, airglow images), the Spectral Airglow Temperature Imager (SATI, airglow irradiance and temperature) and the E-Region Wind Interferometer II (ERWIN2, wind, airglow irradiance and temperature) are co-located at the Polar Environment Atmospheric Research Laboratory (PEARL)in Eureka, Nunavut (80 N, 86 W). These instruments view the wind, temperature and airglow irradiance of hydroxyl (all three) O2 (ERWIN2 and SATI), sodium (PASI), and oxygen green line (PASI and ERWIN2). The viewing locations and specific emissions of the various instruments differ. Nevertheless, the co-location of these instruments provides an excellent opportunity for case studies of specific events and for intercomparison between the different techniques. In this paper we discuss the approach we are using to combine observations from the different instruments. Case studies show that at times the various instruments are in good agreement but at other times they differ. Of particular interest are situations where gravity wave signatures are evident for an extended period of time and one such situation is presented. The discussion includes consideration of the filtering effect of viewing through airglow layers and the extent to which wind, airglow and temperature variations can be associated with the same gravity wave.

  8. Equatorial enhancement of the nighttime OH mesospheric infrared airglow

    Science.gov (United States)

    Baker, D. J.; Thurgood, B. K.; Harrison, W. K.; Mlynczak, M. G.; Russell, J. M.

    2007-05-01

    Global measurements of the hydroxyl mesospheric airglow over an extended period of time have been made possible by the NASA SABER infrared sensor aboard the TIMED satellite which has been functioning since December of 2001. The orbital mission has continued over a significant portion of a solar cycle. Experimental data from SABER for several years have exhibited equatorial enhancements of the nighttime mesospheric OH (Δv=2) airglow layer consistent with the high average diurnal solar flux. The brightening of the OH airglow typically means more H+O3 is being reacted. At both the spring and autumn seasonal equinoxes when the equatorial solar UV irradiance mean is greatest, the peak volume emission rate (VER) of the nighttime Meinel infrared airglow typically appears to be both significantly brighter plus lower in altitude by several kilometres at low latitudes compared with midlatitude findings.

  9. Equatorial enhancement of the nighttime OH mesospheric infrared airglow

    Energy Technology Data Exchange (ETDEWEB)

    Baker, D J [Utah State University, EL-302, Logan, UT 84322-4140 (United States); Thurgood, B K [Utah State University, EL-302, Logan, UT 84322-4140 (United States); Harrison, W K [Utah State University, EL-302, Logan, UT 84322-4140 (United States); Mlynczak, M G [NASA Langley Research Center, Mail Stop 401-B, Hampton, VA 23665-5225 (United States); Russell, J M [Center for Atmospheric Sciences, Hampton University, 23 Tyler Street Hampton, VA 23668 (United States)

    2007-05-15

    Global measurements of the hydroxyl mesospheric airglow over an extended period of time have been made possible by the NASA SABER infrared sensor aboard the TIMED satellite which has been functioning since December of 2001. The orbital mission has continued over a significant portion of a solar cycle. Experimental data from SABER for several years have exhibited equatorial enhancements of the nighttime mesospheric OH ({delta}v=2) airglow layer consistent with the high average diurnal solar flux. The brightening of the OH airglow typically means more H+O{sub 3} is being reacted. At both the spring and autumn seasonal equinoxes when the equatorial solar UV irradiance mean is greatest, the peak volume emission rate (VER) of the nighttime Meinel infrared airglow typically appears to be both significantly brighter plus lower in altitude by several kilometres at low latitudes compared with midlatitude findings.

  10. Venus Night Airglow Distibutions and Variability: NCAR VTGCM Simulations

    Science.gov (United States)

    Brecht, Amanda; Bougher, S.; Gerard, J.; Rafkin, S.; Foster, B.

    2008-09-01

    The National Center for Atmospheric Research (NCAR) thermospheric general circulation model for Venus (VTGCM) is producing results that are comparative to Pioneer Venus and Venus Express data. The model is a three dimensional model that can calculate temperatures, zonal winds, meridional winds, vertical winds, and concentration of specific species. The VTGCM can also compute the O2-IR and NO-UV night airglow intensity distributions. With a lower boundary set at 70 Km and a range of sensitivity tests, the VTGCM is able to show consistent set of results with the nightside temperature and the night airglows. These results can show possible controlling parameters of the O2-IR, NO-UV night airglow layers, and the nightside hot spot. Being able to understand the night airglow distribution and variability provides valuable insight into the changing circulation of Venus’ upper atmosphere and leads to an overall planetary perception of the atmospheric dynamics.

  11. HF-induced airglow at magnetic zenith: theoretical considerations

    OpenAIRE

    E. V. Mishin; Burke, W. J.; Pedersen, T.

    2005-01-01

    International audience Observations of airglow at 630nm (red line) and 557.7nm (green line) during HF modification experiments at the High Frequency Active Auroral Research Program (HAARP) heating facility are analyzed. We propose a theoretical framework for understanding the generation of Langmuir and ion acoustic waves during magnetic zenith injections. We show that observations of HF-induced airglow in an underdense ionosphere as well as a decrease in the height of the emitting volume a...

  12. HF-induced airglow at magnetic zenith: theoretical considerations

    Directory of Open Access Journals (Sweden)

    E. V. Mishin

    2005-01-01

    Full Text Available Observations of airglow at 630nm (red line and 557.7nm (green line during HF modification experiments at the High Frequency Active Auroral Research Program (HAARP heating facility are analyzed. We propose a theoretical framework for understanding the generation of Langmuir and ion acoustic waves during magnetic zenith injections. We show that observations of HF-induced airglow in an underdense ionosphere as well as a decrease in the height of the emitting volume are consistent with this scenario.

  13. The Nonlinear Model of the Response of Airglow to Gravity Waves

    Institute of Scientific and Technical Information of China (English)

    J. Y. Xu; H. Gao; A.V. Mikhalev

    2005-01-01

    In this paper, we develope a timodependent, nonlinear, photochemical-dynamical 2-D model which is composed of 3 models: dynamical gravity wave model, middle atmospheric photochemical model, and airglow layer photochemical model. We use the model to study the effect of the gravity wave propagation on the airglow layer. The comparison between the effects of the different wavelength gravity wave on the airglow emission distributions is made. When the vertical wavelength of the gravity wave is close to or is shorter than the thickness of the airglow layer, the gravity wave can make complex structure of the airglow layer, such as the double and multi-peak structures of the airglow layer. However, the gravity wave that has long vertical wavelength can make large scale perturbation of the airglow emission distribution.

  14. Solar cycle variation of gravity waves observed in OH airglow

    Science.gov (United States)

    Gelinas, L. J.; Hecht, J. H.; Walterscheid, R. L.; Reid, I. M.; Woithe, J.; Vincent, R. A.

    2013-12-01

    Airglow imaging provides a unique means by which to study many wave-related phenomena in the 80 to 100 km altitude regime. Two-dimensional image observations reveal quasi-monochromatic disturbances associated with atmospheric gravity waves (AGWs) as well as small-scale instabilities, often called ripples. Image-averaged temperature and intensity measurements can be used to study the response of the airglow layer to tides and planetary waves, as well as monitor longer-term climatological variations. Here we present results of low and mid-latitude OH airglow observations beginning near solar max of solar cycle 23 and continuing through solar max of cycle 24. Aerospace imagers deployed at Alice Springs (23o42'S, 133o53'E) and Adelaide (34o55'S, 138o36'E) have been operating nearly continuously since ~2001. The imagers employ filters measuring OH Meinel (6, 2) and O2 Atmospheric (0, 1) band emission intensities and temperatures, as well as atmospheric gravity wave parameters. The Aerospace Corporation's Infrared Camera deployed at Maui, HI (20.7N,156.3W), collected more than 700 nights of airglow images from 2002-2005. The camera measures the OH Meinel (4,2) emission at 1.6 um using a 1 second exposure at a 3 second cadence, which allows the study of AGW and ripple features over very short temporal and spatial scales. The camera was relocated to Cerro Pachon, Chile (30.1 S, 70.8 W) and has been operating continuously since 2010. Temperature, intensity and gravity wave climatologies derived from the two Australian airglow imagers span a full solar cycle (solar max to solar max). Emission intensities have been calibrated using background stars, and temperatures have been calibrated with respect to TIMED/SABER temperatures, reducing the influence of instrument degradation on the solar cycle climatology. An automated wave detection algorithm is used to identify quasi monochromatic wave features in the airglow data, including wavelength, wave period and propagation

  15. The Michelson Interferometer for Airglow Dynamics Imaging: Instrument Description

    Science.gov (United States)

    Langille, Jeffery; Ward, William E.; Gault, William A.; Miller, Ian; Scott, Alan

    The Michelson Interferometer for Airglow Dynamics Imaging (MIADI) is a new implementation of the imaging field-widened Michelson interferometer concept. Airglow signatures in the mesopause region are imaged through the interferometer and wind and intensity images are simultaneously recorded. The field-of-view for this instrument is a 30 degree square region. This field will be divided into 100 bins (10 by 10) and measurements of intensity and line-of-sight wind taken for each bin. Two emissions (oxygen green line and hydroxyl) will be viewed simultaneously. The scientific purpose of this instrument is to provide unambiguous information on gravity waves since the background horizontal wind, and wind and irradiance variations will be simultaneously obtained. In the paper, the measurement principle and the characteristics of the instrument will be described and some initial results presented.

  16. The Michelson Interferometer for Airglow Dynamics Imaging (MIADI)

    Science.gov (United States)

    Langille, J.; Nakamura, T.; Ward, W. E.

    2009-05-01

    The Michelson Interferometer for Airglow Dynamics Imaging (MIADI) is a new implementation of the imaging field-widened Michelson interferometer concept which images airglow signatures in the mesopause region and simultaneously records wind and intensity images. The scientific purpose of this instrument is to provide unambiguous information on gravity waves since the background horizontal wind and irradiance variations will be simultaneously obtained. Calibration and characterization of instrument parameters has been completed at a field site in Shigaraki Japan and initial observations have been taken. Co-located alongside MIADI are the MU radar, Na Lidar and several All-Sky Imagers. Observation campaigns are ongoing to acquire simultaneous data sets from these instruments. In this paper, the calibration and characterization results will be summarized. The initial measurements of winds and intensity will be presented and the scientific goals of the current observing campaign outlined.

  17. Contributions of the OH airglow to space object irradiance

    Science.gov (United States)

    Gruninger, John; Duff, James W.; Brown, James H.

    2007-10-01

    We investigated the contributions of the hydroxyl (OH) airglow to the illumination of resident space objects. During nighttime, in a moonless sky, the airglow is the largest contributor to the sky brightness in the visible (vis), the near-infrared (NIR) and short-wave infrared (SWIR) spectral region. The dominant contributors to the airglow are vibrationally excited hydroxyl radicals, OH(ν). The radicals are formed in vibrational states up to υ=9 by the reaction of hydrogen atoms with ozone. The strong emissions, known as Meinel emissions, are sequences with σν= 1-6. Emissions with υ = 3, 4, 5 and 6 occur in the visible and NIR between .4 and 1.0 µm. From 1.0 to 2.5 µm there are very strong emissions from the δν= 2 sequences. The σν= 1 emissions extend into the thermal infrared to 4.5 μm. In this work, we considered four band passes, a vis-NIR band pass, two SABER band passes centered at 1.6 and 2.0 μm, respectively, and a broad band pass around 2.7 µm. SAMM2 was utilized to compute spectra and line of sight radiances. We used line of sight (LOS) radiances to compute the irradiance on a space object that was taken as a flat plate with a Lambertian surface reflectance. Profiles of irradiance versus orientation were calculated. The OH airglow will illuminate a facet even if it is pointing somewhat upward. However, the irradiance in the 2.7 μm band pass comes almost entirely from the atmosphere in the low altitude and the earth emission.

  18. Vacuum-ultraviolet instrumentation for solar irradiance and thermospheric airglow

    Energy Technology Data Exchange (ETDEWEB)

    Woods, T.N.; Rottman, G.J. (National Center for Atmospheric Research, Boulder, CO (United States). High Altitude Observatory); Bailey, S.M.; Solomon, S.C. (Univ. of Colorado, Boulder, CO (United States). Lab. for Atmospheric and Space Physics)

    1994-02-01

    A NASA sounding rocket experiment was developed to study the solar extreme-ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far-ultraviolet (FUV) region were measured remotely from a sounding rocket on October 27, 1992. The rocket experiments also includes EUV instruments from Boston University, but only the National Center for Atmospheric Research's (NCAR)/University of Colorado's (CU) four solar instruments and one airglow instrument are discussed. The primary solar EUV instrument is a 0.25-m Rowland circle EUV spectrograph that has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2-nm resolution. Another solar irradiance instrument is an array of six silicon soft x-ray (XUV) photodiodes, each having different metallic filters coated directly on the photodiodes. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. The fourth solar instrument is a XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc sec. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2-nm spectral resolution.

  19. Near-infrared oxygen airglow from the Venus nightside

    Science.gov (United States)

    Crisp, D.; Meadows, V. S.; Allen, D. A.; Bezard, B.; Debergh, C.; Maillard, J.-P.

    1992-01-01

    Groundbased imaging and spectroscopic observations of Venus reveal intense near-infrared oxygen airglow emission from the upper atmosphere and provide new constraints on the oxygen photochemistry and dynamics near the mesopause (approximately 100 km). Atomic oxygen is produced by the Photolysis of CO2 on the dayside of Venus. These atoms are transported by the general circulation, and eventually recombine to form molecular oxygen. Because this recombination reaction is exothermic, many of these molecules are created in an excited state known as O2(delta-1). The airglow is produced as these molecules emit a photon and return to their ground state. New imaging and spectroscopic observations acquired during the summer and fall of 1991 show unexpected spatial and temporal variations in the O2(delta-1) airglow. The implications of these observations for the composition and general circulation of the upper venusian atmosphere are not yet understood but they provide important new constraints on comprehensive dynamical and chemical models of the upper mesosphere and lower thermosphere of Venus.

  20. Vacuum-ultraviolet instrumentation for solar irradiance and thermospheric airglow

    International Nuclear Information System (INIS)

    A NASA sounding rocket experiment was developed to study the solar extreme-ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far-ultraviolet (FUV) region were measured remotely from a sounding rocket on October 27, 1992. The rocket experiments also includes EUV instruments from Boston University, but only the National Center for Atmospheric Research's (NCAR)/University of Colorado's (CU) four solar instruments and one airglow instrument are discussed. The primary solar EUV instrument is a 0.25-m Rowland circle EUV spectrograph that has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2-nm resolution. Another solar irradiance instrument is an array of six silicon soft x-ray (XUV) photodiodes, each having different metallic filters coated directly on the photodiodes. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. The fourth solar instrument is a XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc sec. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2-nm spectral resolution

  1. Vacuum-ultraviolet instrumentation for solar irradiance and thermospheric airglow

    Science.gov (United States)

    Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

    1994-02-01

    A NASA sounding rocket experiment was developed to study the solar extreme-ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far-ultraviolet (FUV) region were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University, but only the National Center for Atmospheric Research's (NCAR)/University of Colorado's (CU) four solar instruments and one airglow instrument are discussed. The primary solar EUV instrument is a 0.25-m Rowland circle EUV spectrograph that has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2-nm resolution. Another solar irradiance instrument is an array of six silicon soft x-ray (XUV) photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with approximately 15-nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy, providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc sec. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2-nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates.

  2. Single vs multi-level quenching of the hydroxyl airglow

    Science.gov (United States)

    Franzen, Christoph; Espy, Patrick J.; Hibbins, Robert; Djupvik, Anlaug Amanda

    2016-04-01

    The reaction in the upper mesosphere between atomic hydrogen and ozone results in hydroxyl (OH) that is produced in excited vibrational levels 6 through 9. The vibrationally excited OH radiates in a thin (~8 km thick) layer near 87 km, giving rise to the strong near infrared airglow emission that has been used for remote sensing of the mesopause region. The interpretation of the emission relies on accurate knowledge of the population and quenching of the upper states, and open questions remain as to whether the quenching takes place through single- or multi-quantum deactivation. Here we will demonstrate how high quality spectral observations of OH (9,7) and (8,6) airglow emissions are available as background measurements during standard K-band astronomical observations from the Nordic Optical Telescope (18°W, 29°N). These emissions have been analysed to ascertain the quenching of the upper vibrational populations. Together with a steady-state model of these emissions, an estimate of the ratio of single to multi-quantum quenching efficiency and the impact on the populations of the lower vibrational levels will be presented.

  3. Mesospheric hydroxyl airglow signatures of acoustic and gravity waves generated by transient tropospheric forcing

    Science.gov (United States)

    Snively, J. B.

    2013-09-01

    Numerical model results demonstrate that acoustic waves generated by tropospheric sources may produce cylindrical "concentric ring" signatures in the mesospheric hydroxyl airglow layer. They may arrive as precursors to upward propagating gravity waves, generated simultaneously by the same sources, and produce strong temperature perturbations in the thermosphere above. Transient and short-lived, the acoustic wave airglow intensity and temperature signatures are predicted to be detectable by ground-based airglow imaging systems and may provide new insight into the forcing of the upper atmosphere from below.

  4. Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow

    Science.gov (United States)

    Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

    1993-08-01

    A NASA sounding rocket experiment was developed to study the solar extreme ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far ultraviolet (FUV) were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University (Supriya Chakrabarti), but only the National Center for Atmospheric Research (NCAR)/University of Colorado (CU) four solar instruments and one airglow instrument are discussed here. The primary solar EUV instrument is a 1/4 meter Rowland circle EUV spectrograph which has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2 nm resolution. Another solar irradiance instrument is an array of six silicon XUV photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with about 15 nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc-seconds. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2 nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates. The one-dimensional and two-dimensional CODACON detectors were developed at CU by Dr. George Lawrence. The pre-flight and post-flight photometric calibrations were performed at our calibration laboratory and at the Synchrotron Ultraviolet

  5. Calibration of the Berkeley EUV Airglow Rocket Spectrometer

    Science.gov (United States)

    Cotton, Daniel M.; Chakrabarti, Supriya; Siegmund, Oswald

    1989-01-01

    The Berkeley Extreme-ultraviolet Airglow Rocket Spectrometer (BEARS), a multiinstrument sounding rocket payload, made comprehensive measurements of the earth's dayglow. The primary instruments consisted of two near-normal Rowland mount spectrometers: one channel to measure several atomic oxygen features at high spectral resolution (about 1.5 A) in the band passes 980-1040 and 1300-1360 A, and the other to measure EUV dayglow and the solar EUV simultaneously in a much broader bandpass (250-1150 A) at moderate resolution (about 10 A). The payload also included a hydrogen Lyman-alpha photometer to monitor the solar irradiance and goecoronal emissions. The instrument was calibrated at the EUV calibration facility at the University of California at Berkeley, and was subsequently launched successfully on September 30, 1988 aboard a four-stage experimental sounding rocket, Black Brant XII flight 12.041 WT. The calibration procedure and resulting data are presented.

  6. TIMED GUVI and SEE Observations of Solar Irradiance Variations and the Terrestrial Airglow Response

    Science.gov (United States)

    Wolven, B.; Paxton, L.; Morrison, D.; Woods, T.

    2004-12-01

    Since the launch of the TIMED mission in 2001, the SEE and GUVI instruments have observed solar radiance changes during numerous solar flares, and measured their short-term impact on the terrestrial airglow, manifested as changes in both resonantly scattered and photoelectron excited emissions. The continuous coverage and higher time resolution of the GUVI airglow observations, in conjunction with the multispectral (5-color) image format, constitute a unique source of information on the time variation of the solar irradiance in different spectral regions. GUVI limb observations provide additional data on heating and composition changes in the thermosphere in response to these energy inputs. We examine changes in the observed airglow between quiet and flare conditions, and attempt to understand the differences between SEE measurements and the radiances inferred from GUVI airglow data.

  7. OH Airglow and Equatorial Variations Observed by ISUAL Instrument on Board the FORMOSAT 2 Satellite

    Directory of Open Access Journals (Sweden)

    Jan-Bai Nee

    2010-01-01

    Full Text Available OH airglow observed by the ISUAL (Imager of Sprites and Upper Atmospheric Lightning instrument on board the FORMOSAT 2 satellite is reported in this paper. The satellite is sun-synchronous and it returns to the same orbit at the same local time daily. By using this property, we can study the upper atmosphere in detail. With a CCD camera, ISUAL has measured the emission layers of OH Meinel band at 630 nm for several two-week periods in 2004 and 2007 in equatorial regions. ISUAL images are snapshots of the atmosphere 250 km (height _ 1200 km (horizontal distance. These images of OH airglow are analyzed to derive its peak height and latitudinal variations. ISUAL observation is unique in its capability of continuous observation of the upper atmosphere as the satellite travels from south to north along a specific orbit. However, 630 nm filter also measured O(1D at 200 km, and there are interferences between O(1D and OH airglows as as observed from a distance in space. We have studied the overlap of two airglows by simulations, and our final analyses show that OH airglow can be correctly derived with its average peak height of 89 _ 2.1 km usually lying within _ latitude about the equator. ISUAL data reveal detailed structures of equatorial OH airglow such as the existences of a few secondary maxima within the equatorial regions, and the oscillations of the peak latitudes. These results are discussed and compared with previous reports.

  8. Berkeley extreme-ultraviolet airglow rocket spectrometer: BEARS.

    Science.gov (United States)

    Cotton, D M; Chakrabarti, S

    1992-09-20

    We describe the Berkeley extreme-UV airglow rocket spectrometer, which is a payload designed to test several thermospheric remote-sensing concepts by measuring the terrestrial O I far-UV and extreme-UV dayglow and the solar extreme-UV spectrum simultaneously. The instrument consisted of two near-normal Rowland mount spectrometers and a Lyman-alpha photometer. The dayglow spectrometer covered two spectral regions from 980 to 1040 A and from 1300 to 1360 A with 1.5-A resolution. The solar spectrometer had a bandpass of 250-1150 A with an ~ 10-A resolution. All three spectra were accumulated by using a icrochannel-plate-intensified, two-dimensional imaging detector with three separate wedge-and strip anode readouts. The hydrogen Lyman-alpha photometer was included to monitor the solar Lyman-alpha irradiance and geocoronal Lyman-alpha emissions. The instrument was designed, fabricated, and calibrated at the University of California, Berkeley and was successfully launched on 30 September 1988 aboard the first test flight of a four-stage sounding rocket, Black Brant XII. PMID:20733778

  9. A new perspective on the molecular oxygen and hydroxyl airglow emissions

    Science.gov (United States)

    Mlynczak, Martin G.

    The mesospheric molecular oxygen and hydroxyl airglow emissions have traditionally been measured in order to derive minor species abundances or to diagnose dynamical phenomena. We present a new interpretation of these airglow emissions and show them to be fundamental measures of energy deposition from which rates of atmospheric heating are readily derived. The heating rate due to absorption of ultraviolet radiation in the Hartley band of ozone may be derived from simultaneous measurements of the oxygen atmospheric band and infrared atmospheric band volume emission rates independent of knowledge of the ozone density, the solar irradiance, and the ozone absorption cross sections. The heating rates due to key exothermic reactions may be derived directly from appropriate airglow observations independent of the reactant concentrations and the temperature-dependent reaction rates. The accuracy of heating rates derived directly from airglow measurements is also inherently higher than that obtained in standard approaches. We suggest that heating rates derived in this manner be treated as data products and that they be compared with numerical model computations to enhance understanding of atmospheric thermodynamics. An initial comparison of airglow-derived energy deposition rates with deposition rates traditionally computed from numerical models shows agreement to within 20% for the Hartley band of ozone in the lower and upper mesosphere.

  10. Simulations of airglow variations induced by the CO2 increase and solar cycle variation from 1980 to 1991

    Science.gov (United States)

    Huang, Tai-Yin

    2016-09-01

    Airglow intensity and Volume Emission Rate (VER) variations induced by the increase of CO2 gas concentration and F10.7 variation (used as a proxy for the 11-year solar cycle variation) were investigated for the period from 1980 to 1991, encompassing a full solar cycle. Two airglow models are used to simulate the induced variations of O(1S) greenline, O2(0,1) atmospheric band , and OH(8,3) airglow for this study. The results show that both the airglow intensities and peak VERs correlate positively with the F10.7 solar cycle variation and display a small linear trend due to the increase of CO2 gas concentration. The solar-cycle induced airglow intensity variations show that O(1S) greenline has the largest variation (~26%) followed by the O2(0,1) atmospheric band (~23%) and then OH(8,3) airglow (~8%) over the 11 year timespan. The magnitudes of the induced airglow intensity variations by the increase of CO2 gas concentration are about an order of magnitude smaller than those by the F10.7 solar cycle variation. In general, the F10.7 solar cycle variation and CO2 increase do not seem to systematically alter the VER peak altitude of the airglow emissions, though the OH(8,3) VER peak altitude moves up slightly during the years when the F10.7 value falls under 100 SFU.

  11. Characteristics of equatorial gravity waves derived from mesospheric airglow imaging observations

    Directory of Open Access Journals (Sweden)

    S. Suzuki

    2009-04-01

    Full Text Available We present the characteristics of small-scale (<100 km gravity waves in the equatorial mesopause region derived from OH airglow imaging observations at Kototabang (100.3° E, 0.2° S, Indonesia, from 2002 to 2005. We adopted a method that could automatically detect gravity waves in the airglow images using two-dimensional cross power spectra of gravity waves. The propagation directions of the waves were likely controlled by zonal filtering due to stratospheric mean winds that show a quasi-biennial oscillation (QBO and the presence of many wave sources in the troposphere.

  12. Hydroxyl (6−2 airglow emission intensity ratios for rotational temperature determination

    Directory of Open Access Journals (Sweden)

    R. P. Lowe

    Full Text Available OH(6–2 Q1/P1 and R1/P1 airglow emission intensity ratios, for rotational states up to j' = 4.5, are measured to be lower than implied by transition probabilities published by various authors including Mies, Langhoff et al. and Turnbull and Lowe. Experimentally determined relative values of j' transitions yield OH(6–2 rotational temperatures 2 K lower than Langhoff et al., 7 K lower than Mies and 13 K lower than Turnbull and Lowe.Key words: Atmospheric composition and structure (airglow and aurora; pressure, density and temperature

  13. HF-induced airglow structure as a proxy for ionospheric irregularity detection

    Science.gov (United States)

    Kendall, E. A.

    2013-12-01

    The High Frequency Active Auroral Research Program (HAARP) heating facility allows scientists to test current theories of plasma physics to gain a better understanding of the underlying mechanisms at work in the lower ionosphere. One powerful technique for diagnosing radio frequency interactions in the ionosphere is to use ground-based optical instrumentation. High-frequency (HF), heater-induced artificial airglow observations can be used to diagnose electron energies and distributions in the heated region, illuminate natural and/or artificially induced ionospheric irregularities, determine ExB plasma drifts, and measure quenching rates by neutral species. Artificial airglow is caused by HF-accelerated electrons colliding with various atmospheric constituents, which in turn emit a photon. The most common emissions are 630.0 nm O(1D), 557.7 nm O(1S), and 427.8 nm N2+(1NG). Because more photons will be emitted in regions of higher electron energization, it may be possible to use airglow imaging to map artificial field-aligned irregularities at a particular altitude range in the ionosphere. Since fairly wide field-of-view imagers are typically deployed in airglow campaigns, it is not well-known what meter-scale features exist in the artificial airglow emissions. Rocket data show that heater-induced electron density variations, or irregularities, consist of bundles of ~10-m-wide magnetic field-aligned filaments with a mean depletion depth of 6% [Kelley et al., 1995]. These bundles themselves constitute small-scale structures with widths of 1.5 to 6 km. Telescopic imaging provides high resolution spatial coverage of ionospheric irregularities and goes hand in hand with other observing techniques such as GPS scintillation, radar, and ionosonde. Since airglow observations can presumably image ionospheric irregularities (electron density variations), they can be used to determine the spatial scale variation, the fill factor, and the lifetime characteristics of

  14. Application of tomographic inversion in studying airglow in the mesopause region

    Directory of Open Access Journals (Sweden)

    T. Nygrén

    Full Text Available It is pointed out that observations of periodic nightglow structures give excellent information on atmospheric gravity waves in the mesosphere and lower thermosphere. The periods, the horizontal wavelengths and the phase speeds of the waves can be determined from airglow images and, using several cameras, the approximate altitude of the luminous layer can also be determined by triangulation. In this paper the possibility of applying tomographic methods for reconstructing the airglow structures is investigated using numerical simulations. A ground-based chain of cameras is assumed, two-dimensional airglow models in the vertical plane above the chain are constructed, and simulated data are calculated by integrating the models along a great number of rays with different elevation angles for each camera. After addition of random noise, these data are then inverted to obtain reconstructions of the models. A tomographic analysis package originally designed for satellite radiotomography is used in the inversion. The package is based on a formulation of stochastic inversion which allows the input of a priori information to the solver in terms of regularization variances. The reconstruction is carried out in two stages. In the first inversion, constant regularization variances are used within a wide altitude range. The results are used in determining the approximate altitude range of the airglow structures. Then, in the second inversion, constant non-zero regularization variances are used inside this region and zero variances outside it. With this method reliable reconstructions of the models are obtained. The number of cameras as well as their separations are varied in order to find out the limitations of the method.

    Key words. Tomography · Airglow · Mesopause · Gravity waves

  15. First spaceborne observation of the entire concentric airglow structure caused by tropospheric disturbance

    Science.gov (United States)

    Akiya, Y.; Saito, A.; Sakanoi, T.; Hozumi, Y.; Yamazaki, A.; Otsuka, Y.; Nishioka, M.; Tsugawa, T.

    2014-10-01

    Spaceborne imagers are able to observe the airglow structures with wide field of views regardless of the tropospheric condition that limits the observational time of the ground-based imagers. Concentric wave structures of the O2 airglow in 762 nm wavelength were observed over North America on 1 June 2013 from the International Space Station. This was the first observation in which the entire image of the structure was captured from space, and its spatial scale size was determined to be 1200 km radius without assumptions. The apparent horizontal wavelength was 80 km, and the amplitude in the intensity was approximately 20% of the background intensity. The propagation velocity of the structure was derived as 125 ± 62 m/s and atmospheric gravity waves were estimated to be generated for 3.5 ± 1.7 h. Concentric structures observed in this event were interpreted to be generated by super cells that caused a tornado in its early phase.

  16. HF-enhanced 4278-Å airglow: evidence of accelerated ionosphere electrons?

    Science.gov (United States)

    Fallen, C. T.; Watkins, B. J.

    2013-12-01

    We report calculations from a one-dimensional physics-based self-consistent ionosphere model (SCIM) demonstrating that HF-heating of F-region electrons can produce 4278-Å airglow enhancements comparable in magnitude to those reported during ionosphere HF modification experiments at the High-frequency Active Auroral Research Program (HAARP) observatory in Alaska. These artificial 'blue-line' emissions, also observed at the EISCAT ionosphere heating facility in Norway, have been attributed to arise solely from additional production of N2+ ions through impact ionization of N2 molecules by HF-accelerated electrons. Each N2+ ion produced by impact ionization or photoionization has a probability of being created in the N2+(1N) excited state, resulting in a blue-line emission from the allowed transition to its ground state. The ionization potential of N2 exceeds 18 eV, so enhanced impact ionization of N2 implies that significant electron acceleration processes occur in the HF-modified ionosphere. Further, because of the fast N2+ emission time, measurements of 4278-Å intensity during ionosphere HF modification experiments at HAARP have also been used to estimate artificial ionization rates. To the best of our knowledge, all observations of HF-enhanced blue-line emissions have been made during twilight conditions when resonant scattering of sunlight by N2+ ions is a significant source of 4278-Å airglow. Our model calculations show that F-region electron heating by powerful O-mode HF waves transmitted from HAARP is sufficient to increase N2+ ion densities above the shadow height through temperature-enhanced ambipolar diffusion and temperature-suppressed ion recombination. Resonant scattering from the modified sunlit region can cause a 10-20 R increase in 4278-Å airglow intensity, comparable in magnitude to artificial emissions measured during ionosphere HF-modification experiments. This thermally-induced artificial 4278-Å aurora occurs independently of any artificial

  17. Mars dayside temperature from airglow limb profiles : comparison with in situ measurements and models

    Science.gov (United States)

    Gérard, Jean-Claude; Bougher, Stephen; Montmessin, Franck; Bertaux, Jean-Loup; Stiepen, A.

    The thermal structure of the Mars upper atmosphere is the result of the thermal balance between heating by EUV solar radiation, infrared heating and cooling, conduction and dynamic influences such as gravity waves, planetary waves, and tides. It has been derived from observations performed from different spacecraft. These include in situ measurements of orbital drag whose strength depends on the local gas density. Atmospheric temperatures were determined from the altitude variation of the density measured in situ by the Viking landers and orbital drag measurements. Another method is based on remote sensing measurements of ultraviolet airglow limb profiles obtained over 40 years ago with spectrometers during the Mariner 6 and 7 flybys and from the Mariner 9 orbiter. Comparisons with model calculations indicate that they both reflect the CO_2 scale height from which atmospheric temperatures have been deduced. Upper atmospheric temperatures varying over the wide range 270-445 K, with a mean value of 325 K were deduced from the topside scale height of the airglow vertical profile. We present an analysis of limb profiles of the CO Cameron (a(3) Pi-X(1) Sigma(+) ) and CO_2(+) doublet (B(2) Sigma_u(+) - X(2) PiΠ_g) airglows observed with the SPICAM instrument on board Mars Express. We show that the temperature in the Mars thermosphere is very variable with a mean value of 270 K, but values ranging between 150 and 400 K have been observed. These values are compared to earlier determinations and model predictions. No clear dependence on solar zenith angle, latitude or season is apparent. Similarly, exospheric variations with F10.7 in the SPICAM airglow dataset are small over the solar minimum to moderate conditions sampled by Mars Express since 2005. We conclude that an unidentified process is the cause of the large observed temperature variability, which dominates the other sources of temperature variations.

  18. Monitoring Saturn's Upper Atmosphere Density Variations Using Helium 584 Å Airglow

    Science.gov (United States)

    Parkinson, Chris

    2016-10-01

    The study of He 584 Å brightness of Saturn is interesting as the EUV planetary airglow have the potential to yield useful information about mixing and other important parameters in its thermosphere. Resonance scattering of sunlight by He atoms is the principal source of the planetary emission of He 585 Å. The helium is embedded in an absorbing atmosphere of H2 and since it is heavier than the background atmosphere, it's concentration falls off rapidly above the homopause. The scattering region (i.e. where the absorption optical depth in H2 is science objective discussed is the estimation of the helium mixing ratio in the lower atmosphere. Specifically, He emissions come from above the homopause where τ =1 in H2 and therefore the interpretation depends mainly on two parameters: He mixing ratio of the lower atmosphere and Kzz. The occultations of Koskinen et al (2015) give Kzz with an accuracy that has never been possible before and the combination of occultations and airglow therefore provide estimates of the mixing ratio in the lower atmosphere. We have made these estimates at several locations that can be reasonably studied with both occultations and airglow and then average the results. Our results point to a greatly improved estimate of the mixing ratio of He in the upper atmosphere and below. The second topic addressed is regarding constraining the dynamics in the atmosphere by using the estimate of the He mixing ratio from the main objective. Once we have an estimate of the He mixing ratio in the lower atmosphere that agrees with both occultations and airglow, helium becomes an effective tracer species as any variations in the Cassini UVIS helium data are direct indicator of changes in Kzz i.e., dynamics.

  19. Thermospheric airglow emissions - A comparison of measurements from Atlas-1 and theory

    Science.gov (United States)

    Torr, Douglas G.; Torr, Marsha R.; Richards, P. G.

    1993-01-01

    A comprehensive thermospheric model is presently used to derive conditions appropriate to the time of the Atlas-1 Space Shuttle mission, comparing the slant-path intensities thus computed as a function of altitude, latitude, and local time with a dozen major emissions measured in the course of a specific observing sequence. The agreement thus obtained is found to be reasonably good, implying that the major thermospheric airglow-controlling processes are essentially understood.

  20. Equatorial Spread F structures and associated airglow intensity variations observed over Gadanki

    Directory of Open Access Journals (Sweden)

    R. Sekar

    2008-12-01

    Full Text Available Co-ordinated campaigns have been conducted from Gadanki (13.5° N, 79.2° E, dip lat 6.4° N by operating simultaneously the Indian MST radar in ionospheric coherent backscatter mode and by monitoring thermosphere airglow line emissions (630.0 nm and 777.4 nm using a narrow band multi-wavelength scanning photometer during January-March for the past five years (2003–2007 and also during April 2006, as a special campaign. Simultaneous radar and optical observations reveal optical signatures corresponding to a variety of equatorial spread F (ESF structures. The optical signatures corresponding to ESF structures with wave-like bottomside modulations with plasma plumes, confined bottomside flat and wavelike structures, vertically extended plume structure in the absence of bottomside structure apart from the classical plasma depletions and enhancements are obtained during these campaigns. The plasma depletions and enhancements were identified using optical measurements. In addition, estimations of zonal wavelength of the bottomside structures and the inference of shears in the zonal plasma drift in the presence of confined structures, were carried out using bi-directional airglow measurements. Furthermore, it is found that the vertical columnar intensity of OI 630.0 nm airglow exceeded the slanted columnar intensity in the presence of large bottomside structure. The need for the appropriate physical mechanisms for some of the ESF structures and their characterizations with optical observations are discussed.

  1. Mesospheric airglow and ionospheric responses to upward-propagating acoustic and gravity waves above tropospheric sources

    Science.gov (United States)

    Snively, J. B.; Zettergren, M. D.

    2013-12-01

    The existence of acoustic waves (periods ~1-5 minutes) and gravity waves (periods >4 minutes) in the ionosphere above active tropospheric convection has been appreciated for more than forty years [e.g., Georges, Rev. Geophys. and Space Phys., 11(3), 1973]. Likewise, gravity waves exhibiting cylindrical symmetry and curvature of phase fronts have been observed via imaging of the mesospheric airglow layers [e.g., Yue et al., JGR, 118(8), 2013], clearly associated with tropospheric convection; gravity wave signatures have also recently been detected above convection in ionospheric total electron content (TEC) measurements [Lay et al., GRL, 40, 2013]. We here investigate the observable features of acoustic waves, and their relationship to upward-propagating gravity waves generated by the same sources, as they arrive in the mesosphere, lower-thermosphere, and ionosphere (MLTI). Numerical simulations using a nonlinear, cylindrically-axisymmetric, compressible atmospheric dynamics model confirm that acoustic waves generated by transient tropospheric sources may produce "concentric ring" signatures in the mesospheric hydroxyl airglow layer that precede the arrival of gravity waves. As amplitudes increase with altitude and decreasing neutral density, the modeled acoustic waves achieve temperature and vertical wind perturbations on the order of ~10s of Kelvin and m/s throughout the E- and F-region. Using a coupled multi-fluid ionospheric model [Zettergren and Semeter, JGR, 117(A6), 2012], extended for low-latitudes using a 2D dipole magnetic field coordinate system, we investigate acoustic wave perturbations to the ionosphere in the meridional direction. Resulting perturbations are predicted to be detectable by ground-based radar and GPS TEC measurements, or via in situ instrumentation. Although transient and short-lived, the acoustic waves' airglow and ionospheric signatures are likely to in some cases be observable, and may provide important insight into the regional

  2. Calibration of imaging parameters for space-borne airglow photography using city light positions

    Science.gov (United States)

    Hozumi, Yuta; Saito, Akinori; Ejiri, Mitsumu K.

    2016-09-01

    A new method for calibrating imaging parameters of photographs taken from the International Space Station (ISS) is presented in this report. Airglow in the mesosphere and the F-region ionosphere was captured on the limb of the Earth with a digital single-lens reflex camera from the ISS by astronauts. To utilize the photographs as scientific data, imaging parameters, such as the angle of view, exact position, and orientation of the camera, should be determined because they are not measured at the time of imaging. A new calibration method using city light positions shown in the photographs was developed to determine these imaging parameters with high accuracy suitable for airglow study. Applying the pinhole camera model, the apparent city light positions on the photograph are matched with the actual city light locations on Earth, which are derived from the global nighttime stable light map data obtained by the Defense Meteorological Satellite Program satellite. The correct imaging parameters are determined in an iterative process by matching the apparent positions on the image with the actual city light locations. We applied this calibration method to photographs taken on August 26, 2014, and confirmed that the result is correct. The precision of the calibration was evaluated by comparing the results from six different photographs with the same imaging parameters. The precisions in determining the camera position and orientation are estimated to be ±2.2 km and ±0.08°, respectively. The 0.08° difference in the orientation yields a 2.9-km difference at a tangential point of 90 km in altitude. The airglow structures in the photographs were mapped to geographical points using the calibrated imaging parameters and compared with a simultaneous observation by the Visible and near-Infrared Spectral Imager of the Ionosphere, Mesosphere, Upper Atmosphere, and Plasmasphere mapping mission installed on the ISS. The comparison shows good agreements and supports the validity

  3. Median Algorithm for Sector Spectra Calculation from Images Registered by the Spectral Airglow Temperature Imager

    CERN Document Server

    Atanassov, Atanas Marinov

    2011-01-01

    The Spectral Airglow Temperature Imager is an instrument, specially designed for investigation of the wave processes in the Mesosphere-Lower Thermosphere. In order to determine the kinematic parameters of a wave, the values of a physical quantity in different space points and their changes in the time should be known. As a result of the possibilities of the SATI instrument for space scanning, different parts of the images (sectors of spectrograms) correspond to the respective mesopause areas (where the radiation is generated). An approach is proposed for sector spectra determination from SATI images based on ordered statistics instead of meaning. Comparative results are shown.

  4. Discovery of a new orange feature from FeO in the night airglow with the OSIRIS spectrograph

    Science.gov (United States)

    Evans, W. F.; Gattinger, R.; Llewellyn, E. J.; Degenstein, D. A.; Slanger, T. G.

    2010-12-01

    The discovery of a new airglow feature in the earth’s atmosphere is presented. The FeO orange feature has been detected in the night airglow spectrum with the OSIRIS spectrograph on the ODIN spacecraft. The orange chemiluminescent airglow has been measured in the spectral region from 530 nm to 650 nm. The OSIRIS imaging spectrograph measures the airglow spectrum over the 275 to 815 nm wavelength range. At the spectral resolution of OSIRIS, the band systems of FeO appear as a weak continuum-like structure in the 600 nm region at 85 km in the upper mesosphere. As the satellite scans, spectra are obtained of the terrestrial limb with tangent altitudes ranging between 5 km and 110 km. Since the instrument is a CCD spectrograph, all wavelengths are exposed simultaneously thus avoiding the effect of temporal intensity variations inherently present in spectrally scanning instruments. The relative spectral sensitivity over the entire wavelength range has been quantified to yield an estimated 5% precision. In order to maintain accurate on-orbit spectral calibrations an atmospheric radiation model with multiple Rayleigh scattering is employed to regularly update the OSIRIS spectral response. Averages of spectra at a series of tangent limb altitudes were assembled from numerous limb scans at low latitudes. Limb radiance altitude profiles for a number of observed spectral features were obtained from these averaged spectra. These radiance profiles were inverted to obtain volume emission rate altitude profiles. Synthetic spectra for the hydroxyl and O2 Herzberg airglow emission bands were generated and scaled with the observed band intensities to remove the known airglow components in order to isolate the underlying airglow feature. Tropical latitudes were chosen to minimize the classic green airglow continuum from the reaction of nitric oxide with atomic oxygen since nitric oxide is small at 90 km in the tropics. Other potential photochemical sources of the orange glow are

  5. Calibration of the San Marco airglow-solar spectrometer instrument in the extreme ultraviolet

    Science.gov (United States)

    Worden, John; Woods, Thomas N.; Rottman, Gary J.; Schmidtke, Gerhard; Tai, Hongsheng; Doll, Harry G.; Solomon, Stanley C.

    1996-02-01

    The San Marco 5 carried the airglow-solar spectrometer instrument (ASSI). This 18-channel spectrometer measured the solar and terrestrial radiation in the wavelength region between 20 and 700 nm for 9 months in 1988. The ASSI extreme ultraviolet (EUV) channels showed significant sensitivity changes during the mission. The sensitivity changes of the EUV channels are quantified by comparing ASSI solar EUV irradiance measurements to the solar EUV irradiance derived from a solar proxy model. A sensitivity change model is developed that shows that exponential curves can adequately describe the sensitivity changes of the ASSI optics and detectors. The November 10 calibration parameters and the sensitivity change model can be used to derive the EUV terrestrial airglow brightness for the time period of the ASSI mission. Analysis of the solar Lyman-(alpha) irradiance measured by the ASSI, the solar mesospheric explorer (SME), and the upper atmosphere research satellite has led to a revised Lyman-(alpha) irradiance for the San Marco mission. For example, the ASSI November 10, 1988, Lyman-(alpha) measurement is 5.3 X 1011 photons cm-2 s-1 versus the reported SME measurement of 3.35 X 1011 photons cm-2 s-1.

  6. Modeling of Na airglow emission and first results on the nocturnal variation at midlatitude

    Science.gov (United States)

    Bag, T.; Sunil Krishna, M. V.; Singh, Vir

    2015-12-01

    A model for sodium airglow emission is developed by incorporating all the known reaction mechanisms. The neutral, ionic, and photochemical mechanisms are successfully implemented into this model. The values of reaction rate coefficients are based upon the theoretical calculations as well as from experimental observations. The densities of major species are calculated using the continuity equations, whereas for the minor, intermediating, and short-lived species steady state approximation method is used. The modeled results are validated with the rocket, lidar, and photometer observations for a branching ratio of 0.04 for the production of Na(2P) in the reaction NaO + O → Na(2P, 2S). The inputs have been obtained from other physics-based models and ground- and satellite-based observations to give the combined volume emission rate (VER) of Na airglow between 80 and 110 km altitude. In the present study, the model is used to understand the nocturnal variation of Na VER during the solstice conditions. The model results suggest a variation of peak emission layer between 85 and 90 km during summer solstice condition, indicating a lower value of peak emission rate during summer solstice. The emission rates bear a strong correlation with the O3 density during summer solstice, whereas the magnitude of VER follows the Na density during winter solstice. The altitude of peak VER shows an upward shift of 5 km during winter solstice.

  7. Measurement of mesospheric winds using the Michelson Interferometer for Airglow Dynamics Imaging (MIADI)

    Science.gov (United States)

    Langille, Jeffery; Ward, William E.; Nakamura, Takuji

    MIADI images the wind and irradiance fields present in mesospheric airglow signatures using a new implementation of the field widened Michelson technique. The system is unique in its ability to image the mean wind and irradiance as well as the perturbation quantities, allowing for unambiguous gravity wave parameters to be derived using a single optical element. MIADI was installed and tested at the MU radar field site in Shigaraki Japan in 2009. Several nights of observations have been obtained and the initial analysis has been completed. In this presentation, the instrument technique, calibration process and installation/testing will be described and the analysis of the initial wind and irradiance measurements will be presented.

  8. Seasonal dependence of MSTIDs obtained from 630.0 nm airglow imaging at Arecibo

    Science.gov (United States)

    Martinis, C.; Baumgardner, J.; Wroten, J.; Mendillo, M.

    2010-06-01

    All-sky imaging data of 630.0 nm airglow emissions are used to study the seasonal and solar activity dependence of medium-scale traveling ionospheric disturbances (MSTIDs) over Arecibo, Puerto Rico (18.3° N, 66.7° W, 28° N mag lat). MSTIDs are typical F-region signatures at midlatitudes, yet limited statistical results in the American sector hindered the progress in our understanding of these dynamical structures. This study compiles data from 2002 to 2007 and shows for the first time that optically-determined MSTIDs at Arecibo present a semiannual pattern with peak occurrence at both solstices. In the Japanese longitude sector, a similar pattern has been found, but one with a main peak during local summer. This paper explains the high occurrence rate during local winter at Arecibo via E-layer/F-layer coupling and inter-hemispheric coupling, thus accounting for a consistent morphology between the two longitude sectors.

  9. A GIANO-TNG high resolution IR spectrum of the airglow emission

    CERN Document Server

    Oliva, E; Maiolino, R; Baffa, C; Biliotti, V; Bruno, P; Falcini, G; Gavriousev, V; Ghinassi, F; Giani, E; Gonzalez, M; Leone, F; Lodi, M; Massi, F; Montegriffo, P; Mochi, I; Pedani, M; Rossetti, E; Scuderi, S; Sozzi, M; Tozzi, A; Valenti, E

    2013-01-01

    A flux-calibrated high resolution spectrum of the airglow emission is a practical lambda-calibration reference for astronomical spectral observations. It is also useful for constraining the molecular parameters of the OH molecule and the physical conditions in the upper mesosphere. methods: We use the data collected during the first technical commissioning of the GIANO spectrograph at the Telescopio Nazionale Galileo (TNG). The high resolution (R~50,000) spectrum simultaneously covers the 0.95-2.4 micron wavelength range. Relative flux calibration is achieved by the simultaneous observation of spectrophotometric standard star. results: We derive a list of improved positions and intensities of OH infrared lines. The list includes Lambda-split doublets many of which are spectrally resolved. Compared to previous works, the new results correct errors in the wavelengths of the Q-branch transitions. The relative fluxes of OH lines from different vibrational bands show remarkable deviations from theoretical predicti...

  10. Dynamics of the polar mesopause and lower thermosphere region as observed in the night airglow emissions

    International Nuclear Information System (INIS)

    This work utilizes night airglow emissions to deduce temperatures, dynamics, energetics, transport and photochemistry of the polar 80-110 km atmospheric region. The morphological behaviour of the polar 80-110 km region as seen in the night airglow emissions is best described by quasi regular to regular variations in the temperature and in the intensities of the emissions with periods ranging from minutes to a few days. Temperature amplitudes are seen from a few degrees up to ±50 K. Intensity changes up to several hundred percent may occur. Gravity waves from below are generally found to be present in the region, being responsible for much of the short period variations. The long period variations are seen to be related to circulation changes in the lower atmosphere. Stratospheric warmings are generally associated by a cooling of the 80-110 km region by a ratio approximately twice as large in amplitude as the heating at the 10 mbar level. The semidiurnal tide is found to be dominant with a peak to peak amplitude of about 5 K, in contrast to model calculations. Effects from geomagnetic phenomena on the energetics and dynamics of the region are not seen and, if present, have to be small or rare as compared to the influence from below. There is a mesopause temperature maximum at winter solstice. Pronounced differences in the day to day and seasonal behaviour of the odd oxygen associated nightglows at the North and South Pole are found. This may indicate fundamental differences at the two poles in the winter mesopause region circulation and energetics

  11. Use of O2 airglow for calibrating direct atomic oxygen measurements from sounding rockets

    Directory of Open Access Journals (Sweden)

    G. Witt

    2009-06-01

    Full Text Available Accurate knowledge about the distribution of atomic oxygen is crucial for many studies of the mesosphere and lower thermosphere. Direct measurements of atomic oxygen by the resonance fluorescence technique at 130 nm have been made from many sounding rocket payloads in the past. This measurement technique yields atomic oxygen profiles with good sensitivity and altitude resolution. However, accuracy is a problem as calibration and aerodynamics make the quantitative analysis challenging. In general, accuracies better than a factor 2 are not to be expected from direct atomic oxygen measurements. As an example, we present results from the NLTE (non local thermodynamic equilibrium sounding rocket campaign at Esrange, Sweden, in 1998, with simultaneous O2 airglow and O resonance fluorescence measurements. O number densities are found to be consistent with the nightglow analysis, but only within the uncertainty limits of the resonance fluorescence technique. Based on these results, we here describe how better atomic oxygen number densities can be obtained by calibrating direct techniques with complementary airglow photometer measurements and detailed aerodynamic analysis. Night-time direct O measurements can be complemented by photometric detection of the O2 (b1Σg+−X3Σg− atmospheric band at 762 nm, while during daytime the O2 (a1Δg−X3Σg− infrared atmospheric band at 1.27 μm can be used. The combination of a photometer and a rather simple resonance fluorescence probe can provide atomic oxygen profiles with both good accuracy and good height resolution.

  12. Use of O2 airglow for calibrating direct atomic oxygen measurements from sounding rockets

    Directory of Open Access Journals (Sweden)

    G. Witt

    2009-12-01

    Full Text Available Accurate knowledge about the distribution of atomic oxygen is crucial for many studies of the mesosphere and lower thermosphere. Direct measurements of atomic oxygen by the resonance fluorescence technique at 130 nm have been made from many sounding rocket payloads in the past. This measurement technique yields atomic oxygen profiles with good sensitivity and altitude resolution. However, accuracy is a problem as calibration and aerodynamics make the quantitative analysis challenging. Most often, accuracies better than a factor 2 are not to be expected from direct atomic oxygen measurements. As an example, we present results from the NLTE (Non Local Thermodynamic Equilibrium sounding rocket campaign at Esrange, Sweden, in 1998, with simultaneous O2 airglow and O resonance fluorescence measurements. O number densities are found to be consistent with the nightglow analysis, but only within the uncertainty limits of the resonance fluorescence technique. Based on these results, we here describe how better atomic oxygen number densities can be obtained by calibrating direct techniques with complementary airglow photometer measurements and detailed aerodynamic analysis. Night-time direct O measurements can be complemented by photometric detection of the O2 (b1∑g+−X3∑g- Atmospheric Band at 762 nm, while during daytime the O2 (a1Δg−X3∑g- Infrared Atmospheric Band at 1.27 μm can be used. The combination of a photometer and a rather simple resonance fluorescence probe can provide atomic oxygen profiles with both good accuracy and good height resolution.

  13. Climatology of planetary wave type oscillations with periods of 2–20 days derived from O2 atmospheric and OH(6-2) airglow observations at mid-latitude with SATI

    OpenAIRE

    M. J. López-González; Rodríguez, E.; M. García-Comas; Costa, V; Shepherd, M G; Shepherd, G. G.; Aushev, V. M.; S. Sargoytchev

    2009-01-01

    The presence of planetary wave type oscillations at mid-latitudes in the mesosphere/lower thermosphere region has been investigated using airglow observations. The observations were taken with a Spectral Airglow Temperature Imager (SATI) installed at Sierra Nevada Observatory (37.06° N, 3.38° W) at 2900 m height. Airglow data of the column emission rate of the O2 Atmospheric (0-1) band and of the OH Meinel (6-2) band and deduced rotational temperatur...

  14. Mesoscale field-aligned irregularity structures (FAIs) of airglow associated with medium-scale traveling ionospheric disturbances (MSTIDs)

    Science.gov (United States)

    Sun, Longchang; Xu, Jiyao; Wang, Wenbin; Yue, Xinan; Yuan, Wei; Ning, Baiqi; Zhang, Donghe; Meneses, F. C.

    2015-11-01

    In this paper, we report the evolution (generation, amplification, and dissipation) of optically observed mesoscale field-aligned irregularity structures (FAIs) (~150 km) associated with a medium-scale traveling ionospheric disturbance (MSTID) event. There have not been observations of mesoscale FAIs of airglow before. The mesoscale FAIs were generated in an airglow-depleted front of southwestward propagating MSTIDs that were simultaneously observed by an all-sky imager, a GPS monitor, and a digisonde around Xinglong (40.4°N, 30.5° magnetic latitude), China, on 17/18 February 2012. A normalized cross-correlation method has been used to obtain the velocities of mesoscale FAIs and MSTIDs. The mesoscale FAIs had an obvious northwestward relative velocity to main-body MSTIDs (about 87.0 m/s on average). The direction of this relative velocity was roughly parallel to the depleted fronts. Furthermore, the evolution of the mesoscale FAIs was mostly controlled by the intensity of the depleted fronts. Occurred in a highly elevated ionosphere that had a total electron content depletion associated with large negative airglow perturbations (-25%), the mesoscale FAIs grew rapidly when they experienced southeastward wind, which had a speed of about 100 m/s and were measured by a Fabry-Perot interferometer. A northeastward polarization electric field within a depleted airglow front can play a controlling role in the development of the mesoscale FAIs. The electric field can significantly elevate the ionosphere and move the mesoscale FAIs northwestward by the E × B drift. The processes for the generation and development of the polarization electric field and the mesoscale FAIs, however, need further study.

  15. Partially light-controlled imager based on liquid crystal plate and image intensifier for aurora and airglow measurement.

    Science.gov (United States)

    Tang, Yuanhe; Cao, Xiangang; Liu, Hanchen; Shepherd, G G; Liu, Shulin; Gao, Haiyang; Yang, Xusan; Wu, Yong; Wang, Shuiwei

    2012-04-20

    In order to obtain information both of aurora and airglow in one image by the same detector, a PLCI based on liquid crystal plate LCP and super second-generation image intensifier SSGII is proposed in this research. The detection thresholds of the CCD for aurora and airglow are calculated. For the detectable illumination range of 10(4)-10(-2) lx, the corresponding electron count is 1.57×10(5) - 0.2 for every pixel of CCD. The structure and work principle of the PLCI are described. An LC is introduced in the front of CCD to decrease the intensities of aurora in overexposure areas by means of controlling transmittances pixel by pixel, while an image intensifier is set between the LC and CCD to increase the intensity of the weak airglow. The modulation transfer function MTF of this system is calculated as 0.391 at a Nyquist frequency of 15 lp/mm. The curve of transmittance with regard to gray level for the LC is obtained by calibration experiment. Based on the design principle, the prototype is made and used to take photos of objects under strong light greater than 2×10(5) lx. The clear details of [symbols: see text] presented in the image indicate that the PLCI can greatly improve the imaging quality. The theoretical calculations and experiment results prove that this device can extend the dynamic range and it provides a more effective method for upper atmospheric wind measurement.

  16. Upper atmospheric processes as measured by collocated Lidar, infrasound, radiometer and airglow measurements

    Science.gov (United States)

    Le Pichon, A.; Blanc, E.; Assink, J. D.; Ceranna, L.; Pilger, C.; Ross, O.; Keckhut, P.; Hauchecorne, A.; Schmidt, C.; Bittner, M.; Wuest, S.; Rüfenacht, R.; Kaempfer, N.; Smets, P.

    2013-12-01

    To better initialize weather forecasting systems, a key challenge is to understand stratosphere-resolving climate models. The ARISE project (http://arise-project.eu/) aims to design a novel infrastructure integrating different atmospheric observation networks to accurately recover the vertical structure of the wind and temperature from the ground to the mesosphere. This network includes Lidar and mesospheric airglow observations, complemented by continuous infrasound measurements. Together with additional ground-based wind radar system, such complementary techniques help to better describe the interaction between atmospheric layers from the ground to the mesosphere and the influence of large scale waves on the atmospheric dynamics. Systematic comparisons between these observations and the ECMWF upper wind and temperature models (http://www.ecmwf.int/) have been performed at the OHP site (Haute-Provence Observatory, France). The main results are outlined below. - Systematic comparisons between Lidar soundings (NDACC, http://ndacc-lidar.org/) and ECMWF highlight differences increasing with altitude. Below 50 km altitude, differences are as large as 20°K. In average, the temperature appears to be overestimated by ~5 m/s in the stratosphere and underestimated by ~10 m/s in the mesopause. - Comparisons with collocated infrasound measurements provide additional useful integrated information about the structure of the stratospheric waveguide. Below 0.5 Hz, most infrasound signals originate from ocean swells in the North Atlantic region. As expected, since most long-range propagating signals travel in the stratospheric waveguide, improved detection capability occurs downwind. Deviations from this trend are either related to short time-scale variability of the atmosphere (e.g., large-scale planetary waves, stratospheric warming effects), or can be explained by changes in the nature of the source. We investigate possible correlation between unexpected propagation paths and

  17. Solar measurements from the Airglow-Solar Spectrometer Instrument (ASSI) on the San Marco 5 satellite

    Science.gov (United States)

    Woods, Thomas N.

    1994-04-01

    The analysis of the solar spectral irradiance from the Airglow-Solar Spectrometer Instrument (ASSI) on the San Marco 5 satellite is the focus for this research grant. A pre-print copy of the paper describing the calibrations of and results from the San Marco ASSI is attached to this report. The calibration of the ASSI included (1) transfer of photometric calibration from a rocket experiment and the Solar Mesosphere Explorer (SME), (2) use of the on-board radioactive calibration sources, (3) validation of the ASSI sensitivity over its field of view, and (4) determining the degradation of the spectrometers. We have determined that the absolute values for the solar irradiance needs adjustment in the current proxy models of the solar UV irradiance, and the amount of solar variability from the proxy models are in reasonable agreement with the ASSI measurements. This research grant also has supported the development of a new solar EUV irradiance proxy model. We expected that the magnetic flux is responsible for most of the heating, via Alfen waves, in the chromosphere, transition region, and corona. From examining time series of solar irradiance data and magnetic fields at different levels, we did indeed find that the chromospheric emissions correlate best with the large magnetic field levels.

  18. A Climatology of Ripple Instabilities in the OH Airglow at Cerro Pachon, Chile

    Science.gov (United States)

    Gelinas, L. J.; Hecht, J. H.; Walterscheid, R. L.; Rudy, R. J.

    2015-12-01

    Airglow imaging provides a unique means by which to study many wave-related phenomena in the 80 to 100 km altitude regime. Observations reveal quasi-monochromatic disturbances associated with atmospheric gravity waves (AGWs) as well as small-scale instabilities often called ripples. Ripples are wavelike features that resemble AGWs in appearance, but have short horizontal wavelengths (Corporation's Nightglow Imager (ANI) is located at the Andes Lidar Observatory near the crest of Cerro Pachon, Chile. ANI observes nighttime OH emission (near 1.6 microns) every 2 seconds over an approximate 73 degree field of view, which allows the study of AGW and ripple features over very short temporal and spatial scales. An automated wave detection algorithm is used to identify ripple and quasi monochromatic wave features in the ANI data. Ripples are characterized by their wavelength, orientation, drift speed and location in the image. Quasi-monochromatic waves are quantified by wavelength, wave period and propagation direction. We present a climatology of ripple instabilities at Chile, including comparisons to the background quasi-monochromatic wave field. Lidar and radar data are used to determine the background wind and temperatures, which allows comparisons between ripple observations and evanescent regions and potentially unstable regions identified by Richardson number.

  19. Atmospheric wave induced O2 and OH airglow intensity variations: effect of vertical wavelength and damping

    Directory of Open Access Journals (Sweden)

    D. Gobbi

    2011-04-01

    Full Text Available From nocturnal variations of the airglow O2 (0-1 and OH Meinel (6-2 band emission intensity and the rotational temperature, gravity waves and the damping effect in the MLT region were investigated. The data set was obtained from photometer measurements at Rikubetsu (43.5° N, 143.8° E, Japan, from March 2004 to August 2005. The ratio of the amplitude of oscillation and their phase difference between the two emissions were calculated when simultaneous periodic variations were observed. The ratio showed a linear correlation with the phase difference. The vertical wavelength and damping rate were estimated by using a model calculation carried out by previous works. The results show that the wave damping is significant when the vertical wavelength is shorter than 30–40 km. Krassovsky's parameter η, which represents a ratio between the emission intensity and temperature oscillations, was also calculated. The results show that the η also depends on the damping effect.

  20. Tidal and gravity waves study from the airglow measurements at Kolhapur (India)

    Indian Academy of Sciences (India)

    R N Ghodpage; Devendraa Siingh; R P Singh; G K Mukherjee; P Vohat; A K Singh

    2012-12-01

    Simultaneous photometric measurements of the OI 557.7 nm and OH (7, 2) band from a low latitude station, Kolhapur (16.8°N, 74.2°E) during the period 2004–2007 are analyzed to study the dominant waves present in the 80–100 km altitude region of the atmosphere. The nocturnal intensity variations of different airglow emissions are observed using scanning temperature controlled filter photometers. Waves having period lying between 2 and 12 hours have been recorded. Some of these waves having subharmonic tidal oscillation periods 4, 6, 8 and 12 hours propagate upward with velocity lying in the range 1.6–11.3 m/s and the vertical wave length lying between 28.6 and 163 kms. The other waves may be the upward propagating gravity waves or waves resulting from the interaction of inter-mode tidal oscillations, interaction of tidal waves with planetary waves and gravity waves. Some times, the second harmonic wave has higher vertical velocity than the corresponding fundamental wave. Application of these waves in studying the thermal structure of the region is discussed.

  1. Metal Retrievals in the Mesosphere and lower Thermosphere by remote Sensing of Airglow with SCIAMACHY/Envisat

    Science.gov (United States)

    Langowski, M.; von Savigny, C.; Sinnhuber, M.; Aikin, A. C.; Burrows, J. P.

    2013-12-01

    Meteors entering the earth atmosphere containing metals ablate in an altitude of approximately 100 km due to frictional heating. The ablated metals undergo a series of chemical processes, which finally leads to a formation of metal layers between 85-95 km and metal ion layers 5 to 15 km above the metal layer. Although the densities of the metals and their ions are only in the magnitude of a few thousands of particles per cubic centimeter, they strongly emit airglow radiation due to their strong absorption cross sections and oscillator strength. This Airglow can be detected e.g. by grating spectrometers and the the density of the metals and ions can be obtained by inversion of a radiative transfer model. Since the Mesosphere and lower Thermosphere can hardly be accessed by in-situ measurement, as ballons fly to low and satellites typically too high and rockets to sparsly, the airglow emission of the metals and ions is one of the few means in this region to obtain information about transport and wave activities. Furthermore the total meteoric input to earth, which is quite uncertain in a range from 2 to 300 t/day can be estimated from the densties in the metal layers. We present metal and ion retrievals from SCIAMACHY/Envisat which is a satellite based grating spectrometer with a wavelength range of 230 to 2300 nm. The presented results are retrieved from the limb MLT states scanning the atmosphere with tangent altitudes from 50 to 150 km every 2 weeks for one day of data since 2008 until 2012.

  2. Statistical Comparison of Gravity Wave Characteristics Obtained from Airglow All-Sky Observation at Mt. Bohyun, Korea and Shigaraki, Japan

    Science.gov (United States)

    Yang, Tae-Yong; Kwak, Young-Sil; Kim, Yong-Ha

    2015-12-01

    Previously, all-sky airglow images observed at Shigaraki (34.9° N, 136.1° E), Japan, during 2004 and 2005 were analyzed in relation to those observed at Mt. Bohyun (36.2° N, 128.9° E) for a comparison of their gravity wave characteristics (Kim et al. 2010). By applying the same selection criteria of waves and cloud coverages as in the case of Mt. Bohyun all-sky images, we derived apparent wavelengths, periods, phase velocities, and monthly occurrence rates of gravity waves at Shigaraki in this study. The distributions of wavelengths, periods, and speeds derived for Shigaraki were found to be roughly similar to those for Mt. Bohyun. However, the overall occurrence rates of gravity waves at Shigaraki were 36% and 34% for OI 557.7 nm and OH Meinel band airglow layers, respectively, which were significantly higher than those at Mt. Bohyun. The monthly occurrence rates did not show minima near equinox months, unlike those for Mt. Bohyun. Furthermore, the seasonal preferential directions that were clearly apparent for Mt. Bohyun were not seen in the wave propagation trends for Shigaraki. These differences between the two sites imply different origins of the gravity waves near the Korean peninsula and the Japanese islands. The gravity waves over the Japanese islands may originate from sources at various altitudes; therefore, wind filtering may not be effective in causing any seasonal preferential directions in the waves in the airglow layers. Our analysis of the Shigaraki data supports recent theoretical studies, according to which gravity waves can be generated from in situ sources, such as mesosphere wind shear or secondary wave formation, in the mesosphere.

  3. Periodic waves in the lower thermosphere observed by OI630 nm airglow images

    Science.gov (United States)

    Paulino, I.; Medeiros, A. F.; Vadas, S. L.; Wrasse, C. M.; Takahashi, H.; Buriti, R. A.; Leite, D.; Filgueira, S.; Bageston, J. V.; Sobral, J. H. A.; Gobbi, D.

    2016-02-01

    Periodic wave structures in the thermosphere have been observed at São João do Cariri (geographic coordinates: 36.5° W, 7.4° S; geomagnetic coordinates based on IGRF model to 2015: 35.8° E, 0.48° N) from September 2000 to November 2010 using OI630.0 nm airglow images. During this period, which corresponds to almost one solar cycle, characteristics of 98 waves were studied. Similarities between the characteristics of these events and observations at other places around the world were noted, primarily the spectral parameters. The observed periods were mostly found between 10 and 35 min; horizontal wavelengths ranged from 100 to 200 km, and phase speed from 30 to 180 m s-1. These parameters indicated that some of the waves, presented here, are slightly faster than those observed previously at low and middle latitudes (Indonesia, Carib and Japan), indicating that the characteristics of these waves may change at different places. Most of observed waves have appeared during magnetically quiet nights, and the occurrence of those waves followed the solar activity. Another important characteristic is the quasi-monochromatic periodicity that distinguish them from the single-front medium-scale traveling ionospheric disturbances (MSTIDs) that have been observed previously over the Brazilian region. Moreover, most of the observed waves did not present a phase front parallel to the northeast-southwest direction, which is predicted by the Perkins instability process. It strongly suggests that most of these waves must have had different generation mechanisms from the Perkins instability, which have been pointed out as being a very important mechanism for the generation of MSTIDs in the lower thermosphere.

  4. Spatial and Temporal Stability of Airglow Measured in the Meinel Band Window at 1191.3 nm

    Science.gov (United States)

    Nguyen, Hien T.; Zemcov, Michael; Battle, John; Bock, James J.; Hristov, Viktor; Korngut, Phillip; Meek, Andrew

    2016-09-01

    We report on the temporal and spatial fluctuations in the atmospheric brightness in the narrow band between Meinel emission lines at 1191.3 nm using a λ/Δλ = 320 near-infrared instrument. We present the instrument design and implementation, followed by a detailed analysis of data taken over the course of a night from Table Mountain Observatory. At low airmasses, the absolute sky brightness at this wavelength is found to be 5330 ± 30 nW m‑2 sr‑1, consistent with previous measurements of the inter-band airglow at these wavelengths. This amplitude is larger than simple models of the continuum component of the airglow emission at these wavelengths, confirming that an extra emissive or scattering component is required to explain the observations. We perform a detailed investigation of the noise properties of the data and find no evidence for a noise component associated with temporal instability in the inter-line continuum. This result demonstrates that in several hours of ∼100 s integrations the noise performance of the instrument does not appear to significantly degrade from expectations, giving a proof of concept that near-infrared line intensity mapping may be feasible from ground-based sites.

  5. Statistical characteristics of gravity waves observed by an all-sky airglow imager at Maui, HI and Cerro Pachon, Chile

    Science.gov (United States)

    Cao, Bing; Liu, Alan Z.

    2016-07-01

    Many long-term observations, such as airglow imaging, have shown that gravity waves exist in the mesopause region most of the time. These waves deposit momentum and energy into the background atmosphere when dissipating, and thus exert strong influence to the atmosphere. In this study, we focus on (1) the climatology of gravity waves characteristics, (2) the intermittency of gravity wave momentum flux and (3) the duration/lifespan of gravity wave events. These properties have important implications for gravity wave parameterizations. This study is based on multi-year all sky OH airglow observations obtained at Maui, HI (20.7° N, 156.3° W) and the Andes Lidar Observatory in Chile (30.3° S, 70.7° W). The statistical distribution of intrinsic wave parameters and the momentum flux are analyzed. The probability density functions of gravity wave momentum flux and duration can be described by simple functions and are related to the gravity wave intermittency. The probability distributions of the two sites have some similarity but with noticeable differences, indicating different effects of the background flow and wave source on the gravity wave intermittency in the mesopause region.

  6. Spatial and Temporal Stability of Airglow Measured in the Meinel Band Window at 1191.3 nm

    CERN Document Server

    Nguyen, Hien T; Battle, John; Bock, James J; Hristov, Viktor; Korngut, Philip; Meek, Andrew

    2015-01-01

    We report on the temporal and spatial fluctuations in the atmospheric brightness in the narrow band between Meinel emission lines at 1191.3 nm using an R=320 near-infrared instrument. We present the instrument design and implementation, followed by a detailed analysis of data taken over the course of a night from Table Mountain Observatory. The absolute sky brightness at this wavelength is found to be 5330 +/- 30 nW m^-2 sr^-1, consistent with previous measurements of the inter-band airglow at these wavelengths. This amplitude is larger than simple models of the continuum component of the airglow emission at these wavelengths, confirming that an extra emissive or scattering component is required to explain the observations. We perform a detailed investigation of the noise properties of the data and find no evidence for a noise component associated with temporal instability in the inter-line continuum. This result demonstrates that in several hours of ~100s integrations the noise performance of the instrument ...

  7. Statistical characteristics of gravity wave activities observed by an OH airglow imager at Xinglong, in northern China

    Directory of Open Access Journals (Sweden)

    Q. Li

    2011-08-01

    Full Text Available An all-sky airglow imager (ASAI was installed at Xinglong, in northern China (40.2° N, 117.4° E in November 2009 to study the morphology of atmospheric gravity waves (AGWs in the mesosphere and lower thermosphere (MLT region. Using one year of OH airglow imager data from December 2009 to November 2010, the characteristics of short-period AGWs are investigated and a yearlong AGW climatology in northern China is first ever reported. AGW occurrence frequency in summer and winter is higher than that in equinoctial months. Observed bands mainly have horizontal wavelengths from 10 to 35 km, observed periods from 4 to 14 min and observed horizontal phase speeds in the range of 30 to 60 m s−1. Most of the bands propagate in the meridional direction. The propagation directions of the bands show a strong southwestward preference in winter, while almost all bands propagate northeastward in summer. Although the wind filtering in the middle atmosphere may control AGW propagations in the zonal direction, the non-uniform distribution of wave sources in the lower atmosphere may contribute to the anisotropy in the meridional direction in different seasons. Additionally, as an indication of local instability, the characteristics of ripples are also analyzed. It also shows seasonal variations, occurring more often in summer and winter and mainly moving westward in summer and eastward in winter.

  8. Statistical characteristics of gravity wave activities observed by an OH airglow imager at Xinglong, in northern China

    Energy Technology Data Exchange (ETDEWEB)

    Li, Q.; Yuan, W. [Chinese Academy of Sciences, Beijing (China). State Key Lab. of Space Weather; Chinese Academy of Sciences, Beijing (China). Graduate Univ.; Xu, J. [Chinese Academy of Sciences, Beijing (China). State Key Lab. of Space Weather; Yue, J. [National Center for Atmospheric Research, Boulder, CO (United States). High Altitude Observatory; Liu, X. [Chinese Academy of Sciences, Beijing (China). State Key Lab. of Space Weather; Henan Normal Univ., Xinxiang (China). College of Mathematics and Information Science

    2011-07-01

    An all-sky airglow imager (ASAI) was installed at Xinglong, in northern China (40.2 N, 117.4 E) in November 2009 to study the morphology of atmospheric gravity waves (AGWs) in the mesosphere and lower thermosphere (MLT) region. Using one year of OH airglow imager data from December 2009 to November 2010, the characteristics of short-period AGWs are investigated and a yearlong AGW climatology in northern China is first ever reported. AGW occurrence frequency in summer and winter is higher than that in equinoctial months. Observed bands mainly have horizontal wavelengths from 10 to 35 km, observed periods from 4 to 14 min and observed horizontal phase speeds in the range of 30 to 60ms{sup -1}. Most of the bands propagate in the meridional direction. The propagation directions of the bands show a strong southwestward preference in winter, while almost all bands propagate northeastward in summer. Although the wind filtering in the middle atmosphere may control AGW propagations in the zonal direction, the nonuniform distribution of wave sources in the lower atmosphere may contribute to the anisotropy in the meridional direction in different seasons. Additionally, as an indication of local instability, the characteristics of ripples are also analyzed. It also shows seasonal variations, occurring more often in summer and winter and mainly moving westward in summer and eastward in winter. (orig.)

  9. The O2 night airglow in Venus atmosphere from VIRTIS VEX measurements: local time and temporal variation

    Science.gov (United States)

    Zasova, Ludmila; Drossart, Pierre; Piccioni, Giuseppe; Migliorini, Alessandra; Shakun, Alexey; Altieri, Francesca; Gorinov, Dmitry

    Observation of the O2 1.27 µm airglow intensity distribution on the night side of Venus is one of the methods of study of the circulation in upper mesosphere 90-100 km. VIRTIS-M on board Venus Express made these observations in nadir and limb modes in Southern and Northern hemispheres respectively. To avoid high noisy data we use for analysis only those, obtained with exposure > 3 s. It was found that intensity of emission decreases to poles and to terminators in both hemispheres which gives evidence for existence of SS-AS circulation with transport of the air masses through poles and terminators with ascending/descending flows at SS/AS areas. Asymmetry of distribution of intensity of airglow is observed in both hemispheres. Global map for southern hemisphere (from nadir data) has good statistics at φ > 10-20°S and pretty poor at lower latitudes. Maximum emission was found shifted from midnight by 1 - 2 hours to the evening (22-23h) and deep minimum of emission is found at LT=2-4 h at φ > 20°S. This asymmetry is extended up to equatorial region, however statistic is poor there. No evident indication for existence of the Retrograde Zonal Superrotation (RZS) is found: maximum emission in this case, which is resulting from downwards flow, should be shifted to the morning. VIRTIS limb observations cover the low northern latitudes and they are more sparse at higher latitudes. Intensity of airglow at φ = 0 - 20° N shows wide maximum, which is shifted by 1- 2 h from midnight to morning terminator. This obviously indicates that observed O2 night glow distribution in low North latitudes is explained by a superposition of SS-AS flow and RZS circulation at 95-100 km. This behavior is similar to the NO intensity distribution, obtained by SPICAV. Temporal wariation was found at low latitudes of the Northern hemisphere: during 820 days observations three maxima were observed separated by 150 - 200 days approximately.

  10. Oxygen airglow emission on Venus and Mars as seen by VIRTIS/VEX and OMEGA/MEX imaging spectrometers

    Science.gov (United States)

    Migliorini, A.; Altieri, F.; Zasova, L.; Piccioni, G.; Bellucci, G.; Cardesín Moinelo, A.; Drossart, P.; D'Aversa, E.; Carrozzo, F. G.; Gondet, B.; Bibring, J.-P.

    2011-08-01

    Imaging spectrometers are highly effective instruments for investigation of planetary atmospheres. They present the advantage of coupling the compositional information to the spatial distribution, allowing simultaneous study of chemistry and dynamics in the atmospheres of Venus and Mars. In this work, we summarize recent results about the O 2(a 1Δg) night and day glows, respectively obtained by VIRTIS/Venus Express and OMEGA/Mars Express, the imaging spectrometers currently in orbit around Venus and Mars. The case of the O 2(a 1Δg - X 3Σg-) IR emission at 1.27 μm on the night side of Venus and the day side of Mars is analyzed, pointing out dynamical aspects of these planets, like the detection of gravity waves in their atmospheres. The monitoring of seasonal and daily airglow variations provides hints about the photochemistry on these planets.

  11. Solar energy deposition rates in the mesosphere derived from airglow measurements: Implications for the ozone model deficit problem

    Science.gov (United States)

    Mlynczak, Martin G.; Garcia, Rolando R.; Roble, Raymond G.; Hagan, Maura

    2000-07-01

    We derive rates of energy deposition in the mesosphere due to the absorption of solar ultraviolet radiation by ozone. The rates are derived directly from measurements of the 1.27-μm oxygen dayglow emission, independent of knowledge of the ozone abundance, the ozone absorption cross sections, and the ultraviolet solar irradiance in the ozone Hartley band. Fifty-six months of airglow data taken between 1982 and 1986 by the near-infrared spectrometer on the Solar-Mesosphere Explorer satellite are analyzed. The energy deposition rates exhibit altitude-dependent annual and semi-annual variations. We also find a positive correlation between temperatures and energy deposition rates near 90 km at low latitudes. This correlation is largely due to the semiannual oscillation in temperature and ozone and is consistent with model calculations. There is also a suggestion of possible tidal enhancement of this correlation based on recent theoretical and observational analyses. The airglow-derived rates of energy deposition are then compared with those computed by multidimensional numerical models. The observed and modeled deposition rates typically agree to within 20%. This agreement in energy deposition rates implies the same agreement exists between measured and modeled ozone volume mixing ratios in the mesosphere. Only in the upper mesosphere at midlatitudes during winter do we derive energy deposition rates (and hence ozone mixing ratios) consistently and significantly larger than the model calculations. This result is contrary to previous studies that have shown a large model deficit in the ozone abundance throughout the mesosphere. The climatology of solar energy deposition and heating presented in this paper is available to the community at the Middle Atmosphere Energy Budget Project web site at http://heat.budget.gats.inc.com.

  12. Solar Energy Deposition Rates in the Mesosphere Derived from Airglow Measurements: Implications for the Ozone Model Deficit Problem

    Science.gov (United States)

    Mlynczak, Martin G.; Garcia, Rolando R.; Roble, Raymond G.; Hagan, Maura

    2000-01-01

    We derive rates of energy deposition in the mesosphere due to the absorption of solar ultraviolet radiation by ozone. The rates are derived directly from measurements of the 1.27-microns oxygen dayglow emission, independent of knowledge of the ozone abundance, the ozone absorption cross sections, and the ultraviolet solar irradiance in the ozone Hartley band. Fifty-six months of airglow data taken between 1982 and 1986 by the near-infrared spectrometer on the Solar-Mesosphere Explorer satellite are analyzed. The energy deposition rates exhibit altitude-dependent annual and semi-annual variations. We also find a positive correlation between temperatures and energy deposition rates near 90 km at low latitudes. This correlation is largely due to the semiannual oscillation in temperature and ozone and is consistent with model calculations. There is also a suggestion of possible tidal enhancement of this correlation based on recent theoretical and observational analyses. The airglow-derived rates of energy deposition are then compared with those computed by multidimensional numerical models. The observed and modeled deposition rates typically agree to within 20%. This agreement in energy deposition rates implies the same agreement exists between measured and modeled ozone volume mixing ratios in the mesosphere. Only in the upper mesosphere at midlatitudes during winter do we derive energy deposition rates (and hence ozone mixing ratios) consistently and significantly larger than the model calculations. This result is contrary to previous studies that have shown a large model deficit in the ozone abundance throughout the mesosphere. The climatology of solar energy deposition and heating presented in this paper is available to the community at the Middle Atmosphere Energy Budget Project web site at http://heat-budget.gats-inc.com.

  13. A Method of Inversing the Peak Density of Atomic Oxygen Vertical Distribution in the MLT Region From the OI (557.7nm) Night Airglow Intensity

    Institute of Scientific and Technical Information of China (English)

    H. Gao; J.Y. Xu; W. Yuan

    2005-01-01

    In this paper, using the MSISE-90 model as the reference atmosphere, we discuss the feasibility and method of deducing the peak densities of the undisturbed atomic oxygen profiles in the MLT region (the mesosphere and lower thermosphere region) from OI (557.7 nm) night airglow intersities. The peak densities for different seasons, latitudes and longitudes are deduced from OI (557.7nm) airglow intensities through this expression. We analyze the features of inversion relative errors and discuss the influence of the variations in temperature on inversion errors. The results indicate that all inversion errors are less than 5% except for those at high altitudes in the summer hemisphere. And the impact of the variations in temperature on errors is not significant.

  14. Preliminary observations and simulation of nocturnal variations of airglow temperature and emission rates at Pune (18.5°N), India

    Science.gov (United States)

    Fadnavis, S.; Feng, W.; Shepherd, Gordon G.; Plane, J. M. C.; Sonbawne, S.; Roy, Chaitri; Dhomse, S.; Ghude, S. D.

    2016-11-01

    Preliminary observations of the nocturnal variations of the OH(6-2) and O2b(0-1) nighttime airglow in the mesosphere and lower thermosphere are investigated in the context of tidal influence for the tropical latitude station Pune (18.5°N, 73.85°E). This is the only tropical Spectral Airglow Temperature Imager (SATI) station where the tidal variations of mesosphere and lower thermosphere (MLT) temperature have been determined from ground based SATI observations. The SATI observations obtained since October 2012 reveal the influence of the migrating semidiurnal tides during solstice at this tropical station. There is variability in amplitude and phase obtained from SATI observations. In this paper, SATI observations on 10 Dec 2012 and 3 March 2013 are compared with Whole Atmosphere Community Climate Model (WACCM) simulations. The amplitude of semidiurnal tides is ~25 K/30 K on 10 Dec 2012 during solstice for OH/O2 temperature. During equinox SATI data indicates existence of semidiurnal tide also. The airglow observations are compared with simulations from the WACCM. The model underestimates the amplitude of the semi diurnal tide during equinox (1.6 K/2.7 K at 87 km/96 km) and solstice (~3.8 K/4.8 K at 87 km/96 km) for these days. The reason may be related to dampening of tides in the model due to the effect of strong latitudinal shear in zonal wind. The diurnal variation of airglow emission - which the model simulates well - is related to the vertical advection associated with the tides and downward mixing of atomic oxygen.

  15. Night airglows in Venus atmosphere and dynamics around 100 km from VIRTIS-M VEX data. Comparison with the Earth atmosphere.

    Science.gov (United States)

    Zasova, L.; Khatuntsev, I.; Shakun, A.; Piccioni, G.; Drossart, P.

    2012-04-01

    Analysis of the O2 1.27um night airglow in the Venus atmosphere is presented. Night glow is extremely variable in space and local time. However, averaged over all nadir observations for Southern hemisphere and over all nadir observations for Northern hemisphere it allows to study a global circulation around 100 km altitude. The global circulation at these levels may be presented by SS-AS, zonal retrograde, as well tides and waves may influence nightglow distribution. In Southern hemisphere in the latitude range 20-60S a maximum emission is found at 22 - 23 h local time, which correlates with minimum horizontal wind speed (downward flow) and minimum emission is observed at 2-4 h, which correlates with maximum of horizontal wind speed. In Northern hemisphere maximum emission is observed at 1 h in latitude range from equator to 40-50°N. It indicates to existence of superposition of SS-AS and zonal retrograde circulation (in the case of SS-AS maximum emission should be found at midnight). For Northern hemisphere there is no simultaneous wind measurements. Thin O3 layer (Montmessin et al. 2011) from SPICAV data was found in Southern hemisphere for latitudes and local time where high O2 airglow (and consequently OH) intensity was also found by VIRTIS. The O2 night airglow of Venus and Earth are compared.

  16. Relationship between propagation direction of gravity waves in OH and OI airglow images and VHF radar echo occurrence during the SEEK-2 campaign

    Directory of Open Access Journals (Sweden)

    F. Onoma

    2005-10-01

    Full Text Available We report simultaneous observations of atmospheric gravity waves (AGW in OI (557.7nm and OH airglow images and VHF radar backscatter from field-aligned irregularities (FAI in the E-region during the SEEK-2 (Sporadic-E Experiment over Kyushu 2 campaign period from 29 July to 9 August 2002. An all-sky imager was operated at Nishino-Omote (30.5 N, 130.1 E, Japan. On 14 nights, 17 AGW events were detected in OI and OH airglow images. AGW propagated mostly toward the northeast or southeast. From comparison with the E-region FAI occurrence, which is detected by a nearby VHF radar (31.57MHz, we found that AGW tended to propagate southeastward during FAI events. This result suggests that the interaction between AGW and E-region plasma plays an important role in generating FAI. Furthermore, polarization electric fields generated directly by AGW may contribute to the FAI generation.

    Keywords. Atmospheric composition and structure (Airglow and aurora, Ionosphere (Ionospheric irregularities, Mid-latitude ionosphere

  17. Climatology of the O+ temperatures over Arecibo for the historical deep solar minimum using Incoherent Scatter Radar and airglow data.

    Science.gov (United States)

    Santos, P. T.; Brum, C. G. M.; Kerr, R.; Noto, J.

    2014-12-01

    At Arecibo Observatory (AO) a comprehensive description of the ionosphere and thermosphere environment is achieved by the synergy between the Incoherent Scatter Radar (ISR) and the optical instruments nested on site. An example of this synergy is present in his work where optical and radar techniques were reconciled in order to obtain the O+ temperature variability for 2008 and 2009. During this period, a historical deep solar minimum condition was registered with a remarkable absence of sunspots for a long period (translated into a decreasing in the EUV-UV irradiance). This particular feature implies in an important tool to investigate the variability of O+ temperature, once that any variation can be related to season (modulated by the neutral atmosphere) and/or another modulator different than solar energy input. The OII 7320 Å twilight airglow data used in this work were obtained during new moon periods using a high-spectral resolution Fabry-Perot Interferometer (FPI) with CCD array detection. The FPI was configured with 0.9 cm plate spacing, which produced a free spectral range of 0.298Å and a spectral resolution of 0.03Å, sufficient to sample line width temperatures as low as 500K. A very narrow 3Å Full Width at Half Maximum (FWHM) three-cavity interference filter was also used.

  18. Gravity waves in mesopause region induced by thunderstorms over Northern China observed by a no-gap OH airglow imager network

    Science.gov (United States)

    Xu, Jiyao

    2016-07-01

    A no-gap OH airglow all-sky imager network was established in northern China in February 2012. The network is composed of 6 all-sky airglow imagers that make observations of OH airglow gravity waves and cover an area of about 2000 km east and west and about 1400 km south and north. A large number of gravity wave events in the mesopause region induced by thunderstorms were observed by the network during the past 4 years. A comparison of the observations in 2012, 2013, and 2014 are made, which shows that there were more strong thunderstorms take place in 2013 in the northern China and produce more Concentric Gravity Wave (CGW) events. Especially, a series of CGW events were observed by the network nearly every night during the first half of August 2013. These events were also observed by satellite sensors from FY-2, AIRS/Aqua, and VIIRS/Suomi NPP. Combination of the ground imager network with satellites provides multi-level observations of the CGWs from the stratosphere to the mesopause region. In this talk, two representative CGW events in August 2013 are studied in detail and movies of the two events are displayed. One is the CGW on the night of 13 August 2013, likely launched by a single thunderstorm. The temporal and spatial analyses indicate that the CGW horizontal wavelengths agree with the GW dispersion relation within 300 km from the storm center. A gravity wave with horizontal wavelength of about 20 km propagates horizontally to more than 800 km in the mesopause region, probably due to a ducting layer. Another CGW event was induced by two very strong thunderstorms on 09 August 2013. Multi-scale waves with horizontal wavelengths ranging from less than 10 km to 200 km were observed. Many ripples were found, probably due to the breaking of strong gravity waves with large relative OH intensity perturbations of 10%.

  19. Rocket observation of atomic oxygen and night airglow: Measurement of concentration with an improved resonance fluorescence technique

    Directory of Open Access Journals (Sweden)

    K. Kita

    Full Text Available An improved resonant fluorescence instrument for measuring atomic oxygen concentration was developed to avoid the Doppler effect and the aerodynamic shock effect due to the supersonic motion of a rocket. The shock effect is reduced by adopting a sharp wedge-shaped housing and by scanning of the detector field of view to change the distance between the scattering volume and the surface of the housing. The scanning enables us to determine absolute values of atomic oxygen concentration from relative variation of the scattered light signal due to the self-absorption. The instrument was calibrated in the laboratory, and the numerical simulation reproduced the calibration result. Using the instrument, the altitude profile of atomic oxygen concentration was observed by a rocket experiment at Uchinoura (31°N on 28 January 1992. The data obtained from the rocket experiment were not perfectly free from the shock effect, but errors due to the effect were reduced by the data analysis procedure. The observed maximum concentration was 3.8× 1011 cm–3 at altitudes around 94 km. The systematic error is estimated to be less than ±0.7×1011 cm–3 and the relative random error is less than±0.07× 1011 cm–3at the same altitudes. The altitude profile of the OI 557.7-nm airglow was also observed in the same rocket experiment. The maximum volume emission rate was found to be 150 photons cm–3 s–1 at 94 km. The observed altitude profiles are compared with the MSIS model and other in situ observations.

  20. Long-term Trends in Mesospheric Temperatures at high and low latitudes derived from OH airglow spectra of Kiruna FTS and Sloan Digital Sky Survey

    Science.gov (United States)

    Kim, Yongha; Kim, Jeong-Han; Kim, Gawon; Lee, Youngsun

    2016-07-01

    We have analyzed mesospheric temperatures from OH airglow measurements with Fourier Transform Spectrometer (FTS) in the period of 2003 - 2012 at Kiruna (67.9°N, 21.1°E). We also derived mesospheric temperatures from rotational emission lines of the OH airglow (8-3) band in the sky spectra of Sloan Digital Sky Survey (SDSS) in the period of 2000 - 2014. The main objective of SDSS is to make a detailed 3-dimensional map of the universe by observing images and spectra of various celestial objects at Apache Point Observatory (APO, 32°N 105°W). From both temperature sets we first estimated the solar responses of mesospheric temperatures to F10.7 variation and the seasonal variation of mesospheric temperatures. After removing the solar response, we found the long-term mesospheric temperature trends of -4 ˜-6.6 K/decade at Kiruna and -0.02 ± 0.7 K/decade at Apache Point. Our results indicate significant cooling trend at the high latitude but very little or no cooling at the low latitude. Although both trends are comparable and consistent with other studies, the temperature trend from SDSS spectra should be regarded as unique contribution to global monitoring of climate change because the SDSS project is completely independent of climate studies.

  1. Observation of the June 22, 2015 G4 storm by HiT&MiS: an Echelle Spectrograph for Auroral and Airglow Studies

    Science.gov (United States)

    Aryal, S.; Hewawasam, K.; Maguire, R.; Chakrabarti, S.; Cook, T.; Martel, J.; Baumgardner, J. L.

    2015-12-01

    Observation of the June 22, 2015 G4 storm by HiT&MiS: an Echelle Spectrograph for Auroral and Airglow Studies Saurav Aryal1 , Kuravi Hewawasam1, Ryan Maguire1, Supriya Chakrabarti1, Timothy Cook1, Jason Martel1 and Jeffrey L Baumgardner2, (1) University of Massachusetts Lowell, Lowell, MA, United States, (2)Boston University, Boston, MA, United StatesA High-Throughput and Multi-slit Imaging Spectrograph (HiT&MIS) has been developed by our group. The spectrograph uses an echelle grating that operates at high dispersion orders (28-43) such that extended sources for airglow and auroral emissions can be observed at high resolution (about 0.02 nm). By using four slits (instead of the conventional one slit setup), with the appropriate foreoptics it images extended emissions along a long field of view of about 0.1° × 50°. It observes spectral regions around six prominent atmospheric emission lines (HI 656.3 nm, HI 486.1 nm, OI 557.7 nm, OI 630.0 nm, OI 777.4 nm and N+2 427.8 nm) using order sorting interference filters at the entrance slits and a filter mosaic on an image plane. We present observations from the instrument during the June 22, 2015 G4 storm. OI 557.7 nm (green line) and OI 630.0 nm (red line) showed strong brightness enhancements that lasted throughout the night from 8 P.M June 22, 2015 to 3 AM June 23,2015 when compared to the same times after the storm had passed.

  2. Long-term ozone decline and its effect on night airglow intensity of Li 6708 Å at Varanasi (25°N, 83°E) and Halley Bay (76°S, 27°W)

    Indian Academy of Sciences (India)

    P K Jana; I Saha; S Mukhopadhyay

    2011-04-01

    A critical analysis has been made on the long-term yearly and seasonal variations of ozone concentration at Varanasi (25°N, 83°E), India and Halley Bay (76°S, 27°W), a British Antarctic Service Station. The effect of O3 depletion on night airglow emission of Li 6708 Å line at Varanasi and Halley Bay has been studied. Calculations based on chemical kinetics show that the airglow intensity of Li 6708 Å line has also been affected due to the depletion of O3 concentration. The yearly variations and seasonal variations of intensities of Li 6708 Å line for the above two stations are shown and compared. It has been shown that the rate of decrease of intensity of Li 6708 Å line was comparatively more at Halley Bay due to dramatic decrease of Antarctic O3 concentration.

  3. Ozone decline and its effect on night airglow intensity of Na 5893°A at Dumdum (22.5°N, 88.5° E) and Halley Bay (76°S, 27°W)

    Indian Academy of Sciences (India)

    P K Jana; S C Nandi

    2006-10-01

    The paper presents the effect of O3 depletion on night airglow emission of Na 5893 A line at Dumdum (22.5°N, 88.5°E), India and Halley Bay (76°S, 27°W), a British Antarctic service station. Calculations based on chemical kinetics show that the airglow intensity of Na 5893 A line will also be affected due to the depletion of O3 concentration. The nature of yearly variation and seasonal variation of the intensity of Na 5893 A line for the above two stations are shown and compared. It is shown that the rate of decrease of intensity of Na 5893 A line is comparatively more at Halley Bay due to the dramatic decrease of Antarctic O3 concentration. A possible explanation for this dramatic decrease of Antarctic O3 concentration is also mentioned.

  4. Climatology of planetary wave type oscillations with periods of 2–20 days derived from O2 atmospheric and OH(6-2 airglow observations at mid-latitude with SATI

    Directory of Open Access Journals (Sweden)

    V. M. Aushev

    2009-09-01

    Full Text Available The presence of planetary wave type oscillations at mid-latitudes in the mesosphere/lower thermosphere region has been investigated using airglow observations. The observations were taken with a Spectral Airglow Temperature Imager (SATI installed at Sierra Nevada Observatory (37.06° N, 3.38° W at 2900 m height. Airglow data of the column emission rate of the O2 Atmospheric (0-1 band and of the OH Meinel (6-2 band and deduced rotational temperatures from 1998 to 2007 have been used in this study. From these observations a climatology of planetary wave type oscillations at this location is inferred. It has been found that the planetary wave type oscillations of 5-day period is predominant in our data throughout the year, with activity greater than 50% during March/April and October/November months. The planetary wave type oscillations of 2-day period is predominant during both solstices, being predominant during winter solstice in O2 while a 10-day oscillation appears throughout the year with activity around 20% and with maximum activity during spring and autumn equinoxes. The 16-day oscillation has maximum occurrence during autumn-winter while its activity is almost disappeared during spring-summer. No clear seasonal dependence of the amplitude of the planetary wave type oscillations was observed in the cases considered in this study. The waves simultaneously detected in the rotational temperatures deduced from both OH and O2 emissions usually show an upward energy propagation and are affected by dissipation processes.

  5. Climatology of planetary wave type oscillations with periods of 2-20 days derived from O{sub 2} atmospheric and OH(6-2) airglow observations at mid-latitude with SATI

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Gonzalez, M.J.; Rodriguez, E.; Garcia-Comas, M.; Costa, V. [CSIC, Granada (Spain). Inst. de Astrofisica de Andalucia; Shepherd, M.G.; Shepherd, G.G.; Sargoytchev, S. [York Univ., Toronto, ON (Canada). Centre for Research in Earth and Space Science; Aushev, V.M. [National Centre of Space Research and Technology, National Space Agency, Almaty (Kazakhstan). Dept. Inst. of Ionosphere

    2009-07-01

    The presence of planetary wave type oscillations at mid-latitudes in the mesosphere/lower thermosphere region has been investigated using airglow observations. The observations were taken with a Spectral Airglow Temperature Imager (SATI) installed at Sierra Nevada Observatory (37.06 N, 3.38 W) at 2900 m height. Airglow data of the column emission rate of the O{sub 2} Atmospheric (0-1) band and of the OH Meinel (6-2) band and deduced rotational temperatures from 1998 to 2007 have been used in this study. From these observations a climatology of planetary wave type oscillations at this location is inferred. It has been found that the planetary wave type oscillations of 5-day period is predominant in our data throughout the year, with activity greater than 50% during March/April and October/November months. The planetary wave type oscillations of 2-day period is predominant during both solstices, being predominant during winter solstice in O{sub 2} while a 10-day oscillation appears throughout the year with activity around 20% and with maximum activity during spring and autumn equinoxes. The 16-day oscillation has maximum occurrence during autumn-winter while its activity is almost disappeared during spring-summer. No clear seasonal dependence of the amplitude of the planetary wave type oscillations was observed in the cases considered in this study. The waves simultaneously detected in the rotational temperatures deduced from both OH and O{sub 2} emissions usually show an upward energy propagation and are affected by dissipation processes. (orig.)

  6. I. Airglow on Mars: Model predictions for the oxygen IR atmospheric band at 1.27 micrometers, the hydroxyl radical Meinel bands and the hydroxyl radical A-X band system. II. Physical and chemical aeronomy of HD 209458b

    Science.gov (United States)

    Garcia Munoz, Antonio

    The first part of this dissertation is concerned with model predictions of airglow from the O2 IR atmospheric band at 1.27 mum, the OH Meinel bands and the OH A-X band system in the low-latitude neutral atmosphere of Mars. As an observable feature, airglow provides a means to remotely probe the composition, dynamics and energetics of the Martian atmosphere. The daytime emission from the O2 IR atmospheric band, a direct result of ozone photodissociation, has long been known to be a prominent emission of the Martian airglow. The motivation for pursuing the modelling of the nighttime components of the O2 IR atmospheric band and the OH Meinel bands is the potential of these two processes for characterizing the atomic oxygen profile in the 50-80 km region of the atmosphere. Likewise, the OH A-X band system may be useful to constrain the abundance of the hydroxyl radical on the illuminated side of the planet below 60 km. Both, O and OH are indicators of the photochemical state of the atmosphere. The results reported herein are expected to serve as guidelines for prospective observations of the atmosphere of Mars. The second part of the dissertation investigates the physical and chemical aeronomy of HD 209458b. The discovery of this extrasolar planet by radial velocity measurements was announced in 2000. Shortly afterwards, the inference of the mean planetary density from transit observations indicated the plausible gaseous nature of the planet. Later in-transit spectrally-resolved photometric observations revealed a cloud of hydrogen, carbon and oxygen atoms extending to a few planetary radii above the surface of the planet, which has been interpreted as evidence for an escaping atmosphere around HD 209458b. At an orbital distance of 0.05 AU, intense EUV stellar irradiation may lead to the massive escape of the atmosphere. In this work, the composition, escape and energy balance of the atmosphere are consistently modelled. Escape rates and abundances of the main hydrogen

  7. Implementation of a High-Altitude Balloon Payload to Study Thermospheric Wind Speeds through Redline Airglow Emissions of Atomic Oxygen at 630 nm via a Split-field Etalon Doppler Imager Utilizing a Fabry-Perot Interferometer.

    Science.gov (United States)

    Terry, L. B.; Fullmer, R.; Swenson, C.; Marchant, A.; Hooser, P.; Victors, J.; Muchmore, K.; Yin, L.

    2015-12-01

    Little data exists on the wind velocity characteristics of the upper atmosphere. The Red Line Air Glow Experiment is designed to measure the relative density and velocity of the thermosphere at altitudes approximately ranging between 250 and 350 km. To accomplish this, a Split-Field Etalon Imager will make doppler shift interferometry measurements of the oxygen redline at 630 nm wavelength airglow a using a high altitude balloon platform floating at 36 km. The imager collects up to 10 images per hour. Velocity resolution is within a 5 m/s. The Etalon is thermally controlled to within 1 deg C to achieve this goal. The pointing direction of the sensor is determined post-filght using GPS, IMU and three sun imaging sensors. An experimental star camera is included with a potential pointing accuracy of under 5 arc-min. The instrument first flew from Fort Sumner N,M., on August 26, 2014. Due to the short duration (3.5 hours) of the data collection period on this flight, a second flight was requested and awarded, to take place around September 10, 2015. This flight will allow for data collection over a 24 hour period. Both flight results will be included in the final presentation. This project was designed and built by an undergraduate team including students from physics, aerospace, electrical and mechanical engineering and management at both Utah State University and the University of Maryland Eastern Shores as a NASA's Undergraduate Student Instrument Project (USIP).

  8. Mesopause temperatures calculated from the O2(a1Δg twilight airglow emission recorded at Maynooth (53.2°N, 6.4°W

    Directory of Open Access Journals (Sweden)

    J. M. Galligan

    Full Text Available Spectra of the O2(a1Δg airglow emission band at 1.27 µm have been recorded during twilight at Maynooth (53.2°N, 6.4°W using a Fourier transform spectrometer. Synthetic spectra have been generated for comparison with the recorded data by assuming a particular temperature at the emitting altitude, and modelling the absorption of each line in the band as it propagates downward through the atmosphere. The temperature used in generating the synthetic spectra was varied until an optimum fit was obtained between the recorded and synthetic data; this temperature was then attributed to the altitude of the emitting layer. Temperatures derived using this technique for 91 twilight periods over an 18-month period exhibit a strong seasonal behaviour with a maximum in winter and minimum in summer. Results from this study are compared with temperatures calculated from the OH(3, 1 Meinel band recorded simultaneously. In winter OH temperatures exceed O2 values by about 10 K, whereas the opposite situation pertains in summer; this result is interpreted in terms of a possible change in the altitude of the mesopause as a function of season. Estimates of the twilight O2(0, 0 total band intensity indicate that its intensity is lower and that its decay is more rapid in summer than in winter, in agreement with earlier observations.

  9. On applicability of the photochemical-equilibrium approach for retrieval of O and H mesospheric distributions from the satellite-based measurements of the airglow emission and ozone concentration

    Science.gov (United States)

    Feigin, Alexander; Belikovich, Mikhail; Kulikov, Mikhail

    2016-04-01

    Atomic oxygen and hydrogen are known to be among key components for the photochemistry and energy balance of the Earth's atmosphere between approximately 80 and 100 km altitude (mesopause region). Therefore, obtaining information about the vertical distributions of O and H concentrations is an important task in studies of this region. Solving of this problem is rather difficult due to the absence of regular methods which allow one to direct measurements of distributions of these components in mesosphere. However, indirect methods used to retrieve O and H distributions from the satellite-based measurements of the OH and O2(1D) airglow emission, as well as the data of IR and microwave O3 measurements have a sufficiently long development history. These methods are rooted in the use of the condition of photochemical equilibrium of ozone density in the range of altitudes from 50 to 100 km. A significant factor is that an insufficient volume of such measurement data forces researchers to use approximate ("truncated") photochemical-equilibrium conditions. In particular, it is assumed that in the daytime the ozone production reaction is perfectly balanced by ozone photodissociation, whereas during the night the only ozone sink is the reaction of ozone with atomic hydrogen, which, in its turn, leads to formation of excited OH and airglow emission of the latter. The presentation analyzes applicability of the photochemical-equilibrium conditions both in the total and truncated forms for description of the spatio-temporal evolution of mesospheric ozone during a year. The analysis is based on year-long time series generated by a 3D chemical transport model, which reproduces correctly various types of atmosphere dynamics in the range of altitudes from 50 to 100 km. These data are used to determine statistics of the ratio between the correct (calculated dynamically) distributions of the O3 density and its uncontracted and truncated equilibrium values for the conditions of the

  10. Yearly variation and annual cycle of total column ozone over New Delhi (29°N, 77°E), India and Halley Bay (76°S, 27°W), British Antarctic Survey Station and its effect on night airglow intensity of OH(8, 3) for the period 1979–2005

    Indian Academy of Sciences (India)

    P K Jana; D K Saha; D Sarkar

    2012-12-01

    A critical analysis made on the long-term monthly, seasonal, yearly variation and annual cycle of total column ozone (TCO) concentration at New Delhi (29°N,77°E), India and Halley Bay (76°S, 27°W), a British Antarctic Service Station reveals more decline in yearly mean ozone concentration at Halley Bay than at New Delhi from 1979 to 2005. The nature of variations of monthly mean TCO during the months of August and September was the most identical with that of yearly mean ozone values at New Delhi and Halley Bay, respectively, for the same period. Annual cycles of TCO over these stations are completely different for the above period. The effect of O3 depletion on night airglow emission of OH(8, 3) line at New Delhi and Halley Bay has been studied. Calculations based on chemical kinetics show that the airglow intensity of OH(8, 3) has also been affected due to the depletion of O3 concentration. The yearly variations and annual cycle of intensities of OH(8, 3) line for the above two stations are depicted and compared. It has been shown that the rate of decrease of intensity of OH(8, 3) line was comparatively more at Halley Bay due to dramatic decrease of Antarctic O3 concentration.

  11. Yearly variation and annual cycle of total column ozone over New Delhi (29°N, 77°E), India and Halley Bay (76°S, 27°W), British Antarctic Survey Station and its effect on night airglow intensity of OH(8, 3) for the period 1979-2005

    Science.gov (United States)

    Jana, P. K.; Saha, D. K.; Sarkar, D.

    2012-12-01

    A critical analysis made on the long-term monthly, seasonal, yearly variation and annual cycle of total column ozone (TCO) concentration at New Delhi (29°N, 77°E), India and Halley Bay (76°S, 27°W), a British Antarctic Service Station reveals more decline in yearly mean ozone concentration at Halley Bay than at New Delhi from 1979 to 2005. The nature of variations of monthly mean TCO during the months of August and September was the most identical with that of yearly mean ozone values at New Delhi and Halley Bay, respectively, for the same period. Annual cycles of TCO over these stations are completely different for the above period. The effect of O3 depletion on night airglow emission of OH(8, 3) line at New Delhi and Halley Bay has been studied. Calculations based on chemical kinetics show that the airglow intensity of OH(8, 3) has also been affected due to the depletion of O3 concentration. The yearly variations and annual cycle of intensities of OH(8, 3) line for the above two stations are depicted and compared. It has been shown that the rate of decrease of intensity of OH(8, 3) line was comparatively more at Halley Bay due to dramatic decrease of Antarctic O3 concentration.

  12. Laboratory Investigation of the Airglow Bands

    Science.gov (United States)

    Drouin, Brian; Yu, Shanshan; Crawford, Timothy J.; Miller, Charles E.; Yee, Jeng-Hwa

    2013-06-01

    We report the first high spectral resolution laboratory measurements of oxygen A-band night glow simulated using a static discharge cell. Our static discharge system reproduces the conditions of the mesospheric oxygen night glow - suggesting O(^1D) + O_2 as the primary source of the emission. Additionally, use of the static cell has enabled us to collect spectra for rare molecular oxygen isotopologues using isotopically enriched samples. The (0,0), (0,1), and (1,1) b-Xvibrational bands were observed with a Bruker 125 HR for all six isotopologues. The (1,2) and (2,2) bands were observed also for the main isotopologue. The frequencies of the observed (0,1) transitions resolved discrepancies in Raman data for (16-17, 17-17, and 17-18), enabling us to improve the vibrational parameterization of the ground electronic state in the global fit of Yu et al. Rotationally resolved intensities were determined for the (0,0), (0,1) and (1,1) bands. The experimental band intensity ratios I(0,0)/I(0,1) = 13.6 and I(0,0)/I(1,1) = 60 are in excellent agreement with the recent mesospheric remote sensing data. S. Yu, C.E. Miller, B.J. Drouin, H.S.P. Müller, J. Chem. Phys. 136, 024304, 2012

  13. SWIR Hemispherical Air-Glow Plotting System SHAPS

    Science.gov (United States)

    Gonglewski, John D.; Myers, Michael M.; Dayton, David C.; Fertig, Gregory; Allen, Jeffrey; Nolasco, Rudolph; Maia, Franscisco

    2010-10-01

    It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band of wave length 0.9 to 1.7 μm. Numerous studies of these phenomena have demonstrated that the irradiance shows significant temporal and spatial variations in the night sky. Changes in weather patterns, seasons, sun angle, moonlight, etc have the propensity to alter the SWIR air glow irradiance pattern. By performing multiple SWIR measurements a mosaic representation of the celestial hemisphere was constructed and used to investigate these variations over time and space. The experimental setup consisted of two sensors, an InGaAs SWIR detector and a visible astronomical camera, co-located and bore sighted on an AZ-EL gimbal. This gimbal was programmed to view most of the sky using forty five discrete azimuth and elevation locations. The dwell time at each location was 30 seconds with a total cycle time of less than 30 minutes. The visible astronomical camera collected image data simultaneous with the SWIR camera in order to distinguish SWIR patterns from clouds. Data was reduced through batch processing producing polar representations of the sky irradiance as a function of azimuth, elevation, and time. These spatiotemporal variations in the irradiance, both short and long term, can be used to validate and calibrate physical models of atmospheric chemistry and turbulence. In this paper we describe our experimental setup and present some results of our measurements made over several months in a rural marine environment on the Island of Kauai Hawaii.

  14. Helium 10830 Å airglow emission response to solar cycle

    Science.gov (United States)

    Patel, P. P.; Azeem, S. M.; Sivjee, G. G.

    2007-05-01

    It has been suggested by Gadsden [1967] that the radiance of Helium 10830 Å line can be used to monitor the solar irradiance in the EUV. Conversely, we can use the 10830 Å line to study the response of the upper atmosphere over the course of a solar cycle. In this paper we will examine Helium emission line at 10830 Å to study the correlation between brightness of the emission line with F10.7 solar flux. The Helium data was acquired from Michelson Interferometers located at two stations, South Pole Station (90° S), Antarctica and Resolute Bay (74.68° N, 94.90° W), Canada. The data will be examined to isolate periods with no auroral contamination. Long term HeI data, from 1992 to 2005, will be presented to study correlation between Helium brightness and the F10.7 solar flux.

  15. Airglow and magnetic field disturbances over Brazilian region during Chile tsunami (2015)

    CERN Document Server

    Klausner, V; Candido, C M N; Abalde, J R; Fagundes, P R; Kherani, E A

    2015-01-01

    In this work, we present first report on disturbances over Brazilian atmosphere on 16--17 September, 2015 following the Chile tsunami occurrence. Using all-sky imager and magnetometer located at 2330 km away from the epicenter, the presence of disturbances is noted 1--3 hours after the tsunami beginning time and during time which seismic tremor was also felt in the region. We argue that their presence towards continent at 2000-3000 km away from the epicenter offers another example of similar atmospheric response as those observed during Tohoku-Oki tsunami, 2011. This similarity and their appearance during seismic tremor over the region classify them to be of tsunamigenic and/or seismogenic nature.

  16. High resolution spectral analysis of oxygen. III. Laboratory investigation of the airglow bands

    Science.gov (United States)

    Drouin, Brian J.; Yu, Shanshan; Elliott, Ben M.; Crawford, Timothy J.; Miller, Charles E.

    2013-10-01

    We report the first high spectral resolution laboratory measurements of simulated oxygen A-band night glow. Our static discharge system approximates the conditions of the mesospheric oxygen night glow - suggesting O(1D) + O2 (X ^3Σ _g^-) → O(3P) + O2 (b ^1Σ _g^+) → O2 (X ^3Σ _g^-) + hν as the primary source of the emission. Additionally, use of the static cell has enabled us to collect spectra for all six molecular oxygen isotopologues using isotopically enriched samples. The (0,0), (0,1), and (1,1) b - X vibrational bands were observed for all six isotopologues. The (1,2) and (2,2) bands were also observed for 16O2. The frequencies of the observed (0,1) transitions resolved discrepancies in Raman data for 16O17O, 17O2, and 17O18O, enabling us to improve the vibrational parameterization of the ground electronic state global fit. Rotationally resolved intensities were determined for the (0,0), (0,1), and (1,1) bands. The experimental band intensity ratios I(0,0)/I(0,1) = 13.53(24); I(1,1)/I(1,0) = 11.9(65); I(0,0)/I(0,2) = 503(197); and I(1,1)/I(1,2) = 5.6(19) are in excellent agreement with the recent mesospheric remote sensing data and calculated Franck-Condon factors.

  17. Seasonal trends and nightly fluctuations of SWIR air-glow irradiance

    Science.gov (United States)

    Dayton, David C.; Allen, Jeffrey; Nolasco, Rudolph; Gonglewski, John D.; Myers, Michael; Fertig, Gregory

    2011-11-01

    It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band with wavelength between 0.9 and 1.7 μm. This air glow has been proposed as an illumination source for obtaining imagery in the dark of night. By examining short term nightly fluctuations and long term seasonal trends in the ground level irradiance we hope to determine the source reliability for night time low light surveillance and imaging.

  18. Measurements of the helium 584 Å airglow during the Cassini flyby of Venus

    OpenAIRE

    Gérard, Jean-Claude; Gustin, Jacques; Hubert, Benoît; Gladstone, G. R.; Esposito, L. W.

    2011-01-01

    The helium resonance line at 584 Å has been observed with the UltraViolet Imaging Spectrograph (UVIS) Extreme Ultraviolet channel during the flyby of Venus by Cassini at a period of high solar activity. The brightness was measured along the disk from the morning terminator up to the bright limb near local noon. The mean disk intensity was ˜320 R, reaching ˜700 R at the bright limb. These values are slightly higher than those determined from previous observations. The sensitivity of the 584 Å ...

  19. Measurements of the helium 584 Å airglow during the Cassini flyby of Venus

    Science.gov (United States)

    Gérard, J.-C.; Gustin, J.; Hubert, B.; Gladstone, G. R.; Esposito, L. W.

    2011-10-01

    The helium resonance line at 584 Å has been observed with the UltraViolet Imaging Spectrograph (UVIS) Extreme Ultraviolet channel during the flyby of Venus by Cassini at a period of high solar activity. The brightness was measured along the disk from the morning terminator up to the bright limb near local noon. The mean disk intensity was ∼320 R, reaching ∼700 R at the bright limb. These values are slightly higher than those determined from previous observations. The sensitivity of the 584 Å intensity to the helium abundance is analyzed using recent cross-sections and solar irradiance measurements at 584 Å. The intensity distribution along the UVIS footprint on the disk is best reproduced using the EUVAC solar flux model and the helium density distribution from the VTS3 empirical model. It corresponds to a helium density of 8×106 cm-3 at the level of where the CO2 is 2×1010 cm-3.

  20. Far ultraviolet and extreme ultraviolet rocket instrumentation for measuring the solar spectral irradiance and terrestrial airglow

    Science.gov (United States)

    Woods, Thomas N.; Bailey, Scott M.; Solomon, Stanley C.; Rottman, Gary J.

    1992-06-01

    A sounding-rocket experiment is being developed for the study of EUV spectral irradiance and its effects on the upper atmosphere, using three solar EUV instruments devised by the Laboratory for Atmospheric and Space Physics. These include a 25-cm Rowland circle EUV spectrograph, an array of Si X-UV photodiodes, and an X-UV imager with 20 arcsec resolution of the sun.

  1. Novel Stimulated Electromagnetic Emission Observations with Artificial Airglow Using RF Excitation with HAARP

    Science.gov (United States)

    Briczinski, S. J., Jr.; Bernhardt, P. A.; Siefring, C. L.; Michell, R.; Hampton, D. L.; Watkins, B. J.; Bristow, W. A.

    2014-12-01

    Neutral hydrogen plays an important role in determining the state of the plasmasphere and its response to forcing from geomagnetic storms. Hydrogen's solar cycle variation is counterintuitive: there is more hydrogen at solar minimum at 300 km that there is at solar maximum. Similarly there is more hydrogen in winter than in summer and hydrogen density maximizes in the morning. In this presentation we describe these variations and consider some possible causes for them.

  2. Spatial characteristics of airglow and solar-scatter radiance from the earth's atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Huguenin, R.; Wohlers, R.; Weinberg, M.; Huffman, R.; Eastes, R.

    1989-08-09

    Data measured by the Polar BEAR/AIRS UV Experiment were processed to extract spatial-radiance characteristics. Photometer-mode 1304A dayside data measured on Julian Day 219, 1987, near mid-day were analyzed. The spatial structure of thermospheric dayside radiance at 1304A appeared to be controlled principally by turbulence over spatial scales of 10 million - 100 meters, with modifications imposed by Rayleigh-scattering effects and magnetospherically forced phenomena. Spatial structure can be adequately modeled fractally, using dimensions based on Kolmogorov formalism modified by the Rayleigh scattering phase function. Mean radiance can be modeled using existing models of radiant intensity, resonance scattering, and absorption combined with thermospheric composition and general circulation models, such as MSIS-83, scaled to the mean and RHS intensities measured by Polar BEAR. The results can be incorporated in a background radiance simulation model that will provide a means for testing and refining phenomenological models of the structured earth background. This will be important not only for improving physical and chemical models of atmospheric features and processes, but it will allow parametric predictions of spatial structure and clutter to be developed for sensor applications.

  3. Twilight airglow. I - Photoelectrons and forbidden O I 5577-angstrom radiation.

    Science.gov (United States)

    Hays, P. B.; Sharp, W. E.

    1973-01-01

    A payload consisting of a number of experiments to study the earth's atmosphere was launched from White Sands on Feb. 8, 1971. The differential photoelectron flux spectrum was measured as a function of altitude. The energy distribution revealed the N2 vibrational structure appearing at 2.8 V, rising to a maximum at 4 eV, decreasing to an 8-volt-wide plateau at 20 V, and then further decreasing. The ion and electron density distributions were measured simultaneously. An optical measurement of forbidden O I 5577-A radiation was made. Both electron impact on atomic oxygen and dissociative recombination of O2(+) were found to produce this emission above 150 km. The recombination rate for the O(1 S) found from a reported nightglow profile is 2.5 plus or minus 1.5 x 10 to the minus 9th cu cm/sec. Between 140 and 120 km, photodissociation is a source of 5577 radiation. Chapman three-body recombination is dominant below 120 km.

  4. Medium-Scale Traveling Ionospheric Disturbances and Plasma Bubbles Observed by an All-Sky Airglow Imager at Yonaguni, Japan

    OpenAIRE

    Tadahiko Ogawa; Yuichi Otsuka; Kazuo Shiokawa; Takuya Tsugawa; Akinori Saito; Kazuaki Hoshinoo; Keisuke Matunaga; Minoru Kubota; and Mamoru Ishii

    2009-01-01

    We report on night time air glow imaging observations of the low latitude ionosphere by means of a 630-m all-sky imager in stalled in March 2006 at Yonaguni, Japan _ _ _ geomagnetic), about 100 km east of Taiwan. The imager detected medium-scale traveling ionospheric disturbances (MSTIDs) for about 7 hours on the night of 26 May 2006. A dense GPS net work in Japan also ob served the same MSTID event on this night. The imager and GEONET data indicate that most of the MSTIDs prop a gated south ...

  5. Medium-Scale Traveling Ionospheric Disturbances and Plasma Bubbles Observed by an All-Sky Airglow Imager at Yonaguni, Japan

    Directory of Open Access Journals (Sweden)

    Tadahiko Ogawa

    2009-01-01

    Full Text Available We report on night time air glow imaging observations of the low latitude ionosphere by means of a 630-m all-sky imager in stalled in March 2006 at Yonaguni, Japan _ _ _ geomagnetic, about 100 km east of Taiwan. The imager detected medium-scale traveling ionospheric disturbances (MSTIDs for about 7 hours on the night of 26 May 2006. A dense GPS net work in Japan also ob served the same MSTID event on this night. The imager and GEONET data indicate that most of the MSTIDs prop a gated south west ward from the north of Japan to the south of Yonaguni and Taiwan over 4000 km, with a southern limit of _ (geomagnetic latitude _ or lower. On the night of 10 November 2006, the imager observed two weak emission bands that were embedded on the F-region anomaly crest to the south of Yonaguni. The simultaneous electron density profiles from the FORMOSAT-3/COS MIC mission demonstrate that the weak emission bands are due to density depletions in equatorial plasma bubbles. These case studies suggest that the Yonaguni imager in collaboration with other instruments is very suit able for the study of ionospheric disturbances in and around the northern F-region anomaly crest.

  6. Evaluation of Ionospheric Densities Using Coincident OII 83.4 nm Airglow and the Millstone Hill Radar

    CERN Document Server

    Douglas, Ewan S; Stephan, Andrew W; Cashman, Lauren; Bishop, Rebecca L; Budzien, Scott A; Christensen, Andrew B; Hecht, James H; Chakrabarti, Supriya

    2016-01-01

    We test the utility of the OII 83.4 nm emission feature as a measure of ionospheric parameters. Observed with the Remote Atmospheric and Ionospheric Detection System (RAIDS) Extreme Ultraviolet Spectrograph on the International Space Station (ISS), limb profiles of 83.4 nm emissions are compared to predicted dayglow emission profiles from a theoretical model incorporating ground-based electron density profiles measured by the Millstone Hill radar and parameterized by a best-fit Chapman-{\\alpha} function. Observations and models are compared for periods of conjunction between Millstone Hill and the RAIDS fields-of-view. These RAIDS observations show distinct differences in topside morphology between two days, 15 January and 10 March 2010, closely matching the forward model morphology and demonstrating that 83.4 nm emission is sensitive to changes in the ionospheric density profile from the 340 km altitude of the ISS during solar minimum. We find no significant difference between 83.4 nm emission profiles model...

  7. MEx/SPICAM Dayside Exospheric Temperatures Derived from Airglow Emissions and Comparisons with Global Model Simulations: Do We Understand the Variations?

    Science.gov (United States)

    Bougher, S. W.; Stiepen, A.; Gerard, J. M.; Pawlowski, D. J.; Montmessin, F.

    2013-12-01

    For ten years now, the SPectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) instrument on board Mars Express has collected tangential limb dayglow observations of the CO Cameron bands (170-270 nm) and the CO2+ doublet emission lines (289 nm). The CO2+ emission arises from the relaxation of the CO2+* molecule in the B2Σ+ state to the X2Π state. The CO Cameron emissions arise from the forbidden transition between CO in the exited a3 Π triplet state to the ground (X1Σ+) state. CO2+*and CO* molecules are mainly produced in the Martian dayside through photoionization and photoelectron impact. The temperature of the neutral thermosphere-exosphere region of the Martian atmosphere (above 150 km) has been derived from the top scale height of these emission vertical profiles. The database contains temperatures obtained from observations that cover all latitudes, seasons, dayside solar zenith angles, etc. for solar minimum to moderate conditions. A search for the key factors that influence the temperature in this region of the Martian atmosphere is presented. In addition, 3-D global model simulations are conducted appropriate to these SPICAM sampling conditions. Comparisons among Mars Thermosphere General Circulation Model (MTGCM), Mars Global Ionosphere Thermosphere Model (MGITM), and SPICAM derived temperatures are made. The capability of these solar EUV controlled 3-D models to reproduce observed dayside temperatures is discussed.

  8. Cassini UVIS observations of Titan nightglow spectra

    OpenAIRE

    Ajello, Joseph M.; West, Robert A.; Gustin, Jacques; Larsen, Kristopher; Stewart, A. Ian F.; Esposito, Larry W.; Mcclintock, William E.; Holsclaw, Gregory M.; Bradley, E. Todd

    2012-01-01

    In this paper we present the first nightside EUV and FUV airglow limb spectra of Titan showing molecular emissions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed photon emissions of Titan's day and night limb-airglow and disk-airglow on multiple occasions, including during an eclipse observation. The 71 airglow observations analyzed in this paper show EUV (600-1150 Å) and FUV (1150-1900 Å) atomic multiplet lines and band emissions arising from either photoelectron induced fluor...

  9. A first look at the ASSI ultraviolet results

    Science.gov (United States)

    Chakrabarti, S.; Gladstone, G. R.; Tobiska, W. K.; Schmidtke, G.; Doll, H.; Gerard, J.-C.

    1993-01-01

    The Airglow and Solar Spectrometer Instrument (ASSI) on the San Marco D satellite has obtained near-simultaneous measurements of solar irradiances and airglow emissions in the 200-7000 A spectral region. The satellite was placed in an equatorial, elliptical orbit on 25 March 1988, which permitted observations of airglow emissions in the 280-600-km altitude range at various local times. The instrument complement on the satellite provides an opportunity both for self-consistent examination of the excitation mechanisms of various airglow features and for constraining model parameters. An overview of the data obtained by ASSI is presented along with preliminary modeling results of the UV airglow.

  10. A search for evidence of tidal activity in OH(3,l)airglow omissions recorded at Maynooth (53.23° N, 6.35° W)

    OpenAIRE

    Mulligan, F. J.; Nallen, J.J.

    1998-01-01

    Spectra of the Meinel hydroxyl emissions in the wavelength range LO-l.6 um, which originate at altitudes close to the mesopause, have been obtained, using a Fourier transform spectrometer at Maynooth (53.23°N, 6.35*W), Ireland, on all suitable nights during the period December 1992 to July 1995. Rotational temperatures and integrated band intensities have been calculated from the spectra of the OH (3, 1) vibrational band. These data have been analysed for evidence of tidal activity. Ou...

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

    NARCIS (Netherlands)

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

    2014-01-01

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

  12. Chapman Solar Zenith Angle variations at Titan

    Science.gov (United States)

    Royer, Emilie M.; Ajello, Joseph; Holsclaw, Gregory; West, Robert; Esposito, Larry W.; Bradley, Eric Todd

    2016-10-01

    Solar XUV photons and magnetospheric particles are the two main sources contributing to the airglow in the Titan's upper atmosphere. We are focusing here on the solar XUV photons and how they influence the airglow intensity. The Cassini-UVIS observations analyzed in this study consist each in a partial scan of Titan, while the center of the detector stays approximately at the same location on Titan's disk. We used observations from 2008 to 2012, which allow for a wide range of Solar Zenith Angle (SZA). Spectra from 800 km to 1200 km of altitude have been corrected from the solar spectrum using TIMED/SEE data. We observe that the airglow intensity varies as a function of the SZA and follows a Chapman curve. Three SZA regions are identified: the sunlit region ranging from 0 to 50 degrees. In this region, the intensity of the airglow increases, while the SZA decreases. Between SZA 50 and 100 degrees, the airglow intensity decreases from it maximum to its minimum. In this transition region the upper atmosphere of Titan changes from being totally sunlit to being in the shadow of the moon. For SZA 100 to 180 degrees, we observe a constant airglow intensity close to zero. The behavior of the airglow is also similar to the behavior of the electron density as a function of the SZA as observed by Ågren at al (2009). Both variables exhibit a decrease intensity with increasing SZA. The goal of this study is to understand such correlation. We demonstrate the importance of the solar XUV photons contribution to the Titan airglow and prove that the strongest contribution to the Titan dayglow occurs by solar fluorescence rather than the particle impact that predominates at night.

  13. Upper Atmospheric Density Retrievals from UVIS Dayglow Observations of Titan

    Science.gov (United States)

    Stevens, Michael H.; Evans, J. S.; Ajello, J. M.; Bradley, E. T.; Meier, R. R.; Westlake, J. H.; Waite, J. H.

    2012-10-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed Titan’s dayside limb on multiple occasions between 2007-2012. The airglow observations reveal the same variety of EUV (600-1150 λ) and FUV (1150-1900 λ) emissions arising from photoelectron impact and photofragmentation of molecular nitrogen (N2) on Earth. Through spectral analysis we extract radiance profiles for each set of UVIS limb emissions in the EUV and FUV, which are attenuated by methane (CH4). Using a terrestrial airglow model adapted to Titan, we derive the N2 and CH4 density profiles using the prescribed solar irradiance for the relevant Cassini orbit and compare the calculated radiance profiles directly with observations. We find that the Titan airglow can be explained by solar driven processes to within the uncertainties of the UVIS observations. Fluctuations in the observed airglow between flybys suggest compositional changes in the background atmosphere. The source of these compositional changes is not yet known, although the interaction of Titan with Saturn’s magnetosphere has been implicated as an important contributing factor. Here we use unique UVIS airglow observations over Titan’s disk to quantify compositional fluctuations with latitude and local time. We furthermore compare N2 and CH4 densities retrieved from the UVIS airglow to in situ observations by the Cassini Ion and Neutral Mass Spectrometer (INMS) and discuss how the UVIS and INMS variations may be related to Titan’s varying plasma environment.

  14. Ground-satellite conjugate observations of low-latitude travelling ionospheric disturbances

    Science.gov (United States)

    Ceren Moral, Aysegul; Shiokawa, Kazuo; Otsuka, Yuichi; Suzuki, Shin; Liu, Huixin; Yatini, Clara

    2016-07-01

    Equatorial travelling ionospheric disturbances (TIDs) are studied by using three CHAMP satellite overpasses on ground-based 630-nm airglow images. The airglow images are obtained from Kototabang (KTB), Indonesia (geographic coordinates: 0.2S, 100.3E, geomagnetic latitude: 10.6S). From 7-year data from October 2002 to October 2009, April 30, 2006 (event 1), September 28, 2006 (event 2) and April 12, 2004 (event 3) are the only TID events found in both ground and satellite measurements. They show southward-moving structures in 630-nm airglow images. The events 1 and 2 are single pulse with horizontal scales of ~500-1000 km and event 3 show three wave fronts with horizontal scale sizes of 500-700 km. For events 1 and 3, the neutral density in CHAMP shows out-of-phase variations with the airglow intensity, while event 2 is in-phase. For event 1, the relation between electron density and airglow intensity is out of phase, while relationships of event 2 and 3 are unclear. These unclear relationships suggest that ionospheric plasma variation is not the cause of the TIDs. In the case if gravity waves in the thermosphere is the source of the observed TIDs, in-phase and out-of-phase relationships of neutral density and airglow intensity can be explained by different vertical wavelengths of the gravity wave. We estimate possible vertical wavelengths for those events using observed wave parameters and modeled neutral winds.

  15. A New Display Format Relating Azimuth-Scanning Radar Data and All-Sky Images in 3-D

    Science.gov (United States)

    Swartz, Wesley E.; Seker, Ilgin; Mathews, John D.; Aponte, Nestor

    2010-01-01

    Here we correlate features in a sequence of all-sky images of 630 nm airglow with the three-dimensional (3-D) structure of electron densities in the F region above Arecibo. Pairs of 180 azimuth scans (using the Gregorian and line feeds) of the two-beam incoherent scatter radar (ISR) have been plotted in cone pictorials of the line-of-sight electron densities. The plots include projections of the 630 nm airglow onto the ground using the same spatial scaling as for the ISR data. Selected sequential images from the night of 16-17 June 2004 correlate ionospheric plasma features with scales comparable to the ISR density-cone diameter. The entire set of over 100 images spanning about eight hours is available as a movie. The correlation between the airglow and the electron densities is not unexpected, but the new display format shows the 3-D structures better than separate 2-D plots in latitude and longitude for the airglow and in height and time for the electron densities. Furthermore, the animations help separate the bands of airglow from obscuring clouds and the star field.

  16. Compositional Variations from UVIS Observations of Titan's Dayglow and Comparisons with in situ INMS Observations

    Science.gov (United States)

    Stevens, M. H.; Evans, J. S.; Ajello, J. M.; Bradley, E. T.; Meier, R. R.; Westlake, J. H.; Waite, J. H., Jr.

    2012-04-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed Titan’s dayside limb on multiple occasions between 2007 and 2011. The airglow observations reveal the same variety of EUV (600-1150Å) and FUV (1150-1900Å) emissions arising from photoelectron excitation and photofragmentation of molecular nitrogen (N2) on Earth. Through spectral analysis we extract radiance profiles for each set of UVIS limb emissions in the EUV and FUV, which are attenuated by methane (CH4). Using a terrestrial airglow model adapted to Titan, we derive the N2 and CH4 density profiles using the prescribed solar irradiance for the relevant Cassini orbit and compare the calculated radiance profiles directly with observations. We find that the UVIS airglow observations can be explained by solar driven processes, although fluctuations in the observed airglow between flybys suggest compositional changes in the background atmosphere. We compare the compositional variations inferred from the UVIS airglow to in situ observations by the Cassini Ion and Neutral Mass Spectrometer (INMS) from the same Titan orbit and discuss how the variations may be related to Titan’s varying plasma environment.

  17. Climatology of the O(1S) and O(1D) emission rates from WINDII/UARS global measurements

    Science.gov (United States)

    Zhang, Z.; Shepherd, S.

    The Wind Imaging Interferometer WINDII on the Upper Atmospheric Research Satellite UARS has provided a large number of O 1S green line 557 7 nm and O 1D red line 630 0 nm emission rate profiles during 1991-1997 of unprecedented high quality The daytime airglow emission is produced mainly by solar energy deposition and vary according to changes of the solar zenith angle and solar irradiance The nighttime airglow emission rates show strong latitudinal and local time dependences Using both daytime and nighttime measurements the directly solar excited daytime emission rates can be removed and the indirectly excited component is revealed This study presents the seasonal and latitudinal variations of the indirect component of the two airglow emission rates which may be due to tides geomagnetic effects and other physical and photochemical processes

  18. Circulation in upper mesosphere of Venus in the Southern and Northern hemispheres from the O2 1.27 μm night glow (VIRTIS-M/VEX data)

    Science.gov (United States)

    Zasova, L.; Shakun, A.; Khatuntsev, I.; Gorinov, D.; Migliorini, A.; Altieri, F.; Piccioni, G.; Drossart, P.

    2014-04-01

    Mapping spectrometer VIRTIS-M on board Venus Express [1] made observations of the O2 1.27 μm airglow intensity distribution on the night side of Venus in nadir and limb modes in Southern and Northern hemispheres respectively. The work is devoted to comparison of the results, obtained for both hemispheres.

  19. Solar and chemical reaction-induced heating in the terrestrial mesosphere and lower thermosphere

    Science.gov (United States)

    Mlynczak, Martin G.

    1992-01-01

    Airglow and chemical processes in the terrestrial mesosphere and lower thermosphere are reviewed, and initial parameterizations of the processes applicable to multidimensional models are presented. The basic processes by which absorbed solar energy participates in middle atmosphere energetics for absorption events in which photolysis occurs are illustrated. An approach that permits the heating processes to be incorporated in numerical models is presented.

  20. Skycorr: A general tool for spectroscopic sky subtraction

    CERN Document Server

    Noll, S; Kimeswenger, S; Barden, M; Jones, A M; Modigliani, A; Szyszka, C; Taylor, J

    2014-01-01

    Airglow emission lines, which dominate the optical-to-near-IR sky radiation, show strong, line-dependent variability on various time scales. Therefore, the subtraction of the sky background in the affected wavelength regime becomes a problem if plain sky spectra have to be taken at a different time as the astronomical data. A solution of this issue is the physically motivated scaling of the airglow lines in the plain sky data to fit the sky lines in the object spectrum. We have developed a corresponding instrument-independent approach based on one-dimensional spectra. Our code skycorr separates sky lines and sky/object continuum by an iterative approach involving a line finder and airglow line data. The sky lines are grouped according to their expected variability. The line groups in the sky data are then scaled to fit the sky in the science data. Required pixel-specific weights for overlapping groups are taken from a comprehensive airglow model. Deviations in the wavelength calibration are corrected by fitti...

  1. Inter-hemispheric Comparison of Mesospheric Short-period Gravity Wave Propagation

    Science.gov (United States)

    Nielsen, K.; Taylor, M. J.; Collins, R. L.; Irving, B. K.; Negale, M.; Siskind, D. E.; Eckermann, S. D.; Hoppel, K.; Harvey, V.; Russell, J. M.

    2011-12-01

    Mesospheric short-period (≤1-hr) gravity waves are of great importance for dynamics in the mesosphere-lower thermosphere (MLT) region, and are typically measured by instruments capable of high temporal and/or spatial resolutions such as lidars and airglow imagers. These waves have been studied extensively at low- and mid-latitudes where known wave sources are well established. The results show strong dependence on the background wind and temperature fields, which can act as a barrier prohibiting vertical propagation of the waves, as well as providing a ducted environment in which the waves can travel large horizontal distances. In fact, results show that up to 75% of these waves may exhibit ducted wave motion. Recent airglow imaging measurements over Antarctica have revealed a large number of short-period gravity waves in absence of the prominent wave sources present at lower latitudes. In contrast to results at lower latitudes, very few waves (˜5%) observed over Halley (76°S) exhibited Doppler ducted motion. In this work, we utilize airglow imagery, SABER temperature measurements, together with the Navy's high-altitude numerical weather prediction system, NOGAPS-ALPHA, to investigate propagation conditions (particularly, the role of thermal ducting) over Rothera (68°S). Data acquired from a newly installed airglow imager operating at Poker Flat, Alaska (65°N) and the co-located lidar provide an opportunity to perform an inter-hemispheric comparison of propagation conditions over two polar sites at similar latitudes.

  2. Proceedings of the 13th annual meeting on upper atmosphere studies by optical methods

    International Nuclear Information System (INIS)

    A total of 41 papers were presented under the following session topics: Atmospheric emissions; auroral features and dynamics; auroral pulsations; airglow and atmospheric parameters; atmospheric constituents; instrumentation and data handling; and observation programs. The report presents the full text or abstracts of 31 of the lectures given at the meeting. 25 of the papers are seperate input to the data base from this report

  3. Study of mid-latitude 5577A CI dayglow emissions. Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Hume, E.E.

    1992-01-01

    Summary of thesis: The green line (5577angstroms) is a bright, persistent component of the visible airglow. It is produced by an electric quadruple transition from the metastable second excited state (1So) to the first excited state (1D2) of atomic oxygen. These two excited states all lie in the same electron shell of the atom and have the same electron configuration as the ground state of 1s22s22p4, which is the 3P2,1,0. This emission is present in both the daytime and night airglow and in the aurora, and despite a long history of study it is still not fully understood. The emission in the dayglow and the nightglow is relatively homogeneous spatially and global in coverage. In the aurora, the emission is much brighter than the airglow, high structured and very localized being restricted to higher latitudes. The structure of the 5577angstroms emission with altitude and the chemistry responsible for the production of the emission are complex. The vertical structure for the emission has two distinct layers in the airglow each with its own set of production and loss mechanisms. the chemistry for either of these layers is not completely known. The auroral emission is not understood either since it overlaps the upper and lower layer altitudes and it tends to contain some parts of the chemistry of both layers as sources and losses.

  4. Cassini UVIS observations of Titan nightglow spectra

    Science.gov (United States)

    Ajello, Joseph M.; West, Robert A.; Gustin, Jacques; Larsen, Kristopher; Stewart, A. Ian F.; Esposito, Larry W.; McClintock, William E.; Holsclaw, Gregory M.; Bradley, E. Todd

    2012-12-01

    In this paper we present the first nightside EUV and FUV airglow limb spectra of Titan showing molecular emissions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed photon emissions of Titan's day and night limb-airglow and disk-airglow on multiple occasions, including during an eclipse observation. The 71 airglow observations analyzed in this paper show EUV (600-1150 Å) and FUV (1150-1900 Å) atomic multiplet lines and band emissions arising from either photoelectron induced fluorescence and solar photo-fragmentation of molecular nitrogen (N2) or excitation by magnetosphere plasma. The altitude of the peak UV emissions on the limb during daylight occurred inside the thermosphere at the altitude of the topside ionosphere (near 1000 km altitude). However, at night on the limb, a subset of emission features, much weaker in intensity, arise in the atmosphere with two different geometries. First, there is a twilight photoelectron-excited glow that persists with solar depression angle up to 25-30 degrees past the terminator, until the solar XUV shadow height passes the altitude of the topside ionosphere (1000-1200 km). The UV twilight glow spectrum is similar to the dayglow but weaker in intensity. Second, beyond 120° solar zenith angle, when the upper atmosphere of Titan is in total XUV darkness, there is indication of weak and sporadic nightside UV airglow emissions excited by magnetosphere plasma collisions with ambient thermosphere gas, with similar N2 excited features as above in the daylight or twilight glow over an extended altitude range.

  5. Temporal and spectral variations of the photoelectron flux and solar irradiance during an X class solar flare

    Science.gov (United States)

    Peterson, W. K.; Chamberlin, P. C.; Woods, T. N.; Richards, P. G.

    2008-06-01

    Photoelectrons are the main energy source of airglow used to diagnose the state of the ionosphere-thermosphere system. Because of measurement uncertainties and substantial gaps in the historical record, parameterized models of the EUV irradiance and photoelectron flux are generally used to estimate airglow intensities. This paper compares observed and modeled photoelectron spectra from an X3 class flare that occurred on July 15, 2002. The photoelectron data were obtained from the FAST satellite. Model photoelectron spectra were obtained from the Field Line Inter-hemispheric Plasma (FLIP) model using 10 s cadence solar spectra at 1 nm resolution from the Flare Irradiance Spectral Model (FISM). The observed and modeled spectra agree well temporally and spectrally within the uncertainties of the models and data. Systematic differences found between observed and modeled photoelectron spectra suggest that the solar irradiance from FISM could be improved at wavelengths shortward of 17 nm.

  6. A reanalysis of rocket measurements of the ultraviolet dayglow

    Science.gov (United States)

    Link, R.; Gladstone, G. R.; Chakrabarti, S.; Mcconnell, J. C.

    1988-01-01

    Rocket measurements of O I 989, 1304, 1356 A and N2 Lyman-Birge-Hopfield band emission in the midlatitude dayglow reported by Gentieu et al. (1979) and Eastes et al. (1985) are reexamined. MSIS-83 atomic oxygen densities, the 1304 and 1356 A excitation cross sections of Zipf and Erdman (1985), and SMM solar 1304 A irradiance measurements are consistent with the observed O I and N2 emission intensities. Atmosphere Explorer E (AE-E) measurements of the solar EUV irradiance near solar maximum are consistent with the 1980 rocket airglow data, but the solar EUV irradiance required to explain the 1978 airglow data is a factor of 1.5 larger than indicated by AE-E. Enhancement of the 1304 A excitation cross section due to radiative entrapment of cascade-feeding photons is much less than the factor of two predicted by the cascade model of Julienne and Davis (1976).

  7. Wave Signatures in the Polar Mesopause Region during the January, 2009 Sudden Stratospheric Warming

    Science.gov (United States)

    Ward, W. E.; Kristoffersen, S.; Vail, C.

    2012-12-01

    Observations on a two minute cadence at the Polar Environment Atmospheric Research Laboratory (PEARL, Eureka, Nunavut, 80N) with an all sky imager and a Doppler Imaging Interferometer were taken during the January, 2009 major stratospheric warming. These observations complement temperature and irradiance measurments previously reported from the same location. Oscillations with periods of 4 days, 2.5 days, 24 hours, 16 hours 12 hours and 8 hours are observed during this warming period. In addition shorter period oscillations in the airglow observations and wind observations are observed. This paper summarizes these observations and delineates the evolution of these features and the large scale winds during this warming event.Meridional winds from Doppler shifts in the oxygen green line airglow observed with the ERWIN II instrument from January 16-31, 2009. Individual points are observations every 2 minutes with an error of 2 m/s.

  8. An analysis of ionospheric dayglow from observations of the Naval Postgraduate School Middle Ultraviolet Spectrograph (MUSTANG)

    Science.gov (United States)

    Marron, Antony C.

    1993-12-01

    Middle ultraviolet spectra of the atmospheric airglow were obtained from a March 1992 rocket flight of the NPS MUSTANG instrument. These spectra are analyzed from 1900 to 3100 A, over an altitude range of 100 to 320 km. The data are modeled with computer generated synthetic spectra for the following emissions: N2 Vegard Kaplan (VK); N2 Lyman - Birge - Hopfield (LBH); and NO gamma, delta, and epsilon bands. A best fit procedure was developed. The resulting synthetic spectra agree well with obtained airglow data. Confirmation was made of the theoretical self absorption versus non-self absorption processes of the NO (0,0), (1,0), and (2,0) gamma resonance band emissions. NO self absorption is a necessary inclusion of any atmospheric nitric oxide analysis stratagem. Profiles of temperature versus altitude and NO column density versus altitude for the rocket flight are estimated.

  9. Observation of mesospheric gravity waves at Comandante Ferraz Antarctica Station (62° S

    Directory of Open Access Journals (Sweden)

    P. B. Souza

    2009-06-01

    Full Text Available An airglow all-sky imager was operated at Comandante Ferraz Antarctica Station (62.1° S, 58.4° W, between April and October of 2007. Mesospheric gravity waves were observed using the OH airglow layer during 43 nights with good weather conditions. The waves presented horizontal wavelengths between 10 and 60 km and observed periods mainly distributed between 5 and 20 min. The observed phase speeds range between 5 m/s and 115 m/s; the majority of the wave velocities were between 10 and 60 m/s. The waves showed a preferential propagation direction towards the southwest in winter (May to July, while during spring (August to October there was an anisotropy with a preferential propagation direction towards the northwest. Unusual mesospheric fronts were also observed. The most probable wave source could be associated to orographic forcing, cold fronts or strong cyclonic activity in the Antarctica Peninsula.

  10. Recent observations of dynamic variations of the thermosphere and ionosphere by the Optical Mesosphere Thermosphere Imagers (OMTIs)

    Science.gov (United States)

    Shiokawa, Kazuo; Otsuka, Yuichi; Oyama, Shin-ichiro; Lakshmi Narayanan, Viswanathan; Ceren Moral, Aysegul

    2016-07-01

    The Optical Mesosphere Thermosphere Imagers (OMTIs) consist of fourteen all-sky cooled-CCD imagers, five Fabry-Perot interferometers (FPIs), three meridian scanning photometers, and four airglow temperature photometers. They measure two-dimensional pattern, Doppler wind, and temperature through airglow emissions from oxygen (wavelength: 557.7 nm) and OH (near infrared band) in the mesopause region (80-100 km) and from oxygen (630.0 nm) in the thermosphere/ionosphere (200-300 km). They are in automatic operation at 14 stations at Australia, Indonesia, Thailand, far-east Russia, Japan, Canada, Hawaii, Norway, and Nigeria. Station information and quick look plots are available at http://stdb2.stelab.nagoya-u.ac.jp/omti/. In this presentation we show recent observations of the dynamical variations of the thermosphere and ionosphere observed by OMTIs at various latitudes from the equator to the auroral zone.

  11. Wave-coupling from the troposphere to the mesosphere and thermosphere observed by the Optical Mesosphere Thermosphere Imagers (OMTIs)

    Science.gov (United States)

    Shiokawa, Kazuo; Otsuka, Yuichi; Takeo, Daiki; Fujinami, Hatsuki

    2016-07-01

    The airglow emissions from the mesopause region and the thermosphere are very useful to monitor dynamical variations of the neutral and plasma atmosphere in the upper atmosphere. The Optical Mesosphere Thermosphere Imagers (OMTIs) measure two-dimensional pattern, Doppler wind, and temperature through airglow emissions from oxygen (wavelength: 557.7 nm) and OH (near infrared band) in the mesopause region (80-100 km) and from oxygen (630.0 nm) in the thermosphere/ionosphere (200-300 km) at various locations in the world. Station information and quick look plots are available at http://stdb2.stelab.nagoya-u.ac.jp/omti/. In this presentation we show recent observations by OMTIs for the vertical coupling of atmospheric gravity waves from the troposphere to the mesopause region and to the thermosphere/ionosphere.

  12. Variability of the nitric oxide nightglow at Venus during solar minimum

    Science.gov (United States)

    Royer, E. M.; Montmessin, F.; Marcq, E.

    2016-05-01

    We present results from a NO airglow inversion method based on Venus Express data acquired from 2006 to 2010, during the last solar minimum period. We retrieve an altitude of 114 ± 10 km for the emission peak of the NO layer, with an associated scale height of 20 ± 10 km and an average limb brightness of 59.3 kR with a standard deviation of 63 kR. The inversion method allows for the quantification of the horizontal homogeneity of the NO layer. Images of the SPICAV field of view show a great variability of airglow morphologies, with NO layers that can be horizontally homogenous and continuous over distances exceeding 100 km, as well as sporadic patches of NO on a smaller horizontal scale. Frequent secondary emissions seen at lower tangent altitudes are the signatures of the complex dynamics of the upper Venusian atmosphere.

  13. Observations of Polar Dynamics in the Mesosphere and Lower Thermosphere from the Polar Environment Atmospheric Research Laboratory

    OpenAIRE

    2013-01-01

    A suite of instruments capable of observing phenomena in the polar mesosphere and lower thermosphere has been established at the Polar Environment Atmospheric Research Laboratory (PEARL) situated in the Canadian high Arctic at Eureka, Nunavut, Canada (80N, 86W). Observations with some instruments started in 2007 but the full suite started operation in 2008.Instruments located at this site include a meteor radar, a Rayleigh lidar, a Spectral Airglow Temperature Imager (SATI), an all sky airglo...

  14. Response of the Upper Atmosphere to Variations in the Solar Soft X-Ray Irradiance

    Science.gov (United States)

    Bailey, Scott Martin

    1995-11-01

    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 airglow, the magnitude of the solar energy deposition must be known. Previous analyses have used the electron impact excited Lyman-Birge-Hopfield (LBH) bands of N _2 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 N_2 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 thermosphere 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, S.M.

    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 airglow, 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.

  16. Active Experiment with High-Power Electron Gun in the Polar Region (Plan)

    OpenAIRE

    Sasaki,Susumu/Kaneko,Osamu/Kawashima,Nobuki/Yagi,Yasuyuki/Akai,Kazunori/Nakai,Yutaka

    1981-01-01

    A plan of a high-power electron beam experiment in the polar region is discussed. An electron beam is quite useful for studying space plasma phenomena as one of the active experiments. The main objective of the experiment is to study the aurora/airglow and various kinds of waves artificially excited by the electron beam, as compared with natural ones. It can be also used to trace the magnetic field line in the polar region.

  17. EARTHQUAKE LIGHTS IN LEGENDS OF THE GREEK ORTHODOXY

    OpenAIRE

    Florinsky, I.V.

    2015-01-01

    Local legends may contain information about real geological events of the past. Earthquake lights (EQL) can occur in the atmosphere over earthquake epicenter areas and adjacent faults before and during quakes. They may look like diffuse airglow, flashes, fiery pillars, and luminous balls. EQL may cause a mystical experience probably due to the influence of their electromagnetic fields on the brain. Subjective perception and interpretation of EQL depend on religious and cultural traditions. We...

  18. Characterization of VHF radar observations associated with equatorial Spread F by narrow-band optical measurements

    Directory of Open Access Journals (Sweden)

    R. Sekar

    2004-09-01

    Full Text Available The VHF radars have been extensively used to investigate the structures and dynamics of equatorial Spread F (ESF irregularities. However, unambiguous identification of the nature of the structures in terms of plasma depletion or enhancement requires another technique, as the return echo measured by VHF radar is proportional to the square of the electron density fluctuations. In order to address this issue, co-ordinated radar backscatter and thermospheric airglow intensity measurements were carried out during March 2003 from the MST radar site at Gadanki. Temporal variations of 630.0-nm and 777.4-nm emission intensities reveal small-scale ("micro" and large-scale ("macro" variations during the period of observation. The micro variations are absent on non-ESF nights while the macro variations are present on both ESF and non-ESF nights. In addition to the well-known anti-correlation between the base height of the F-region and the nocturnal variation of thermospheric airglow intensities, the variation of the base height of the F-layer, on occasion, is found to manifest as a bottomside wave-like structure, as seen by VHF radar on an ESF night. The micro variations in the airglow intensities are associated with large-scale irregular plasma structures and found to be in correspondence with the "plume" structures obtained by VHF radar. In addition to the commonly observed depletions with upward movement, the observation unequivocally reveals the presence of plasma enhancements which move downwards. The observation of enhancement in 777.4-nm airglow intensity, which is characterized as plasma enhancement, provides an experimental verification of the earlier prediction based on numerical modeling studies.

  19. GALEX Observations of Diffuse UV Radiation at High Spatial Resolution from the Sandage Nebulosity

    OpenAIRE

    Sujatha, N. V.; Murthy, Jayant; Karnataki, Abhay; Henry, Richard Conn; Bianchi, Luciana

    2008-01-01

    Using the GALEX ultraviolet imagers we have observed a region of nebulosity first identified as starlight scattered by interstellar dust by Sandage (1976). Apart from airglow and zodiacal emission, we have found a diffuse UV background of between 500 and 800 \\phunit in both the \\galex FUV (1350 -- 1750 \\AA) and NUV (1750 -- 2850 \\AA). Of this emission, up to 250 \\phunit is due to \\htwo fluorescent emission in the FUV band; the remainder is consistent with scattering from interstellar dust. We...

  20. Gravity wave transmission diagram

    Science.gov (United States)

    Tomikawa, Yoshihiro

    2016-07-01

    A possibility of gravity wave propagation from a source region to the airglow layer around the mesopause has been discussed based on the gravity wave blocking diagram taking into account the critical level filtering alone. This paper proposes a new gravity wave transmission diagram in which both the critical level filtering and turning level reflection of gravity waves are considered. It shows a significantly different distribution of gravity wave transmissivity from the blocking diagram.

  1. Twinkling Lights in the Nightside Upper Atmosphere: How Nightglow Contributes to our Understanding of Global Dynamics

    OpenAIRE

    Brecht, Amanda; Bougher, S.; Stiepen, Arnaud; Soret, Lauriane; Gérard, Jean-Claude

    2015-01-01

    Upper atmospheres of planets continuously emit photons in the UV, Visible, and IR regions of the electromagnetic spectrum. Some of these emissions are classified as airglow, which includes dayglow and nightglow. There are several mechanisms to create these emissions, but this presentation will focus on nightglow emissions resulting from photochemistry of neutral components. These neutral components originate on the dayside and are transported from the dayside to the nightside of a planet, ...

  2. Spatial and temporal variability of SWIR air glow measurements

    Science.gov (United States)

    Allan, Jeffery; Dayton, David; Gonglewski, John; Myers, Michael; Nolasco, Rudolf

    2011-05-01

    It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band between 0.9 and 1.7 μm wave length. This phenomenon, often referred to as airglow, has been demonstrated as an effective illumination source for passive low light level night time imaging applications. It addition it has been shown that observation of the spatial and temporal variations of the illumination can be used to characterize atmospheric tidal wave actions in the airglow region. These spatio-temporal variations manifest themselves as traveling wave patterns whose period and velocity are related to the wind velocity at 85 km as well as the turbulence induced by atmospheric vertical instabilities. In this paper we present nearly a year of airglow observations over the whole sky, showing long term and short term fluctuations to characterize SWIR night time image system performance.

  3. Titan's night-glow mechanisms

    Science.gov (United States)

    Lavvas, P.; West, R. A.; Gronoff, G.

    2014-04-01

    Observations of Titan's emissions during its 2009 eclipse by Saturn revealed a weak airglow around the moon, as well as a brighter emission from its disk (Fig.1). We explore here the potential mechanisms that could generate these emissions and more specifically the role of magnetospheric plasma and cosmic rays in the upper and lower atmosphere, respectively [2]. We consider excitation of N2 by these energy sources and calculate the resulting emissions through a detailed model of N2 airglow [3](Fig.2), followed by careful radiation transfer of the emitted photons through the atmosphere, and into the UVIS and ISS instruments (Figs 3 & 4). Our results indicate that the observed limb emissions are consistent with magnetospheric plasma energy input, while emissions instigated by cosmic ray excitation deep in the atmosphere are strongly attenuated by the haze and can not explain the observed disk emissions [4](Tables 1 & 2). We discuss possible contributions from other sources that could potentially explain the disk observations. These include airglow from other species, chemiluminescence, aerosol particle fluorescence, and scattered light from the stellar background.

  4. New measurements by the TIMED solar extreme-ultraviolet experiment: Implications for thermospheric modeling

    Science.gov (United States)

    Solomon, S. C.; Bailey, S. M.; Eparvier, F. G.; Gladstone, G. R.; Paxton, L. J.; Woods, T. N.

    2003-04-01

    The Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite, launched in December 2001, is now performing comprehensive new measurements of the solar irradiance spectrum in the extreme-ultraviolet and soft X-ray regions. The TIMED solar EUV experiment (SEE) consists of an ultraviolet spectrometer and an X-ray photometer, and performs a full-disk spectral measurement once per orbit. Comparison of TIMED/SEE measurements to contemporaneous satellite observations from the Student Nitric Oxide Explorer (SNOE) and a calibration rocket shows that solar irradiance in the XUV spectral range, from about 1 to 25 nm, is significantly more intense than previous observations. SEE solar spectra can be used as inputs to thermosphere/ionosphere models, including photoelectron/airglow models, thermosphere global mean models, and general circulation models. The resulting revisions to predicted photoelectron fluxes, ionization rates, electron density, ion composition, odd-nitrogen composition, and airglow emission rates show improved agreement with observations. We compare predictions to measurements for some of these, including ground based measurements of ionospheric parameters and airglow measurements by the TIMED global ultraviolet imager.

  5. Horizontal structure and propagation characteristics of mesospheric gravity waves observed by Antarctic Gravity Wave Imaging/Instrument Network (ANGWIN), using a 3-D spectral analysis technique

    Science.gov (United States)

    Matsuda, Takashi S.; Nakamura, Takuji; Murphy, Damian; Tsutsumi, Masaki; Moffat-Griffin, Tracy; Zhao, Yucheng; Pautet, Pierre-Dominique; Ejiri, Mitsumu K.; Taylor, Michael

    2016-07-01

    ANGWIN (Antarctic Gravity Wave Imaging/Instrument Network) is an international airglow imager/instrument network in the Antarctic, which commenced observations in 2011. It seeks to reveal characteristics of mesospheric gravity waves, and to study sources, propagation, breaking of the gravity waves over the Antarctic and the effects on general circulation and upper atmosphere. In this study, we compared distributions of horizontal phase velocity of the gravity waves at around 90 km altitude observed in the mesospheric airglow imaging over different locations using our new statistical analysis method of 3-D Fourier transform, developed by Matsuda et al. (2014). Results from the airglow imagers at four stations at Syowa (69S, 40E), Halley (76S, 27W), Davis (69S, 78E) and McMurdo (78S, 156E) out of the ANGWIN imagers have been compared, for the observation period between April 6 and May 21 in 2013. In addition to the horizontal distribution of propagation and phase speed, gravity wave energies have been quantitatively compared, indicating a smaller GW activity in higher latitude stations. We further investigated frequency dependence of gravity wave propagation direction, as well as nightly variation of the gravity wave direction and correlation with the background wind variations. We found that variation of propagation direction is partly due to the effect of background wind in the middle atmosphere, but variation of wave sources could play important role as well. Secondary wave generation is also needed to explain the observed results.

  6. Post midnight spread-F occurrence over Waltair (17.7° N, 83.3° E during low and ascending phases of solar activity

    Directory of Open Access Journals (Sweden)

    K. Niranjan

    Full Text Available A study carried out on the occurrence of post midnight spread-F events at a low-latitude station, Waltair (17.7° N, 83.3° E, India revealed that its occurrence is maximum in the summer solstice months of the low solar activity period and decreases with an increase in the sunspot activity. The F-region virtual height variations show that 80% of these spread-F cases are associated with an increase in the F-region altitude. It is suggested with the support of the night airglow 6300 A zenith intensity data obtained with co-located ground-based night airglow photometer and electron temperature data from the Indian SROSS C2 satellite that the seasonal variation of the occurrence and probable onset times of the post midnight spread-F depend on the characteristics of the highly variable semipermanent equatorial Midnight Temperature Maximum (MTM.

    Key words. Ionosphere (ionospheric irregularities; ionosphere atmosphere interactions Atmospheric composition and structure (airglow and Aurora

  7. Nonlinear regression method for estimating neutral wind and temperature from Fabry-Perot interferometer data.

    Science.gov (United States)

    Harding, Brian J; Gehrels, Thomas W; Makela, Jonathan J

    2014-02-01

    The Earth's thermosphere plays a critical role in driving electrodynamic processes in the ionosphere and in transferring solar energy to the atmosphere, yet measurements of thermospheric state parameters, such as wind and temperature, are sparse. One of the most popular techniques for measuring these parameters is to use a Fabry-Perot interferometer to monitor the Doppler width and breadth of naturally occurring airglow emissions in the thermosphere. In this work, we present a technique for estimating upper-atmospheric winds and temperatures from images of Fabry-Perot fringes captured by a CCD detector. We estimate instrument parameters from fringe patterns of a frequency-stabilized laser, and we use these parameters to estimate winds and temperatures from airglow fringe patterns. A unique feature of this technique is the model used for the laser and airglow fringe patterns, which fits all fringes simultaneously and attempts to model the effects of optical defects. This technique yields accurate estimates for winds, temperatures, and the associated uncertainties in these parameters, as we show with a Monte Carlo simulation.

  8. Twin mesospheric bores observed over Brazilian equatorial region

    Science.gov (United States)

    Medeiros, A. F.; Paulino, I.; Taylor, M. J.; Fechine, J.; Takahashi, H.; Buriti, R. A.; Lima, L. M.; Wrasse, C. M.

    2016-01-01

    Two consecutive mesospheric bores were observed simultaneously by two all-sky cameras on 19 December 2006. The observations were carried out in the northeast of Brazil at two different stations: São João do Cariri (36.5° W, 7.4° S) and Monteiro (37.1° W, 7.9° S), which are by about 85 km apart. The mesospheric bores were observed within an interval of ˜ 3 h in the NIR OH and OI557.7 nm airglow emissions. Both bores propagated to the east and showed similar characteristics. However, the first one exhibited a dark leading front with several trailing waves behind and progressed into a brighter airglow region, while the second bore, observed in the OH layer, was comprised of several bright waves propagating into a darker airglow region. This is the first paper to report events like these, called twin mesospheric bores. The background of the atmosphere during the occurrence of these events was studied by considering the temperature profiles from the TIMED/SABER satellite and wind from a meteor radar.

  9. Determining rotational temperatures from the OH(8-3 band, and a comparison with OH(6-2 rotational temperatures at Davis, Antarctica

    Directory of Open Access Journals (Sweden)

    F. Phillips

    2004-04-01

    Full Text Available Rotational temperatures derived from the OH(8–3 band may vary by ~18K depending on the choice of transition probabilities. This is of concern when absolute temperatures or trends determined in combination with measurements of other hydroxyl bands are important. In this paper, measurements of the OH(8–3 temperature-insensitive Q/P and R/P line intensity ratios are used to select the most appropriate transition probabilities for use with this band. Aurora, airglow and solar and telluric absorption in the OH(8–3 band are also investigated. Water vapour absorption of P1(4, airglow or auroral contamination of P1(2 and solar absorption in the vicinity of P1(5 are concerns to be considered when deriving rotational temperatures from this band.

    A comparison is made of temperatures derived from OH(6–2 and OH(8–3 spectra collected alternately at Davis (69° S, 78° E in 1990. An average difference of ~4K is found, with OH(8–3 temperatures being warmer, but a difference of this magnitude is within the two sigma uncertainty limit of the measurements.

    Key words. Atmospheric composition and structure airglow and aurora; pressure, density, and temperature

  10. Skycorr: A general tool for spectroscopic sky subtraction

    Science.gov (United States)

    Noll, S.; Kausch, W.; Kimeswenger, S.; Barden, M.; Jones, A. M.; Modigliani, A.; Szyszka, C.; Taylor, J.

    2014-07-01

    Context. Airglow emission lines, which dominate the optical-to-near-infrared sky radiation, show strong, line-dependent variability on time scales from minutes to decades. Therefore, the subtraction of the sky background in the affected wavelength regime becomes a problem if plain-sky spectra have to be taken at a different time from the astronomical data. Aims: A solution of this problem is the physically motivated scaling of the airglow lines in the plain-sky data to fit the sky lines in the object spectrum. We have developed a corresponding instrument-independent approach based on one-dimensional spectra. Methods: Our code skycorr separates sky lines and sky/object continuum by an iterative approach involving a line finder and airglow line data. The sky lines, which mainly belong to OH and O2 bands, are grouped according to their expected variability. The line groups in the sky data are then scaled to fit the sky in the science data. Required pixel-specific weights for overlapping groups are taken from a comprehensive airglow model. Deviations in the wavelength calibration are corrected for by fitting Chebyshev polynomials and rebinning via asymmetric damped sinc kernels. The scaled sky lines and the sky continuum are subtracted separately. Results: ESO-VLT X-shooter data covering 2.5 h with a good time resolution were selected to illustrate the performance. Data taken six nights and about one year before were also used as reference sky data. The variation of the sky-subtraction quality as a function of time difference between the object and sky data depends on changes in the airglow intensity, atmospheric transparency, and instrument calibration. Except for short time intervals of a few minutes, the sky line residuals were between 2.1 and 5.5 times weaker than for sky subtraction without fitting. Additional tests showed that skycorr performs consistently better than the method of Davies (2007, MNRAS, 375, 1099) developed for ESO-VLT SINFONI data.

  11. Measuring Anthropogenic Sky Glow Using a Natural Sky Brightness Model

    Science.gov (United States)

    Duriscoe, Dan M.

    2013-11-01

    Anthropogenic sky glow (a result of light pollution) combines with the natural background brightness of the night sky when viewed by an observer on the earth's surface. In order to measure the anthropogenic component accurately, the natural component must be identified and subtracted. A model of the moonless natural sky brightness in the V-band was constructed from existing data on the Zodiacal Light, an airglow model based on the van Rhijn function, and a model of integrated starlight (including diffuse galactic light) constructed from images made with the same equipment used for sky brightness observations. The model also incorporates effective extinction by the atmosphere and is improved at high zenith angles (>80°) by the addition of atmospheric diffuse light. The model may be projected onto local horizon coordinates for a given observation at a resolution of 0.05° over the hemisphere of the sky, allowing it to be accurately registered with data images obtained from any site. Zodiacal Light and integrated starlight models compare favorably with observations from remote dark sky sites, matching within ± 8 nL over 95% of the sky. The natural airglow may be only approximately modeled, errors of up to ± 25 nL are seen when the airglow is rapidly changing or has considerable character (banding); ± 8 nL precision may be expected under favorable conditions. When subtracted from all-sky brightness data images, the model significantly improves estimates of sky glow from anthropogenic sources, especially at sites that experience slight to moderate light pollution.

  12. A Sounding Rocket experiment to Validate Ultraviolet Remote Sensing of the Upper Atmosphere and Ionosphere

    Science.gov (United States)

    Chakrabarti, S.; Stephan, A. W.; Erickson, P. J.; Cook, T.; Mende, S. B.

    2009-12-01

    Despite decades of observations and interpretations of ultraviolet airglow, advancing the derivation of physical parameters of the ionosphere and atmosphere beyond the current successes presents difficult challenges due to the lack of comprehensive understanding of the fundamental detailed physics that surrounds the associated airglow emission process. The daytime thermosphere, while better characterized than the ionosphere, is still subject to uncertainties caused by the need for somewhat ad-hoc modeling using a multi-step process that creates the UV airglow emissions. The state of the field for the daytime ionosphere is currently based on only a few dozen profiles obtained from sounding rocket and satellite missions, none of which were designed to obtain the necessary comprehensive set of measurements. We have designed a sounding rocket experiment that will validate extreme and far ultraviolet (EUV/FUV) remote sensing of the ionosphere and thermosphere during day time. The sounding rocket data will be coordinated with simultaneous observations by an Incoherent Scatter Radar which will provide altitude profiles of daytime electron density, ion composition, electron and ion temperatures, and ion drifts due to winds and electric fields as well as neutral temperature profiles. The instruments aboard the sounding rocket will observe full-disk solar EUV and FUV irradiance measurements in the 2 - 131 nm band along with a high speed multi-wavelength photometer package that will provide altitude profiles of thermospheric neutral species along the rocket track. The dayglow instrument will cover 60 - 140 nm spectral range and observe the emissions in a direction perpendicular to the rocket axis, which will point towards the Sun. With these measurements, we hope to answer how well the EUV and FUV dayglow measurements can be used to provide a self-consistent measure of the day time ionosphere-thermosphere space environment.

  13. What can we do with an atmospheric seismometer moving at 8 km/s?

    Science.gov (United States)

    Garcia, R.; Brissaud, Q.; Martin, R.; Komatitsch, D.; Doornbos, E.; Bruinsma, S.

    2014-12-01

    The solid/ocean/atmosphere coupling of terrestrial planets has been widely investigated through detection and imaging of electron density perturbations in the ionosphere.Recently, two new observations methods have proven their efficiency: perturbations of airglow emissions and variations of the drag of very low Earth orbit satellites.The perturbations of these observables are mainly due to air density variations induced by post-seismic infrasounds or atmospheric gravity waves generated by tsunamis.Even if the airglow emissions present the great advantage of providing an imaging capability, the weakness of the airglow signal induces long integration time, and does not allow to infer high frequency infrasound signals.Moreover, restrictions on observation conditions and line of sight integration reduce the capability of detailed imaging of atmospheric wavefronts.On the other hand, variations of the satellite drag provide only one measurement point along the satellite orbit.However, the unprecedented quality of the data of GOCE mission allows a precise estimate of air density perturbations, but also vertical and cross track winds estimates.Consequently, this capability to measure the vibrations induced by atmospheric waves along 3 axes is very similar to the one of a ground seismometer.We first present some polarisation analysis using these data in order to discriminate between infrasonic waves, gravity waves and perturbations induced by thermosphere dynamics.Then, we summarize some recent developments in numerical modeling of atmospheric and acoustic and gravity wave propagation with SPECFEM software.Finally, we present how this numerical tool will allow to perform studies comparable to what was done in solid seismology.We conclude by a prospect on the application of these observables and numerical tools to other terrestrial planets.

  14. A study of the feasibility and performance of an active/passive imager using silicon focal plane arrays and incoherent continuous wave laser diodes

    Science.gov (United States)

    Vollmerhausen, Richard H.

    This dissertation describes an active/passive imager (API) that provides reliable, nighttime, target acquisition in a man-portable package with effective visual range of about 4 kilometers. The reflective imagery is easier to interpret than currently used thermal imagery. Also, in the active mode, the API provides performance equivalent to the big-aperture, thermal systems used on weapons platforms like tanks and attack helicopters. This dissertation describes the research needed to demonstrate both the feasibility and utility of the API. Part of the research describes implementation of a silicon focal plane array (SFPA) capable of both active and passive imaging. The passive imaging mode exceeds the nighttime performance of currently fielded, man-portable sensors. Further, when scene illumination is insufficient for passive imaging, the low dark current of SFPA makes it possible to use continuous wave laser diodes (CWLD) to add an active imaging mode. CWLD have advantages of size, efficiency, and improved eye safety when compared to high peak-power diodes. Because of the improved eye safety, the API provides user-demanded features like video output and extended range gates in the active as well as passive imaging modes. Like any other night vision device, the API depends on natural illumination of the scene for passive operation. Although it has been known for decades that "starlight" illumination is actually from diffuse airglow emissions, the research described in this dissertation provides the first estimates of the global and temporal variation of ground illumination due to airglow. A third related element of the current research establishes the impact of atmospheric aerosols on API performance. We know from day experience that atmospheric scattering of sunlight into the imager line-of-sight can blind the imager and drastically degrade performance. Atmospheric scattering of sunlight is extensively covered in the literature. However, previous literature did not

  15. 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.

  16. High Resolution Imagery of Haarp-Induced Optical Emissions

    Science.gov (United States)

    Kendall, E. A.

    2012-12-01

    One powerful technique for diagnosing radio frequency interactions in the ionosphere is to use ground-based optical instrumentation. High-frequency (HF), heater-induced optical emission observations can be used to diagnose electron energies and distributions in the heated region, illuminate natural and/or artificially induced ionospheric irregularities, determine ExB plasma drifts, and measure quenching rates by neutral species. Optical emissions are caused by HF-accelerated electrons colliding with various atmospheric constituents, which in turn emit a photon. The most common emissions are 630.0 nm O(1D), 557.7 nm O(1S), and 427.8 nm N2+(1NG). Since fairly wide field-of-view imagers are typically deployed in airglow campaigns, it is not well-known what meter-scale features exist in the artificial airglow emissions. Telescopic imaging provides high resolution spatial coverage of ionospheric irregularities and goes hand in hand with other observing techniques such as GPS scintillation, radar, and ionosonde. Imaging can be used to verify the interpretation of data from these other instruments, and this in turn allows confidence in such measurements when airglow cannot be observed (high solar angle or cloud cover). Telescopic imaging of airglow is the only technique capable of simultaneously determining the properties of ionospheric irregularities at decameter resolution over a range of several kilometers. The HAARP telescopic imager consists of two cameras, a set of optics for each camera, and a robotic mount that supports and orients the system. The camera and optics systems are identical except for the camera lenses: one has a wide-angle lens (~19 degrees) and the other has a telescopic lens (~3 degrees). The telescopic imager has a resolution of ~20 m in the F layer and ~10 m in the E layer, which allows the observation of decameter- and kilometer-scale features. Telescopic data has been recorded at HAARP for several years and images will be presented showing

  17. Ionospheric modification at twice the electron cyclotron frequency

    International Nuclear Information System (INIS)

    In 2004, a new transmission band was added to the HAARP high-frequency ionospheric modification facility that encompasses the second electron cyclotron harmonic at altitudes between ∼220 and 330 km. Initial observations indicate that greatly enhanced airglow occurs whenever the transmission frequency approximately matches the second electron cyclotron harmonic at the height of the upper hybrid resonance. This is the reverse of what happens at higher electron cyclotron harmonics. The measured optical emissions confirm the presence of accelerated electrons in the plasma

  18. Circulation of Venus upper mesosphere.

    Science.gov (United States)

    Zasova, Ludmila; Gorinov, Dmitry; Shakun, Alexey; Altieri, Francesca; Migliorini, Alessandra; Piccioni, Giuseppe; Drossart, Pierre

    2014-05-01

    Observation of the O2 1.27 μm airglow intensity distribution on the night side of Venus is one of the methods of study of the circulation in upper mesosphere 90-100 km. VIRTIS-M on board Venus Express made these observations in nadir and limb modes in Southern and Northern hemispheres respectively. Global map of the O2 night glow is published (Piccioni et al. 2009). In this work we use for analysis only data, obtained with exposure > 3 s to avoid high noisy data. It was found that intensity of emission decreases to poles and to terminators (similar to Piccioni et al.2009) in both hemispheres, which gives evidence for existence of SS-AS circulation with transport of the air masses through poles and terminators with ascending/descending flows at SS/AS areas. However, asymmetry of distribution of intensity of airglow is observed in both hemispheres. Global map for southern hemisphere (from nadir data) has good statistics at φ > 10-20° S and pretty poor at low latitude. Maximum emission is shifted from midnight by 1 - 2 hours to the evening (22-23h) and deep minimum of emission is found at LT=2-4 h at φ > 20° S. This asymmetry is extended up to equatorial region, however statistic is poor there. No evident indication for existence of the Retrograde Zonal Superrotation (RZS) is found: maximum emission in this case, which is resulting from downwards flow, should be shifted to the morning. The thermal tides, gravity waves are evidently influence on the night airglow distribution. VIRTIS limb observations cover the low northern latitudes and they are more sparse at higher latitudes. Intensity of airglow at φ = 0 - 20° N shows wide maximum, which is shifted by 1- 2 h from midnight to morning terminator. This obviously indicates that observed O2 night glow distribution in low North latitudes is explained by a superposition of SS-AS flow and RZS circulation at 95-100 km. This behavior is similar to the NO intensity distribution, obtained by SPICAV.

  19. Theoretical support to NRL's upper atmospheric branch: Physics and chemistry of the upper and middle atmospheres with emphasis on daytime, nighttime, and auroral optical emissions

    Science.gov (United States)

    1991-06-01

    Significant advances were made in the ability to model physical processes in the thermosphere (airglow and aurora) and middle atmosphere. These advances came in the form of code development and improved methods for updating input parameters (most notably, cross sections). Important advances were also made in the development of an algorithm for deducing O3 and O2 density profiles from full solar disk extinction measurements to be made by the instrument Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) on board the upper atmosphere research satellite (UARS).

  20. Solar influence on the O(1S) and O(1D) dayglow emission rates: Global-scale measurements by WINDII on UARS

    Science.gov (United States)

    Zhang, S.; Sheperd, G.

    More than 130,000 emission rate profiles of the O(^1D) dayglow (630 nm) and 500,000 of the O(^1S) (557.7nm) dayglow were observed by WINDII on UARS during 1991-1997, which provides an unprecedented and unigue database for studying the mechanisms and global climatology of the two airglow layers, and the energy balance and effects of dynamics and solar storms on the atmosphere-ionosphere-magnetosphere system. Empirical models are derived from WINDII measurements for the two emission rates as functions of the solar zenith angle and solar irradiance using the F10.7 cm flux as a proxy.

  1. The evolution of a breaking mesospheric bore wave packet

    OpenAIRE

    Stockwell, R G.; Taylor, M. J.; Nielsen, K.; Jarvis, M J

    2011-01-01

    All-sky CCD observations of mesospheric gravity waves have been made from Halley Station Antarctica (75.5°S, 26.7°W) as part of a collaborative research program between British Antarctic Survey, U.K. and Utah State University, USA. A mesospheric bore event was observed in the nightglow emissions over a period of several hours on the 27th of May, 2001. Two dimensional S-Transform (ST) analysis is applied to the airglow images of this bore event. This local spectral technique allows one to calc...

  2. Effects of a Large Mesospheric Temperature Enhancement on the Hydroxyl Rotational Temperature as Observedfrom the Ground

    OpenAIRE

    Melo, S. M.L.; R. P. Lowe; Pendleton Jr., W. R.; Taylor, Michael J.; Williams, B.; C. Y. She

    2001-01-01

    The rotational temperature obtained from the rotational population distribution in the bands of the hydroxyl airglow has been shown to be a suitable proxy for the temperature at a height of 87 km [She and Lowe, 1998]. In this paper we examine in detail simultaneous observations on November 2–3, 1997, at Fort Collins, Colorado (41°N, 105°W), with both a sodium temperature lidar and the Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) OH mesospheric temperature mapper during wh...

  3. Auroral spectrograph data annals of the international geophysical year, v.25

    CERN Document Server

    Carrigan, Anne; Norman, S J

    1964-01-01

    Annals of the International Geophysical Year, Volume 25: Auroral Spectrograph Data is a five-chapter text that contains tabulations of auroral spectrograph data. The patrol spectrograph built by the Perkin-Elmer Corporation for the Aurora and Airglow Program of the IGY is a high-speed, low-dispersion, automatic instrument designed to photograph spectra of aurora occurring along a given magnetic meridian of the sky. Data from each spectral frame were recorded on an IBM punched card. The data recorded on the cards are printed onto the tabulations in this volume. These tabulations are available

  4. Letter to the EditorOn the use of the sunspot number for the estimation of past solar and upper atmosphere conditions from historical and modern auroral observations

    Directory of Open Access Journals (Sweden)

    J. M Vaquero

    2005-07-01

    Full Text Available In this short contribution the use of different sunspot numbers for the estimation of past solar and upper atmosphere conditions from historical and modern auroral observations realised by Schröder et al. (2004 is analysed. Moreover, some comments are made on the relationships between mean annual visual observations of the auroras at middle latitudes of Europe and the mean annual sunspot number during 1780–1829. Keywords. Atmospheric composition and structure (Airglow and aurora – Magnetospheric physics (Auroral phenomena, solar wind-magnetosphere interactions – History of geophysics (Solar-planetary relationship

  5. A review on recent upper atmosphere atomic oxygen measurements

    Science.gov (United States)

    Kaufmann, Martin; Ern, Manfred; Riese, Martin; Zhu, Yajun

    2016-07-01

    Atomic oxygen is a key player in the upper mesosphere lower and thermosphere chemistry, energy balance, and dynamics. In recent years, a few new global datasets of this species have been presented. They are based on airglow measurements from low earth satellites. Surprisingly, the atomic oxygen abundance differs by 30-50% for similar atmospheric conditions. This paper gives an overview on the various atomic oxygen datasets available so far and presents most recent results obtained from measurements of the SCIAMACHY instrument on Envisat. Differences between the datasets are discussed.

  6. Dominant winter-time mesospheric wave signatures over a low latitude station, Hawaii (20.8°N): An investigation

    Indian Academy of Sciences (India)

    A Taori; M Taylor

    2010-06-01

    We utilize mesospheric O2 airglow emission intensity and temperature data collected during January–February 2003 on 17 consecutive nights from Maui, Hawaii (20.8°N, 156.2°W) to study the dominant and long period wave features at mesospheric altitudes. Apart from large day-to-day variability, it is found that nocturnal data for the period under consideration was dominated by a terdiurnal tide-like wave. Together, a quasi 5-day wave is also noticed with significant amplitude.

  7. Unexpected variability of Martian hydrogen escape

    OpenAIRE

    Chaffin, Michael S.; Chaufray, Jean-Yves; Stewart, Ian; Montmessin, Franck; Schneider, Nicholas M.; Bertaux, Jean-Loup

    2014-01-01

    International audience Mars today is much drier than the Earth, though they likely began with similar relative amounts of water. One potential cause for this discrepancy is hydrogen loss to space, which may have removed a large fraction of Mars' initial water. Here we demonstrate an order-of-magnitude change in the Martian hydrogen escape rate in 2007, inconsistent with established models for the source of escaping hydrogen. We analyze 121.6 nm (hydrogen Lyman-α) airglow observations made ...

  8. Atmospheric coupling of Tsunami: observations from Tohoku and impact on tsunami physical properties and phase/group velocities

    Science.gov (United States)

    Lognonne, P. H.; Kherani, E. A.; Coisson, P.; Astafyeva, E.; Occhipinti, G.; Rolland, L. M.; Yahagi, T.; Khelfi, K.; Sladen, A.; Hebert, H.; Makela, J. J.

    2012-12-01

    Tsunamis, through a dynamic coupling between the ocean and atmosphere, are generating atmospheric waves, detected in the ionosphere for tsunamis with amplitudes as much as 1 cm in the open ocean. Signals associated to the Tohoku tsunami have therefore been observed with huge signal to noise ratio, not only over Japan, but all over the Pacific, up to Chili. These signals have been moreover modelled, not only for the Total Electronic Contents perturbation signals, but also of the airglow detected for the first time over Hawaii and for the magnetic perturbations detected in Japan. We present in this paper the two sides of this coupling. The first side resumes the different observations and modelling of the Tohoku ionospheric signals observed by GEONET, by the GSI magnetic network and by Airglow cameras in Hawaii and Chili. Comparison between data and modelling are shown. The second side present the effects of the atmospheric coupling on the tsunami properties, i.e. amplitudes, phase/group velocities and excitation coefficients. By taking into account the coupling of tsunami with both the solid Earth and atmosphere, we show that specific resonances between the ocean and the atmosphere exist, enabling to understand the large and peaked signal spectrum. Local Time and geographical variations of this coupling is studied, as well as its dependence with the ocean depth. The impacts of atmospheric coupling on the propagation travel time of tsunamis is finally presented and discussed.

  9. Experiment S001: Zodiacal Light Photography

    Science.gov (United States)

    Ney, E. P.; Huch, W. F.

    1971-01-01

    Observations made during the Gemini 5, 9, and 10 missions in the context of their relation to ground-based and balloon-based experiments on dim-light phenomena are reported. Zodiacal light is the visible manifestation of dust grains in orbit around the sun. The negatives that were exposed on the Gemini 9 mission were studied by the use of an isodensitracer to produce intensity isophotes. Data on the following factors were obtained: (1) intensity distribution of the zodiacal light, both morning and evening; (2) the height and intensity of the airglow at various geographic positions; and (3) intensity distribution of the Milky Way in the region of the sky near Cygnus. Also, a previously unreported phenomenon was discovered. This phenomenon appeared as an upward extension of the normal 90-kilometer airglow layer. The extension was in the form of wisps or plumes approximately 5 deg wide and extending upward approximately 5 deg. The results obtained from pictures exposed on the Gemini 10 mission were of qualitative or geometrical value only.

  10. Suomi satellite brings to light a unique frontier of nighttime environmental sensing capabilities.

    Science.gov (United States)

    Miller, Steven D; Mills, Stephen P; Elvidge, Christopher D; Lindsey, Daniel T; Lee, Thomas F; Hawkins, Jeffrey D

    2012-09-25

    Most environmental satellite radiometers use solar reflectance information when it is available during the day but must resort at night to emission signals from infrared bands, which offer poor sensitivity to low-level clouds and surface features. A few sensors can take advantage of moonlight, but the inconsistent availability of the lunar source limits measurement utility. Here we show that the Day/Night Band (DNB) low-light visible sensor on the recently launched Suomi National Polar-orbiting Partnership (NPP) satellite has the unique ability to image cloud and surface features by way of reflected airglow, starlight, and zodiacal light illumination. Examples collected during new moon reveal not only meteorological and surface features, but also the direct emission of airglow structures in the mesosphere, including expansive regions of diffuse glow and wave patterns forced by tropospheric convection. The ability to leverage diffuse illumination sources for nocturnal environmental sensing applications extends the advantages of visible-light information to moonless nights. PMID:22984179

  11. Long Term Trend and 11-Year Cyclic Variations in Mesopause Temperature Data Observed by Michelson Interferometers at Arctic and Antarctic Sites

    Science.gov (United States)

    Azeem, I.; Sivjee, G. G.; Won, Y.-

    2006-05-01

    The response of the mesopause temperature to solar cycle variations has been investigated using OH airglow observations from Michelson Interferometer instruments located at Eureka (80o N, 85.56º W), Canada, Resolute Bay (74.68º N, 94.90º W), Canada, and South Pole Station, Antarctica (90o S). These aforementioned stations have been making continuous measurements of temperature and airglow emissions during the six months of each polar winter night. In this paper we present our results to elucidate solar cycle and long-term trend in the MI temperature time series data. We discuss mesospheric seasonal variation in the Northern and Southern hemispheres and compare these mesopause temperatures to highlight similarities and disagreements observed in the OH temperature response to solar cycle at Arctic and Antarctic sites. In addition, we also present He 10830Å line as a way of monitoring the response of the thermosphere to changes in solar irradiance in the EUV region over a solar cycle period.

  12. Sounding of the Atmosphere using Broadband Emission Radiometry observations of daytime mesospheric O2(1Δ) 1.27 μm emission and derivation of ozone, atomic oxygen, and solar and chemical energy deposition rates

    Science.gov (United States)

    Mlynczak, Martin G.; Marshall, B. Thomas; Martin-Torres, F. Javier; Russell, James M.; Thompson, R. Earl; Remsberg, Ellis E.; Gordley, Larry L.

    2007-08-01

    We report observations of the daytime O2(1Δ) airglow emission at 1.27 μm recorded by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite. The measured limb radiances are inverted to yield vertical profiles of the volume emission rate of energy from the O2 molecule. From these emission rates we subsequently derive the mesospheric ozone concentrations using a nonlocal thermodynamic equilibrium (non-LTE) radiative and kinetic model. Rates of energy deposition due to absorption of ultraviolet radiation in the Hartley band of ozone are also derived, independent of knowledge of the ozone abundance and solar irradiances. Atomic oxygen concentrations are obtained from the ozone abundance using photochemical steady state assumptions. Rates of energy deposition due to exothermic chemical reactions are also derived. The data products illustrated here are from a test day (4 July 2002) of SABER Version 1.07 data which are now becoming publicly available. This test day illustrates the high quality of the SABER O2(1Δ) airglow and ozone data and the variety of fundamental science questions to which they can be applied.

  13. Measurement of two-dimensional Doppler wind fields using a field widened Michelson interferometer.

    Science.gov (United States)

    Langille, Jeffery A; Ward, William E; Scott, Alan; Arsenault, Dennis L

    2013-03-10

    An implementation of the field widened Michelson concept has been applied to obtain high resolution two-dimensional (2D) images of low velocity (irradiance measurements to be determined on a bin by bin basis with an accuracy of less than 2.5 m/s from CCD images over the observed field of view. The interferometer scanning mirror position is controlled to subangstrom precision with subnanometer repeatability using the multi-application low-voltage piezoelectric instrument control electronics developed by COM DEV Ltd.; it is the first implementation of this system as a phase stepping Michelson. In this paper the calibration and characterization of the Doppler imaging system is described and the planned implementation of this new technique for imaging 2D wind and irradiance fields using the earth's airglow is introduced. Observations of Doppler winds produced by a rotating wheel are reported and shown to be of sufficient precision for buoyancy wave observations in airglow in the mesopause region of the terrestrial atmosphere. PMID:23478764

  14. HEUVAC: A new high resolution solar EUV proxy model

    Science.gov (United States)

    Richards, Philip G.; Woods, Thomas N.; Peterson, William K.

    This paper presents a new high-resolution version of the solar EUV irradiance model for aeronomic calculations (HEUVAC) that is designed to facilitate comparisons with measured spectra and enable more accurate calculations of ionization rates, airglow emission rates, and photoelectron calculations. The HEUVAC model bins can range from 0.1 to 100 nm and extends the EUV model below 5 nm. The new solar EUV irradiance calculations with the high resolution irradiance model show good agreement with the most recent solar EUV irradiance measurements from the solar EUV experiment (SEE) instrument on the thermosphere, ionosphere, mesosphere, energetics, and dynamics satellite. Also, photoelectron fluxes calculated from both the SEE measured and EUVAC modeled solar EUV irradiances agree well with photoelectron flux measurements by the FAST satellite. The good agreement of the EUVAC and SEE derived photoelectron fluxes with the FAST measured fluxes at solar maximum lends support to an earlier finding that the previous reference solar EUV irradiances from the Atmosphere Explorer measurements need to be adjusted upward by a factor of 2 3 below 25 nm wavelength. This result is important for remote sensing of the ionosphere and thermosphere because, as this paper shows, the airglow emission rates calculated using the SEE and HEUVAC models are 50% higher than those based on earlier solar EUV irradiance models. The calculations also show that for solar maximum conditions on 21 April 2002, most of the degradation of the escaping photoelectron flux takes place below 1000 km altitude.

  15. A review of recent MLT studies at low latitudes

    Directory of Open Access Journals (Sweden)

    B. R. Clemesha

    2004-09-01

    Full Text Available Recent years have shown a continuing interest in studies of the mesosphere-lower thermosphere region at low latitudes, with more than 50 papers dealing specifically with this area published over the past 5 years. Experimental ground-based work has been carried out mainly in South America and the Caribbean, India and the Pacific areas. Subjects of interest include gravity waves, tides and planetary waves, the temperature structure of the mesopause region, with special reference to temperature inversions and the two-level mesopause, sporadic neutral layers and their relationship with ionized layers, the possible effects of the micrometeoroid influx, and long-term trends in the MLT region. Experimental techniques in use include MF, MST and meteor radar, lidar, airglow (including satellite-borne limb-scanning measurements and rocket-borne instruments. Airglow imaging has shown itself to be a particularly useful technique, mainly for studying gravity wave propagation in the MLT region. This paper will present highlights of recent work and will discuss some of the problems which remain to be resolved.

  16. Mesospheric temperatures from observations of the hydroxyl (6–2 emission above Davis, Antarctica: A comparison of rotational and Doppler measurements

    Directory of Open Access Journals (Sweden)

    J. L. Innis

    Full Text Available We present observations of the hydroxyl (6–2 airglow lines from ~ 87 km altitude obtained at Davis station, Antarctica, in the austral winter of 1999. Nine nights of observations were made of the P-branch near λ840 nm with a Czerny-Turner scanning spectrometer (CTS; at the same time, high-resolution Fabry-Perot Spectrometer (FPS spectra were collected of the Q1(1 doublet at λ834 nm. Rotational temperatures were determined from the CTS observations, while Doppler temperatures were derived from the line-widths of the FPS Q1(1 spectra. Absolute temperatures determined by these methods are uncertain by ~ 2 and ~ 20 K, respectively. For the comparison we set the value of the reflective finesse of the FPS at λ834 nm so the mean FPS temperature from one night of simultaneous data was equal to that from the CTS, and then looked at the measured variations in each data set for the other eight nights. Both instruments show the upper mesosphere temperature to vary in a similar manner to within the observational errors of the measurements, implying an equivalence of the rotational and Doppler temperatures. We believe that this is the first published simultaneous, same-site, comparison of rotational and Doppler temperatures from the OH emission.

    Key words. Atmospheric composition and structure (airglow and aurora; pressure density and temperature; instruments and techniques

  17. Lines and continuum sky emission in the near infrared: observational constraints from deep high spectral resolution spectra with GIANO-TNG

    CERN Document Server

    Oliva, E; Scuderi, S; Benatti, S; Carleo, I; Lapenna, E; Mucciarelli, A; Baffa, C; Biliotti, V; Carbonaro, L; Falcini, G; Giani, E; Iuzzolino, M; Massi, F; Sanna, N; Sozzi, M; Tozzi, A; Ghedina, A; Ghinassi, F; Lodi, M; Harutyunyan, A; Pedani, M

    2015-01-01

    Aims Determining the intensity of lines and continuum airglow emission in the H-band is important for the design of faint-object infrared spectrographs. Existing spectra at low/medium resolution cannot disentangle the true sky-continuum from instrumental effects (e.g. diffuse light in the wings of strong lines). We aim to obtain, for the first time, a high resolution infrared spectrum deep enough to set significant constraints on the continuum emission between the lines in the H-band. Methods During the second commissioning run of the GIANO high-resolution infrared spectrograph at La Palma Observatory, we pointed the instrument directly to the sky and obtained a deep spectrum that extends from 0.97 to 2.4 micron. Results The spectrum shows about 1500 emission lines, a factor of two more than in previous works. Of these, 80% are identified as OH transitions; half of these are from highly excited molecules (hot-OH component) that are not included in the OH airglow emission models normally used for astronomical ...

  18. Can Ground-based Telescopes Detect The Oxygen 1.27 Micron Absorption Feature as a Biomarker in Exoplanets ?

    CERN Document Server

    Kawahara, Hajime; Takami, Michihiro; Fujii, Yuka; Kotani, Takayuki; Murakami, Naoshi; Tamura, Motohide; Guyon, Olivier

    2012-01-01

    The oxygen absorption line imprinted in the scattered light from the Earth-like planets has been considered as the most promising metabolic biomarker of the exo-life. We examine the feasibility of the detection of the oxygen 1.27 micron band from habitable exoplanets, in particular, around late-type stars with a 30 m class ground-based telescope with a future instrument. We analyzed the night airglow around 1.27 micron with IRCS/echelle spectrometer on Subaru and found that the strong telluric emission from atmospheric oxygen molecules declines by an order of magnitude by the midnight. With compilation of nearby star catalogues combined with the sky background model, we estimate the detectability of the oxygen absorption band from an Earth twin, if exists, around nearby stars. We find that the most dominant photon noise of the oxygen 1.27 micron detection comes from the night airglow if the leakage is suppressed enough to detect the planet. We conclude that the future detectors for which the detection contras...

  19. An extreme ultraviolet spectrometer experiment for the Shuttle Get Away Special Program

    Science.gov (United States)

    Conway, R. R.; Mccoy, R. P.; Meier, R. R.; Mount, G. H.; Prinz, D. K.; Young, J. M.; Carruthers, G. R.

    1984-01-01

    An extreme ultraviolet (EUV) spectrometer experiment operated successfully during the STS-7 mission in an experiment to measure the global and diurnal variation of the EUV airglow. The spectrometer is an F 3.5 Wadsworth mount with mechanical collimator, a 75 x 75 mm grating, and a bare microchannel plate detector providing a spectral resolution of 7 X FWHM. Read-out of the signal is through discrete channels or resistive anode techniques. The experiment includes a microcomputer, 20 Mbit tape recorder, and a 28V, 40 Ahr silver-zinc battery. It is the first GAS payload to use an opening door. The spectrometer's 0.1 x 4.2 deg field of view is pointed vertically out of the shuttle bay. During the STS-7 flight data were acquired continuously for a period of 5 hours and 37 minutes, providing spectra of the 570 A to 850 A wavelength region of the airglow. Five diurnal cycles of the 584 A emission of neutral helium and the 834 A emission of ionized atomic oxygen were recorded. The experiment also recorded ion events and pressure pulses associated with thruster firings. The experiment is to fly again on Mission 41-F.

  20. Cassini UVIS Solar Zenith Angle Studies of Titan Dayglow Based on N2 High Resolution Spectroscopy

    Science.gov (United States)

    Ajello, Joseph; West, Robert; Holsclaw, Greg; Royer, Emilie; Heays, Alan; Bradley, Todd; Stevens, Michael

    2014-11-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed photon emissions of Titan’s day and night limb-airglow on multiple occasions, including during an eclipse observation. On one occasion the UVIS made a Solar Zenith Angle (SZA) study of the Titan limb dayglow (2011 DOY 171) from about 70 to 95 degrees SZA. The UV intensity variation observations of the N2 photoelectron excited spectral features from the EUV (563-118.2 nm) and FUV (111.5-191.2nm) sub-systems followed a Chapman function. For other observations at night on the limb, the emission features are much weaker in intensity. Beyond 120 deg SZA, when the upper atmosphere of Titan below 1200 km is in total XUV darkness, there is an indication of weak and sporadic night side UV airglow emission excited by magnetosphere plasma collisions with ambient thermosphere gas, with similar N2 excited features as above in the daylight or twilight glow over an extended altitude range. We have analyzed the UVIS airglow spectra with models based on high resolution laboratory electron impact induced fluorescence spectra. We have measured high-resolution (FWHM = 0.2 Å) extreme-ultraviolet (EUV, 800-1350 Å) laboratory emission spectra of molecular nitrogen excited by electron impact at 20 and 100 eV. Molecular emission was observed to vibrationally-excited ground state levels as high as v''=17, from the a 1Πg , b 1Πu, and b‧ 1Σu+ excited valence states and the Rydberg series c‧n+1 1Σu+, cn 1Πu and o 1Πu for n between 3 and 9. A total of 491 emission features were observed from N2 electronic-vibrational transitions and atomic N I and N II multiplets. Their emission cross sections were measured.The blended molecular emission bands were disentangled with the aid of a model which solves the coupled-Schroedinger equation

  1. S-NPP VIIRS DNB Dark Offset and Detector Dark Current Trending Study

    Science.gov (United States)

    Sun, Z.; Chen, W.; DeLuccia, F.; Moy, G.

    2015-12-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) Day-Night Band (DNB) is a panchromatic band in the VisNIR spectral range from 0.5 to 0.9 μm with a dynamic range from 3x10-9 to about 0.02 W cm-2 sr-1. DNB achieves this large dynamic range by having three gain stages: low gain (LGS), mid gain (MGS), and high gain (HGS). HGS is the average of two redundant detector arrays, HGA and HGB. The HGS offset determination is critically important to improve the imagery capability and calibration accuracy and stability at novel low radiances. Currently, the dark offset is determined on a monthly basis by observing new moon data in the dark regions in the Pacific Ocean. The data is mainly comprised of detector dark current, electronic/clock offsets, artificial illumination sources, and nighttime airglow contamination. The first two are instrument phenomena/characterizations and the last two are scene contaminations.In this presentation, we discuss the long-term growth in offset with short-term fluctuations we have captured since the beginning of the mission. We associate the long-term growth with dark current increase. We show that the offset rate of change over time is proportional to the number of Charge Coupled Device (CCD) elements aggregated to comprise a DNB pixel. We compare offset growth rate from new moon data in the dark ocean and that from calibration sector data at the same time; which contain very limited scene contaminations. We associate the short-term variability in offset growth with airglow effects that survive the filtering process used to derive the offsets from dark ocean data. These spurious offset fluctuations are removed from the offset LUTs via long time scale smoothing of the offsets. The remaining persistent time average contribution due to airglow can be estimated by comparison of the pitch maneuver propagated offsets determined from deep space scans early in the mission and the offsets determined from the dark regions in the Pacific Ocean.

  2. Network for the Detection of Mesopause Change (NDMC)

    Science.gov (United States)

    Bittner, M.; Espy, P.; French, J.; Höppner, K.; Scheer, J.; Taylor, M.

    2009-04-01

    The Network for the Detection of Mesopause Change (NDMC) is a global program with the mission to promote international cooperation among research groups investigating the mesopause region (80-100 km) with the goal of early identification of changing climate signals. This program involves the coordinated study of atmospheric variability at all time scales, the exchange of existing know-how, and the coordinated development of improved observation, analysis techniques and modeling. The initial emphasis is on mesopause region airglow techniques utilizing the existing ground-based and satellite measurement capabilities. Participation or association of researchers using other techniques in the same altitude region will be actively developed. NDMC is concerned with coupling processes and will interface with related activities throughout the atmosphere. It is affiliated with the Global Atmosphere Watch program of the World Meteorological Organization and with the Network for the Detection of Atmospheric Composition Change.

  3. The Network for the Detection of Mesopause Change (NDMC)

    Science.gov (United States)

    Bittner, Michael; Espy, Patrick; French, John; Höppner, Kathrin; Scheer, Jürgen; Taylor, Michael J.

    The Network for the Detection of Mesopause Change (NDMC) is a global program with the mis-sion to promote international cooperation among research groups investigating the mesopause region (80-100 km) with the goal of early identification of changing climate signals. This program involves the coordinated study of atmospheric variability at all time scales, the exchange of existing know-how, and the coordinated development of improved observation, analysis techniques and modeling. The initial emphasis is on mesopause region airglow tech-niques utilizing the existing ground-based and satellite measurement capabilities. Participation or association of researchers using other techniques in the same altitude region will be actively developed. NDMC is concerned with coupling processes and will interface with related activities throughout the atmosphere. It is affiliated with the Global Atmosphere Watch program of the World Meteorological Organization and with the Network for the Detection of Atmospheric Composition Change.

  4. CISCO: Cooled Infrared Spectrograph and Camera for OHS on the Subaru Telescope

    Science.gov (United States)

    Motohara, Kentaro; Iwamuro, Fumihide; Maihara, Toshinori; Oya, Shin; Tsukamoto, Hiroyuki; Imanishi, Masatoshi; Terada, Hiroshi; Goto, Miwa; Iwai, Jun'ichi; Tanabe, Hirohisa; Hata, Ryuji; Taguchi, Tomoyuki; Harashima, Takashi

    2002-04-01

    This paper describes a Cooled Infrared Spectrograph and Camera for OHS (CISCO), mounted on the Nasmyth focus of the Subaru telescope. It is primarily designed as a back-end camera of the OH-Airglow Suppressor (OHS), and is also used as an independent, general-purpose near-infrared camera/spectrograph. CISCO is based on a single 1024 × 1024 format HgCdTe HAWAII array detector, and is capable of either wide-field imaging of 1'.8 × 1'.8 field-of-view or low-resolution spectroscopy from 0.9 to 2.4 μm. The limiting magnitudes measured during test observations were found to be J=23.5 mag and K' = 22.4 mag (imaging, 1" aperture, S/N = 5, 1hr exposure).

  5. Model insights into energetic photoelectrons measured at Mars by MAVEN

    Science.gov (United States)

    Sakai, Shotaro; Rahmati, Ali; Mitchell, David L.; Cravens, Thomas E.; Bougher, Stephen W.; Mazelle, Christian; Peterson, W. K.; Eparvier, Francis G.; Fontenla, Juan M.; Jakosky, Bruce M.

    2015-11-01

    Photoelectrons are important for heating, ionization, and airglow production in planetary atmospheres. Measured electron fluxes provide insight into the sources and sinks of energy in the Martian upper atmosphere. The Solar Wind Electron Analyzer instrument on board the MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft measured photoelectrons including Auger electrons with 500 eV energies. A two-stream electron transport code was used to interpret the observations, including Auger electrons associated with K shell ionization of carbon, oxygen, and nitrogen. It explains the processes that control the photoelectron spectrum, such as the solar irradiance at different wavelengths, external electron fluxes from the Martian magnetosheath or tail, and the structure of the upper atmosphere (e.g., the thermal electron density). Our understanding of the complex processes related to the conversion of solar irradiances to thermal energy in the Martian ionosphere will be advanced by model comparisons with measurements of suprathermal electrons by MAVEN.

  6. Modeling the Thermosphere/Ionosphere Response to Large Solar Flares and Geomagnetic Storms

    Science.gov (United States)

    Solomon, S. C.; Lu, G.; Qian, L.; Richmond, A. D.; Woods, T. N.

    2004-05-01

    During October-November 2003, a series of large coronal mass ejections and solar flares caused significant changes in the terrestrial upper atmosphere and ionosphere. We have simulated these effects using the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). Solar photon inputs to the model were obtained from solar irradiance instruments on the TIMED and SORCE satellites, and auroral forcing obtained using the AMIE procedure. This study enables quantification of the relative importance of photon and auroral forcing of ionosphere/thermosphere density and temperature. Ion density enhancements and airglow intensities derived from the model results can be compared to observations to investigate the simulation fidelity during these extraordinary events.

  7. New Solar Extreme-Ultraviolet and Soft X-ray Measurements: Model Comparisons with Thermosphere and Ionosphere Observations

    Science.gov (United States)

    Solomon, S. C.; Bailey, S. M.; Christensen, A. B.; Eparvier, F. G.; Gladstone, G. R.; Paxton, L. J.; Wolven, B. C.; Woods, T. N.

    2002-05-01

    The Solar EUV Experiment (SEE) on the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) spacecraft is performing the first comprehensive measurements of the extreme-ultraviolet and soft X-ray region of the solar spectrum since the end of the Atmosphere Explorer (AE) mission in 1981. Comparison of TIMED/SEE measurements to contemporaneous satellite observations and a calibration rocket shows that solar irradiance in the soft X-ray and hard EUV spectral ranges, from about 2 to 25 nm, is much more intense than the AE-era observations. Using these new results as inputs to thermosphere/ionosphere models causes revisions to predicted photoelectron fluxes, ionization rates, electron density, ion composition, odd-nitrogen composition, and airglow emission rates. We compare predictions to measurements for some of these, including ground based measurements of ionospheric parameters during the first phase of the TIMED mission and far-ultraviolet dayglow limb profiles measured by the GUVI instrument.

  8. Scientific objectives of the Solar Mesosphere Explorer mission

    Science.gov (United States)

    Thomas, G. E.; Barth, C. A.; Hansen, E. R.; Hord, C. W.; Lawrence, G. M.; Mount, G. H.; Rottman, G. J.; Rusch, D. W.; Stewart, A. I.; Thomas, R. J.

    1980-01-01

    The paper describes the NASA Solar Mesosphere Explorer mission which will study mesospheric ozone and the processes which form and destroy it, measure the ozone density and its altitude distribution from 30 to 80 km, monitor incoming solar UV radiation, and provide a rigorous test of the photochemical equilibrium theory of the mesospheric oxygen-hydrogen system. Five instruments will be carried on the polar-orbiting spacecraft: UV ozone, IR airglow, and visible NO2 programmable Ebert-Fastie spectrometers, a four-channel IR radiometer, and a solar UV spectrometer. Atmospheric measurements will be made of the mesospheric and stratospheric ozone density distribution, water vapor density distribution, temperature profile, ozone photolysis rate, and NO2 density distribution. In addition, the solar UV monitor will measure both the 0.2-0.31 micron spectral region and the Lyman-alpha (0.1216 micron) contribution to the solar irradiance.

  9. Atmospheric soundings from Mount Abu

    Science.gov (United States)

    Sharma, Som; Sinha, H. S. S.

    2005-06-01

    An atmospheric science laboratory was set up at Gurushikhar, in the campus of PRL's Infrared observatory, in 1994. A variety of scientific instruments were housed in the atmospheric science laboratory to explore the Earth's ionosphere and neutral atmosphere. A powerful Nd-YAG laser based Lidar, a multi-wavelength all sky imaging system, Day-night-airglow photometer/spectrometer and a proton precession magnetometer are in operation along with a surface ozone sampler, a carbon mono-oxide analyzer and a UV radiometer (measures solar ultraviolet irradiance between 280 and 320 nm). This article highlights the neutral density and temperature measurements by the lidar as well as Atmospheric/Ionospheric parameters derived by other instruments.

  10. Solar EUV irradiance from the San Marco ASSI - A reference spectrum

    Science.gov (United States)

    Schmidtke, Gerhard; Woods, Thomas N.; Worden, John; Rottman, Gary J.; Doll, Harry; Wita, Claus; Solomon, Stanley C.

    1992-11-01

    The only satellite measurement of the solar EUV irradiance during solar cycle 22 has been obtained with the Airglow Solar Spectrometer Instrument (ASSI) aboard the San Marco 5 satellite flown in 1988. The ASSI in-flight calibration parameters are established by using the internal capabilities of ASSI and by comparing ASSI results to the results from other space-based experiments on the ASSI calibration rocket and the Solar Mesospheric Explorer (SME). A solar EUV irradiance spectrum derived from ASSI observations on November 10, 1988 is presented as a reference spectrum for moderate solar activity for the aeronomy community. This ASSI spectrum should be considered as a refinement and extension of the solar EUV spectrum published for the same day by Woods and Rottman (1990).

  11. Solar Irradiance Variation and the Response of the Upper Atmosphere - A Review of Recent Progress in the International TIGER Program

    Science.gov (United States)

    Solomon, Stanley

    Solar irradiance in the ultraviolet, extreme-ultraviolet, and X-ray spectral regions are a key determinant of the state and variation of upper atmosphere and ionosphere parameters, including densities, temperatures, composition, photoelectron fluxes, airglow emission processes, and magnetosphere-ionosphere coupling. The Thermosphere-Ionosphere-Geosphere Research (TIGER) program was established in 1998 with the objective of obtaining a better quantitative understanding of variations in solar irradiance and the effects on the upper atmosphere. The TIGER program has contributed to progress in this area through an ongoing series of conferences, workshops, publications, and data exchange. Advances in measurement and modeling of the solar spectrum have led to improved understanding of the atmosphere/ionosphere response, and to closure between models and measurements in several areas. In this paper, a brief overview of recent results is provided, some critical outstanding questions are identified, and the prospects for new solar and terrestrial observational programs are described.

  12. STS-39 AFP-675 CIRRIS-1A in OV-103's payload bay (PLB)

    Science.gov (United States)

    1991-01-01

    STS-39's Air Force Program 675 (AFP-675) Uniformly Redundant Array (URA) and Cryogenic Infrared Radiance Instrumentation for Shuttle 1A (CIRRIS-1A) mounted on the experiment support system (ESS) pallet are documented in Discovery's, Orbiter Vehicle (OV) 103's, payload bay (PLB). Part of the ESS pallet power distribution system thermal covering is visible at the bottom of the frame. AFP-675 is a Department of Defense (DOD)-sponsored collection of experiments whose objective is to gather data on the Earth's atmosphere (aurora, Earth limb, and airglow), celestial objects, and the environment in and around the PLB. In the background are the aft PLB bulkhead, the vertical tail, and the orbital maneuvering system (OMS) pods.

  13. STS-39 AFP-675 and STP-1 MPESS in OV-103's payload bay (PLB)

    Science.gov (United States)

    1991-01-01

    An overview of Discovery's, Orbiter Vehicle (OV) 103's, aft payload bay (PLB) documents a variety of STS-39's payloads. In the foreground is the Space Test Payload 1 (STP-1) multipurpose experiment support structure (MPESS) with the Spacecraft Kinetic Infrared Test (SKIRT) (left), ascent particle monitor (APM) (center), and advanced liquid feed experiment (ALFE) (two canisters) visible. Behind the STP-1 is the Air Force Program 675 (AFP-675) experiment support structure (ESS) with ESS tape recorders (left), Uniformly Redundant Array (URA) (front),and Cryogenic Infrared Radiance Instrumentation for Shuttle 1A (CIRRIS-1A) (center back) visible. The ESS pallet power distribution system thermal covering (gold-colored) is visible at the bottom. AFP-675 is a Department of Defense (DOD)-sponsored collection of experiments whose objective is to gather data on the Earth's atmosphere (aurora, Earth limb, and airglow), celestial objects, and the environment in and around the PLB. In the backgroun

  14. Determination of SATI Instrument Filter Parameters by Processing Interference Images

    CERN Document Server

    Atanassov, Atanas Marinov

    2010-01-01

    This paper presents a method for determination of interference filter parameters such as the effective refraction index and the maximal transmittance wavelength on the basis of image processing of a spectrogram produced by Spectrometer Airglow Temperature Imager instrument by means of data processing. The method employs the radial sections for determination of points from the crests and valleys in the spectrograms. These points are involved in the least square method for determination of the centres and radii of the crests and valleys. The use of the image radial sections allows to determine the maximal number of crests and valleys in the spectrogram. The application of the least square fitting leads to determination of the image centers and radii of the crests and valleys with precision higher than one pixel. The nocturnal course of the filter parameters produced by this method is presented and compared with that of the known ones. The values of the filter parameters thus obtained are closer to the laborator...

  15. New image measurements of the gravity wave propagation characteristics from a low latitude Indian station

    Directory of Open Access Journals (Sweden)

    M. Sivakandan

    2015-08-01

    Full Text Available The image observations of mesospheric O(1S 558 nm have been performed from a low latitude Indian station, Gadanki (13.5° N; 79.2° E using a CCD based all sky camera system. Based on three years (from year 2012 to the year 2014 of image data during March–April, we characterize the small scale gravity wave properties. We noted 50 strong gravity wave event and 19 ripple events to occur. The horizontal wavelengths of the gravity waves are found to vary from 12 to 42 km with the phase velocity ranging from 20 to 90 km. In most cases, these waves were propagating towards north with only a few occasions of southward propagation. The outgoing longwave radiation data suggest that lower atmospheric convection was most possible reason for the generation of the waves observed in the airglow data.

  16. The generalization of upper atmospheric wind and temperature based on the Voigt line shape profile.

    Science.gov (United States)

    Zhang, Chunmin; He, Jian

    2006-12-25

    The principle of probing the upper atmospheric wind field, which is the Voigt profile spectral line shape, is presented for the first time. By the Fourier Transform of Voigt profile, with the Imaging Spectroscope and the Doppler effect of electromagnetic wave, the distribution and calculation formulae of the velocity field, temperature field, and pressure field of the upper atmosphere wind field are given. The probed source is the two major aurora emission lines originated from the metastable O(1S) and O(1D) at 557.7nm and 630.0nm. From computer simulation and error analysis, the Voigt profile, which is the correlation of the Gaussian profile and Lorentzian profile, is closest to the actual airglow emission lines. PMID:19532147

  17. Evidence of meso-scale structure in the high-latitude thermosphere

    Directory of Open Access Journals (Sweden)

    A. L. Aruliah

    Full Text Available There is a widely held assumption that the thermospheric neutral gas is slow to respond to magnetospheric forcing owing to its large inertia and therefore, may be treated as a steady state background medium for the more dynamic ionosphere. This is shown to be over simplistic. The data presented here compare direct measurements of the thermospheric neutral winds made in Northern Scandinavia by Fabry-Perot Interferometers (FPIs with direct measurements of the ionosphere made by the EISCAT radar and with model simulations. These comparisons will show that the neutral atmosphere is capable of responding to ionospheric changes on mesoscale levels, i.e., spatial and temporal scale sizes of less than a few hundred kilometres and tens of minutes, respectively.

    Key words. Atmospheric composition and structure (air-glow and aurora; instruments and techniques – Ionosphere (ionosphere-atmosphere interactions

  18. Small-scale field-aligned currents caused by tropical cyclones as observed by the SWARM satellites above the ionosphere

    Science.gov (United States)

    Aoyama, T.; Iyemori, T.; Nakanishi, K.

    2014-12-01

    We present case studies of small-scale magnetic fluctuations above typhoons, hurricanes and cyclones as observed by the swarm constellation. It is reported lately that AGWs(atmospheric gravity waves) generated by meteorological phenomena in the troposphere such as typhoons and tornadoes, large earthquakes and volcanic eruptions propagate to the mesosphere and thermosphere. We observe them in various forms(e.g. airglows, ionospheric disturbances and TEC variations). We are proposing the following model. AGWs caused by atmospheric disturbances in the troposphere propagate to the ionospheric E-layer, drive dynamo action and generate field-aligned currents. The satellites observe magnetic fluctuations above the ionosphere. In this presentation, we focus on cases of tropical cyclone(hurricanes in North America, typhoons in North-West Pacific).

  19. Leonid storm research

    CERN Document Server

    Rietmeijer, Frans; Brosch, Noah; Fonda, Mark

    2000-01-01

    This book will appeal to all researchers that have an interest in the current Leonid showers It contains over forty research papers that present some of the first observational results of the November 1999 Leonid meteor storm, the first storm observed by modern observing techniques The book is a first glimpse of the large amount of information obtained during NASA's Leonid Multi-Instrument Aircraft Campaign and groundbased campaigns throughout the world It provides an excellent overview on the state of meteor shower research for any professional researcher or amateur meteor observer interested in studies of meteors and meteoroids and their relation to comets, the origin of life on Earth, the satellite impact hazard issue, and upper atmosphere studies of neutral atom chemistry, the formation of meteoric debris, persistent trains, airglow, noctilucent clouds, sprites and elves

  20. MAMA Spectroscopic Sensitivity and Focus Monitor Cycle 21

    Science.gov (United States)

    Sana, Hugues

    2013-10-01

    Monitor sensitivity of each MAMA grating mode to detect any change due tocontamination or other causes. Also monitor the STIS focus in a spectroscopic and animaging mode.Obtain exposures in each of the 2 low-resolution MAMA spectroscopic modes every 4 months, in each of the 2 medium-resolution modes once a year, and in each of the 4 echelle modes every 3 months,using unique calibration standards for each mode, and ratio the results to the firstobservations to detect any trends. In addition, each L-mode sequence will be preceded by twospectroscopic ACQ/PEAKs with the CCD/G230LB and crossed linear patterns, with the purpose of measuringthe focus {PSF across the dispersion as a function of UV wavelength}; and each M-mode sequence will be preceded by aCCD/F28X50OII direct image also to monitor the focus.Whenever possible, obtain parallel airglow spectra with COS.

  1. MAMA Spectroscopic Sensitivity and Focus Monitor Cycle 19

    Science.gov (United States)

    Bostroem, Azalee

    2011-10-01

    Monitor sensitivity of each MAMA grating mode to detect any change due tocontamination or other causes. Also monitor the STIS focus in a spectroscopic and animaging mode.Obtain exposures in each of the 2 low-resolution MAMA spectroscopic modes every 4 months, in each of the 2 medium-resolution modes once a year, and in each of the 4 echelle modes every 3 months,using unique calibration standards for each mode, and ratio the results to the firstobservations to detect any trends. In addition, each L-mode sequence will be preceded by twospectroscopic ACQ/PEAKs with the CCD/G230LB and crossed linear patterns, with the purpose of measuringthe focus {PSF across the dispersion as a function of UV wavelength}; and each M-mode sequence will be preceded by aCCD/F28X50OII direct image also to monitor the focus.Whenever possible, obtain parallel airglow spectra with COS.

  2. MAMA Spectroscopic Sensitivity and Focus Monitor Cycle 20

    Science.gov (United States)

    Holland, Stephen

    2012-10-01

    Monitor sensitivity of each MAMA grating mode to detect any change due tocontamination or other causes. Also monitor the STIS focus in a spectroscopic and animaging mode.Obtain exposures in each of the 2 low-resolution MAMA spectroscopic modes every 4 months, in each of the 2 medium-resolution modes once a year, and in each of the 4 echelle modes every 3 months,using unique calibration standards for each mode, and ratio the results to the firstobservations to detect any trends. In addition, each L-mode sequence will be preceded by twospectroscopic ACQ/PEAKs with the CCD/G230LB and crossed linear patterns, with the purpose of measuringthe focus {PSF across the dispersion as a function of UV wavelength}; and each M-mode sequence will be preceded by aCCD/F28X50OII direct image also to monitor the focus.Whenever possible, obtain parallel airglow spectra with COS.

  3. MAMA Spectroscopic Sensitivity and Focus Monitor Cycle 18

    Science.gov (United States)

    Osten, Rachel

    2010-09-01

    Monitor sensitivity of each MAMA grating mode to detect any change due tocontamination or other causes. Also monitor the STIS focus in a spectroscopic and animaging mode.Obtain exposures in each of the 2 low-resolution MAMA spectroscopic modes every 4 months, in each of the 2 medium-resolution modes once a year, and in each of the 4 echelle modes every 3 months,using unique calibration standards for each mode, and ratio the results to the firstobservations to detect any trends. In addition, each L-mode sequence will be preceded by twospectroscopic ACQ/PEAKs with the CCD/G230LB and crossed linear patterns, with the purpose of measuringthe focus {PSF across the dispersion as a function of UV wavelength}; and each M-mode sequence will be preceded by aCCD/F28X50OII direct image also to monitor the focus.Whenever possible, obtain parallel airglow spectra with COS.

  4. Near-infrared thermal emissivity from ground based atmospheric dust measurements at ORM

    CERN Document Server

    Lombardi, G; Ortolani, S; Melnick, J; Ghedina, A; Garcia, A; Molinari, E; Gatica, C

    2011-01-01

    We present an analysis of the atmospheric content of aerosols measured at Observatorio del Roque de los Muchachos (ORM; Canary Islands). Using a laser diode particle counter located at the Telescopio Nazionale Galileo (TNG) we have detected particles of 0.3, 0.5, 1.0, 3.0, 5.0 and 10.0 um size. The seasonal behavior of the dust content in the atmosphere is calculated. The Spring has been found to be dustier than the Summer, but dusty conditions may also occur in Winter. A method to estimate the contribution of the aerosols emissivity to the sky brightness in the near-infrared (NIR) is presented. The contribution of dust emission to the sky background in the NIR has been found to be negligible comparable to the airglow, with a maximum contribution of about 8-10% in the Ks band in the dusty days.

  5. CISCO Cooled Infrared Spectrograph and Camera for OHS on the Subaru Telescope

    CERN Document Server

    Motohara, K; Maihara, T; Oya, S; Tsukamoto, H; Imanishi, M; Terada, H; Goto, M; Iwai, J; Tanabe, H; Hata, R; Taguchi, T; Harashima, T

    2002-01-01

    This paper describes a Cooled Infrared Spectrograph and Camera for OHS (CISCO), mounted on the Nasmyth focus of the Subaru telescope. It is primarily designed as a back-end camera of the OH-Airglow Suppressor (OHS), and is also used as an independent, general-purpose near-infrared camera/spectrograph. CISCO is based on a single 1024x1024 format HgCdTe HAWAII array detector, and is capable of either wide-field imaging of 1.8'x1.8' field-of-view or low-resolution spectroscopy from 0.9 to 2.4 um. The limiting magnitudes measured during test observations were found to be J=23.5mag and K'=22.4mag (imaging, 1" aperture, S/N=5, 1 hr exposure).

  6. Ultraviolet spectrographs for thermospheric and ionospheric remote sensing

    International Nuclear Information System (INIS)

    The Naval Research Laboratory (NRL) has been developing far- and extreme-ultraviolet spectrographs for remote sensing the Earth's upper atmosphere and ionosphere. The first of these sensors, called the Special Sensor Ultraviolet Limb Imager (SSULI), will be flying on the Air Force's Defense Meteorological Satellite Program (DMSP) block 5D3 satellites as an operational sensor in the 1997-2010 time frame. A second sensor, called the High-resolution ionospheric and Thermospheric Spectrograph (HITS), will fly in late 1995 on the Air Force Space Test Program's Advanced Research and Global Observation Satellite (ARGOS, also known as P91-1) as part of NRL's High Resolution Airglow and Auroral Spectroscopy (HIRAAS) experiment. Both of these instruments are compact and do not draw much power and would be good candidates for small satellite applications. The instruments and their capabilities are discussed. Possible uses of these instruments in small satellite applications are also presented

  7. Case study of a mesospheric wall event over Ferraz station, Antarctica (62° S

    Directory of Open Access Journals (Sweden)

    C. M. Denardini

    2011-01-01

    Full Text Available On 16–17 July 2007 during an observational campaign at Comandante Ferraz Antarctic Station (62° S, 58° W, a mesospheric wall was observed with an airglow all-sky imager. The wave appeared like an extensive dark region in the all-sky airglow images, with a large depletion in the OH emission. Simultaneous mesospheric winds measured with a MF radar at Rothera station and temperature profiles from SABER instrument, on board of TIMED satellite, were used to obtain the propagation condition of the wave. Wind measurements during four days, around the time of observation of the wave, are presented in order to discuss the type and consistence of the duct in which this wave was propagating. By using wavelet analysis and tidal amplitude components we found that 12 and 8 h components were the most important periodicities around the time interval of the wave observation. A collocated imaging spectrometer, for mesospheric temperature measurements, has been operated simultaneously with the all-sky imager. Direct effects of the mesospheric front have been seen in the spectrometric measurements, showing an abrupt decrease in both OH intensity and rotational temperature when the wave front passes overhead. The main contribution of the present work is the investigation of the type of duct in which the wall event was propagating. We found evidences for a thermal duct structure to support the mesospheric wall propagation. This result was obtained by two types of analysis: (a the tidal components analysis and winds filtering (harmonic analysis, and (b comparison between the terms of the m2 dispersion relation.

  8. Comparison of calculation models for determination of the mesopause temperature using SATI images

    Science.gov (United States)

    Atanassov, Atanas Marinov

    2011-06-01

    The Spectral Airglow Temperature Imager is an instrument for ground-based spectroscopic measurements of the night-glow atmosphere emissions. This instrument was developed specially for gravity wave investigation. The measured airglow spectra are matched to synthetic spectra calculated in advance for determination of the temperature in the mesopause region where the radiation maximum of some О 2 emissions is situated. The synthetic spectra are transformed into a format which corresponds to the measured spectra in order to be matched. This transformation is based on the known values of the refractive index and the central wavelength of the interference filter used. A substantial part of the processing algorithms of the SATI images is connected with determination of these two filter parameters. The results of the original and newly-proposed algorithms for filter parameter calculation and their importance for the final results for temperature determination on the basis of the О 2 (864-868 nm) emission measurements are presented. Considerable systematic differences (˜20 K) between temperatures at different points in the mesopause retrieved by the two algorithms are established. The advantage of the proposed algorithm over the original one is illustrated by retrieved rotational temperatures and by lower error values. Furthermore, the irregular errors in the nocturnal variation of the temperature retrieved by the original algorithm are absent when the proposed approach is applied. The error investigation in the calculations and the stability of the individual components of the processing algorithms and the calculation models may be helpful in achieving better results and enhancing the potentialities of the SATI instrument.

  9. Geomagnetism and climate I: the last 400 years

    Science.gov (United States)

    Nevanlinna, H.; Shumilov, O.; Mörner, N.-A.; Dergachev, V.

    2003-04-01

    During the last 400 years there seems to exist a close linkage between sunspot activity and paleoclimate. The combined Schwabe Gleisberg cycles provide a good approximation of past climate. Changes in the phase of the sunspot cycles exhibit a very close correlation with observed changes in climate for the last 150 years. The heliomagnetic aa-index provides a close correlation with climate over the last 150 years. The close correlation between sunspot activity and atmospheric changes in radiocarbon indicates that changes in heliomagnetic interaction with the Earth’s magnetosphere play a central role in this solar-terrestrial interaction; via its modulation of the cosmic ray flux or its modulation of Earth’s rate of rotation. Variations in cosmic ray flux have the capacity of affecting Earth’s climate via its modulation of airglow and cloudiness (especially at the level around 15 km). There is a good correlation between Solar Wind intensity and Earth’s rate of rotation (LOD), implying that variations in Solar Wind intensity (sunspot activity) act in retarding and speeding up in the spin rate of Planet Earth. During the Spörer, Maunder and Dalton Sunspot Minima, the Earth’s rate of rotation was significantly speeded-up, affecting the ocean surface circulation and the atmospheric circulation as to create significant changes in local climate; “Little Ice Ages” in western and northern Europe and “Little Interglacial” in southwest Europe and northwest Africa. In conclusion, Earth’s climate seems closely driven by changes in sunspot activity. This correlation may operate via the cosmic ray effects on airglow and/or cloudiness, or via the heliomagnetic (Solar Wind) effects on Earth’s rate of rotation, or a combination of these processes. Changes in the Earth’s own internal geomagnetic field seem to have played little or no role during this time period. Nor are there any reasons to advocate major changes in Solar irradiance.

  10. Morphology of 557.7 nm dayglow emission under varying solar activity conditions

    Science.gov (United States)

    Krishna, M. V. Sunil; Singh, Vir

    The atomic oxygen emission at 557.7 nm is the most widely observed airglow feature in the upper mesosphere and lower thermospheric regions. The approximation of solar irradiance fluxes is very crucial in the modeling of this emission. The recently introduced Solar2000 EUV flux model is a suitable candidate to provide the solar EUV flux for any level of solar activity on any given day. The Solar2000 EUV flux model has not been tested for its applicability in the airglow modeling studies. In the present study a comprehensive model has been developed to study the 557.7 nm dayglow emission using Solar2000 EUV flux model. This study presents the model results of diurnal and yearly variations of 557.7 nm dayglow emission under equinox conditions. The effect of varying solar activity on this emission is studied for a period of five years (2001-2005) at a fixed date of April 3. This date is chosen due to the fact of large variations in the solar activity during the period of five years. The volume emission rates obtained from the model in the upper mesospheric region are found higher than the observed results. This discrepancy is due to the extremely high values of solar EUV flux generated by the Solar2000 EUV flux model at 102.5 and 103.7 nm wavelengths. The model is found in good agreement with the measurements in the thermospheric region. The morphology is presented as a function of F10.7 solar index for five years (2001 -2005) equator and 45° N at a fixed longitude.

  11. Mesospheric minor species determinations from rocket and ground-based i.r. measurements

    Science.gov (United States)

    Ulwick, J. C.; Baker, K. D.; Baker, D. J.; Steed, A. J.; Pendleton, W. R.; Grossmann, K.; Brückelmann, H. G.

    As part of the MAP/WINE campaign the infrared hydroxyl airglow layer was investigated at Kiruna, Sweden, by simultaneous measurements with rocket probes of OH ≠ and O2( a1Δg) infrared emissions and concentrations of odd oxygen species (O and O 3). Coordinated measurements of OH ≠ and O2( a1Δg) zenith radiance and emission spectra and their time histories were made from the ground. The rocket-borne Λ = 1.55 μm radiometer ( ΔΛ ≊ 0.23 μm) provided volume emission rates for OH for both rocket ascent and descent, showing a peak near 87 km with a maximum of nearly 10 6 photons sec -1 cm -3. The atomic oxygen distribution showed a concentration of about 10 11 cm -3 between 88 and 100 km, dropping off sharply below 85 km. The ground-based radiometer at Λ = 1.56 μm, which had a similar filter bandpass to the rocket-borne instrument, yielded an equivalent of 130 kR for the total OH Δv = 2 sequence, which is consistent with the zenith-corrected rocket-based sequence radiance value of ≌ 110 kR. The rotational temperature of the OH night airglow obtained from the rotational structure of the OH M (3,1) band observed by the ground-based interferometer was about 195K at the time of the rocket measurement. Atomic oxygen concentrations were calculated from the OH profile and show agreement with the directly measured values. Atomic hydrogen concentrations of a few times 10 7 cm -3 near 85 km were inferred from the data set.

  12. Regional variations of mesospheric gravity-wave momentum flux over Antarctica

    Directory of Open Access Journals (Sweden)

    P. J. Espy

    2006-03-01

    Full Text Available Images of mesospheric airglow and radar-wind measurements have been combined to estimate the difference in the vertical flux of horizontal momentum carried by high-frequency gravity waves over two dissimilar Antarctic stations. Rothera (67° S, 68° W is situated in the mountains of the Peninsula near the edge of the wintertime polar vortex. In contrast, Halley (76° S, 27° W, some 1658 km to the southeast, is located on an ice sheet at the edge of the Antarctic Plateau and deep within the polar vortex during winter. The cross-correlation coefficients between the vertical and horizontal wind perturbations were calculated from sodium (Na airglow imager data collected during the austral winter seasons of 2002 and 2003 at Rothera for comparison with the 2000 and 2001 results from Halley reported previously (Espy et al., 2004. These cross-correlation coefficients were combined with wind-velocity variances from coincident radar measurements to estimate the daily averaged upper-limit of the vertical flux of horizontal momentum due to gravity waves near the peak emission altitude of the Na nightglow layer, 90km. The resulting momentum flux at both stations displayed a large day-to-day variability and showed a marked seasonal rotation from the northwest to the southwest throughout the winter. However, the magnitude of the flux at Rothera was about 4 times larger than that at Halley, suggesting that the differences in the gravity-wave source functions and filtering by the underlying winds at the two stations create significant regional differences in wave forcing on the scale of the station separation.

  13. Polar ionospheric responses to solar wind IMF changes

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    Full Text Available Auroral and airglow emissions over Eureka (89° CGM during the 1997-98 winter show striking variations in relation to solar wind IMF changes. The period January 19 to 22, 1998, was chosen for detailed study, as the IMF was particularly strong and variable. During most of the period, Bz was northward and polar arcs were observed. Several overpasses by DMSP satellites during the four day period provided a clear picture of the particle precipitation producing the polar arcs. The spectral character of these events indicated excitation by electrons of average energy 300 to 500 eV. Only occasionally were electrons of average energy up to ~1 keV observed and these appeared transitory from the ground optical data. It is noted that polar arcs appear after sudden changes in IMF By, suggesting IMF control over arc initiation. When By is positive there is arc motion from dawn to dusk, while By is negative the motion is consistently dusk to dawn. F-region (anti-sunward convections were monitored through the period from 630.0 nm emissions. The convection speed was low (100-150 m/s when Bz was northward but increased to 500 m/s after Bz turned southward on January 20.

    Key words: Atmospheric composition and structure (airglow and aurora - Ionosphere (particle precipitation - Magnetospheric Physics (polar cap phenomena

  14. Ionospheric and Thermospheric Imaging from Geosynchronous Orbit

    Science.gov (United States)

    McCoy, R. P.; Wood, K.; Dymond, K. F.; Thonnard, S. E.; Cannon, K.; Makela, J.

    2001-12-01

    The Office of Naval Research is sponsoring the development of an ultraviolet imaging system to test the concept of real-time synoptic observations of the ionosphere and thermosphere from geosynchronous orbit. The observational hardware consists of two ultraviolet telescopes mounted to a two-axis gimbal to measure airglow radiances on the disk and limb of the Earth. A far-ultraviolet telescope will use a filter wheel with filters to image atomic oxygen emission at 130.4 nm, 135.6 nm, and molecular nitrogen emission at 143.0 nm. An extreme-ultraviolet telescope will image the oxygen ion airglow at 83.4 nm. The oxygen emission measurements will be used to infer nightside ionospheric total electron content (TEC) on the disk and electron density profiles on the limb. On the dayside the oxygen ion measurements will be used to determine electron density profiles, and the oxygen and nitrogen measurements will be used to infer thermospheric neutral density profiles on the limb and O/N2 ratios on the disk. The telescope fields of view cover a 1000 km x 1000 km region with 10 km x 10 km resolution. A goal for nightside TEC measurements is to obtain images with 100 second integrations and to be able to track ionospheric irregularities in real time as "weather systems". Ratios of oxygen nightglow measurements will be used to explore the possibility of providing three dimensional measurements of the ionosphere. These telescopes will be mounted aboard an Air Force Space Test Program satellite which will be launched into geosynchronous orbit over the continental U. S. for about year and then moved over the Indian Ocean for an additional seven years.

  15. Infrasonic induced mesopause temperature perturbations. As an early indicator for the detection of tsunamis and other geo-hazards

    International Nuclear Information System (INIS)

    Complete text of publication follows. Many geo-hazards such as earthquakes, tsunamis, volcanic eruptions, severe weather etc. cause infrasonic waves which can travel over large distances (several thousand kilometers) in the atmosphere. These longitudinal pressure waves contribute to the coupling of the various atmospheric altitude layers and directly lead to temperature perturbations. Temperature fluctuations connected with the above mentioned events usually are very weak at the surface, but the amplitude increases with height because of the exponential decrease of atmospheric pressure with increasing altitude. At the mesopause region (∼87 km height) signal intensities should be about four to five orders of magnitude larger than on the ground. The modeling structure of infrasound propagation as well as of acoustic heating is presented. Subject of the present study is to show the potential of the GRIPS (Ground-based Infrared P-branch Spectrometer) measurement system which is currently used at DLR-DFD to monitor climate signals in the mesopause region, to better understand the impact of atmospheric dynamics on larger-scale circulation, to validate satellite-based measurements and to evaluate climate and atmospheric models. GRIPS utilises the airglow phenomenon. Mesopause temperatures (at ∼87 km height) are currently and routinely derived night by night from observations of hydroxyl (OH*) emissions in the near infrared using two ground-based infrared spectrometers (GRIPS 3 and GRIPS 5). The main idea of the presentation is to demonstrate the feasibility of using the modulation of OH*-temperatures caused by infrasonic waves travelling through the airglow layer, which are generated by geo-hazards such as tsunamis and to quantify acoustic heating rates. The system is expected to add value to multi-hazard early warning systems.

  16. From Sumatra 2004 to Tuhoku-Oki 2011: what we learn about Tsunami detection by ionospheric sounding.

    Science.gov (United States)

    Occhipinti, G.; Rolland, L.; Coisson, P.; Watada, S.; Makela, J. J.; Hebert, H.; Lognonne, P. H.

    2014-12-01

    The recent tsunamigenic Tohoku earthquake (2011) strongly affirms, again, after the 26 December 2004, the necessity to open new paradigms in oceanic monitoring. Detection of ionospheric anomalies following the Sumatra earthquake tsunami (e.g., Occhipinti et al. 2006) demonstrated that ionosphere is sensitive to earthquake and tsunami propagation: ground and oceanic vertical displacement induces acoustic-gravity waves propagating within the neutral atmosphere and detectable in the ionosphere. Observations supported by modelling proved that tsunamigenic ionospheric anomalies are deterministic and reproducible by numerical modeling via the ocean/neutral-atmosphere/ionosphere coupling mechanism (Occhipinti et al., 2008). To prove that the tsunami signature in the ionosphere is routinely detected we show here perturbations of total electron content (TEC) measured by GPS and following tsunamigenic eartquakes from 2004 to 2010 (Rolland et al. 2010, Occhipinti et al., 2013, Occhipinti, 2014), nominally, Sumatra (26 December, 2004 and 12 September, 2007), Chile (14 November, 2007), Samoa (29 September, 2009) and the recent Tohoku-Oki (11 Mars, 2011). In addition to GPS/TEC observations close to the epicenter and measured by GEONET network, new exciting measurements in the far-field were performed by Airglow measurement in Hawaii: those measurements show the propagation of the IGWs induced by the Tohoku tsunami in the Pacific Ocean (Occhipinti et al., 2011). Based on the observations close to the epicenter, mainly performed by GPS networks located in Sumatra, Chile and Japan, we highlight the TEC perturbation observed within the first hour after the seismic rupture. This perturbation contains informations about the ground displacement, as well as the consequent sea surface displacement resulting in the tsunami. In this talk we present all this new tsunami observations in the ionosphere and we discuss, under the light of modelling, the potential role of ionospheric sounding

  17. Mesopause temperature perturbations caused by infrasonic waves as a potential indicator for the detection of tsunamis and other geo-hazards

    Directory of Open Access Journals (Sweden)

    M. Bittner

    2010-07-01

    Full Text Available Many geo-hazards such as earthquakes, tsunamis, volcanic eruptions, severe weather, etc., produce acoustic waves with sub-audible frequency, so called infrasound. This sound propagates from the surface to the middle and upper atmosphere causing pressure and temperature perturbations. Temperature fluctuations connected with the above mentioned events usually are very weak at the surface, but the amplitude increases with height because of the exponential decrease of atmospheric pressure with increasing altitude. At the mesopause region (80–100 km height signal amplitudes are about two to three orders of magnitude larger than on the ground.

    The GRIPS (GRound-based Infrared P-branch Spectrometer measurement system operated by the German Remote Sensing Data Center of the German Aerospace Center (DLR-DFD derives temperatures of the mesopause region by observing hydroxyl (OH airglow emissions in the near infrared atmospheric emission spectrum originating from a thin layer at approximately 87 km height.

    The GRIPS instrument is in principle suited for the detection of infrasonic signals generated by e.g. tsunamis and other geo-hazards. This is due to the fact that the infrasound caused by such events should induce observable short-period fluctuations in the OH airglow temperatures. First results obtained during a field campaign performed at the Environmental Research Station "Schneefernerhaus", Zugspitze (47.4° N, 11.0° E from October to December 2008 are presented regarding potential sources of meteorological and orographical origin.

    An adequate distinction of the overlapping infrasonic signatures caused by different infrasound sources in the OH temperature record is needed for the ascription to the proper source. The approach presented here could form a contribution to a hazard monitoring and early warning system.

  18. 四分束风成像偏振干涉仪信噪比的研究%The signal-to-noise ratio of the quarter beam of wind imaging polarization interferometer∗

    Institute of Scientific and Technical Information of China (English)

    张宣妮; 张淳民; 艾晶晶

    2013-01-01

    The novel static polarization wind imaging interferometer adopts four-face pyramid prism and polarization array to obtain four different phase interferograms on four sections of CCD once. It can detect the target in real time and overcome the moving mirror scan detection mode defect that leads to be unable to accurately detect the rapily changing target. For the signal beam that is split into four equal parts, their intensities drop significantly, so whether the signal can be detected is a key problem. In this paper, the target spectral characteristic of the airglow is taken as the starting point of analysis, then the optical transmission properties and response of the NSPWII system and CCD signal-to-noise ratio are analyzed. Finally the conclusion is obtained that weak signal (such as night airglow) cannot be detected in the conventional detecting mode. Some improving measure is presented which extends light integration time, adopts pixel merger technology and select high sensitivity CCD (as electron multiplication CCD), they all can improve the signal-to-noise ratio effectively. After integrated using the these measures, the signal-to-noise ratio and responsiveness of NSPWII system are calculated. In view of the rapid changes of cost and objectives, only pixel binning is adopted, and the simulated curve of signal-to-noise ratio versus digital output is obtained. The result shows that the weak signal as night airglow can be detected.%  新型静态偏振风成像干涉仪采用四面角锥棱镜与偏振阵列的组合结构,在CCD的四个分区上一次得到四个不同相位的干涉图,可以实现对目标的实时探测,克服了动镜扫描探测模式不能对快速变化目标进行精确探测的缺陷。由于光束被四等分,强度大幅度下降,微弱的气辉信号能否被探测到成为研究的关键。本文从目标气辉光谱的特性出发,分析了静态偏振风成像干涉仪系统的光学

  19. Extreme ultraviolet spectral irradiance measurements since 1946

    Science.gov (United States)

    Schmidtke, G.

    2015-03-01

    In the physics of the upper atmosphere the solar extreme ultraviolet (EUV) radiation plays a dominant role controlling most of the thermospheric/ionospheric (T/I) processes. Since this part of the solar spectrum is absorbed in the thermosphere, platforms to measure the EUV fluxes became only available with the development of rockets reaching altitude levels exceeding 80 km. With the availability of V2 rockets used in space research, recording of EUV spectra started in 1946 using photographic films. The development of pointing devices to accurately orient the spectrographs toward the sun initiated intense activities in solar-terrestrial research. The application of photoelectric recording technology enabled the scientists placing EUV spectrometers aboard satellites observing qualitatively strong variability of the solar EUV irradiance on short-, medium-, and long-term scales. However, as more measurements were performed more radiometric EUV data diverged due to the inherent degradation of the EUV instruments with time. Also, continuous recording of the EUV energy input to the T/I system was not achieved. It is only at the end of the last century that there was progress made in solving the serious problem of degradation enabling to monitore solar EUV fluxes with sufficient radiometric accuracy. The data sets available allow composing the data available to the first set of EUV data covering a period of 11 years for the first time. Based on the sophisticated instrumentation verified in space, future EUV measurements of the solar spectral irradiance (SSI) are promising accuracy levels of about 5% and less. With added low-cost equipment, real-time measurements will allow providing data needed in ionospheric modeling, e.g., for correcting propagation delays of navigation signals from space to earth. Adding EUV airglow and auroral emission monitoring by airglow cameras, the impact of space weather on the terrestrial T/I system can be studied with a spectral terrestrial

  20. Creation of polar cap patches

    Science.gov (United States)

    Hosokawa, K.; Taguchi, S.; Ogawa, Y.

    2014-12-01

    Polar cap patches, which are islands of enhanced plasma density drifting anti-sunward, are one of the outstanding phenomena in the polar cap F region ionosphere. In the last decade, data from all-sky airglow imagers have been extensively used for better understanding the propagation of patches in the central polar cap region. But still, it has been rather difficult to capture the birth of patches in their generation region near the dayside cusp, because, in most places, the dayside part of the polar cap ionosphere is sunlit even in winter. In Longyearbyen (78.1N, 15.5E), Norway, however, optical observations are possible near the dayside cusp region in a limited period around the winter solstice. This enables us to directly image how polar cap patches are born in the cusp. In this paper, we present a few intervals of daytime optical observations, during which polar cap patches were generated within the field-of-view of an all-sky imager in Longyearbyen. During all the intervals studied here, we identified several signatures of poleward moving auroral forms (PMAF) in the equatorward half of the field-of-view, which are known as ionospheric manifestations of dayside reconnection. Interestingly, patches were directly produced from such poleward moving auroral signatures and propagated poleward along the anti-sunward convection near the cusp. In the literature, Lorentzen et al. (2012) first reported such a direct production of patches from PMAFs. During the current observations, however, we succeeded in tracking the propagation of patches until they reached the poleward edge of the field-of-view of the imager. This confirms that the faint airglow structures produced from PMAFs were actually transported for a long distance towards the central polar cap area; thus, polar cap patches were produced. From this set of observations, we suggest that polar cap patches during moderately disturbed conditions (i.e, non-storm time conditions) can be directly produced by the

  1. The O-STATES Sounding Rocket Project - First Results

    Science.gov (United States)

    Hedin, J.

    2015-12-01

    In October 2015, the sounding rocket project O-STATES was conducted from Esrange Space Center (67.9°N, 21.1°E) in northern Sweden. The acronym O-STATES stands for "Oxygen Species and Thermospheric Airglow in The Earth's Sky" and the basic idea is that comprehensive information on the composition, specifically atomic oxygen in the ground state O and first excited state O(1D), and temperature of the lower thermosphere can be obtained from a limited set of optical measurements. Starting point for the analysis are daytime measurements of the O2(b1∑g+ - X3∑g-) Atmospheric Band system in the spectral region 755-780 nm and the O(1D-3P) Red Line at 630 nm. In the daytime lower thermosphere O(1D) is produced by O2 photolysis and the excited O2(b) state is mainly produced by energy transfer from O(1D) to the O2(X) ground state. In addition to O2 photolysis, both electron impact on O and dissociative recombination of O2+ are major sources of O(1D) in the thermosphere. Recent laboratory studies at SRI demonstrate that the O2(b) production populates the vibrational levels v=1 and v=0 in a ratio of ~4. While O2(b, v=0) is essentially unquenched, O2(b, v=1) is subject to collisional quenching that is dominated by O at altitudes above 160 km. Hence, the ratio of the Atmospheric Band emission from O2(b, v=1) and O2(b, v=0) is a measure of the O density. Finally, the spectral shape of the O2 Atmospheric Band is temperature dependent and spectrally resolved measurements of the Atmospheric Bands thus provide a measure of atmospheric temperature. This O2 Atmospheric Band analysis has been advocated as a technique for thermospheric remote sensing under the name Global Oxygen and Temperature (GOAT) Mapping. With O-STATES we want to characterize the GOAT technique by in-situ analysis of the O2 Atmospheric Band airglow and the underlying excitation mechanisms. By performing this dayglow analysis from a rocket payload, detailed local altitude profiles of the relevant emissions and

  2. Atomic oxygen and temperature in the lower thermosphere from the O-STATES sounding rocket project

    Science.gov (United States)

    Hedin, Jonas; Gumbel, Jörg; Megner, Linda; Stegman, Jacek; Seo, Mikael; Khaplanov, Mikhail; Slanger, Tom; Kalogerakis, Konstantinos; Friedrich, Martin; Torkar, Klaus; Eberhart, Martin; Löhle, Stefan; Fasoulas, Stefanos

    2016-04-01

    In October 2015 the O-STATES payload was launched twice from Esrange Space Center (67.9° N, 21.1° E) in northern Sweden, first into moderately disturbed and then into calm geomagnetic conditions. The basic idea of O-STATES ("Oxygen Species and Thermospheric Airglow in The Earth's Sky") is that comprehensive information on the composition, specifically atomic oxygen in the ground state O(3P) and first excited state O(1D), and temperature of the lower thermosphere can be obtained from a limited set of optical measurements. Starting point for the analysis are daytime measurements of the O2(b1 ∑ g+ ‑ X3 ∑ g‑) Atmospheric Band system in the spectral region 755-780 nm and the O(1D-3P) Red Line at 630 nm. In the daytime lower thermosphere, O(1D) is produced by O2 photolysis and the excited O2(b) state is mainly produced by energy transfer from O(1D) to the O2(X) ground state. In addition to O2 photolysis, both electron impact on O(3P) and dissociative recombination of O2+ are major sources of O(1D) in the thermosphere. Laboratory studies at SRI International have shown that O2(b) production in vibrational level v=1 dominates. While O2(b, v=0) is essentially unquenched, O2(b, v=1) is subject to collisional quenching that is dominated by O at altitudes above 160 km. Hence, the ratio of the Atmospheric Band emission from O2(b, v=1) and O2(b, v=0) is a measure of the O density at sufficiently high altitudes. In addition, the spectral shape of the O2 Atmospheric Band is temperature dependent and spectrally resolved measurements of the Atmospheric Bands thus provide a measure of atmospheric temperature. This O2 Atmospheric Band analysis has been suggested as a new technique for thermospheric remote sensing under the name Global Oxygen and Temperature (GOAT) Mapping. With O-STATES we want to characterize the GOAT technique by in-situ analysis of the O2 Atmospheric Band airglow and the underlying excitation mechanisms. By performing this dayglow analysis from a rocket

  3. Observation of a mesospheric front in a dual duct over King George Island, Antarctica

    Directory of Open Access Journals (Sweden)

    J. V. Bageston

    2011-05-01

    Full Text Available A mesospheric bore was observed with an all-sky airglow imager on the night of 9–10 July 2007 at Ferraz Station (62° S, 58° W, located on King George island on the Antarctic Peninsula. The observed bore propagated from southwest to northeast with a well defined wave front and a series of crests behind the main front. There was no evidence of dissipation during its propagation within the field of view. The wave parameters were obtained via a 2-D Fourier transform of the imager data providing a horizontal wavelength of 33 km, an observed period of 6 min, and a horizontal phase speed of 92 m s−1. Simultaneous mesospheric winds were measured with a medium frequency (MF radar at Rothera Station (68° S, 68° W and temperature profiles were obtained from the SABER instrument on the TIMED satellite. These wind and temperature profiles were used to estimate the propagation environment of the bore. A wavelet technique was applied to the wind in the plane of bore propagation at the OH emission height spanning three days centered on the bore event to define the dominant periodicities. Results revealed a dominance of near-inertial periods, and semi-diurnal and terdiurnal tides suggesting that the ducting structure enabling bore propagation occurred on large spatial scales. The observed tidal motions were used to reconstruct the winds employing a least-squares method, which were then compared to the observed ducting environment. Results suggest an important contribution of large-scale winds to the ducting structure, but with buoyancy frequency variations in the vertical also expected to be important. These results allow us to conclude that the bore was supported by a duct including contributions from both winds and temperature (or stability. A co-located airglow temperature imager operated simultaneously with the all-sky imager confirmed that the bore event was the dominant small-scale wave event during the analysis interval.

  4. Night Sky Background Analysis for the Cherenkov Telescope Array using the Atmoscope instrument

    CERN Document Server

    Gaug, Markus

    2013-01-01

    The site selection group for the future Cherenkov Telescope Array (CTA) has deployed sensitive light sensors at 9 candidate sites, 5 of them in the Southern and 4 in the Northern hemisphere. The sensors are equipped with a PIN diode and a calibrated V-filter, and a blue/UV filter matching the spectral response of the photomultipliers to be employed in the CTA cameras. All sensor installations, denominated "Atmoscopes", have been cross-calibrated before deployment, and their sensitivity is monitored every two to five months. We show that a thoroughly developed model of the integral contribution of starlight to the overall light measure serves as an additional cross-calibration for each device during each night, reducing the systematic uncertainty of this measurement to less than 15%. The starlight can then be subtracted from the measurements, and the residuals compared among the different sites. We show that in most cases a decomposition into the contributions from zodiacal light, airglow and anthropogenic lig...

  5. Atmospheric Photochemistry

    Science.gov (United States)

    Massey, Harrie; Potter, A. E.

    1961-01-01

    The upper atmosphere offers a vast photochemical laboratory free from solid surfaces, so all reactions take place in the gaseous phase. At 30 km altitude the pressure has fallen to about one-hundredth of that at ground level, and we shall, rather arbitrarily, regard the upper atmosphere as beginning at that height. By a little less than 100 km the pressure has fallen to 10(exp -3) mm Hg and is decreasing by a power of ten for every 15 km increase in altitude. Essentially we are concerned then with the photochemistry of a nitrogen-oxygen mixture under low-pressure conditions in which photo-ionization, as well as photodissociation, plays an important part. Account must also be taken of the presence of rare constituents, such as water vapour and its decomposition products, including particularly hydroxyl, oxides of carbon, methane and, strangely enough, sodium, lithium and calcium. Many curious and unfamiliar reactions occur in the upper atmosphere. Some of them are luminescent, causing the atmosphere to emit a dim light called the airglow. Others, between gaseous ions and neutral molecules, are almost a complete mystery at this time. Similar interesting phenomena must occur in other planetary atmospheres, and they might be predicted if sufficient chemical information were available.

  6. Investigation of a mesospheric bore event over northern China

    Directory of Open Access Journals (Sweden)

    Q. Li

    2013-03-01

    Full Text Available A mesospheric bore event was observed using an OH all-sky airglow imager (ASAI at Xinglong (40.2° N, 117.4° E, in northern China, on the night of 8–9 January 2011. Simultaneous observations by a Doppler meteor radar, a broadband sodium lidar, and TIMED/SABER OH intensity and temperature measurements are used to investigate the characteristics and environment of the bore propagation and the possible relations with the Na density perturbations. The bore propagated from northeast to southwest and divided the sky into bright and dark halves. The calculations show that the bore has an average phase velocity of 68 m s−1. The crests following the bore have a horizontal wavelength of ~ 22 km. These parameters are consistent with the hydraulic jump theory proposed by Dewan and Picard, as well as the previous bore reports. Simultaneous wind measurements from the Doppler meteor radar at Shisanling (40.3° N, 116.2° E and temperature data from SABER on board the TIMED satellite are used to characterize the propagating environment of the bore. The result shows that a thermal-Doppler duct exists near the OH layer that supports the horizontal propagation of the bore. Simultaneous Na lidar observations at Yanqing (40.4° N, 116.0° E suggest that there is a downward displacement of Na density during the passage of the mesospheric bore event.

  7. Status of UHE CR Orbital Fluorescence Detector Tus

    Science.gov (United States)

    Klimov, P.; Garipov, G.; Khrenov, B.; Kalmykov, N.; Morozenko, V.; Panasyuk, M.; Sharakin, S.; Shirokov, A.; Yashin, I.; Biktemerova, S.; Grinyuk, A.; Naumov, D.; Tkachev, L.; Tkachenko, A.; Saprykin, O.; Park, I.; Lee, J.; Na, G.; Martinez, O.; Salazar, H.

    2011-06-01

    The pioneer space fluorescence ultra high energy cosmic rays (UHE CR) detector TUS, is preparing in SINP MSU, Russia. The main goal of this project is study of cosmic rays beyond GZK cut-off (50 EeV). It consists of segmented Fresnel-type mirror concentrator (area 1.86 m2 , focal distance 1.5 m) and photo receiver (256 pixels - PMT R1463). Total FOV of detector is 9 × 9 degrees. Developed electronics allow events measurements in various time scales, and provide PMT gain control to operate with any atmosphere UV background. Night atmosphere radiation depends mainly on moon phase and atmosphere air-glow and was studied in "Tatiana-1" and "Tatiana-2" experiments. The electronics of TUS were tested in space conditions during these experiments. Recently, detector TUS was included into "Mikhailo Lomonosov" satellite scientific payload. This satellite should be launched at the end of 2011 in honour of Russian scientist and founder of Moscow State University M.V. Lomonosov. TUS will study various extreme phenomena which produce UV light in the atmosphere (UHECR, transient luminous events) and will be a "pathfinder" for further projects (JEM-EUSO, MEMS Space Telescope).

  8. Solar EUV irradiance derived from a sounding rocket experiment on November 10, 1988

    Energy Technology Data Exchange (ETDEWEB)

    Woods, T.N.; Rottman, G.J. (Univ. of Colorado, Boulder (United States))

    1990-05-01

    The solar EUV irradiance from 30 to 100 nm was obtained from a sounding rocket experiment launched from the White Sands Missile Range, New Mexico, on November 10, 1988. This measurement will be used to cross calibrate the Airglow-Solar Spectrometer Instrument on the San Marco D/L satellite. The solar EUV spectrograph had pre- and post-flight photometric calibrations with an average uncertainty of 6% at the Synchrotron Ultraviolet Radiation Facility (SURF) at the National Institute of Standards and Technology. The observed solar EUV irradiance is about 20% less than the solar EUV flux from a proxy model based on the daily 10.7-cm solar flux (F{sub 10.7}) and its 81-day mean () and the AE-E solar EUV data taken in the 1970's. This measurement was obtained during the ascending phase of the solar cycle 22, while the AE-E data were obtained during the ascending phase of solar cycle 21. Measurements of the solar Lyman {alpha} irradiance at 121.6 nm were also obtained with an nitric oxide ionization cell. The derived Lyman {alpha} flux is 3.30 {plus minus} 0.5 ({times} 10{sup 11} photons s{sup {minus}1} cm{sup {minus}2}) as compared to 3.35 {plus minus} 0.3 derived from the Solar Mesospheric Explorer solar data on November 10, 1988.

  9. Comparative solar EUV flux for the San Marco ASSI

    Science.gov (United States)

    Tobiska, W. K.; Chakrabarti, S.; Schmidtke, G.; Doll, H.

    1993-01-01

    The Airglow and Solar Spectrometer Instrument (ASSI) on the San Marco D/L satellite has measured solar extreme ultraviolet irradiances. The data are currently being released for analysis. As a preliminary step in evaluating this important dataset, modeled solar irradiances from 4 to 105 nm are presented for comparison to the San Marco data. The comparable flux for March-December 1988 is obtained from a revised and extended empirical solar EUV model derived from OSO 1, OSO 3, OSO 4, OSO 6, AEROS A, and AE-E satellite and six rocket flight datasets. Solar rotational features are prominent on several occasions in the model time series. A useful example is the modeled integrated flux between 30-31 nm which includes the Si XI (30.3-nm) and He II (30.4-nm) irradiance. The modeled flux in this 1-nm range shows both an absolute 22 percent increase from beginning to end of mission and a solar rotational variability with a typical peak-to-valley ratio of 14 percent.

  10. Ionization by Cosmic Rays in the Atmosphere of Titan

    Science.gov (United States)

    Norman, R. B.; Gronoff, G.; Mertens, C. J.; Blattnig, S.

    2011-12-01

    In-situ measurements by Cassini-Huygens have shown the importance of ionizing particles (solar photons, magnetospheric electrons and protons, cosmics rays) on the atmosphere of Titan. Ionizing particles play an important role in the atmospheric chemistry of Titan and must therefore be accurately modeled to understand the contribution of the differing sources of ionization. To model the initial galactic cosmic ray environment, the Badwar-O'Neill cosmic ray spectrum model was adapted for use at Titan. The Aeroplanets model, an electron transport model for the study of airglow and aurora, was then coupled to the Planetocosmics model, a Monte-carlo cosmic ray transport and energy deposition model, to compute ion production from cosmic rays. In addition, the NAIRAS model, a cosmic ray irradiation model adapted for fast computations, was adopted to the Titan environment and, for the first time, used to compute an ionization profile on a planet other than Earth and compared to the Planetocosmics results. For the first time, the importance of high charge cosmic rays on the ionization of the Titan atmosphere was demonstrated. High charge cosmic rays were found to be especially important below an altitude of 400 km, contributing significantly to the total ionization. Specifically, between 200 km and 400 km, alpha and higher charge cosmic rays are responsible for 40% of the ionization. The increase due to high charge cosmic rays was found for both the Planetocosmics and NAIRAS models.

  11. Earth FUV Dayglow Response to the 20 January 2005 Solar Flare: TIMED and IMAGE Observations

    Science.gov (United States)

    Retherford, K. D.; Gladstone, R.; Solomon, S. C.; Immel, T. J.

    2005-05-01

    An X-class solar flare occurred on 20 January 2005 when the TIMED and IMAGE spacecraft were both well positioned to observe the response of Earth's dayglow emission intensity. Brightness enhancements during the flare relative to just before were determined at tangent altitudes of peak emission viewed toward the limb with TIMED. The TIMED observations were made at low solar zenith angles and show flare enhancements of roughly 15%, 30%, 30%, and 60%, respectively, for OI 130.4 nm, OI 135.6 nm, N2 LBH Short, and N2 LBH Long modes of the TIMED/GUVI instrument. However, GUVI observations of HI Lyman-alpha emission brightness do not show a significant brightness change. This lack of change in HI Lyman-alpha dayglow brightness is consistent with no significant change (airglow sources most affected by the EUV and x-ray components of solar irradiance variability. We report our preliminary analysis of the response of FUV dayglow emissions to this event.

  12. Dynamics and constituent measurements with the Waves Michelson Interferometer

    Science.gov (United States)

    Ward, W. E.; Wang, D. Y.; Kowalski, M.; Gault, W. A.; Bell, A.

    The Waves Michelson Interferometer WaMI is an imaging Michelson interferometer designed to provide altitude profiles of wind temperature ozone atomic oxygen and density from the stratopause to the lower thermosphere This is accomplished through simultaneous measurements of the Doppler shifts line widths and irradiance of emission lines in airglow emissions O2 IR atmospheric band OH and O 1S These measurements are crucial to an understanding the behaviour of the upper stratosphere and mesosphere and its role in the middle atmosphere Observations in this region are complicated by observational issues and subtleties in the dynamical forcings Amplitudes of gravity waves and tides are substantial and as a result temperatures and winds exhibit strong variability In addition vertical and horizontal displacements associated with these waves are significant so that the interpretation of constituent signatures becomes difficult By providing simultaneous profiles of a number of quantities of dynamical interest WaMI has the potential to resolve a number of these observational issues and to provide insights into the dynamics and constituent transport in this region These measurements would be most valuable if they were part of a multiple satellite mission tentatively termed the D-Train D for dynamics each satellite of which sampled a different local time In this talk the measurement and inversion approach being developed for WaMI is described The importance of these measurements for interpreting the behaviour of the atmosphere in the upper stratosphere and

  13. Solar Flare Effects on the Thermosphere and Ionosphere

    Science.gov (United States)

    Solomon, S.; Qian, L.; Rodgers, E.; Bailey, S.

    The Solar Extreme-ultraviolet Experiment SEE on the TIMED satellite and by the X-ray Photometer System XPS on the SORCE satellite provide the first comprehensive irradiance measurements of the complete solar spectrum during large solar flares However the soft X-ray portion of these observations are performed using silicon photodiodes coated with metallic filters to provide photometric measurements with multiple band passes which leads to complexities in obtaining spectral information A new analysis technique developed specifically for flare conditions is used to infer flare spectra in this region These are combined with spectrographic measurements in the extreme ultraviolet and far ultraviolet and applied to the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model TIE-GCM The electron content neutral density and airglow response to large flares during the declining phase of solar cycle 23 are calculated using this model and compared to several measurement sets obtaining good agreement This supports both the validity of the solar X-ray analysis and the modeling methodology showing that although flare-driven effects in the upper atmosphere are significant they are shorter and of much smaller magnitude than geomagnetic disturbances

  14. Modeling of 8446 A dayglow emission in the northern hemisphere

    Science.gov (United States)

    Mallepula Venkata, S.; Singh, V.

    2009-12-01

    The atomic oxygen OI 8446 A emission is a prominent airglow feature observed in the thermosphere. This emission has a long observational history in twilight and aurora. This emission is very useful in understanding the varying levels of atomic oxygen concentration at these altitudes. A comprehensive model is developed to study the 8446 A dayglow emission incoporating different production processes. The emission profiles are obtained with the help of recently developed Solar2000 EUV (Extreme Ultra Violet) flux model also known as Solar Irradiance Platform. A span of five years (2001-2005) is chosen to study the effect of solar activity on this emission. The emission is modeled for April 3 which lies under equinox conditions. In the year 2001 the solar F10.7 index on the chosen date was as high as 223.1 which is the case of solar maximum. The F10.7 variation during the mentioned five year period is between 223 and 80, this window gives an opportunity to study this emission for different solar activity conditions. It is found that the intensity does not vary linearly with the F10.7 solar index. The OI 8446 A emission is found to be very sensitive to the solar activity. The results of modeling of yearly and diurnal variation of volume emission rate and intensity at different locations in the northern hemisphere are discussed.

  15. Application of thermospheric general circulation models for space weather operations

    Science.gov (United States)

    Fuller-Rowell, T.; Minter, C.; Codrescu, M.

    Solar irradiance is the dominant source of heat, ionization, and dissociation of the thermosphere, and to a large extent drives the global dynamics, and controls the neutral composition and density structure. Neutral composition is important for space weather applications because of its impact on ionospheric loss rates, and neutral density is critical for satellite drag prediction. The future for thermospheric general circulation models for space weather operations lies in their use as state propagators in data assimilation techniques. The physical models can match empirical models in accuracy provided accurate drivers are available, but their true value comes when combined with data in an optimal way. Two such applications have recently been developed. The first utilizes a Kalman filter to combine space-based observation of airglow with physical model predictions to produce global maps of neutral composition. The output of the filter will be used within the GAIM (Global Assimilation of Ionospheric Measurement) model developed under a parallel effort. The second filter uses satellite tracking and remote sensing data for specification of neutral density. Both applications rely on accurate estimates of the solar EUV and magnetospheric drivers.

  16. HIRISE observations of daytime aurora over boston from ground in response to the magnetic disturbance of october 30, 2003 as corroborated by the TIMED measurements from space

    Science.gov (United States)

    Pallamraju, D.; Chakrabarti, S.

    HIRISE (High Resolution Imaging Spectrograph using Echelle grating) is a high-resolution spectrograph built at Boston University, which is capable of making unambiguous ground-based daytime airglow/aurora measurements. HIRISE has been making daytime red line (OI 630.0nm) emission measurements from Boston (42.2° N, 71° W) on all clear sky days since April 2003. On October 30, 2003, in response to a severe geomagnetic disturbance, HIRISE measured intense daytime red line emissions of 15 KR (scattered background continuum around 2 MRÅ-1)^at 1500 LT (2000 UT; SZA around 75°), which are a factor of 6 -- 8 greater when compared to the typical quiet time dayglow emission rates at that time. Interplanetary magnetic field (IMF) Bz stayed negative throughout that day but showed a monotonic increase from --20 nT at 0 UT to --15 nT by 24 UT. IMF By was mostly positive (around 5 nT) throughout the day, which is known to move the precipitation/interaction region towards postnoon time, raising interest on whether the magnetospheric cusps moved as far down to mid-latitudes on this day. GUVI (Global UltraViolet Imager) onboard TIMED (Thermosphere, Ionosphere, and Mesosphere Energetics and Dynamics) satellite showed nearly an order of magnitude enhancements in irradiances of 1356 and LBH emissions during this time as compared to the quiet time values. Comparison against TIMED Doppler Interferometer (TIDI) brightness data will also be made. These different simultaneous measurements will be presented.

  17. Comparison of Data From Far Ultraviolet Limb Scanning and Imaging Instrumentation Aboard the Advanced Research and Global Observation Satellite (ARGOS)

    Science.gov (United States)

    Walker, P. W.; Carruthers, G. R.; Dymond, K. F.; Finch, M. A.; McDonald, S. E.; Nicholas, A. C.; Thonnard, S. E.; Budzien, S. A.; McCoy, R. P.

    2001-05-01

    The ARGOS satellite includes two Naval Research Laboratory experiments that monitor naturally occurring far ultraviolet emissions in the Earth's upper atmosphere. Coincident observations between these two instruments, the Global Imaging Monitor of the Ionosphere (GIMI) and the Low Resolution Airglow and Auroral Spectrograph (LORAAS), have been obtained. The GIMI instrument produces 9 ° x 9 ° limb images with passband coverage between 131 and 200 nm. The LORAAS instrument provides the spectral distribution from 80 to 170 nm for 2.4 ° x 17 ° field of regard. The two instruments are coaligned aboard the spacecraft, aft-looking in the orbital plane. Preliminary comparisons of observations obtained from the imaging and scanning instruments under quiet geomagnetic conditions are reported, including irradiances and spectral distributions. By combining the GIMI data with that from LORAAS, the study of the dynamics of the ionosphere can be expanded to investigate both horizontal and vertical distrubutions and their variances. The improved capability can extend to the study of active periods with highly variable and disturbed ionospheres, and examples are discussed from data acquired during periods of high geomagnetic activity. These results provide the first direct comparison between near simultaneous limb scans and images from ARGOS, and show promise as a validation technique to improve capabilities for the study of ionospheric variability.

  18. Where goes the Thermospheric Ionospheric GEospheric Research (TIGER) initiative?

    Science.gov (United States)

    Schmidtke, Gerhard; Radicella, Sandro M.; Jacobi, Christoph; Thuillier, Gerard; Nikutowski, Bernd; Erhardt, Christian; Eparvier, Francis G.

    The 10th TIGER/COSPAR symposium raises the questions: What have been the issues, tasks and aims of TIGER at the end of the 20th century? Where we will have to go now? - Over the span of the TIGER initiative great strides have been made in observing and understanding the EUV solar spectral irradiance. Carefully calibrated observations from TIMED-SEE, SDO-EVE, SOLACES and SOLSPEC, PROBA-2 LYRA, and others have provided new insights into this important and highly variable energy input to the geospace environment. Agreement in terms of variability and absolute scales between recent solar irradiance data sets will be shown as well as improvements in solar and atmosphere irradiance modeling. Precise and continuous EUV measurements can be used to monitor solar variability and its effect on the upper atmosphere/ionosphere (T/I) system at time scales from days to decades by using them as input for ionospheric models or ionospheric proxies or indices. Even more, there is growing interest in scientific support for further improving the GNSS data evaluation which for new on-line EUV/UV measuring methods with airglow monitoring will be discussed. These methods would also improve the quantitative monitoring of space weather effects in the geospheric T/I system.

  19. The evolution of a breaking mesospheric bore wave packet

    Science.gov (United States)

    Stockwell, R. G.; Taylor, M. J.; Nielsen, K.; Jarvis, M. J.

    2011-10-01

    All-sky CCD observations of mesospheric gravity waves have been made from Halley Station Antarctica (75.5°S, 26.7°W) as part of a collaborative research program between British Antarctic Survey, U.K. and Utah State University, USA. A mesospheric bore event was observed in the nightglow emissions over a period of several hours on the 27th of May, 2001. Two dimensional S-Transform (ST) analysis is applied to the airglow images of this bore event. This local spectral technique allows one to calculate the wave parameters as a function of time and space. It is observed that the horizontal phase speed and wavelength decrease over time as the amplitude attenuates. Simultaneously with this wave event the background wind experiences a large acceleration in the direction of the wave propagation. Mesospheric bore theory calculations are used to estimate the bore duct depth and it is shown that as the wave packet evolves, the bore duct collapses (decreasing in its vertical extent). As the bore duct shrinks, the wave's group velocity decelerates, the amplitude attenuates, and the wave dissipates.

  20. Water vapour and the equatorial mesospheric semi-annual oscillation (MSAO

    Directory of Open Access Journals (Sweden)

    R. L. Gattinger

    2013-01-01

    Full Text Available Observations of the mesospheric semi-annual oscillation (MSAO in the equatorial region have been reported dating back several decades. Seasonal variations in both species densities and airglow emissions are well documented. The extensive observations available offer an excellent case study for comparison with model simulations. The broad range of measurements is summarised with emphasis on the 80 to 100 km region. Photochemical model simulations are described for near-equinox and near-solstice conditions, the two times with notable differences in the observed MSAO parameters. Diurnal tides are included in order to facilitate comparisons of observations made at different local times. The roles of water vapour as the "driver" species and ozone as the "response" species are examined to test for consistency between the model results and observations. The model simulations suggest the interactions between eddy mixing and background vertical advection play a significant role in the MSAO phenomenon. At the equator, 90 km altitude, the derived eddy mixing rate is approximately 1 × 106 cm2 s−1 and vertical advection 0.8 cm s−1. For April the corresponding values are 4 × 105 cm2 s−1 and 0.1 cm s−1.

  1. Ionospheric modifications in high frequency heating experiments

    International Nuclear Information System (INIS)

    Featured observations in high-frequency (HF) heating experiments conducted at Arecibo, EISCAT, and high frequency active auroral research program are discussed. These phenomena appearing in the F region of the ionosphere include high-frequency heater enhanced plasma lines, airglow enhancement, energetic electron flux, artificial ionization layers, artificial spread-F, ionization enhancement, artificial cusp, wideband absorption, short-scale (meters) density irregularities, and stimulated electromagnetic emissions, which were observed when the O-mode HF heater waves with frequencies below foF2 were applied. The implication and associated physical mechanism of each observation are discussed and explained. It is shown that these phenomena caused by the HF heating are all ascribed directly or indirectly to the excitation of parametric instabilities which instigate anomalous heating. Formulation and analysis of parametric instabilities are presented. The results show that oscillating two stream instability and parametric decay instability can be excited by the O-mode HF heater waves, transmitted from all three heating facilities, in the regions near the HF reflection height and near the upper hybrid resonance layer. The excited Langmuir waves, upper hybrid waves, ion acoustic waves, lower hybrid waves, and field-aligned density irregularities set off subsequent wave-wave and wave-electron interactions, giving rise to the observed phenomena

  2. "Twisted Beam" SEE Observations of Ionospheric Heating from HAARP

    Science.gov (United States)

    Briczinski, S. J.; Bernhardt, P. A.; Siefring, C. L.; Han, S.-M.; Pedersen, T. R.; Scales, W. A.

    2015-10-01

    Nonlinear interactions of high power HF radio waves in the ionosphere provide aeronomers with a unique space-based laboratory capability. The High-Frequency Active Auroral Research Program (HAARP) in Gakona, Alaska is the world's largest heating facility, yielding effective radiated powers in the gigawatt range. New results are present from HAARP experiments using a "twisted beam" excitation mode. Analysis of twisted beam heating shows that the SEE results obtained are identical to more traditional patterns. One difference in the twisted beam mode is the heating region produced is in the shape of a ring as opposed to the more traditional "solid spot" region from a pencil beam. The ring heating pattern may be more conducive to the creation of stable artificial airglow layers because of the horizontal structure of the ring. The results of these runs include artificial layer creation and evolution as pertaining to the twisted beam pattern. The SEE measurements aid the interpretation of the twisted beam interactions in the ionosphere.

  3. Ultraviolet spectrometer observations of Neptune and triton

    Energy Technology Data Exchange (ETDEWEB)

    Broadfoot, A.L.; Forrester, W.T.; Hall, D.T.; Herbert, F.; Holberg, J.B.; Hunten, D.M.; Lunine, J.I.; Sandel, B.R.; Schneider, N.M.; Shemansky, D.E.; Yelle, R.E. (Univ. of Arizona, Tuscon (USA)); Moos, H.W.; Strobel, D.F. (Johns Hopkins Univ., Baltimore, MD (USA)); Atreya, S.K.; Donahue, T.M. (Univ. of Michigan, Ann Arbor (USA)); Bertaux, J.L.; Blamont, J.E. (CNRS, Verrieres-le-Buisson (France)); McConnell, J.C. (York Univ., Downsview, Ontario (Canada)); Dessler, A.J. (Rice Univ., Houston, TX (USA)); Smith, G.R. (Northwest College, Powell, WY (USA)); Krasnopolsky, V.A. (Space Research Institute, Moscow (USSR)); Linick, S. (California Institute of Technology, Pasadena (USA))

    1989-12-15

    Results from the occultation of the sun by Neptune imply a temperature of 750 {plus minus} 150 kelvins in the upper levels of the atmosphere (composed mostly of atomic and molecular hydrogen) and define the distributions of methane, acetylene, and ethane at lower levels. The ultraviolet spectrum of the sunlit atmosphere of Neptune resembles the spectra of the Jupiter, Saturn, and Uranus atmospheres in that it is dominated by the emissions of H Lyman {alpha} (340 {plus minus} 20 rayleighs) and molecular hydrogen. The extreme ultraviolet emissions in the range from 800 to 1100 angstroms at the four planets visited by Voyager scale approximately as the inverse square of their heliocentric distances. Weak auroral emissions have been tentatively identified on the night side of Neptune. Airglow and occultation observations of Triton's atmosphere show that it is composed mainly of molecular nitrogen, with a trace of methane near the surface. The temperature of Triton's upper atmosphere is 95 {plus minus} 5 kelvins, and the surface pressure is roughly 14 microbars.

  4. Ultraviolet spectrometer observations of neptune and triton.

    Science.gov (United States)

    Broadfoot, A L; Atreya, S K; Bertaux, J L; Blamont, J E; Dessler, A J; Donahue, T M; Forrester, W T; Hall, D T; Herbert, F; Holberg, J B; Hunter, D M; Krasnopolsky, V A; Linick, S; Lunine, J I; McConnell, J C; Moos, H W; Sandel, B R; Schneider, N M; Shemansky, D E; Smith, G R; Strobel, D F; Yelle, R V

    1989-12-15

    Results from the occultation of the sun by Neptune imply a temperature of 750 +/- 150 kelvins in the upper levels of the atmosphere (composed mostly of atomic and molecular hydrogen) and define the distributions of methane, acetylene, and ethane at lower levels. The ultraviolet spectrum of the sunlit atmosphere of Neptune resembles the spectra of the Jupiter, Saturn, and Uranus atmospheres in that it is dominated by the emissions of H Lyman alpha (340 +/- 20 rayleighs) and molecular hydrogen. The extreme ultraviolet emissions in the range from 800 to 1100 angstroms at the four planets visited by Voyager scale approximately as the inverse square of their heliocentric distances. Weak auroral emissions have been tentatively identified on the night side of Neptune. Airglow and occultation observations of Triton's atmosphere show that it is composed mainly of molecular nitrogen, with a trace of methane near the surface. The temperature of Triton's upper atmosphere is 95 +/- 5 kelvins, and the surface pressure is roughly 14 microbars. PMID:17756000

  5. Direct Numerical Simulations of Small-Scale Gravity Wave Instability Dynamics in Variable Stratification and Shear

    Science.gov (United States)

    Mixa, T.; Fritts, D. C.; Laughman, B.; Wang, L.; Kantha, L. H.

    2015-12-01

    Multiple observations provide compelling evidence that gravity wave dissipation events often occur in multi-scale environments having highly-structured wind and stability profiles extending from the stable boundary layer into the mesosphere and lower thermosphere. Such events tend to be highly localized and thus yield local energy and momentum deposition and efficient secondary gravity wave generation expected to have strong influences at higher altitudes [e.g., Fritts et al., 2013; Baumgarten and Fritts, 2014]. Lidars, radars, and airglow imagers typically cannot achieve the spatial resolution needed to fully quantify these small-scale instability dynamics. Hence, we employ high-resolution modeling to explore these dynamics in representative environments. Specifically, we describe numerical studies of gravity wave packets impinging on a sheet of high stratification and shear and the resulting instabilities and impacts on the gravity wave amplitude and momentum flux for various flow and gravity wave parameters. References: Baumgarten, Gerd, and David C. Fritts (2014). Quantifying Kelvin-Helmholtz instability dynamics observed in noctilucent clouds: 1. Methods and observations. Journal of Geophysical Research: Atmospheres, 119.15, 9324-9337. Fritts, D. C., Wang, L., & Werne, J. A. (2013). Gravity wave-fine structure interactions. Part I: Influences of fine structure form and orientation on flow evolution and instability. Journal of the Atmospheric Sciences, 70(12), 3710-3734.

  6. Simultaneous Observations of Mesoscale Gravity Waves Over the Central US with CRRL Na Doppler Lidars and USU Temperature Mapper

    Directory of Open Access Journals (Sweden)

    Lu Xian

    2016-01-01

    Full Text Available We present the first coordinated study of a 1-h mesoscale gravity wave event detected simultaneously by a Na Doppler lidar at Boulder, CO (40.1°N, 105.2°W, and a Na Doppler lidar and an airglow temperature mapper (AMTM at Logan, UT (41.7°N, 111.8°W in the mesopause region on 27 Nov. 2013. The vertical and horizontal wavelengths are ~16.0±0.3 and 342.0±10.4 km, corresponding to vertical and horizontal phase speeds of ~4.4±0.1 and 95.0±3.0 m/s, respectively. The wave propagates from Logan to Boulder with an azimuth angle of ~138.1±1.7° clockwise from North. A uniqueness of this study is that the 1-h wave amplitudes on vertical winds have been quantified for the first time by the STAR Na lidar at Boulder. The GW polarization relation between vertical wind and temperature is evaluated. The intrinsic period of the wave is Doppler shifted to ~100 min by a background wind of 40 m/s, which is confirmed by USU lidar wind observations. This study illustrates a great potential of combining multiple instruments to fully characterize mesoscale gravity waves and inspect their intrinsic properties

  7. Voyager Ultraviolet Spectrometers calibration and the heliosphere neutrals composition: reassessment

    CERN Document Server

    Ben-Jaffel, Lotfi

    2016-01-01

    The Voyagers (V) 1 and 2 Ultraviolet Spectrometers (UVS) data harvest covers outer planets encounters, heliosphere sky-background measurements, and stellar spectrophotometry. Because their operation period overlaps with many ultraviolet missions, the V1 and V2 UVS calibration with other spectrometers are invaluable. Here we revisit the UVS calibration to assess the intriguing 243 % (V1) and 156 % (V2) sensitivity enhancements recently proposed. Using the Saturn Lyman-$\\alpha$ airglow, observed in-situ by both Voyagers, and remotely by IUE, we match the Voyager values to IUE, taking into account the shape of the Saturn Lyman-$\\alpha$ line observed with the Goddard High Resolution Spectrograph onboard the Hubble Space Telescope. For all known ranges of the interplanetary hydrogen density, we show that the V1 and V2 UVS sensitivities cannot be enhanced by the amounts thus far proposed. The same diagnostic holds for distinct channels covering the diffuse HeI 58.4 nm emission. Our prescription is to keep the origi...

  8. On recent measurements from the Andes Lidar Observatory

    Science.gov (United States)

    Liu, Alan Z.; Snively, Jonathan; Heale, Christopher; Cao, Bing

    2016-07-01

    The Andes Lidar Observatory is an upper atmosphere observatory located in Cerro Pachón, Chile (30.3S, 70.7W). It houses a Na Wind/Temperature Lidar, an all sky airglow imager, a mesospheric temperature mapper, an infrared imager and a meteor radar. This suite of instrumentation provides comprehensive measurements of the mesopause region and enables detailed study of wave dynamics. With the recent upgrade of the Na lidar, many complex dynamic processes were observed and resolved in detail. I will present several intriguing phenomena seen in the lidar measurement from recent campaigns, and a detailed analysis of a complex wave propagation event, which involved a large vertical wind oscillation exceeding 10 m/s. A nonlinear gravity wave model was able to reproduce most of the observed features. The results suggest that the wave experienced partial reflections at two altitudes and a critical layer in between, resulting in large vertical wind amplitude and multi-layer distribution of wave energy.

  9. The Climatology of Neutral Winds in the MLT Region as Observed From Orbit

    Science.gov (United States)

    Niciejewski, R.; Skinner, W.; Gell, D.; Cooper, M.; Marsh, A.; Killeen, T.; Wu, Q.; Solomon, S.; Ortland, D.; Drob, D.; Emmert, J.

    2005-12-01

    Unique observations of the horizontal neutral winds in the altitude range 70 to 115 km have been performed from satellite platforms by HRDI and WINDII (UARS) and by TIDI (TIMED), the former since September 1991 and the latter since January 2002. All three experiments observed airglow on the terrestrial limb and derived vertical wind profiles of geophysical quantities by inverting altitude scans of Doppler shifted emission spectra. As a result, the global mesosphere / lower thermosphere region has been sampled for 14 years by a common technique resulting in an unparalleled neutral wind database. This database will be one of the key contributions to an improved Horizontal Wind Model (HWM). This paper will describe results from the first long term climatological study of the MLT region based on satellite wind measurements. The basic dynamic structure in the MLT is a tide, which also has long-term variation that has similar periods to the 27-month QBO (quasi-biennial oscillation) and the SAO (semi-annual oscillation). Signatures of ultra-long variability require analysis of the full wind database.

  10. Ionospheric effects of rocket exhaust products (HEAO-C, Skylab and SPS-HLLV)

    Energy Technology Data Exchange (ETDEWEB)

    Zinn, J; Sutherland, D; Stone, S N; Duncan, L M; Behnke, R

    1980-10-01

    This paper reviews the current state of our understanding of the problem of ionospheric F-layer depletions produced by chemical effects of the exhaust gases from large rockets, with particular emphasis on the Heavy Lift Launch Vehicles (HLLV) proposed for use in the construction of solar power satellites. The currently planned HLLV flight profile calls for main second-stage propulsion confined to altitudes below 124 km, and a brief orbit-circularization maneuver at apogee. The second-stage engines deposit 9 x 10/sup 31/ H/sub 2/O and H/sub 2/ molecules between 56 and 124 km. Model computations show that they diffuse gradually into the ionospheric F region, where they lead to weak but widespread and persistent depletions of ionization and continuous production of H atoms. The orbit-circularization burn deposits 9 x 10/sup 29/ exhaust molecules at about 480-km altitude. These react rapidly with the F2 region 0/sup +/ ions, leading to a substantial (factor-of-three) reduction in plasma density, which extends over a 1000- by 2000-km region and persists for four to five hours. Also described are experimental airglow and incoherent-scatter radar measurements performed in conjunction with the 1979 launch of satellite HEAO-C, together with prelaunch and post-launch computations of the ionospheric effects. Several improvements in the model have been driven by the experimental observations. The computer model is described in some detail.

  11. Ionospheric effects of rocket exhaust products (HEAO-C, Skylab and SPS-HLLV)

    International Nuclear Information System (INIS)

    This paper reviews the current state of our understanding of the problem of ionospheric F-layer depletions produced by chemical effects of the exhaust gases from large rockets, with particular emphasis on the Heavy Lift Launch Vehicles (HLLV) proposed for use in the construction of solar power satellites. The currently planned HLLV flight profile calls for main second-stage propulsion confined to altitudes below 124 km, and a brief orbit-circularization maneuver at apogee. The second-stage engines deposit 9 x 1031 H2O and H2 molecules between 56 and 124 km. Model computations show that they diffuse gradually into the ionospheric F region, where they lead to weak but widespread and persistent depletions of ionization and continuous production of H atoms. The orbit-circularization burn deposits 9 x 1029 exhaust molecules at about 480-km altitude. These react rapidly with the F2 region 0+ ions, leading to a substantial (factor-of-three) reduction in plasma density, which extends over a 1000- by 2000-km region and persists for four to five hours. Also described are experimental airglow and incoherent-scatter radar measurements performed in conjunction with the 1979 launch of satellite HEAO-C, together with prelaunch and post-launch computations of the ionospheric effects. Several improvements in the model have been driven by the experimental observations. The computer model is described in some detail

  12. Sounding Rockets within Swedish National Balloon and Rocket Programme- Providing Access to Space from Esrange

    Science.gov (United States)

    Sjolander, K.; Karlsson, T.; Lockowandt, C.

    2015-09-01

    Initiated in 2012 by the Swedish National Space Board (SNSB), a new programme dedicated for Swedish scientists to gain access to space using balloons and sounding rockets was started. This programme promotes the possibility to ensure continuity in both the science and the technology used. The sounding rocket part of this national programme started with three possible missions. SPIDER (Small Payloads for Investigation of Disturbances in Electrojet by Rockets) from the Space and Plasma physics department of KTH, 0-STATES (Oxygen Species and Thermospheric Airglow in The Earth's Sky) from the Department of Meteorology Stockholm University (MISU) and LEEWAVES (Local Excitation and Effects of Waves on Atmospheric VErtical Structure) that is collaboration between KTH and MISU. These three missions were planned for launches in 2015 and 2016. SSc has been contracted on a launch ticket basis to provide the launch and service to the scientific instrumentation. This paper presents the SPIDER, 0-STATES and LEEWAVES missions focussing on a mission related technical solutions perspective.

  13. Vertical Distribution of Vibrationally Excited Hydroxyl

    Science.gov (United States)

    Grygalashvyly, Mykhaylo; Becker, Erich; Sonnemann, Gerd

    2016-04-01

    Knowledge about the vertical distribution of the vibrationally excited states of hydroxyl (OH*) is important for the interpretation of airglow measurements with respect to dynamical processes in the mesopause region. We derive an approximate analytical expression for the distribution of OH* that highlights the dependence on atomic oxygen and temperature. In addition, we use an advanced numerical model for the formation and relaxation of OH* and investigate the distributions of the different vibrationally exited states of OH*. For the production of OH*, the model includes the reaction of atomic hydrogen with ozone, as well as the reaction of atomic oxygen with hydroperoxy radicals. As loss processes we include 1) deactivation by atomic oxygen, molecular oxygen, and molecular nitrogen, 2) spontaneous emission, and 3) loss due to chemical reaction with atomic oxygen. All these processes take the dependence on the vibrational number into account. The quenching by molecular and atomic oxygen is parameterized by a multi-quantum relaxation scheme. This diagnostic model for OH* has been implemented as part of a chemistry-transport model that is driven by the dynamics simulated with the KMCM (Kühlungsborn Mechanistic general Circulation Model). Numerical results confirm that emission from excited states with higher vibrational number is weaker and emanates from higher altitudes. In addition we find that the OH*-peak altitudes depend significantly on season and latitude. This behavior is mainly controlled by the corresponding variations of atomic oxygen and temperature, as is also confirmed by the aforementioned approximate theory.

  14. Lightning Detection by LAC Onboard the Japanese Venus Climate Orbiter, Planet-C

    Science.gov (United States)

    Takahashi, Y.; Yoshida, J.; Yair, Y.; Imamura, T.; Nakamura, M.

    2008-06-01

    Lightning activity in Venus has been a mystery for a long period, although many studies based on observations both by spacecraft and by ground-based telescope have been carried out. This situation may be attributed to the ambiguity of these evidential measurements. In order to conclude this controversial subject, we are developing a new type of lightning detector, LAC (Lightning and Airglow Camera), which will be onboard Planet-C (Venus Climate Orbiter: VCO). Planet-C will be launched in 2010 by JAXA. To distinguish an optical lightning flash from other pulsing noises, high-speed sampling at 50 kHz for each pixel, that enables us to investigate the time variation of each lightning flash phenomenon, is adopted. On the other hand, spatial resolution is not the first priority. For this purpose we developed a new type of APD (avalanche photo diode) array with a format of 8×8. A narrow band interference filter at wavelength of 777.4 nm (OI), which is the expected lightning color based on laboratory discharge experiment, is chosen for lightning measurement. LAC detects lightning flash with an optical intensity of average of Earth’s lightning or less at a distance of 3 Rv. In this paper, firstly we describe the background of the Venus lightning study to locate our spacecraft project, and then introduce the mission details.

  15. Status of development of lightning detector for PLANET-C mission

    Science.gov (United States)

    Takahashi, Y.; Hoshino, N.; Sato, M.; Teraguchi, T.

    2008-12-01

    Magnetometer onboard Venus Express detected whistler mode waves whose source can be considered to be lightning discharge occurring well below the spacecraft orbit. However, there still remain some uncertainties to conclude finally such waves are originated by lightning discharge in the atmosphere. In order to identify the discharge phenomena in the atmosphere of Venus without any doubt, we plan to observe the lightning activity with high-speed optical detector onboard Planet-C, the Japanese Venus Climate Orbiter mission which will be launched in 2010 by JAXA. We are developing a new type of lightning detector, LAC (Lightning and Airglow Camera). Main difference from other equipments which have provided evidences of lightning existence in Venus is the high-speed sampling rate at 50kHz for each pixel, enabling us to distinguish the optical lightning flash from other pulsing noises. On the other hand, spatial resolution is not first priority as the first detector of Venus lightning. New type of APD (avalanche photo diode) array with a format of 8 x 8 is used and a narrow band interference filter at wavelength of 777.4 nm (OI) is selected for lightning measurement. The development is now at the stage for designing and manufacturing the flight model, based on the performance and environmental tolerance of the proto model. Especially, the algorithm for self- triggering is carefully improved in order to exclude false-trigger by other pulse-like noise.

  16. Development and field tests of a narrowband all-reflective spatial heterodyne spectrometer.

    Science.gov (United States)

    Corliss, J B; Harris, W M; Mierkiewicz, E J; Roesler, F L

    2015-10-20

    We describe the design, development, and performance of a narrowband, all-reflective, unaliased spatial heterodyne spectrometer (SHS) that has been tested in observations at the focus of the 1.6 m main telescope of the McMath-Pierce solar telescope on Kitt Peak. The all-reflective SHS described herein is a highly robust common-path Fourier transform spectrometer without moving parts that, over a limited spectral region, combines the large field of view and high resolving power characteristic of interference spectrometers but at substantially reduced instrument size and optical tolerances. The self-scanned region of wavelength space and resolving power of the SHS are determined by the beam size, the diffraction grating groove density, the number of detector elements, and the fixed orientation of a set of pilot mirrors. The results presented here represent the first successful implementation of this reflective SHS design for field use. We discuss concepts behind the unaliased reflective SHS design and report the performance of the instrument when used to observe terrestrial airglow and absorption features, the solar spectrum, and the Jovian spectrum near λ=6300  Å, at the achieved resolving power (R=λ/δλ) of R>100,000. The results confirm that reflective SHS instruments can deliver effective interferometric performance in the visible to the far-ultraviolet wavelengths with commercial optics of moderate surface quality. PMID:26560368

  17. Response of Thermospheric Hydrogen to Solar Variability and Greenhouse Gases

    Science.gov (United States)

    Nossal, S. M.; Qian, L.; Solomon, S. C.; Burns, A. G.; Wang, W.; Mierkiewicz, E. J.; Roesler, F. L.; Woodward, R. C., Jr.

    2015-12-01

    Geocoronal hydrogen forms the upper boundary of the Earth's HOx chemisty and is a byproduct of methane and water vapor below. We will discuss observational and modeling studies of the upper atmospheric hydrogen response to the solar cycle and increases in greenhouse gases. The Wisconsin Northern hemisphere hydrogen airglow data set spans over two solar cycles. These data show a statistically significant solar cycle variation and a possible increase in intensity between successive solar maximum periods. We will discuss these data in the context of recent modeling studies with a single-column version of the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model. We investigate mechanisms associated with the solar cycle and greenhouse gas forcing of hydrogen by separately doubling carbon dioxide and methane, as well as doubling both together. These simulations indicate that carbon dioxide cooling, as well as methane changes to the source species for hydrogen, both lead to predicted increases in the upper thermospheric hydrogen density and that the response of hydrogen to greenhouse gases depends on the phase of the solar cycle. However, the effect of greenhouse gas doubling is not as large as the modeled solar cycle variability of thermospheric hydrogen. I will discuss results from these simulations and comparisons to observations.

  18. Characterizing Near-Infrared Sky Brightness in the Canadian High Arctic

    CERN Document Server

    Sivanandam, Suresh; Abraham, Roberto; Tekatch, Anthony; Steinbring, Eric; Ngan, Wayne; Welch, Doug L; Law, Nicholas M

    2012-01-01

    We present the first measurements of the near-infrared (NIR), specifically the J-band, sky background in the Canadian High Arctic. There has been considerable recent interest in the development of an astronomical observatory in Ellesmere Island; initial site testing has shown promise for a world-class site. Encouragement for our study came from sky background measurements on the high Antarctic glacial plateau in winter that showed markedly lower NIR emission when compared to good mid-latitude astronomical sites due to reduced emission from OH airglow lines. This is possibly a Polar effect and may also be present in the High Arctic. To test this hypothesis, we carried out an experiment which measured the the J-band sky brightness in the High Arctic during winter. We constructed a zenith-pointing, J-band photometer, and installed it at the Polar Environment Atmospheric Research Laboratory (PEARL) near Eureka, Nunavut (latitude: 80 degrees N). We present the design of our photometer and our results from our shor...

  19. Global Observations of the 630-nm Nightglow and Patterns of Brightness Measured by ISUAL

    Directory of Open Access Journals (Sweden)

    Chih-Yu Chiang

    2013-01-01

    Full Text Available This study investigates the distributions and occurrence mechanisms of the global local-midnight airglow brightness through FORMOSAT-2/ISUAL satellite imaging observations. We focus on the OI 630.0 nm nightglow emission at altitudes of ~250 km along equatorial space. The database used in this study included data from 2007 to 2008 under solar minimum conditions. The data were classified into four specified types in the statistical study. We found that the occurrence of equatorial brightness was often in the vicinity of the geographic equator and mostly at equinoxes with a tendency to move toward the summer hemisphere as the season changes. Conjugate brightness occurring simultaneously on both sides of the geomagnetic equator was observed predominantly in the northern winter. Furthermore, midnight brightness appeared to have lower luminosity from May to July. We suggest that the global midnight brightness associated with the locations and seasons was the result of several effects which include the influence of the thermospheric midnight temperature maximum (MTM, summer-to-winter neutral wind, and ionospheric anomalies.

  20. MAVEN Primary Mission Results from the Imaging UltraViolet Spectrograph: Aurora, Meteor Showers, Dayglow and Corona

    Science.gov (United States)

    Schneider, Nicholas

    2016-07-01

    The Imaging Ultraviolet Spectrograph (IUVS) is one of nine science instruments aboard the Mars Atmosphere and Volatile and EvolutioN (MAVEN) spacecraft. Its payload is dedicated to exploring the upper atmosphere of Mars and understanding the magnitude and drivers of Mars' atmospheric escape rate. The instrument is among the most powerful spectrographs sent to another planet, with several key capabilities: (1) separate Far-UV & Mid-UV channels for stray light control, (2) a high resolution echelle mode to resolve deuterium and hydrogen emission, (3) internal instrument pointing and scanning capabilities to allow complete mapping and nearly continuous operation, and (4) optimization for airglow studies. I will present an overview of selected IUVS results, including: • The impact of Comet Siding Spring's tail on Mars' atmosphere; • The discovery of diffuse aurora at Mars, and its contrast with previously detected discrete aurora near crustal fields; • Significant seasonal and short-timescale variability in thermospheric dayglow emissions; • Global ozone maps spanning six months of seasonal evolution; and • Mapping of the Mars H and O coronas, to measure the escape rates of H and O and their variability.

  1. Concurrent observations at the magnetic equator of small-scale irregularities and large-scale depletions associated with equatorial spread F

    CERN Document Server

    Hickey, D A; Rodrigues, F S; Varney, R H; Milla, M A; Nicolls, M J; Strømme, Anja; Arratia, J F

    2015-01-01

    In 2014 an all-sky imager (ASI) and an Advanced Modular Incoherent Scatter Radar consisting of 14 panels (AMISR-14) system were installed at the Jicamarca Radio Observatory. The ASI measures airglow depletions associated with large-scale equatorial spread F irregularities (10s-100s km), while AMISR-14 detects small-scale irregularities (0.34 m). This study presents simultaneous observations of equatorial spread F (ESF) irregularities at 10-100 km scales using the all sky-imager, at 3 m scales using the JULIA (Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere) radar, and at 0.34 m scales using the AMISR-14 radar. We compare data from the three instruments on the night of 20-21 August, 2014 by locating the radar scattering volume in the optical images. During this night no topside plumes were observed, and we only compare with bottomside ESF. AMISR-14 had five beams perpendicular to the magnetic field covering ~200 km in the east-west direction at 250 km altitude. Comparing the rada...

  2. Quality studies of the data taking conditions for the Auger fluorescence detector

    Energy Technology Data Exchange (ETDEWEB)

    Caruso, R.; Fonte, R.; Insolia, A.; Petrera, S.; Rodriquez Martino, J.; /Rome U.,Tor Vergata

    2005-07-01

    As more than half of the Fluorescence Detector (FD) of the Auger Observatory is completed, data taking is becoming a routine job. It is then necessary to follow strict procedures to assure the quality of the data. An overview of the data taking methods is given. The nature of the FD background signal is due to the night sky brightness (stars and planet faint light, moonlight, twilight, airglow, zodiacal and artificial light) and to the electronic background (photomultiplier and electronic noise). The analysis of the fluctuations in the FADC signal (variance analysis), directly proportional to the background mean light level, performed for each night of data taking is used to monitor the FD background signal. The data quality is analyzed using different techniques, described in detail. Examples of trigger rates, number of stereo events, dead time due to moonlight, weather or hardware problems are given. The analysis comprises several months of data taking, giving an overview of the FD capabilities, performance and allowing a systematic study of data and their correlation with the environment.

  3. LAICE CubeSat mission for gravity wave studies

    Science.gov (United States)

    Westerhoff, John; Earle, Gregory; Bishop, Rebecca; Swenson, Gary R.; Vadas, Sharon; Clemmons, James; Davidson, Ryan; Fanelli, Lucy; Fish, Chad; Garg, Vidur; Ghosh, Alex; Jagannatha, Bindu B.; Kroeker, Erik; Marquis, Peter; Martin, Daniel; Noel, Stephen; Orr, Cameron; Robertson, Robert

    2015-10-01

    The Lower Atmosphere/Ionosphere Coupling Experiment (LAICE) CubeSat mission will focus on understanding the interaction of atmospheric gravity waves generated by weather systems in the lower atmosphere with the mesosphere, lower thermosphere, and ionosphere (MLTI). Specifically, LAICE will focus on the energy and momentum delivered by these waves and attempt to connect the wave sources and the wave effects in three widely different altitude ranges, substantially adding to our knowledge of critical coupling processes between disparate atmospheric regions. The LAICE mission consists of a 6U CubeSat with a four-instrument payload. The retarding potential analyzer (RPA) will provide in-situ ion density and temperature measurements. A four-channel photometer will measure density and temperature variations in the mesosphere through observations of O2 (0, 0) Atmospheric band and O2 Herzberg I band airglows. There are two pressure sensors that comprise the Space Pressure Suite (SPS): the Space Neutral Pressure Instrument (SNeuPI) and the LAICE Ionization gauge Neutral Atmosphere Sensor (LINAS). Both will provide neutral density measurements, but SNeuPI is a prototype sensor that will be validated by LINAS. This CubeSat mission, scheduled for launch in early 2016 from the International Space Station, provides a cost-effective approach to measuring low altitude in-situ parameters along with simultaneous imaging that is capable of addressing the fundamental questions of atmospheric gravity wave coupling in the MLTI region.

  4. New Horizons Constraints on Charon's Present Day Atmosphere

    CERN Document Server

    Stern, S A; Gladstone, G R; Steffl, A J; Cheng, A F; Young, L A; Weaver, H A; Olkin, C B; Ennico, K; Parker, J W; Parker, A H; Lauer, T R; Zangari, A; Summers, M

    2016-01-01

    We report on a variety of standard techniques used by New Horizons including a solar ultraviolet occultation, ultraviolet airglow observations, and high-phase look-back particulate search imaging to search for an atmosphere around Pluto's large moon Charon during its flyby in July 2015. Analyzing these datasets, no evidence for a present day atmosphere has been found for 14 potential atomic and molecular species, all of which are now constrained to have pressures below 0.3 nanobar, as we describe below, these are much more stringent upper limits than the previously available 15-110 nanobar constraints (e.g., Sicardy et al. 2006); for example, we find a 3$\\sigma$ upper limit for an N$_2$ atmosphere on Charon is 4.2 picobars and a 3$\\sigma$ upper limit for the brightness of any atmospheric haze on Charon of I/F=2.6x10$^{-5}$. A radio occultation search for an atmosphere around Charon was also conducted by New Horizons but will be published separately by other authors.

  5. Detection of small scale fluctuations in the near-IR cosmic infrared background from long exposure 2MASS fields

    CERN Document Server

    Kashlinsky, A; Mather, J; Skrutskie, M F; Cutri, R M

    2002-01-01

    We report first results for the cosmic infrared background (CIB) fluctuations at 1.25, 1.65 and 2.17 micron obtained from long exposures constructed from 2MASS standard star fields. We have co-added and analyzed scans from one such field with a total exposure time > 1 hour, and removed sources and other artifacts. The stars and galaxies were clipped out to K_s~19^m leaving only high-z galaxies (or possibly local low-surface-brightness systems). The residual component of the diffuse emission on scales from a few arc-sec to a few arc-min has a power-law slope consistent with emission produced by clustered galaxies. The noise (and residual artifacts) contribution to the signal is small and the colors of the signal are very different from Galactic stars or air-glow. We therefore identify the signal as CIB fluctuations from the faint unresolved galaxies. We show that the present-day galaxies with no evolution would produce a significant deficit in the observed CIB fluctuations. Thus the dominant contribution to th...

  6. Doppler shifted H Ly α emission from Jupiter's aurora

    International Nuclear Information System (INIS)

    IUE observations of the aurora on Jupiter have been performed with high spectral resolution in a search for Doppler shifted H Ly α emission produced through charge exchange by fast precipitating protons, as observed in the Earth's aurora. No emission has been observed corresponding to proton energies greater than 200 eV, placing a strict upper limit on the contribution of KeV - MeV protons to the production of Jupiter's aurora. However, a large fraction of the H Ly α emission has appeared Doppler-shifted mainly toward the blue by roughly 50 km/sec, corresponding to a kinetic energy of 10-20 eV for a fast proton or H atom, and there are higher velocity wings on the line extending out to equivalent energies of 150-200 eV. The blue shift indicates motion up out of the atmosphere, and the authors suggest that the emission results from the in situ acceleration of ionospheric protons in Jupiter's auroral ionosphere by analogy to the ionospheric potentials observed in the Earth's auroral zones. These observations demonstrate that the acceleration of ionospheric plasma in an H2 atmosphere can lead to bright Ly α emission, with implications for the production of the outer planet airglow emissions

  7. A Dual Narrowband Survey for H\\alpha\\ Emitters at z=2.2: Demonstration of the Technique and Constraints on the H\\alpha\\ Luminosity Function

    CERN Document Server

    Lee, Janice C; Spitler, L; Labbe, I; Salim, S; Persson, S E; Ouchi, M; Dale, D; Monson, A; Murphy, D

    2012-01-01

    We present first results from a narrowband imaging program for intermediate redshift emission-line galaxies using the newly commissioned FourStar infrared camera at the 6.5m Magellan telescope. To enable prompt identification of H\\alpha\\ emitters, a pair of custom 1% filters, which sample low-airglow atmospheric windows at 1.19 \\mu m and 2.10 \\mu m, is used to detect both H\\alpha\\ and [OII]\\lambda 3727 emission from the same redshift volume at z=2.2. Initial observations are taken over a 130 arcmin^2 area in the CANDELS-COSMOS field. The exquisite image quality resulting from the combination of the instrument, telescope, and standard site conditions (~0.55" FWHM) allows the 1.19 \\mu m and 2.10 \\mu m data to probe 3\\sigma\\ emission-line depths down to 1.0e-17 erg/s/cm^2 and 1.2e-17 erg/s/cm^2 respectively, in less than 10 hours of integration time in each narrowband. For H\\alpha\\ at z=0.8 and z=2.2, these fluxes correspond to observed star formation rates of ~0.3 and ~4 Msun/yr respectively. We find 122 source...

  8. An Overview of High-Altitude Balloon Experiments at the Indian Institute of Astrophysics

    CERN Document Server

    Safonova, Margarita; Sreejith, A G; Mathew, Joice; Sarpotdar, Mayuresh; Ambily, S; Nirmal, K; Talnikar, Sameer; Hadigal, Shripathy; Prakash, Ajin; Murthy, Jayant

    2016-01-01

    The High-Altitude Ballooning programme began at Indian Institute of Astrophysics, Bangalore, in the year 2011 with the primary purpose of developing and flying low-cost scientific payloads on a balloon-borne platform. Some of the science goals are studies of the phenomena occurring in the upper atmosphere, of airglow and zodiacal light, and observations of extended astronomical objects such as, for example, comets, from near space (20 to 30 km). A brief summary and results of the tethered flights carried out at CREST campus are given in Ref.~1. Here we present a complete overview of the 9 free-flying balloon experiments conducted from March 2013 to November 2014. We describe the launch procedures, payloads, methods of tracking and recovery of the payloads. Since we fall in the light/medium balloon category, the weight of the payload is limited to less than 5 kg --- we use a 3-D printer to fabricate lightweight boxes and structures for our experiments. We are also developing in-house lightweight sensors and co...

  9. Correlations of mesospheric winds with subtle motion of the Arctic polar vortex

    Directory of Open Access Journals (Sweden)

    Y. Bhattacharya

    2010-01-01

    Full Text Available This paper investigates the relationship between high latitude upper mesospheric winds and the state of the stratospheric polar vortex in the absence of major sudden stratospheric warmings. A ground based Michelson Interferometer stationed at Resolute Bay (74°43' N, 94°58' W in the Canadian High Arctic is used to measure mesopause region neutral winds using the hydroxyl (OH Meinel-band airglow emission (central altitude of ~85 km. These observed winds are compared to analysis winds in the upper stratosphere during November and December of 1995 and 1996; years characterized as cold, stable polar vortex periods. Correlation of mesopause wind speeds with those from the upper stratosphere is found to be significant for the 1996 season when the polar vortex is subtly displaced off its initial location by a strong Aleutian High. These mesopause winds are observed to lead stratospheric winds by approximately two days with increasing (decreasing mesospheric winds predictive of decreasing (increasing stratospheric winds. No statistically significant correlations are found for the 1995 season when there is no such displacement of the polar vortex.

  10. Spectroscopy of diffuse light in dust clouds. Scattered light and the solar neighbourhood radiation field

    CERN Document Server

    Lehtinen, K

    2012-01-01

    The optical surface brightness of dark nebulae is mainly due to scattering of integrated starlight by classical dust grains. It contains information on the impinging interstellar radiation field, cloud structure, and grain scattering properties. We have obtained spectra of the scattered light from 3500 to 9000 Angstrom in two globules, the Thumbprint Nebula and DC303.8-14.2. We use observations of the scattered light to study the impinging integrated starlight spectrum as well as the scattered H-alpha and other line emissions from all over the sky. We search also for the presence of other than scattered light in the two globules. We obtained long-slit spectra encompassing the whole globule plus adjacent sky in a one-slit setting, thus enabling efficient elimination of airglow and other foreground sky components. We calculated synthetic integrated starlight spectra for the solar neighbourhood using HIPPARCOS-based stellar distributions and the spectral library of Pickles. Spectra are presented separately for t...

  11. Planetary and Gravity Waves in the Mesosphere and Lower Thermosphere

    Science.gov (United States)

    Vincent, R. A.

    1985-01-01

    Rocket and ground based studies of the mesosphere and lower thermosphere show that waves play an important role in the dynamics of their region. The waves manifest themselves in wind, temperature, density, pressure, ionization and airglow fluctuations in the 80-120 km height range. Rockets have enabled the density and temperature structure to be measured with excellent height resolution, while long term studies of wind motions using MST, partial reflection and meteor radars and, more recently, lidar investigations of temperature and density, have enabled the temporal behaviour of the waves to be better understood. A composite of power spectra is shown of wind motions measured near the mesopause at widely separated locations and illustrates how wave energy is distributed as a function of frequency. The spectra show three distinct parts; (1) a long period section corresponding to periods longer than 24 h; (2) a section between 12 and 24 h priod where the spectra are dominated by narrow; peaks associated with the semidiurnal and diurnal tides and (3) a section at periods less than 12 h where the spectral density decreases montonically (except for the 8 h tidal peak). The long period section is associated with transient planetary scale waves while the short period motions are caused by gravity waves.

  12. Obituary: Joseph Wyan Chamberlain, 1928-2004

    Science.gov (United States)

    Hunten, Donald M.

    2004-12-01

    are glad that his last nineteen active years were spent in that role. In the 1960's the AAS had no Division for Planetary Sciences (DPS), and the group organized an annual series of five Arizona Conferences on Planetary Atmospheres. By 1967 several members of the community felt that a DPS was needed; the AAS Council asked Joe to serve as chair of the organizing committee, and when the Division was formed he became the first Chairman. In 1971, he became Director of the NASA Lunar Science Institute and a few years later Professor of Space Physics and Astronomy at Rice University (Houston). After retirement as Professor Emeritus in 1992, he returned to Tucson where he continued an active interest in golf, opera, chess and satirical humor. Joe's program at Yerkes began with observations of aurora and airglow, making use of the wonderful spectrographs designed and built by Meinel. Among his many contributions was the identification and analysis of a band system in the airglow that now bears his name. His interests shifted toward the theoretical; for example, he applied the radiative-transfer theory of his colleague Chandrasekhar to the sodium twilight airglow. In 1961 he published Theory of the Aurora and Airglow, a book so influential that it was reprinted a few years ago by the American Geophysical Union. In the same period his interest in interplanetary hydrogen led to a low-velocity model that was at odds with Eugene N. Parker's model of the solar wind, and a debate ensued until observations showed Parker to be essentially correct. But the Chamberlain ideas were applied to the structure of the Earth's hydrogen exosphere, and for 40 years this work has been accepted as definitive. Later he studied the reduction of the hydrogen escape rate by the "cooling" that results from the loss of the energy carried by the escaping atoms. Joe was selected to deliver the 1961 Helen Warner lecture and chose the topic "The upper atmospheres of the planets." This paper clearly expounds

  13. Sprites and lightning in Venus: constraints for observations by the Planet-C mission

    Science.gov (United States)

    Takahashi, Y.; Yair, Y.; Goto, Y.; Sentman, D.; Yoshida, J.; Sato, M.; Hoshino, N.

    2007-12-01

    Lightning activity in Venus has been mystery for long period, although many studies based on observations both by spacecrafts and by ground-based telescope have been carried out. This situation may be attributed to the ambiguity of these evidential measurements. In order to conclude this controversial subject, we are developing a new type of lightning detector, LAC (Lightning and Airglow Camera), which will be onboard Planet-C (Venus Climate Orbiter: VCO). PLanet-C will be launched in 2010 by JAXA. To distinguish optical lightning flash from other pulsing noises, high-speed sampling at 50kHz for each pixel, that enables us to investigate the time variation of each lightning flash phenomenon, is adopted. On the other hand, spatial resolution is not first priority. For this purpose we developed new type of APD (avalanche photo diode) array with a format of 8 x 8. Narrow band interference filter at wavelength of 777.4 nm (OI), which is expected lightning color based on laboratory discharge experiment, is chosen for lightning measurement. LAC detects lightning flash with an optical intensity of average of Earth's lightning or less at a distance of 3 Rv. We also present results of theoretical calculations of the expected occurrance heights and emissions of sprites above thunderstorms in the CO2 atmosphere of Venus and the Hydrogen-Helium atmospheres of Jupiter and Saturn. General detection methodology of sprites/lightning in planetary atmospheres by orbiting spacecraft will be discussed.

  14. OH(6-2 spectra and rotational temperature measurements at Davis, Antarctica

    Directory of Open Access Journals (Sweden)

    P. A. Greet

    Full Text Available The OH(6-2 band was monitored during 1990 at Davis, Antarctica (68.6°S, 78.0°E using a Czerny-Turner scanning spectrometer. Spectra obtained with a 0.15-nm bandwidth and wavelength steps of 0.005 nm have been recorded in an attempt to isolate auroral features. This has enabled detailed study of weak features in the region λ837.5–855.5 nm. These weak features can contribute to the apparent intensity of P-branch lines and to the background. Their presence is allowed for in our calculation of rotational temperature, but the P1(3 line is excluded because of significant contamination. An average temperature of 221±2 K is obtained from a selected data set of 104 spectra. The mid-winter average temperature, for the months of May, June and July, is 224±2 K, which is consistent with the 1986 CIRA model values for mid-winter at this height and latitude, but this result is dependent on the choice of transition probabilities. Preliminary assessments of seasonal and diurnal variations in rotational temperature and intensity are presented.

    Key words. Atmospheric composition and structure · Airglow and aurora; Middle-atmosphere composition and chemistry · Pressure · density and temperature

  15. Directional Filtering Due to Mesospheric Wind Shear on the Propagation of Acoustic-gravity Waves

    Institute of Scientific and Technical Information of China (English)

    YU Yonghui; CHEN Wei; WANG Yachong

    2013-01-01

    Gravity waves with periods close to the Brunt-V(a)is(a)l(a) period of the upper troposphere are often observed at mesopause altitudes as short period,quasi-monochromatic waves.The assumption that these short period waves originate in the troposphere may be problematic because their upward propagation to the mesosphere and lower thermosphere region could be significantly impeded due to an extended region of strong evanescence above the stratopause.To reconcile this apparent paradox,an alternative explanation is proposed in this paper.The inclusion of mean winds and their vertical shears is sufficient to allow certain short period waves to remain internal above the stratopause and to propagate efficiently to higher altitudes.A time-dependent numerical model is used to demonstrate the feasibility of this and to determine the circumstances under which the mesospheric wind shears play a role in the removal and directional filtering of short period gravity waves.Finally this paper concludes that the combination of the height-dependent mean winds and the mean temperature structure probably explains the existence of short period,quasi-monochromatic structures observed in airglow images of mesopause region.

  16. Propagation of short-period gravity waves at high-latitudes during the MaCWAVE winter campaign

    Directory of Open Access Journals (Sweden)

    K. Nielsen

    2006-07-01

    Full Text Available As part of the MaCWAVE (Mountain and Convective Waves Ascending Vertically winter campaign an all-sky monochromatic CCD imager has been used to investigate the properties of short-period mesospheric gravity waves at high northern latitudes. Sequential measurements of several nightglow emissions were made from Esrange, Sweden, during a limited period from 27–31 January 2003. Coincident wind measurements over the altitude range (~80–100 km using two meteor radar systems located at Esrange and Andenes have been used to perform a novel investigation of the intrinsic properties of five distinct wave events observed during this period. Additional lidar and MSIS model temperature data have been used to investigate their nature (i.e. freely propagating or ducted. Four of these extensive wave events were found to be freely propagating with potential source regions to the north of Scandinavia. No evidence was found for strong orographic forcing by short-period waves in the airglow emission layers. The fifth event was most unusual exhibiting an extensive, but much smaller and variable wavelength pattern that appeared to be embedded in the background wind field. Coincident wind measurements indicated the presence of a strong shear suggesting this event was probably due to a large-scale Kelvin-Helmholtz instability.

  17. The Puzzling Detection of X-rays From Pluto by Chandra

    CERN Document Server

    Lisse, C M; Wolk, S J; Bagenal, F; Stern, S A; Gladstone, G R; Cravens, T E; Hill, M E; Kollmann, P; Weaver, H A; Strobel, D F; Elliott, H A; McComas, D J; Binzel, R P; Snios, B T; Bhardwaj, A; Chutjian, A; Young, L A; Olkin, C B; Ennico, K A

    2016-01-01

    Using Chandra ACIS-S, we have obtained imaging Xray spectrophotometry of the Pluto system in support of the New Horizons flyby on 14 July 2015. 174 ksec of observations were obtained on 4 visits in Feb 2014 to Aug 2015. We measured a net signal of 6.8 counts and a noise level of 1.2 counts in a comoving 11 x 11 pixel box (100 x 100 R_Pluto) in the 0.31 to 0.60 keV passband for a detection at > 99.95 C.L. The Pluto photons do not match the background spectrum, are coincident with a 90% flux aperture comoving with Pluto, and are not sky source confused. The mean 0.31 to 0.60 keV Xray power from Pluto is 200 MW, in the midrange of Xray power levels seen for known solar system emission sources: auroral precipitation, solar Xray scattering, and charge exchange (CXE) between solar wind (SW) ions & atmospheric neutrals. We eliminate auroral effects as a source, as Pluto has no known magnetic field & the New Horizons Alice UV spectrometer detected no airglow from Pluto during the flyby. Nano-scale atmospheric...

  18. Ionospheric modification by high-power radio waves

    International Nuclear Information System (INIS)

    Powerful, high-frequency radio waves have been used to temporarily modify the ionosphere. Thermal and parametric interactions have led to a diverse range of observed phenomena, including generation of density striations and artificial spread-F, enhancements of electron plasma waves, production of extrathermal electron fluxes and enhanced airglow, modification of the D-region temperature and densities, wideband signal attenuation, and self-focusing and scattering of the electromagnetic waves. The physics of ionospheric modification by high-power radio waves is reviewed in the context of our current theoretical understanding; disturbance generation mechanisms are qualitatively described. In addition, results of recent experiments are summarized in which ionospheric irregularities are generated and their evolution and decay processes investigated in detail. The effects and potential controlled applications of these HF ionospheric modifications for various RF systems studies are discussed. The C3I scientific community provides an important motivation for these ionospheric modification studies; their increased interaction and active participation in experimental design and interpretation are encouraged

  19. Spherical EUV and Plasma Spectrometer (seps) -a Monitor to Measure the Plasma and EUV Environment in Space

    Science.gov (United States)

    Brunner, Raimund; Schmidtke, Gerhard; Konz, Werner; Pfeffer, Wilfried

    A low-cost monitor to measure the EUV and plasma environment in space is presented. The device consists of three (or more) isolated spheres, a metallic sphere, one or more highly trans-parent Inner Grids and Outer Grids. Each one is being connected to a sensitive floating elec-trometer. By setting different potentials to the grids as well as to the sphere and varying one or more of their voltages, measurements of spectral solar EUV irradiance (15-200 nm), of local plasma parameters such as electron and ion densities, electron energies and temperatures as well as ion compositions and debris events can be derived from the current recordings. This detector does not require any (solar) pointing device. The primary goal is to study the impact of solar activity events (e.g. CMEs) as well as subsequent reactions of the ionospheric/thermospheric systems (including space weather occurences). The capability of SEPS for measuring EUV pho-ton fluxes as well as plasma parameters in the energy range from 0 to +/-70 eV is demonstrated by laboratory measurements as performed in the IPM laboratory, at BESSY-PTB electron syn-chrotron in Berlin and at ESA/ESTEC plasma chamber. Based on the laboratory recording of plasma recombination EUV emission the sensor is suitable to detect also auroral and airglow radiations. -The state of the art in the development of this device is reported.

  20. Ionospheric modifications in high frequency heating experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Spencer P. [Department of Electrical and Computer Engineering, Polytechnic School of Engineering, New York University, 5 MetroTech Center, Brooklyn, New York 11201 (United States)

    2015-01-15

    Featured observations in high-frequency (HF) heating experiments conducted at Arecibo, EISCAT, and high frequency active auroral research program are discussed. These phenomena appearing in the F region of the ionosphere include high-frequency heater enhanced plasma lines, airglow enhancement, energetic electron flux, artificial ionization layers, artificial spread-F, ionization enhancement, artificial cusp, wideband absorption, short-scale (meters) density irregularities, and stimulated electromagnetic emissions, which were observed when the O-mode HF heater waves with frequencies below foF2 were applied. The implication and associated physical mechanism of each observation are discussed and explained. It is shown that these phenomena caused by the HF heating are all ascribed directly or indirectly to the excitation of parametric instabilities which instigate anomalous heating. Formulation and analysis of parametric instabilities are presented. The results show that oscillating two stream instability and parametric decay instability can be excited by the O-mode HF heater waves, transmitted from all three heating facilities, in the regions near the HF reflection height and near the upper hybrid resonance layer. The excited Langmuir waves, upper hybrid waves, ion acoustic waves, lower hybrid waves, and field-aligned density irregularities set off subsequent wave-wave and wave-electron interactions, giving rise to the observed phenomena.

  1. An empirical determination of the production efficiency for auroral 6300 AA emmission by energetic electrons

    International Nuclear Information System (INIS)

    Auroral data from the Soft Particle Spectrometer and the Red Line Photometer on the ISIS-2 spacecraft have been selected to form an electron energy flux and optical auroral emission data base. The energy fluxes are stored as integrated fluxes over four energy bands, and the corresponding stored optical emission rates are corrected for airglow and for albedo. Because of the variety of electron energy spectra represented in the data base it was possible to perform a regression analysis that yielded the production efficiency for the production of emission for each of the four bands. While the results of this analysis are interesting to compare with theoretical predictions of 6300 AA excitation processes, these statistical results are not as precise as the comparisons of individual experiments where all parameters, such as the atmospheric composition and temperature profiles are measured. The significance of this approach is that it permits a multiparameter description of an electron energy spectrum, and its relationship to a specific optical emission, by purely empirical means. This is particularly useful in the interpretation of ISIS-2 data from the instruments which provided the results, but should find further application in optical-particle auroral studies. (author)

  2. Obituary: Joseph Wyan Chamberlain, 1928-2004

    Science.gov (United States)

    Hunten, Donald M.

    2004-12-01

    are glad that his last nineteen active years were spent in that role. In the 1960's the AAS had no Division for Planetary Sciences (DPS), and the group organized an annual series of five Arizona Conferences on Planetary Atmospheres. By 1967 several members of the community felt that a DPS was needed; the AAS Council asked Joe to serve as chair of the organizing committee, and when the Division was formed he became the first Chairman. In 1971, he became Director of the NASA Lunar Science Institute and a few years later Professor of Space Physics and Astronomy at Rice University (Houston). After retirement as Professor Emeritus in 1992, he returned to Tucson where he continued an active interest in golf, opera, chess and satirical humor. Joe's program at Yerkes began with observations of aurora and airglow, making use of the wonderful spectrographs designed and built by Meinel. Among his many contributions was the identification and analysis of a band system in the airglow that now bears his name. His interests shifted toward the theoretical; for example, he applied the radiative-transfer theory of his colleague Chandrasekhar to the sodium twilight airglow. In 1961 he published Theory of the Aurora and Airglow, a book so influential that it was reprinted a few years ago by the American Geophysical Union. In the same period his interest in interplanetary hydrogen led to a low-velocity model that was at odds with Eugene N. Parker's model of the solar wind, and a debate ensued until observations showed Parker to be essentially correct. But the Chamberlain ideas were applied to the structure of the Earth's hydrogen exosphere, and for 40 years this work has been accepted as definitive. Later he studied the reduction of the hydrogen escape rate by the "cooling" that results from the loss of the energy carried by the escaping atoms. Joe was selected to deliver the 1961 Helen Warner lecture and chose the topic "The upper atmospheres of the planets." This paper clearly expounds

  3. Linking Atmospheric Gravity Wave Research to the Undergraduate Curriculum

    Science.gov (United States)

    Gay, J.; Nielsen, K.

    2015-12-01

    Atmospheric gravity waves are often generated in the lower atmosphere and can, under favorable atmospheric conditions, propagate into the mesosphere and lower thermosphere. As a consequence of this vertical propagation, the waves carry momentum fluxes and energy from the lower atmosphere into the near-space environment, providing a strong coupling across atmospheric layers. While these waves have been observed and studied in details for decades, there are still many questions to be addressed regarding the tropospheric source location and nature of individually observed waves in the mesosphere. In an effort to increase undergraduate student research experiences, we are linking atmospheric gravity wave research and undergraduate curriculum to improve both academic and scholarly experiences by our students. In this particular case, we present a research project addressing the identification of tropospheric source locations of mesospheric waves observed by airglow imagers. The project involves observations, theory, and modeling techniques with a strong emphasis on how each part plays a role in the curriculum. Specifically, a simple ray tracing model is propagating observed waves downwards through the atmosphere until the point of origin is reached. In the process, we apply basic calculus, numerical methods, and simple fluid dynamics related to course taught at the undergraduate level.

  4. LA Palma Night-Sky Brightness

    CERN Document Server

    Benn, C R; Benn, Chris R.; Ellison, Sara L.

    1998-01-01

    The brightness of the moonless night sky above La Palma was measured on 427 CCD images taken with the Isaac Newton and Jacobus Kapteyn Telescopes on 63 nights during 1987 - 1996. The median sky brightness at high elevation, high galactic latitude and high ecliptic latitude, at sunspot minimum, is B = 22.7, V = 21.9, R = 21.0, similar to that at other dark sites. The main contributions to sky brightness are airglow and zodiacal light. The sky is brighter at low ecliptic latitude (by 0.4 mag); at solar maximum (by 0.4 mag); and at high airmass (0.25 mag brighter at airmass 1.5). Light pollution (line + continuum) contributes < 0.03 mag in U, approximately 0.02 mag in B, approximately 0.10 mag in V, approximately and 0.10 mag in R at the zenith. This paper is a summary of results which are presented in full elsewhere (Benn & Ellison 1998, La Palma Technical Note 115).

  5. Statistical study of the GPS phase scintillation associated with plasma blobs

    Science.gov (United States)

    Jin, Yaqi; Miloch, Wojciech; Moen, Joran

    2016-04-01

    We present a study of the space weather effect of GNSS scintillation in the auroral/polar cap ionosphere with multi-instrument observations, including GNSS scintillation receiver, all-sky imager, and EISCAT radar. We focus on the period when polar cap patches (islands of high density F region plasma with density enhanced more than twice above the surrounding) exit the polar cap. When the patch exits into the nightside auroral region (and then it is termed blob), the GNSS phase scintillation can be enhanced; indicating that the blob is important for the scintillation study [Jin et al., 2014]. In the present study, we expand the data set to see how representative it is. From November of 2010 to February of 2014, 41.4 hours of data from all-sky imager were collected in 16 days when the airglow patches were observed to hit the nightside aurora and when the aurora covered a quarter of the all-sky imager field of view at Ny-Ålesund. The collocated GNSS scintillation receiver is used to study the scintillation impact. This study clearly shows that the scintillation level of a blob is higher than the scintillation level of the corresponding patch. However, no clear relation between the blob scintillation and the pre-conditioning of polar cap patches is found. Furthermore, the aurora alone did not produce strong scintillation. This implies that the aurora plays a role in structuring of the blob and increases its scintillation level. We also look into possible instability mechanisms which produce the plasma density irregularities.

  6. Extreme ultraviolet (EUV) solar spectral irradiance (SSI) for ionospheric application - history and contemporary state-of-art

    Science.gov (United States)

    Schmidtke, G.; Jacobi, Ch.; Nikutowski, B.; Erhardt, Ch.

    2014-11-01

    After a historical survey of space related EUV measurements in Germany and the role of Karl Rawer in pursuing this work, we describe present developments in EUV spectroscopy and provide a brief outlook on future activities. The group of Karl Rawer has performed the first scientific space project in Western Europe on 19th October 1954. Then it was decided to include the field of solar EUV spectroscopy in ionospheric investigations. Starting in 1957 an intensified development of instrumentation was going on to explore solar EUV radiation, atmospheric airglow and auroral emissions until the institute had to stop space activities in the early nineteen-eighties. EUV spectroscopy was continued outside of the institute during eight years. This area of work was supported again by the institute developing the Auto-Calibrating Spectrometers (SolACES) for a mission on the International Space Station (ISS). After more than six years in space the instrument is still in operation. Meanwhile the work on the primary task also to validate EUV data available from other space missions has made good progress. The first results of validating those data and combine them into one set of EUV solar spectral irradiance are very promising. It will be recommended for using it by the science and application community. Moreover, a new low-cost type of an EUV spectrometer is presented for monitoring the solar EUV radiation. It shall be further developed for providing EUV-TEC data to be applied in ionospheric models replacing the Covington index F10.7. Applying these data for example in the GNSS signal evaluation a more accurate determination of GNSS receiver positions is expected for correcting the propagation delays of navigation signals traveling through the ionosphere from space to earth. - Latest results in the field of solar EUV spectroscopy are discussed, too.

  7. Data-model comparison search analysis of coincident PBO Balmer α, EURD Lyman β geocoronal measurements from March 2000

    Science.gov (United States)

    Bishop, J.; Mierkiewicz, E. J.; Roesler, F. L.; Gómez, J. F.; Morales, C.

    2004-05-01

    Recent Lyman series and Balmer series airglow measurements provide a fresh opportunity to investigate the density distribution and variability of atomic hydrogen in the upper atmosphere. Dedicated nightside Balmer α Fabry-Perot spectrometer measurements at the Pine Bluff Observatory (PBO), University of Wisconsin-Madison, have been acquired since late 1999 taking advantage of several technological advances. Extreme ultraviolet spectral radiance measurements by the Espectrógrafo Ultravioleta extremo para la Radiación Difusa (EURD) instrument on the Spanish MINISAT-1 satellite from October 1997 to December 2001 provide extensive sets of geocoronal Lyman β, Lyman γ and He 584 Å emission intensities. In this paper, coincident EURD Lyman β and PBO Balmer α radiance measurements from the early March 2000 new moon period are presented. In addition to serving as examples of the data sets now available, the data volume poses an analysis challenge not faced in prior geocoronal studies. A data-model comparison search procedure employing resonance radiation transport results for extensive sets of parametric density distribution models is being developed for use in analyses of multiple large data sets; this is described, and example results for the PBO and EURD March 2000 data sets are presented. The tightness of the constraints obtained for the solar line-center Lyman β irradiance and the atomic hydrogen column abundance is somewhat surprising, given the crudeness of the parameter binning in the search procedure and the fact that a small number of recognized corrections remain to be made to each data set.

  8. Solar UV Irradiances and Associated Issues for the Atmosphere and Ionosphere

    Science.gov (United States)

    Tobiska, W.

    Several new solar proxies have been developed in the past year as the beginning of a second generation solar UV modeling and forecasting capability. These proxies help characterize the energy input into operational space physics models that provide information content on the neutral thermosphere and ionosphere. Between 1999-2000, a full solar spectrum was developed (SOLAR2000) for use in numerical atmospheric and ionospheric models relevant to climatological studies and the E10.7 index was produced for empirical thermospheric and ionospheric model applications. In 20012002, new proxies have been derived including a sunspot number, Rsn, for use by operational HF radio ray-trace algorithms and the Qeuv thermospheric heating rate for use by the aeronomy community to compare airglow-derived versus solar-derived upper atmosphere heating. The Peuv heat production term has also been developed as an index for comparing solar heating to joule heating on a global scale. The S(t) index is the integrated solar spectrum used for solar radiation pressure calculations related to spacecraft attitude control. Finally, the Tinf is the exospheric temperature that is provided for long-term climate change studies. Second generation modeling and forecasting is in development and includes higher cadence solar input information beyond daily flux values where solar flare characterization will soon become reality. The second generation forecasting is also incorporating improved algorithms ranging from wavelet transforms to solar dynamo theory in order to specify solar variability on seven time scales from nowcast and 72-hour forecast to 5 solar cycle estimation. These new proxies are derivatives of the SOLAR2000 model whose solar irradiance specification is compliant with the developing ISO draft standard WD 21348 for Determining Solar Irradiances.

  9. MAVEN Imaging UV Spectrograph Results on the Mars Atmosphere and Atmospheric Escape

    Science.gov (United States)

    Chaffin, Michael; Schneider, Nick; McClintock, Bill; Stewart, Ian; Deighan, Justin; Jain, Sonal; Clarke, John; Holsclaw, Greg; Montmessin, Franck; Lefevre, Franck; Chaufray, Jean-Yves; Stiepen, Arnaud; Crismani, Matteo; Mayyasi, Majd; Evans, Scott; Stevens, Mike; Yelle, Roger; Jakosky, Bruce

    2016-04-01

    The Imaging Ultraviolet Spectrograph (IUVS) is one of nine science instruments aboard the Mars Atmosphere and Volatile and EvolutioN (MAVEN) spacecraft, whose payload is dedicated to exploring the upper atmosphere of Mars and understanding the magnitude and drivers of Mars' atmospheric escape rate. IUVS uses ultraviolet light to investigate the lower and upper atmosphere and ionosphere of Mars. The instrument is among the most powerful spectrographs sent to another planet, with several key capabilities: (1) separate Far-UV & Mid-UV channels for stray light control, (2) a high resolution echelle mode to resolve deuterium and hydrogen emission, (3) internal instrument pointing and scanning capabilities to allow complete mapping and nearly continuous operation, and (4) optimization for airglow studies. IUVS, along with other MAVEN instruments, obtains a comprehensive picture of the current state of the Mars upper atmosphere and ionosphere and the processes that control atmospheric escape. We present an overview of selected IUVS results, including (1) the discovery of diffuse aurora at Mars, and its contrast with previously detected discrete aurora localized near crustal magnetic fields; (2) widespread detection of mesospheric clouds; (3) Significant seasonal and short-timescale variability in thermospheric composition; (4) Global ozone maps spanning six months of seasonal evolution; and (5) mapping of the Mars H and O coronas, deriving the escape rates of H and O and their variability. This last is of particular importance for understanding the long term evolution of Mars and its atmosphere, with the observed preset escape of H potentially capable of removing a large fraction of Mars' initial water inventory, and the differential escape of O relative to H potentially providing a net source of oxidizing power to the atmosphere and planet at present, in contrast with a photochemical theory that predicts stoichiometrically balanced escape. The atmospheric and escape

  10. The roles of vertical advection and eddy diffusion in the equatorial mesospheric semi-annual oscillation (MSAO

    Directory of Open Access Journals (Sweden)

    R. L. Gattinger

    2013-08-01

    Full Text Available Observations of the mesospheric semi-annual oscillation (MSAO in the equatorial region have been reported dating back several decades. Seasonal variations in both species densities and airglow emissions are well documented. The extensive observations available offer an excellent case study for comparison with model simulations. A broad range of MSAO measurements is summarised with emphasis on the 80–100 km region. The objective here is not to address directly the complicated driving forces of the MSAO, but rather to employ a combination of observations and model simulations to estimate the limits of some of the underlying dynamical processes. Photochemical model simulations are included for near-equinox and near-solstice conditions, the two times with notable differences in the observed MSAO parameters. Diurnal tides are incorporated in the model to facilitate comparisons of observations made at different local times. The roles of water vapour as the "driver" species and ozone as the "response" species are examined to test for consistency between the model results and observations. The simulations suggest the interactions between vertical eddy diffusion and background vertical advection play a significant role in the MSAO phenomenon. Further, the simulations imply there are rigid limits on vertical advection rates and eddy diffusion rates. For August at the Equator, 90 km altitude, the derived eddy diffusion rate is approximately 1 × 106 cm2 s−1 and the vertical advection is upwards at 0.8 cm s−1. For April the corresponding values are 4 × 105 cm2 s−1 and 0.1 cm s−1. These results from the current 1-D model simulations will need to be verified by a full 3-D simulation. Exactly how vertical advection and eddy diffusion are related to gravity wave momentum as discussed by Dunkerton (1982 three decades ago remains to be addressed.

  11. Challenge of lightning detection with LAC on board Akatsuki spacecraft

    Science.gov (United States)

    Takahashi, Yukihiro; Sato, Mitsutero; Imai, Masataka; Yair, Yoav; Fischer, Georg; Aplin, Karen

    2016-04-01

    Even after extensive investigations with spacecraft and ground-based observations, there is still no consensus on the existence of lightning in Venus. It has been reported that the magnetometer on board Venus Express detected whistler mode waves whose source could be lightning discharge occurring well below the spacecraft. On the other hand, with an infrared sensor, VIRTIS of Venus Express, does not show the positive indication of lightning flashes. In order to identify the optical flashes caused by electrical discharge in the atmosphere of Venus, at least, with an optical intensity of 1/10 of the average lightning in the Earth, we built a high-speed optical detector, LAC (Lightning and Airglow Camera), on board Akatsuki spacecraft. The unique performance of the LAC compared to other instruments is the high-speed sampling rate at 32 us interval for all 32 pixels, enabling us to distinguish the optical lightning flash from other pulsing noises. Though, unfortunately, the first attempt of the insertion of Akatsuki into the orbit around Venus failed in December 2010, the second one carried out in December 7 in 2015 was quite successful. We checked out the condition of the LAC on January 5, 2016, and it is healthy as in 2010. Due to some elongated orbit than that planned originally, we have umbra for ~30 min to observe the lightning flash in the night side of Venus every ~10 days, starting on April 2016. Here we would report the instrumental status of LAC and the preliminary results of the first attempt to observe optical lightning emissions.

  12. A case study of Ionospheric storm effects during long-lasting southward IMF Bz driven geomagnetic storm

    Science.gov (United States)

    Liu, J., Sr.

    2014-12-01

    Multiple instrumental observations including GPS TEC, foF2 and hmF2 from ionosondes, vertical ion drift measurements from C/NOFS, magnetometer data and far-ultraviolet airglow measured by TIMED/GUVI are used to investigate the profound ionospheric disturbances at mid- and low-latitudes during the 14-17 July 2012 geomagnetic storm event, which was featured by prolonged southward interplanetary geomagnetic field component for about 30 hours below -10 nT. In the East Asian/Australian sector, latitudinal profile of TEC variations in the main phase were characterized by three bands of increments and separated by weak depressions in the Equatorial Ionospheric Anomaly (EIA) crest regions, which were caused by the combined effects of disturbance dynamo electric fields (DDEF) and equatorward neutral winds. In the recovery phase, strong inhibition of EIA occurred and the summer crest of EIA disappeared on 16 July due to the combined effects of intrusion of neutral composition disturbance zone as shown by the TIME/GUVI O/N2 measurements and long-lasting daytime westward DDEF inferred from the equatorial electric electrojet (EEJ) observations. The transit time of DDEF over the dip equator from westward to eastward is around 2200 LT. In the American longitude, the salient ionospheric disturbances in the summer hemisphere were characterized by daytime periodical intrusion of negative phase for three consecutive days in the recovery phase, preceded by storm enhanced density (SED) plume in the initial phase. In addition, multiple short-lived prompt penetration electric fields (PPEF) appeared during stable southward IMF Bz in the recovery phase and were responsible for enhanced the EIA and equatorial ionospheric uplift around sunset.

  13. A case study of ionospheric storm effects during long-lasting southward IMF Bz-driven geomagnetic storm

    Science.gov (United States)

    Liu, Jing; Liu, Libo; Nakamura, Takuji; Zhao, Biqiang; Ning, Baiqi; Yoshikawa, A.

    2014-09-01

    Multiple instrumental observations including GPS total electron content (TEC), foF2 and hmF2 from ionosondes, vertical ion drift measurements from Communication/Navigation Outage Forecasting System, magnetometer data, and far ultraviolet airglow measured by Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics/Global Ultraviolet Imager (TIMED/GUVI) are used to investigate the profound ionospheric disturbances at midlatitude and low latitude during the 14-17 July 2012 geomagnetic storm event, which was featured by prolonged southward interplanetary geomagnetic field component for about 30 h below -10 nT. In the East Asian/Australian sector, latitudinal profile of TEC variations in the main phase were characterized by three bands of increments and separated by weak depressions in the equatorial ionospheric anomaly (EIA) crest regions, which were caused by the combined effects of disturbance dynamo electric fields (DDEF) and equatorward neutral winds. In the recovery phase, strong inhibition of EIA occurred and the summer crest of EIA disappeared on 16 July due to the combined effects of intrusion of neutral composition disturbance zone as shown by the TIMED/GUVI O/N2 measurements and long-lasting daytime westward DDEF inferred from the equatorial electrojet observations. The transit time of DDEF over the dip equator from westward to eastward is around 2200 LT. In the American longitude, the salient ionospheric disturbances in the summer hemisphere were characterized by daytime periodical intrusion of negative phase for three consecutive days in the recovery phase, preceded by storm-enhanced density plume in the initial phase. In addition, multiple short-lived prompt penetration electric fields appeared during stable southward interplanetary magnetic field (IMF) Bz in the recovery phase and were responsible for enhanced the EIA and equatorial ionospheric uplift around sunset.

  14. Thermospheric zonal temperature gradients observed at low latitudes

    Directory of Open Access Journals (Sweden)

    P. R. Fagundes

    Full Text Available Fabry-Perot interferometer (FPI measurements of thermospheric temperatures from the Doppler widths of the OI 630 nm nightglow emission line have been carried out at Cachoeira Paulista (23° S, 45° W, 16° S dip latitude, Brazil. The east-west components of the thermospheric temperatures obtained on 73 nights during the period from 1988 to 1992, primarily under quiet geomagnetic conditions, were analyzed and are presented in this paper. It was observed that on 67% of these nights, the temperatures in both the east and west sectors presented similar values and nocturnal variations. However, during 33% of the nights, the observed temperatures in the west sector were usually higher than those observed in the east sector, with zonal temperature gradients in the range of 100 K to 600 K, over about an 800 km horizontal distance. Also, in some cases, the observed temperatures in the east and west sectors show different nocturnal variations. One of the possible sources considered for the observed zonal temperature gradients is the influence of gravity wave dissipation effects due to waves that propagate from lower altitudes to thermospheric heights. The observed zonal temperature gradients could also be produced by orographic gravity waves originated away, over the Andes Cordillera in the Pacific Sector, or by dissipation of orographic gravity waves generated over the Mantiqueira Mountains in the Atlantic sector by tropospheric disturbances (fronts and/or subtropical jet streams.

    Key words. Atmospheric composition and structure (air-glow and aurora; thermosphere - composition and chemistry Ionosphere (equatorial ionosphere

  15. Photochemistry-emission coupled model for Europa and Ganymede

    Directory of Open Access Journals (Sweden)

    Cessateur Gaël

    2016-01-01

    Full Text Available In the frame of the JUICE mission, preliminary studies of the Jupiter’s icy moons, such as Ganymede and Europa, are mandatory. The present paper aims at characterizing the impact of the solar UV flux and its variability on their atmospheres. The solar UV radiation is responsible for the photoionization, photodissociation, and photoexcitation processes within planetary atmospheres. A 1-D photoabsorption model has been developed for different observational geometries, on the basis of a neutral atmospheric model. Considering various production and loss mechanisms but also the transport of oxygen atoms, we estimate the red and green line emissions from photo impact-induced excitation only. These dayglow emissions can represent few percent of the global airglow emission, mainly dominated by electron-induced excitation in auroral regions. For limb viewing conditions, red line emission is bright enough to be detected from actual spectrometers, from 338 R to 408 R according to the solar activity. This is also the case for the green line with 8 R at limb viewing. Considering a different neutral atmosphere model, with an O2 column density 50% more important, leads to a 14% increase in the red line emissions for limb viewing close to the surface. This difference could be important enough to infer which neutral model is the most likely. However, uncertainties on the solar UV flux might also prevent to constrain the O2 column density when using ground-based observations in the visible only. The impact of solar flares on the red line emissions for Europa has also been investigated within a planetary space weather context.

  16. Effects of solar zenith angles on CO Cameron bands emission intensities in the dayside atmosphere of Mars: MEX/SPICAM observations

    Science.gov (United States)

    Pothuraju, Thirupathaiah; Haider, Syed A.

    2016-07-01

    We have developed a model to calculate the photoelectron energy fluxes and emission intensities of the CO Cameron bands in the upper atmosphere of Mars between solar zenith angles 0° to 90°. The production and loss mechanisms of CO (a ^{3}Π) are incorporated in the model. The atmospheric neutral parameters are adopted from the Mars Climate Database (v5.2). The required solar EUV fluxes are taken from the Solar2000 model (v2.37) and scaled to Mars. The photoelectron fluxes are calculated at different solar zenith angles using an analytical yield spectrum approach based on the Monte Carlo method. In this model we have assumed that crustal magnetic fields are horizontal in direction. Thus, photoelectrons are losing their energy at the same height where they are produced. This assumption is valid at mid and high latitudes where magnetic fields are mostly horizontal. We have also developed a coupled chemistry model to calculate the ion and electron density at different solar zenith angles, which are used in the airglow model. The model results are compared with the observations provided by the SPICAM onboard MEX. Our model reproduces the observed intensity profiles quite well. The CO (a ^{3}Π) is produced due to photoelectron excitation/dissociation, photodissociation, and dissociative recombination processes. It is destroyed by CO _{2}, CO and radiative decay. It is found that photon and photoelectron dissociation are dominant production processes of CO (a ^{3}Π), while radiative decay is a major loss mechanism of this state. The estimated photoelectron fluxes, production rates and intensities are decreasing with increasing solar zenith angles.

  17. Extension of the AURIC Radiative Transfer Model for Mars Atmospheric Research

    Science.gov (United States)

    Evans, J. S.; Lumpe, J. D.; Correira, J.; Stewart, A. I.; Schneider, N. M.; Deighan, J.

    2013-12-01

    We present recent updates to the Atmospheric Ultraviolet Radiance Integrated Code (AURIC) model that allow it to be used as a forward model for Mars atmospheric research. AURIC is a state of the art far ultraviolet (FUV) to near-infrared (NIR) atmospheric radiance model that has been used extensively for analysis and modeling of terrestrial upper atmospheric remote sensing data. We present recent updates to the Atmospheric Ultraviolet Radiance Integrated Code (AURIC) model that allow it to be used as a forward model for Mars atmospheric research. AURIC is a state of the art far ultraviolet (FUV) to near-infrared (NIR) atmospheric radiance model that has been used extensively for analysis and modeling of terrestrial upper atmospheric remote sensing data. The airglow modeling capabilities of AURIC make it a powerful tool that can be used to characterize optical backgrounds, simulate data from both rocket and satellite-borne optical instrumentation, and serve as a forward model driver for geophysical retrieval algorithms. Upgrades made to allow modeling of the Martian atmosphere include 1-D Mars photochemistry and molecular transport and the addition of the following molecular band systems: CO Cameron; CO Fourth Positive Group; CO2+ Fox-Duffendack-Barker; CO2+ UV Doublet; CO Hopfield-Birge (B-X); and CO+ First Negative Group. Furthermore, a prototype AURIC-Titan model has also been developed, allowing comparison of AURIC spectral radiances with Cassini-Huygens/UVIS data [Stevens et al., 2011; Stevens et al., in preparation]. Extension of AURIC to the atmospheres of Pluto and it's largest moon, Charon, is also ongoing in support of NASA's New Horizons mission [Stevens, Evans, and Gladstone, 2012; 2013].

  18. Data Impact of the DMSP F18 SSULI UV Data on the Operational GAIM Model

    Science.gov (United States)

    Dandenault, P. B.; Metzler, C. A.; Nicholas, A. C.; Coker, C.; Budzien, S. A.; Chua, D. H.; Finne, T. T.; Dymond, K.; Walker, P. W.; Schunk, R. W.; Scherliess, L.; Gardner, L. C.

    2011-12-01

    The Naval Research Laboratory (NRL) has developed five ultraviolet remote sensing instruments for the United States Air Force (USAF) Defense Meteorological Satellite Program (DMSP). The DMSP satellites are launched in a near-polar, sun-synchronous orbit at an altitude of approximately 830 km. Each Special Sensor Ultraviolet Limb Imager (SSULI) instrument measures vertical profiles of the natural airglow radiation from atoms, molecules and ions in the upper atmosphere and ionosphere by viewing the earth's limb within a tangent altitude range of approximately 50 km to 750 km. Limb observations are made from the extreme ultraviolet (EUV) to the far ultraviolet (FUV) over the wavelength range of 80 nm to 170 nm, with 1.8 nm resolution. Data products from SSULI observations include nightglow and dayglow Sensor Data Records (SDRs), as well as Environmental Data Records (EDRs) which contain vertical profiles of electron (Ne) densities, N2, O2, O, O+, and Temperature, hmF2, NmF2 and vertical Total Electron Content (TEC). On October 18, 2009, the third SSULI sensor launched from Vandenberg Air Force Base aboard the DMSP F18 spacecraft. The Calibration and Validation of the F18 instrument has completed and the SSULI program is scheduled to go operational at the Air Force Weather Agency (AFWA) in Fall 2011. The SSULI F18 data are ingested by the Global Assimilation of Ionospheric Measurements (GAIM) space weather model, which was developed by Utah State University and has been used operationally at AFWA since February 2006. A brief overview of the SSULI F18 SDR data assimilation process with GAIM is provided and the impact of the SSULI 1356 Å emission on the GAIM model is examined for spring and summer 2011 nightside data in the low-latitude region.

  19. Electron loss rates from the outer radiation belt caused by the filling of the outer plasmasphere: the calm before the storm

    Energy Technology Data Exchange (ETDEWEB)

    Borovsky, Joseph E [Los Alamos National Laboratory; Denton, Michael H [LANCASTER UNIV

    2009-01-01

    Measurements from 7 spacecraft in geosynchronous orbit are analyzed to determine the decay rate of the number density of the outer electron radiation belt prior to the onset of high-speed-stream-driven geomagnetic storms. Superposed-data analysis is used wan(?) a collection of 124 storms. When there is a calm before the storm, the electron number density decays exponentially before the storm with a 3.4-day e-folding time: beginning about 4 days before storm onset, the density decreases from {approx}4x10{sup -4} cm{sup -3} to {approx}1X 10{sup -4} cm{sup -3}. When there is not a calm before the storm, the number-density decay is very smalL The decay in the number density of radiation-belt electrons is believed to be caused by pitch-angle scattering of electrons into the atmospheric loss cone as the outer plasmasphere fills during the calms. While the radiation-belt electron density decreases, the temperature of the electron radiation belt holds approximately constant, indicating that the electron precipitation occurs equally at all energies. Along with the number density decay, the pressure of the outer electron radiation belt decays and the specific entropy increases. From the measured decay rates, the electron flux to the atmosphere is calculated and that flux is 3 orders of magnitude less than thermal fluxes in the magnetosphere, indicating that the radiation-belt pitch-angle scattering is 3 orders weaker than strong diffusion. Energy fluxes into the atmosphere are calculated and found to be insufficient to produce visible airglow.

  20. Observation of a mesospheric front in a thermal-doppler duct over King George Island, Antarctica

    Directory of Open Access Journals (Sweden)

    J. V. Bageston

    2011-12-01

    Full Text Available A mesospheric front was observed with an all-sky airglow imager on the night of 9–10 July 2007 at Ferraz Station (62° S, 58° W, located on King George island on the Antarctic Peninsula. The observed wave propagated from southwest to northeast with a well defined wave front and a series of crests behind the main front. The wave parameters were obtained via a 2-D Fourier transform of the imager data providing a horizontal wavelength of 33 km, an observed period of 6 min, and a horizontal phase speed of 92 m s−1. Simultaneous mesospheric winds were measured with a medium frequency (MF radar at Rothera Station (68° S, 68° W and temperature profiles were obtained from the SABER instrument on the TIMED satellite. These wind and temperature profiles were used to estimate the propagation environment of the wave event. A wavelet technique was applied to the wind in the plane of wave propagation at the OH emission height spanning three days centered on the front event to define the dominant periodicities. Results revealed a dominance of near-inertial periods, and semi-diurnal and terdiurnal tides suggesting that the ducting structure enabling mesospheric front propagation occurred on large spatial scales. The observed tidal motions were used to reconstruct the winds employing a least-squares method, which were then compared to the observed ducting environment. Results suggest an important contribution of large-scale winds to the ducting structure, but with buoyancy frequency variations in the vertical also expected to be important. These results allow us to conclude that the wave front event was supported by a duct including contributions from both winds and temperature.

  1. Quantum yield for O-atom production in the VUV photodissociation of CO2 using the time-sliced velocity-mapped imaging (TS-VMI) method

    Science.gov (United States)

    Jackson, William M.

    2016-10-01

    VUV photodissociation above 10.5 eV is considered the primary region for photochemical destruction of CO2 by solar radiation. There is enough photon energy in this region so that in addition to ground state O(3PJ) and CO(1Σ +) that can be produced during photodissociation excited species such as atomic oxygen O(1D) and O(1S), as well as excited carbon monoxide CO(a3Π, a'3Σ+) also can be formed. Electronic excited oxygen atom and carbon monoxide are the species that are responsible for the airglows in atmospheres of the solar planets and comets. Therefore, detail photodissociation quantum yields for these excited species from CO2 are critical in interpreting the chemistry in these solar system bodies. We have previously shown that the time-sliced velocity-mapped imaging (TS-VMI) technique can provide detailed branching ratio information about photodissociation of diatomic molecules.1, 2 However, to date we have not been able to show how this technique can be use to determine absolute quantum yields for the products produced in the VUV photodissociation of CO2. In this talk we will describe how the known quantum yields for the photodissociation O2 to O(3P2), O(3P1), O(3P0) and O(1D) can be used to determine quantum yields of similar products in the photodissociation of CO2.[1] Yu Song, Hong Gao, Yih Chung Chang, D. Hammouténe, H. Ndome, M. Hochlaf, William M. Jackson, and C. Y. Ng, Ap. J., 819:23 (13pp), 2016; doi:10.3847/0004-637X/819/1/23.[2] Hong Gao, Yu Song, William M. Jackson and C. Y. Ng, J. Chem. Phys, 138, 191102, 2013.

  2. Interactions between small and medium scale gravity waves in the mesosphere and lower thermosphere

    Science.gov (United States)

    Heale, Christopher; Snively, Jonathan

    2016-07-01

    Gravity waves play a prominent role in the momentum and energy budget of the Earth's upper atmosphere [e.g. Fritts and Alexander ,Rev. Geophys., 41, 1003, 2003]. Small scale waves with large vertical wavelengths are able to propagate into the thermosphere where they will dissipate and deposit their energy and momentum [e.g. Vadas and Fritts, J. Geoph. Res.,110, D15103, 2005; Yiǧit et al., J. Geophys. Res.-Atmospheres, 114, D07101, 14, 2009; Liu et al., Ann. Geophys., 31, 2013; Heale et al., J. Geophys. Res. Space Physics, 119, 2014]. However, small scale waves are also prone to refraction, reflection, filtering, and instabilities by the temperature and wind structure of the atmosphere. One of the primary sources of variability on scales relevant to these small-scale waves is other, larger scale waves. The use of multiple instruments and Airglow keograms has begun to uncover the richness of the spectrum in the atmosphere, but interaction and relatively poorly understood [e.g. Fritts et al., J. Geophys. Res. Atmos., 119, 2014; Bossert et al., J. Geophys. Res. Atmos., 120, 2015; Lu et al., J. Geophys. Res. Atmos., 120, 2015; Yuan et al., J. Geophys. Res. Atmos., 121, 2016]. We use a 2D nonlinear, compressible numerical model to investigate the character of interactions between small-scale and medium-scale gravity waves at varied amplitudes as they approach nonlinearity. We investigate the relative importance of linear and nonlinear interaction processes and their effects on the propagation of multiple wave packets, and the possibility of energy exchanges and the threshold of onset for instability or breaking within the waves. Furthermore, we assess the validity of linear interpretations of observational data where coherent large-amplitude waves are detected at multiple, separated scales.

  3. Observation sequences and onboard data processing of Planet-C

    Science.gov (United States)

    Suzuki, M.; Imamura, T.; Nakamura, M.; Ishi, N.; Ueno, M.; Hihara, H.; Abe, T.; Yamada, T.

    Planet-C or VCO Venus Climate Orbiter will carry 5 cameras IR1 IR 1micrometer camera IR2 IR 2micrometer camera UVI UV Imager LIR Long-IR camera and LAC Lightning and Airglow Camera in the UV-IR region to investigate atmospheric dynamics of Venus During 30 hr orbiting designed to quasi-synchronize to the super rotation of the Venus atmosphere 3 groups of scientific observations will be carried out i image acquisition of 4 cameras IR1 IR2 UVI LIR 20 min in 2 hrs ii LAC operation only when VCO is within Venus shadow and iii radio occultation These observation sequences will define the scientific outputs of VCO program but the sequences must be compromised with command telemetry downlink and thermal power conditions For maximizing science data downlink it must be well compressed and the compression efficiency and image quality have the significant scientific importance in the VCO program Images of 4 cameras IR1 2 and UVI 1Kx1K and LIR 240x240 will be compressed using JPEG2000 J2K standard J2K is selected because of a no block noise b efficiency c both reversible and irreversible d patent loyalty free and e already implemented as academic commercial software ICs and ASIC logic designs Data compression efficiencies of J2K are about 0 3 reversible and 0 1 sim 0 01 irreversible The DE Digital Electronics unit which controls 4 cameras and handles onboard data processing compression is under concept design stage It is concluded that the J2K data compression logics circuits using space

  4. A coordinated study of 1 h mesoscale gravity waves propagating from Logan to Boulder with CRRL Na Doppler lidars and temperature mapper

    Science.gov (United States)

    Lu, Xian; Chen, Cao; Huang, Wentao; Smith, John A.; Chu, Xinzhao; Yuan, Tao; Pautet, Pierre-Dominique; Taylor, Mike J.; Gong, Jie; Cullens, Chihoko Y.

    2015-10-01

    We present the first coordinated study using two lidars at two separate locations to characterize a 1 h mesoscale gravity wave event in the mesopause region. The simultaneous observations were made with the Student Training and Atmospheric Research (STAR) Na Doppler lidar at Boulder, CO, and the Utah State University Na Doppler lidar and temperature mapper at Logan, UT, on 27 November 2013. The high precision possessed by the STAR lidar enabled these waves to be detected in vertical wind. The mean wave amplitudes are ~0.44 m/s in vertical wind and ~1% in relative temperature at altitudes of 82-107 km. Those in the zonal and meridional winds are 6.1 and 5.2 m/s averaged from 84 to 99 km. The horizontal and vertical wavelengths inferred from the mapper and lidars are ~219 ± 4 and 16.0 ± 0.3 km, respectively. The intrinsic period is ~1.3 h for the airglow layer, Doppler shifted by a mean wind of ~17 m/s. The wave packet propagates from Logan to Boulder with an azimuth angle of ~135° clockwise from north and an elevation angle of ~ 3° from the horizon. The observed phase difference between the two locations can be explained by the traveling time of the 1 h wave from Logan to Boulder, which is about ~2.4 h. The wave polarization relations are examined through the simultaneous quantifications of the three wind components and temperature. This study has developed a systematic methodology for fully characterizing mesoscale gravity waves, inspecting their intrinsic properties and validating the derivation of horizontal wave structures by applying multiple instruments from coordinated stations.

  5. The Limb-Imaging Ionospheric and Thermospheric Extreme-Ultraviolet Spectrograph (LITES) on the ISS

    Science.gov (United States)

    Stephan, Andrew W.; Finn, Susanna C.; Cook, Timothy A.; Chakrabarti, Supriya; Budzien, Scott A.

    2015-04-01

    The Limb-imaging Ionospheric and Thermospheric Extreme-ultraviolet Spectrograph (LITES) is being prepared for flight in early 2016 aboard the Space Test Program Houston 5 (STP-H5) experiment pallet to the International Space Station (ISS). LITES is an imaging spectrograph that spans 60-140 nm and will obtain limb profiles of the ionosphere, along with the key upper atmospheric constituents O and N2. During the day, LITES measures the OII 83.4 and 61.7 nm emissions that are produced by solar photoionization of atomic oxygen in the lower thermosphere. The 83.4 nm emission is resonantly scattered by ionospheric O+, and thus its altitude profile is formed by both the initial ionization brightness and the ionospheric content. The 61.7 nm emission is not scattered and is used to constrain the photoionization brightness in the retrieval. At night, recombination of O+ and electrons produces optically thin emissions at 91.1 and 135.6 nm that are used to tomographically reconstruct the two-dimensional ionosphere in the orbital plane.These observations will be complemented and validated by ground-based data from an international network of digisondes, visible spectrographs, and imagers, which will provide ground truth for the space-based measurements. Additionally, the STP-H5 mission includes the GPS Radio Occultation and Ultraviolet Photometer Co-located (GROUP-C) experiment that consists of a high-sensitivity, nadir-viewing photometer that measures the nighttime ionospheric airglow at 135.6 nm, and a GPS receiver that measures ionospheric electron content and scintillation. We will discuss the LITES measurements and science goals, and how LITES data will be combined with these other experiments to study low and middle latitude ionospheric structures on a global scale.

  6. Analysis of traveling ionospheric disturbances (TIDs) in GPS TEC launched by the 2011 Tohoku earthquake

    Science.gov (United States)

    Crowley, Geoff; Azeem, Irfan; Reynolds, Adam; Duly, Timothy M.; McBride, Patrick; Winkler, Clive; Hunton, Don

    2016-05-01

    Traveling ionospheric disturbances (TIDs) have been detected using various measurement techniques, including HF sounders, incoherent scatter radars, in situ measurements, and optical techniques. However, observations of TIDs have tended to be sparse and there is a need for additional observations to provide new scientific insight into the geophysical source phenomenology and wave propagation physics. The dense network of GPS receivers around the globe offers a relatively new data source to observe and monitor TIDs. In this paper, we use total electron content (TEC) measurements from ~4000 GPS receivers throughout the continental United States to observe TIDs associated with the 11 March 2011 Tohoku tsunami. The tsunami propagated across the Pacific to the U.S. west coast over several hours, and we show that corresponding TIDs were observed in the US. Using this network of GPS receivers we present a 2D imaging of TEC perturbations and calculate various TID parameters, including horizontal wavelength, speed, and period. Well-formed, planar TIDs were detected over the west coast of the U.S. ~10 h after the earthquake. Fast Fourier transform analysis of the observed waveforms revealed that the period of the wave was 15.1 min with a horizontal wavelength of 194.8 km, phase velocity of 233.0 m/s, and an azimuth of 105.2° (propagating nearly due east in the direction of the tsunami wave). These results are consistent with the TID observations in airglow measurements from Hawaii earlier in the day and with other GPS TEC observations.

  7. Observations of Traveling Ionospheric Disturbances (TIDs) Over the United States Associated With the Tsunami Generated by the 2011 Tohoku Earthquake

    Science.gov (United States)

    Duly, T. M.; Azeem, I.; Crowley, G.; Vadas, S.; Makela, J. J.; Reynolds, A.

    2015-12-01

    The March 11, 2011 Tohoku earthquake generated a massive tsunami off the Pacific coast of Japan which in turn forced intense atmospheric gravity waves (AGW) that were seen in GPS Total Electron Content (TEC) data and airglow measurements as traveling ionospheric disturbance (TID) signatures as far away as Hawaii. What is unknown is how far these TIDs traveled after being launched by the tsunami and the role of the underlying neutral atmosphere on their propagation characteristics. For the first time, we show that TIDs associated with the Tohoku tsunami were observed in GPS TEC data for several hours over the west coast of the US and as far inland as Colorado. The results presented here show a range of TIDs generated by gravity wave packets propagating into the ionosphere from below. We present results indicating the presence of TIDs with periods ranging from 15 to 30 minutes, and horizontal wavelengths from 150 km to 400 km. The azimuth of the observed TID wave train was 121.8 ± 1.8° (angle measured in degrees east of north), which matches the azimuth of the tsunami near the Pacific coast of the US. The observed period of the TIDs was one of the spectral components of the tsunami wave packet as it approached the Pacific coast of the US. These results suggest that the tsunami was the source of the TIDs over the US. Additionally, the TID periods and horizontal wavelengths clearly vary in longitude. These variations agree with theoretical gravity wave results concerning propagation and dissipation in the thermosphere.

  8. SWIR detectors for night vision at AIM

    Science.gov (United States)

    Figgemeier, H.; Benecke, M.; Hofmann, K.; Oelmaier, R.; Sieck, A.; Wendler, J.; Ziegler, J.

    2014-06-01

    Detectors for the short-wave infrared (SWIR) spectral range are particularly suitable for observation under hazy weather conditions as well as under twilight or moon light conditions. In addition, SWIR detectors allow using the airglow for observation under moonless sky. SWIR detectors are commonly based on InGaAs or HgCdTe (MCT) and demand extremely low dark currents to ensure a high signal-to-noise ratio under low background light conditions. AIM has developed a read-out integrated circuit (ROIC) with 640×512 pixels and a 15 μm pixel pitch for low light level applications. The ROIC supports analog or digital correlated double sampling (CDS) for the reduction of reset-noise (also known as kTC-noise). Along with CDS, a rolling shutter (RS) mode has been implemented. The input stage of the ROIC is based on a capacitive transimpedance amplifier (CTIA) with two selectable gain settings. The dark current of our SWIR MCT detectors has recently been significantly reduced to allow for high operating temperatures. In contrast to InGaAs, the MCT material offers the unique possibility to adjust the cut-off wavelength according to the application while maintaining the matching of the lattice constant to the one of the CdZnTe substrate. The key electro-optical performance parameters of lately developed MCT based SWIR Focal Plane Arrays (FPA) with a 1.75 μm cut-off wavelength will be presented. In addition, AIMs SWIR detectors covering the spectral range from 0.9 μm to 2.5 μm and available in formats of 384×288 pixels - 24 μm pitch and 1024×256 pixels - 24×32 μm2, will be introduced.

  9. Mesospheric, Thermospheric, and Ionospheric Responses to Acoustic and Gravity Waves Generated by Transient Forcing

    Science.gov (United States)

    Snively, J. B.; Zettergren, M. D.

    2014-12-01

    Strong acoustic waves with periods ~1-4 minutes have been confirmed to perturb the ionosphere following their generation by earthquakes [e.g., Garcia et al., GRL, 40(5), 2013] and volcanic eruption events [e.g., Heki, GRL, 33, L14303, 2006]. Clear acoustic and gravity wave signatures have also been reported in ionospheric data above strong tropospheric convection [Nishioka, GRL, 40(21), 2013], and prior modeling results suggest that convectively-generated acoustic waves with ~3-4 minute periods are readily detectable above their sources in TEC [Zettergren and Snively, GRL, 40(20), 2013]. These observations have provided quantitative insight into the coupling of processes occurring near Earth's surface with the upper atmosphere and ionosphere over short time-scales. Here, we investigate acoustic waves and short-period gravity waves generated by sources near ground level, and the observable responses of the mesosphere, lower-thermosphere, and ionosphere (MLTI) systems. Numerical simulations are performed using a nonlinear, compressible, atmospheric dynamics model, in cylindrically-axisymmetric coordinates, to investigate wave generation, upward propagation, steepening, and dissipation. Acoustic waves may produce observable signatures in the mesospheric hydroxyl airglow layer [e.g., Snively, GRL, 40(17), 2013], and can strongly perturb the lower-thermosphere and E- and F-region ionosphere, prior to the arrival of simultaneously-generated gravity waves. Using a coupled multi-fluid ionospheric model [Zettergren and Semeter, JGR, 117(A6), 2012], extended for mid and low latitudes using a 2D dipole magnetic field coordinate system [Zettergren and Snively, GRL, 40(20), 2013], we investigate its response to realistic acoustic wave perturbations. In particular, we demonstrate that the MLT and ionospheric responses are significantly and nonlinearly determined by the acoustic wave source geometry, spectrum, and amplitude, in addition to the local ambient state of the

  10. Physics of the Space Environment

    Science.gov (United States)

    Vasyliünas, Vytenis M.

    This book, one in the Cambridge Atmospheric and Space Science Series, joins a growing list of advanced-level textbooks in a field of study and research known under a variety of names: space plasma physics, solar-terrestrial or solar-planetary relations, space weather, or (the official name of the relevant AGU section) space physics and aeronomy. On the basis of graduate courses taught by the author in various departments at the University of Michigan, complete with problems and with appendices of physical constants and mathematical identities, this is indeed a textbook, systematic and severe in its approach. The book is divided into three parts, in length ratios of roughly 6:4:5. Part I, “Theoretical Description of Gases and Plasmas,” starts by writing down Maxwell's equations and the Lorentz transformation (no nonsense about any introductory material of a descriptive or historical nature) and proceeds through particle orbit theory, kinetics, and plasma physics with fluid and MHD approximations to waves, shocks, and energetic particle transport. Part II, “The Upper Atmosphere,” features chapters on the terrestrial upper atmosphere, airglow and aurora, and the ionosphere. Part III, “Sun-Earth Connection,” deals with the Sun, the solar wind, cosmic rays, and the terrestrial magnetosphere. The book thus covers, with two exceptions, just about all the topics of interest to Space Physics and Aeronomy scientists, and then some (the chapter on the Sun, for instance, briefly discusses also topics of the solar interior: thermonuclear energy generation, equilibrium structure, energy transfer, with a page or two on each). One exception reflects a strong geocentric bias: there is not one word in the main text on magnetospheres and ionospheres of other planets and their interaction with the solar wind (they are mentioned in a few problems). The other exception: the chapter on the terrestrial magnetosphere lacks a systematic exposition of the theory of

  11. Photographic surface photometry of the Milky Way. III - Photometry of the central area of the Galaxy in the ultraviolet

    Science.gov (United States)

    Proell, H. J.; Schmidt-Kaler, T.; Schlosser, W.

    1983-01-01

    6 photographic plates, taken at La Silla, Chile, with the spherical mirror super-wide-angle camera of the Astronomisches Institut der Ruhr Universität Bochum (see paper I: Schmidt-Kaler, Th. et al., 1982) were measured to study the surface brightness distribution in the area around the centre of the Milky Way, between galactic longitudes 297° and 27°, and latitudes - 30° to + 30°, with an angular resolution of 0.°3 × 0.°3 (Fig. 5). In section 2 the plate material and details of the reductions are presented, so far as not already given in paper I. During the photometric scanning of the plates all stars brighter than a limiting magnitude mlim were marked by hand, and the corresponding data points were replaced by an average from neighbouring points (section 3). Defined at the level of 50% elimination, mlim ≌ 8.m0 (in U). Figure 4 shows the effect of various methods of eliminating bright stars. The errors of the surface photometry are discussed in section 4. The internal mean error of the intensity of one data point, as determined from the scatter from the 6 plates, is ± 9.4%. This error is split into an additive component ± 8 S10U (S10 = intensity of a star of 10m), mostly due to the contributions of airglow and scattered light, and a multiplicative component of ± 7.5%, mostly due to the uncertainty of the photographic characteristic curve. Possible systematic errors are estimated and upper limits for these are given in table II. Section 5 presents the results of the photometry. For the sake of clear representation in the isophote map (Fig 5) data with intermediate intensities 110 paragraph we discuss the structure of the Milky Way central region in U, in particular those spiral filaments which appear inclined to the galactic equator (shingles, corrugations). The three shingles discovered by Schmidt-Kaler and Schlosser (1973) in the next-inner spiral arm-I and an additional feature appear if the data-field of the UV photometry is spatially differentiated

  12. The high-resolution microchannel plate detector for FUV spectroscopy in the BepiColombo mission

    Science.gov (United States)

    Murakami, Go; Ezawa, Fukuhiro; Yoshioka, Kazuo; Yoshikawa, Ichiro; Chassefiere, Eric; Maria, Jean-Luc

    Mariner-10 UV measurements and telescopic spectroscopy from the Earth identified six elements (Ca, Na, K, H, He, and O) in the Mercury's exosphere. Other species are expected, e.g. H2 , OH, and some noble gasses (Ar, Ne, and Xe). All species representative of the surface composition, directly produced by impact vaporization driven by micrometeoroids, physical sputtering, photo-stimulated desorption, and thermal desorption from the regolith, should also be present. To determine the composition of the Mercury's exosphere, the PHEBUS (Probing of Hermean Exosphere By Ultraviolet Spectroscopy) instrument on Mercury Planetary Orbiter (MPO) will measure the emission lines of the exosphere. PHEBUS is a dual FUV-EUV spectrometer working in the wavelength range from 55 to 315 nm. We are now developing the compact detector system sensitive to FUV airglow emissions of the Mercury. The FUV detector is required to have high spatial resolution (80 µm) so that the wavelength resolution of the PHEBUS instrument should be 2 nm at the FUV range. The FUV detector consists of a Cs2 Te photocathode, microchannel plates (MCPs), and a resistive anode encoder (RAE). In a position-sensitive system with an RAE, the spatial resolution is determined by the signal-to-noise ratios at the anode terminals. Therefore, a high and stable electron gain of MCPs allows the position determination of each photoelectron event with high spatial resolution. We studied a method for achieving a high and stable electron gain. We fabricated a test model of the FUV detector incorporating a clamped pair of MCPs (V-stack) followed by a gap and a clamped triplet of MCPs (Z-stack) in cascade. We have investigated the effect of the negative potential applied across the inter-stack (V-Z) gap on the PHD and the spatial resolution by means of calculation and experiments. The calculation with a simple ballistic model showed that the negative inter-stack potential reduced the size of the electron cloud by 70%. The result

  13. First measurement of helium on Mars: Implications for the problem of radiogenic gases on the terrestrial planets

    Science.gov (United States)

    Krasnopolsky, V. A.; Bowyer, S.; Chakrabarti, S.; Gladstone, G. R.; Mcdonald, J. S.

    1994-01-01

    108 +/- 11 photons of the martian He 584-A airglow detected by the Extreme Ultraviolet Explorer (EUVE) satellite during a 2-day exposure (January 22-23, 1993) correspond to the effective disk average intensity of 43 +/- 10 Rayleigh (Ra). Radiative transfer calculations, using a model atmosphere appropriate to the conditions of the observation and having an exospheric temperature of 210 +/- 20 K, result in a He mixing ratio of 1.1 +/- 0.4 ppm in the lower atmosphere. Nonthermal escape of helium is due to electron impact ionization and pickup of He(+) by the solar wind, to collisions with hot oxygen atoms, and to charge exchange with molecular species with corresponding column loss rates of 1.4 x 10(exp 5), 3 x 10(exp 4), and 7 x 10(exp 3)/sq cm/s, respectively. The lifetime of helium on Mars is 5 x 10(exp 4) years. the He outgassing rate, coupled with the Ar-40 atmospheric abundance and with the K:U:Th ratio measured in the surface rocks, is used as input to a single two-reservoir degassing model which is applied to Mars and then to Venus. A similar model with known abundances if K, U, and Th is applied to Earth. The models for Earth and Mars presume loss of all argon accumulated in the atmospheres during the first billion years by large-scale meteorite and planetesimal impacts. The models show that the degassing coefficients for all three planets may be approximated by function delta = delta(sub 0) x (t(sub 0)/t)(exp 1/2) with delta(sub 0) = 0.1, 0.04, and 0.0125 Byr for Earth, Venus, and Mars, respectively. After a R(exp 2) correction this means that outgassing processes on Venus and Mars are weaker than on Earth by factors of 3 and 30, respectively. Mass ratios of U and Th are almost the same for all three planets, while potassiumis depleted by a factor of 2 in Venus and Mars. Mass ratio of helium and argon are close to 5 x 10(exp -9) and 2 x 10(exp -8) g/g in the interiors of all three planets. The implications of these results are discussed.

  14. Geomagnetism and climate V: general conclusions

    Science.gov (United States)

    Mörner, N.-A.; Nevanlinna, H.; Dergachev, V.; Shumilov, O.; Raspopov, O.; Abrahamsen, N.; Pilipenko, O.; Trubikhin, V.; Gooskova, E.

    2003-04-01

    The shielding capacity of the Earth’s geomagnetic field is a prime factor regulating the flux into the atmosphere of galactic cosmic ray (in its turn controlling the 14C and 10Be production). This shielding capacity is controlled both by the Earth’s own geomagnetic field variability and by the Solar Wind variations. The Solar Wind interaction with the magnetosphere also affects the Earth’s rate of rotation (as recorded in the correlation between LOD and Sunspot activity). This opens for three possible lines of Solar Terrestrial interaction. (1) Changes in the total irradiance (known to be very small, however, over a full sun spot cycle). (2) Changes in cosmic ray flux reaching into the Earth’s atmosphere where it has the potential of affecting airglow and cloudiness (especially the cloudiness at a height in the order of 15 km). (3) Changes in the Earth’s rate of rotation affecting the oceanic circulation redistributing ocean-stored heat and water masses. The Spörer, Maunder and Dalton sun spot minima seem all to have led to periods of rotational acceleration pulling Arctic water down the European coasts and displacing the warm Gulf Stream towards Gibraltar. The geomagnetic field as regulator of cosmic ray flux and rotational potential is likely to have played a significant role even over longer time periods. It should be noted, however, the geometry of the Earth’s geomagnetic field cannot have differed very much due to frozen plasma conditions even at excursions and reversals. If the recorded sunspot and geomagnetic cycles are extrapolated into the future they predict a new low (“Little Ice Age”) in the years 2050 2100 (i.e. a scenario very different from that presented by IPCC). Our study of the relation between geomagnetism and climate has shown that geomagnetic field changes have played an important role in modulation Earth’s climate. These changes may originate from internal planetary sources (i.e. the Earth’s own geomagnetic field) as well

  15. Results from the SolACES instrument onboard the International Space Station (ISS)

    Science.gov (United States)

    Schmidtke, Gerhard; Eparvier, Francis; Brunner, Raimund; Woods, Thomas; Jacobi, Christoph; Thuillier, Gerard; Nikutowski, Bernd; Erhardt, Christian

    2012-07-01

    The SolACES instrument has to be seen in the context of more than 50 years of intensive research in EUV spectroscopy in space with solar, terrestrial and planetary airglow and auroral emissions included. The results from four years of solar spectral irradiance (SSI) recordings performed by SolACES will be presented. The first part will cover the instrumental performance with respect to the primary capability of frequent in-orbit re-calibration in the ISS environment. Among the advantages of the measuring system there are multiple instrumental possibilities to cross-check the results providing a high degree of reliability to the spectral irradiance derived. The results from an inter-comparison of the global TEC variability with modelled global TEC using TIMED/SEE and SolACES EUV data and modelled global TEC using F10.7 data will be presented beyond the last solar minimum. The correlation of global TEC data with models using EUV data is higher than the correlation of global TEC with models using F10.7. Deviations of the modelled global TEC data from the modelled ones with SSI EUV data are pointing to geomagnetic disturbances e.g. as caused by solar wind and coronal mass ejections (CMEs). Similar to the short-term recordings exhibiting different temporal intensity changes in phase and amplitude with wavelength also the long-term SSI data show temporal shifts with wavelength during the extended solar minimum 2008-2009. Data from the ISS SOLAR instruments SOLSPEC and SolACES are suggesting that each solar emission reaches its own solar minimum. Finally a proposal will be explained to develop SSI indices from the data acquired so far. For the spectral region from 121-400 nm the reconstruction of SSI indices could be performed using the Mg II index and neutron-monitor measurements. The data available from the latest and still on-going space missions could provide the data sets to cover the wavelength range shorter than 121 nm. The path of the data analysis and the results

  16. Photoelectron fluxes observed by FAST compared with model predictions incorporating SNOE observations of the solar soft X-ray irradiance

    Science.gov (United States)

    Bailey, S. M.; Peterson, W. K.; Solomon, S. C.; Carlson, C. W.; McFadden, J. P.

    2001-12-01

    Photoelectrons are those electrons produced when atoms or molecules in the upper atmosphere are photoionized. These electrons carry the excess energy of the photon remaining from the ionization and can have energies up to and greater than 1 keV. Photoelectrons are important in that they play a significant role in the energetics of the upper atmosphere, resulting in ionization, dissociation, and excitation of atoms and molecules. There have been long standing issues with regard to understanding the magnitude of the terrestrial photoelectron flux as models have not been able to reproduce the observations without scaling the solar soft X-ray irradiance by factors of two to four. The Fast Auroral Snapshot (FAST) spacecraft was launched in August of 1996. While its primary goals focus on the study of auroral energetic particles, in January of 1999 it began making low-latitude observations. From measurements by the FAST energetic electron sensor, upward flowing photoelectron fluxes in the energy range of 50 eV to 1 keV have been obtained. These measurements are in agreement with earlier measurements of the terrestrial photoelectron flux. The Student Nitric Oxide Explorer (SNOE) spacecraft was launched in February of 1998. Since then it has been making daily observations of the solar soft X-ray irradiance in bandpasses of 2 - 7, 6 - 19, and 17 - 20 nm. SNOE observes larger values of the solar soft X-ray irradiance than reported by earlier observations or predicted by empirical models; however, the SNOE observations are in agreement with many suggestions of the solar soft X-ray irradiance obtained from geophysical observations such as airglow and electron densities. These irradiance measurements are used in a photoelectron model that includes transport. Observations of photoelectron fluxes for the first solar rotation of 1999 are modeled. The model photoelectron spectra are in good agreement with the observed photoelectron spectra over most of the 50 eV to 1 keV energy

  17. Advanced Ionospheric Sensing using GROUP-C and LITES aboard the ISS

    Science.gov (United States)

    Budzien, S. A.; Stephan, A. W.; Chakrabarti, S.; Finn, S. C.; Cook, T.; Powell, S. P.; O'Hanlon, B.; Bishop, R. L.

    2015-12-01

    The GPS Radio Occultation and Ultraviolet Photometer Co-located (GROUP-C) and Limb-imaging Ionospheric and Thermospheric Extreme-ultraviolet Spectrograph (LITES) experiments are manifested for flight aboard the International Space Station (ISS) in 2016 as part of the Space Test Program Houston #5 payload. The two experiments provide technical development and risk-reduction for future DoD space weather sensors suitable for ionospheric specification, space situational awareness, and data products for global ionosphere assimilative models. In addition, the combined instrument complement of these two experiments offers a unique opportunity to study structures of the nighttime ionosphere. GROUP-C includes an advanced GPS receiver providing ionospheric electron density profiles and scintillation measurements and a high-sensitivity far-ultraviolet photometer measuring horizontal ionospheric gradients. LITES is an imaging spectrograph that spans 60-140 nm and will obtain high-cadence limb profiles of the ionosphere and thermosphere from 150-350 km altitude. In the nighttime ionosphere, recombination of O+ and electrons produces optically thin emissions at 91.1 and 135.6 nm that can be used to tomographically reconstruct the two-dimensional plasma distribution in the orbital plane below ISS altitudes. Ionospheric irregularities, such as plasma bubbles and blobs, are transient features of the low and middle latitude ionosphere with important implications for operational systems. Irregularity structures have been studied primarily using ground-based systems, though some spaced-based remote and in-situ sensing has been performed. An ionospheric observatory aboard the ISS would provide new capability to study low- and mid-latitude ionospheric structures on a global scale. By combining for the first time high-sensitivity in-track photometry, vertical ionospheric airglow spectrographic imagery, and recent advancements in UV tomography, high-fidelity tomographic reconstruction of

  18. Statistical Analysis for VHF Radar Parameters at SÃO LUÍS, Jicamarca and Christmas Island Equatorial Stations

    Science.gov (United States)

    de la cruz cueva, R. Y.; Paula, E. R.; Kherani, E. A.

    2013-05-01

    Equatorial Spread F (ESF) is a manifestation of ionospheric interchange instabilities in the nighttime equatorial F region. These instabilities generate plasma density irregularities with scale sizes ranging from kilometers to thousands of kilometers. The irregularities can be detected from varieties of instruments such as digisonde, coherent and incoherent scatter radars, in situ space probes, and airglow photometers. In the present study, statistics of various aspects of spread F occurrence are presented from HF/VHF radar and incoherent scatter radar located at three equatorial stations: Christmas Island (2oN, 202.6oE, 2.9oN dip latitude, VHF radar), São Luís (2.59oS, 315.8oE, 0.5oS dip latitude, HF radar) and Jicamarca (12oS, 283.1oE, 0.6oN dip latitude, ISR). The radar parameters presented here are the onset altitude and onset time of the bottom-type and plume, and the peak altitude of the plume which are known to be associated with the spread F occurrence characteristics. The study reveals novel features namely, seasonal and solar flux dependence of spread F occurrence over Christmas island /São Luís, and longitudinal dependence of spread F occurrence characteristics from these three stations based on the chosen parameters. The importance of this work lies in the radar parameter empirical model developed combining statistical analysis of three equatorial and longitudinally separated stations, which is important to study the irregularity generation mechanisms, for space weather forecasting and nowcasting programs, and improving scintillation warning models. These parameters show generally linear correlation with solar flux index (F10.7 cm) and variation with season and magnetic declination angle. The fit correlation with F10.7cm is shown as useful information to implement one spread-F development empirical model based on small scale irregularities detected by VHF radars.

  19. Tle Triangulation Campaign by Japanese High School Students as a Space Educational Project of the Ssh Consortium Kochi

    Science.gov (United States)

    Yamamoto, Masa-Yuki; Okamoto, Sumito; Miyoshi, Terunori; Takamura, Yuzaburo; Aoshima, Akira; Hinokuchi, Jin

    and sprite halos with stripes like wave structures on airglow were successfully imaged in January 2010. In this talk, four years activities of the SSH consortium Kochi will be presented by participating high-school students and teachers with their own impressions.

  20. Exploring the interior structure of Venus with balloons and satellites

    Science.gov (United States)

    Mimoun, David; Cutts, Jim; Stevenson, Dave

    2015-04-01

    Although present daily in our sky as the brightest object at dusk and dawn, many characteristics of Venus remains a mystery. Its dense atmosphere hides the surface from orbital viewing, and the extreme conditions experienced at its surface (460°C, almost 100 bar of pressure at the surface) pose a formidable challenge to the sustained survival and operation of planetary landers. Despite their sharply contrasting atmospheres, Venus is not very different from Earth in size, its composition should be very similar, its orbit is very close to be circular and it is only a little closer to the Sun ( 0.7 A.U). So what are the processes that turned the twin sister of our planet into such a different object? And how can we better understand the processes that have shaped the terrestrial planets, and to understand their formation history? With its harsh surface environment, conventional seismology on Venus, requiring seismometers to be deployed at the surface for months or even years seems impractical. In June 2014, the Keck Institute for Space Studies (KISS) at the California Institute of Technology sponsored a one-week workshop with 30 specialists in the key techniques and technologies relevant to investigating Venus's interior structure focusing on alternative approaches to seismology . As the vertical component of surface motion on Venus is very efficiently coupled into the atmosphere as infrasonic waves, especially at low frequency, several alternative approaches to detecting seismic events can be considered. Seismo-acoustic waves propagate upwards producing pressure fluctuations in the middle atmosphere of Venus and the seismic wave energy is ultimately dissipated by local heating, ionospheric perturbation, or airglow. These atmospheric perturbations can therefore be recorded either in-situ (with a barometer network, deployed on balloons floating in the cloud layer near 55 km) or remotely via optical imaging or electromagnetic sounding deployed on a spacecraft. A report

  1. TIMED Doppler Interferometer: Overview and recent results

    Science.gov (United States)

    Killeen, T. L.; Wu, Q.; Solomon, S. C.; Ortland, D. A.; Skinner, W. R.; Niciejewski, R. J.; Gell, D. A.

    2006-10-01

    The Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite carries a limb-scanning Fabry-Perot interferometer designed to perform remote-sensing measurements of upper atmosphere winds and temperatures globally. This instrument is called the TIMED Doppler Interferometer, or TIDI. This paper provides an overview of the TIDI instrument design, on-orbit performance, operational modes, data processing and inversion procedures, and a summary of wind results to date. Daytime and nighttime neutral winds in the mesosphere and lower thermosphere/ionosphere (MLTI) are measured on TIDI using four individual scanning telescopes that collect light from various upper atmosphere airglow layers on both the cold and warm sides of the high-inclination TIMED spacecraft. The light is spectrally analyzed using an ultrastable plane etalon Fabry-Perot system with sufficient spectral resolution to determine the Doppler line characteristics of atomic and molecular emissions emanating from the MLTI. The light from all four telescopes and from an internal calibration field passes through the etalon and is combined on a single image plane detector using a Circle-to-Line Interferometer Optic (CLIO). The four geophysical fields provide orthogonal line-of-sight measurements to either side of the satellite's path and these are analyzed to produce altitude profiles of vector winds in the MLTI. The TIDI wind measurements presented here are from the molecular oxygen (0-0) band, covering the altitude region 85-105 km. The unique TIDI design allows for more extended local time coverage of wind structures than previous wind-measuring instruments from high-inclination satellites. The TIDI operational performance has been nominal except for two anomalies: (1) higher than expected background white light caused by a low-level light leak and (2) ice deposition on cold optical surfaces. Both anomalies are well understood and the instrumental modes and data analysis techniques have been

  2. Dynamics and Predictability of Deep Propagating Atmospheric Gravity Waves

    Science.gov (United States)

    Doyle, J.; Fritts, D. C.; Smith, R.; Eckermann, S. D.

    2012-12-01

    An overview will be provided of the first field campaign that attempts to follow deeply propagating gravity waves (GWs) from their tropospheric sources to their mesospheric breakdown. The DEEP propagating gravity WAVE experiment over New Zealand (DEEPWAVE-NZ) is a comprehensive, airborne and ground-based measurement and modeling program focused on providing a new understanding of GW dynamics and impacts from the troposphere through the mesosphere and lower thermosphere (MLT). This program will employ the new NSF/NCAR GV (NGV) research aircraft from a base in New Zealand in a 6-week field measurement campaign in June-July 2014. The NGV will be equipped with new lidar and airglow instruments for the DEEPWAVE measurement program, providing temperatures and vertical winds spanning altitudes from immediately above the NGV flight altitude (~13 km) to ~100 km. The region near New Zealand is chosen since all the relevant GW sources occur strongly here, and upper-level winds in austral winter permit GWs to propagate to very high altitudes. Given large-amplitude GWs that propagate routinely into the MLT, the New Zealand region offers an ideal natural laboratory for studying these important GW dynamics and effects impacting weather and climate over a much deeper atmospheric layer than previous campaigns have attempted (0-100 km altitude). The logistics of making measurements in the vicinity of New Zealand are potentially easier than from the Andes and Drake Passage region. A suite of GW-focused modeling and predictability tools will be used to guide NGV flight planning to GW events of greatest scientific significance. These models will also drive scientific interpretation of the GW measurements, together providing answers to the key science questions posed by DEEPWAVE about GW dynamics, morphology, predictability and impacts from 0-100 km. Preliminary results will be presented from high-resolution and adjoint models applied over areas featuring deep wave propagation. The high

  3. Thermospheric winds and temperatures above Mawson, Antarctica, observed with an all-sky imaging, Fabry-Perot spectrometer

    Directory of Open Access Journals (Sweden)

    C. Anderson

    2009-05-01

    Full Text Available A new all-sky imaging Fabry-Perot spectrometer has been installed at Mawson station (67°36' S, 62°52' E, Antarctica. This instrument is capable of recording independent spectra from many tens of locations across the sky simultaneously. Useful operation began in March 2007, with spectra recorded on a total of 186 nights. Initial analysis has focused on the large-scale daily and average behavior of winds and temperatures derived from observations of the 630.0 nm airglow line of atomic oxygen, originating from a broad layer centered around 240 km altitude, in the ionospheric F-region.

    The 1993 Horizontal Wind Model (HWM93, NRLMSISE-00 atmospheric model, and the Coupled Thermosphere/Ionosphere Plasmasphere (CTIP model were used for comparison. During the geomagnetically quiet period studied, observed winds and temperatures were generally well modelled, although temperatures were consistently higher than NRLMSISE-00 predicted, by up to 100 K. CTIP temperatures better matched our data, particularly later in the night, but predicted zonal winds which were offset from those observed by 70–180 ms−1 westward. During periods of increased activity both winds and temperatures showed much greater variability over time-scales of less than an hour. For the active night presented here, a period of 45 min saw wind speeds decrease by around 180 ms−1, and temperatures increase by approximately 100 K. Active-period winds were poorly modelled by HWM93 and CTIP, although observed median temperatures were in better agreement with NRLMSISE-00 during such periods.

    Average behavior was found to be generally consistent with previous studies of thermospheric winds above Mawson. The collected data set was representative of quiet geomagnetic and solar conditions. Geographic eastward winds in the afternoon/evening generally continued until around local midnight, when winds turned equatorward. Geographic meridional and

  4. Detection of Callisto's oxygen atmosphere with the Hubble Space Telescope

    Science.gov (United States)

    Cunningham, Nathaniel J.; Spencer, John R.; Feldman, Paul D.; Strobel, Darrell F.; France, Kevin; Osterman, Steven N.

    2015-07-01

    We report the result of a search for evidence of an O2-dominated atmosphere on Callisto, using the high far-ultraviolet sensitivity of the Hubble Space Telescope Cosmic Origins Spectrograph (COS). Observations of Callisto's leading/Jupiter-facing hemisphere show, for the first time, variable-strength atomic oxygen (O I) emissions with brightness up to 4.7 ± 0.7 Rayleighs for the O I 1304 Å triplet and 1.9 ± 0.4 Rayleighs for the O I 1356 Å doublet, averaged over the 2.5 arcsec. diameter COS aperture. Because the observations were made in Earth's shadow, and are brighter than expected emission from nighttime geocoronal airglow or other plausible sources, we are confident that they originate from Callisto or its immediate vicinity. In addition, COS's limited (∼1 arcsec) spatial resolution implies a 2σ detection of excess 1356 Å emission concentrated on the disk of Callisto itself, with brightness 3.2 ± 1.6 Rayleighs. The (O I 1356 Å)/(O I 1304 Å) emission ratio from Callisto's disk favors dissociative excitation of O2, suggesting that O2 is the dominant atmospheric component rather than other possible oxygen-bearing alternatives. Photoelectrons, rather than magnetospheric electrons, are the most likely source of the dissociative excitation. This detection yields an O2 column density of ∼4 × 1015 cm-2 on the leading/Jupiter facing hemisphere, which implies that Callisto's atmosphere is collisional and is the fourth-densest satellite atmosphere in the Solar System, in addition to being the second-densest O2-rich collisional atmosphere in the Solar System, after Earth. Longitudinal variations in published densities of ionospheric electrons suggest that O2 densities in Callisto's trailing hemisphere, which we did not observe, may be an order of magnitude greater. The aperture-filling emissions imply that there is also an extended corona of predominantly O I 1304 Å emission around Callisto, with observed strength of 1-4 Rayleighs, likely due to solar

  5. On the temporal variability of the OH* emission layer at the mesopause: a study based on SD-WACCM4 and SABER

    Directory of Open Access Journals (Sweden)

    S. Kowalewski

    2014-01-01

    Full Text Available Airglow observations are a fundamental tool to study the mesospheric part of the atmosphere. In particular the OH* emission layer is subject of many theoretical and observational studies. The choice of different transition bands of the OH* emission can introduce systematic differences between these studies, hence a profound knowledge of these differences is required for comparison. One systematic difference is given by the vertical displacements between OH* profiles due to different transition bands. A previous study has shown that the vertical displacement is highly sensitive to quenching with atomic oxygen. In this work we follow up this idea by investigating the diurnal as well as the seasonal response of OH* to changes in concentrations of atomic and molecular oxygen, the two most effective quenching species of OH*. For this task we employ a quenching model to calculate vertical OH* concentration profiles from simulations made with the SD-WACCM4 chemistry transport model. From this approach we find that despite the strong impact of O and O2 quenching on the vertical OH* structure, a considerable variability between the vertical displacements of different OH* transition bands is also induced by the natural variability of the O3 and H profiles, which primarily participate in the formation of the mesospheric OH* layer. This in particular applies for the diurnal evolution of the vertical displacements, which cannot be explained by changes in abundances of OH* quenching species only. On the other hand, vertical displacements between OH* transition bands and the amount of effective O and O2 quenching show a coherent semi-annual oscillation at lower latitudes that is in phase with the seasonal variability of the diurnal migrating tide. In particular the role of O2 quenching shows a new aspect of the semi-annual oscillation that, to our knowledge, has not been discussed before. By comparison with limb radiance observations from the SABER

  6. Spread F – an old equatorial aeronomy problem finally resolved?

    Directory of Open Access Journals (Sweden)

    R. F. Woodman

    2009-05-01

    Full Text Available One of the oldest scientific topics in Equatorial Aeronomy is related to Spread-F. It includes all our efforts to understand the physical mechanisms responsible for the existence of ionospheric F-region irregularities, the spread of the traces in a night-time equatorial ionogram – hence its name – and all other manifestations of the same. It was observed for the first time as an abnormal ionogram in Huancayo, about 70 years ago. But only recently are we coming to understand the physical mechanisms responsible for its occurrence and its capricious day to day variability. Several additional techniques have been used to reveal the spatial and temporal characteristics of the F-region irregularities responsible for the phenomenon. Among them we have, in chronological order, radio star scintillations, trans-equatorial radio propagation, satellite scintillations, radar backscatter, satellite and rocket in situ measurements, airglow, total electron content techniques using the propagation of satellite radio signals and, recently, radar imaging techniques. Theoretical efforts are as old as the observations. Nevertheless, 32 years after their discovery, Jicamarca radar observations showed that none of the theories that had been put forward could explain them completely. The observations showed that irregularities were detected at altitudes that were stable according to the mechanisms proposed. A breakthrough came a few years later, again from Jicamarca, by showing that some of the "stable" regions had become unstable by the non-linear propagation of the irregularities from the unstable to the stable region of the ionosphere in the form of bubbles of low density plasma. A problem remained, however; the primary instability mechanism proposed, an extended (generalized Rayleigh-Taylor instability, was too slow to explain the rapid development seen by the observations. Gravity waves in the neutral background have been proposed as a seeding mechanism to

  7. Utah Valley University Field Station at Capitol Reef National Park: A Venue for Improved Student Learning and Retention

    Science.gov (United States)

    Nielsen, K.; Schultz, M.; Williams, B.; Gay, J.; Johnson, S.; Dunn, P.

    2015-12-01

    faint upper atmospheric airglow emissions. This presentation details the upper atmospheric undergraduate educational program at UVU, and will also include a section regarding the newly established interdisciplinary air pollution educational program, and how communities outside of UVU can use the facility.

  8. Recent Activities on the Embrace Space Weather Regional Warning Center: the New Space Weather Data Center

    Science.gov (United States)

    Denardini, Clezio Marcos; Dal Lago, Alisson; Mendes, Odim; Batista, Inez S.; SantAnna, Nilson; Gatto, Rubens; Takahashi, Hisao; Costa, D. Joaquim; Banik Padua, Marcelo; Campos Velho, Haroldo

    2016-07-01

    the ionospheric profiles in two equatorial sites and in two low latitude sites; (b) several solar radio telescopes to monitor solar activity (under development); (c) the matrix of the GNSS TEC map over South America; (d) the Embrace Airglow All-sky Imagers Network (Embrace GlowNet); and (d) the Embrace Magnetometer Network (Embrace Magnet), all of them in South America. Also, the system allows subscription to space weather alerts and reports. Contacting Author: C. M. Denardini (clezio.denardin@inpe.br)

  9. TIMED Science With the Space Physics Data Facility's (SPDF) Data and Models Services

    Science.gov (United States)

    Bilitza, D.; McGuire, R. E.; Kovalick, T.; Candey, R. M.; Leckner, H.

    2005-12-01

    NASA's Space Physics Data Facility (SPDF) provides access to a large volume of data and models that are of relevance to Ionospheric, Thermospheric and Mesospheric (ITM) physics and to the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission in particular. SPDF has developed a number of web systems to facilitate user access to important data and model resources and is making these services available through Web Services (or Application Programming Interfaces, API) directly to applications such as VxOs. The Coordinated Data Analysis web (CDAWeb) provides access to data from most of NASA's currently operating space science satellites and many of the earlier missions covering the full expanse of the Earth-Sun system from mesosphere to heliosphere. CDAWeb lets user plot data using a wide range of parameter display options including mapped images and movies; capabilities also include parameter listings and data downloads in CDF and ASCII format. TIMED data display options, for example, include GUVI airglow intensities and TIDI neutral wind vectors in a transverse Mercator projection that shows simultaneously both poles and the equatorial region. Coupled with CDAWeb's comprehensive coverage of solar wind parameters the TIMED data will provide new insights into the ITM response to solar and magnetic storms. SPDF's SSCWeb interface enables users to plot orbits for the majority of space physics satellites and to query for magnetic field line conjunctions between multiple spacecraft and ground stations and for magnetic region occupancy and thus enables coordinates science investigation between TIMED and CEDAR ground stations. Recently an Interactive 3-D orbit viewer was added to SSCWeb. Access to legacy data from older ITM satellite missions is provided through the ATMOWeb browse and download system enabling the study of solar cycle effects on ITM parameters. SPDF's Modelweb service is the front-end to a unique collection of solar-terrestrial databased

  10. Identification of gravity wave sources using reverse ray tracing over Indian region

    Directory of Open Access Journals (Sweden)

    M. Pramitha

    2014-07-01

    Full Text Available Reverse ray tracing method is successfully implemented for the first time in the Indian region for identification of the sources and propagation characteristics of the gravity waves observed using airglow emissions from Gadanki (13.5° N, 79.2° E and Hyderabad (17.5° N, 78.5° E. Wave amplitudes are also traced back for these wave events by including both radiative and diffusive damping. Background temperature and wind data obtained from MSISE-90 and HWM-07 models, respectively, are used for the ray tracing. For Gadanki region suitability of these models is tested. Further, a climatological model of background atmosphere for Gadanki region has been developed using a long-term of nearly 30 years of observations available from a variety of ground-based (MST radar, radiosonde, MF radar, rocket-, and satellite-borne measurements. For considering real-time atmospheric inputs, ERA-Interim products are utilized. By this reverse ray method, the source locations for nine wave events could be identified to be in the upper troposphere, whereas, for five other events the waves seem to have been ducted in the mesosphere itself. Uncertainty in locating the terminal points in the horizontal direction is estimated to be within 50–100 and 150–300 km for Gadanki and Hyderabad wave events, respectively. This uncertainty arises mainly due to non-consideration of the day-to-day variability in tidal amplitudes. As no convection in-and-around the terminal points are noticed, it is unlikely to be the source. Interestingly, large (~9 m s−1 km−1 vertical shear in the horizontal wind is noted near the ray terminal points (at 10–12 km altitude and is identified to be the source for generating the nine wave events. Conditions prevailing at the terminal points for each of the 14 events are also provided. These events provide leads to a greater understanding of the tropical lower and upper atmospheric coupling through gravity waves.

  11. Human Settlements in the South-Central U.S., Viewed at Night from the International Space Station

    Science.gov (United States)

    Dawson, Melissa; Evans, Cynthia; Stefanov, William; Wilkinson, M. Justin; Willis, Kimberly; Runco, Susan

    2012-01-01

    A recent innovation of astronauts observing Earth from the International Space Station (ISS) is documenting human footprints by photographing city lights at night time. One of the earliest night-time images from the ISS was the US-Mexico border at El Paso-Ciudad Juarez. The colors, patterns and density of city lights document the differences in the cultural settlement patterns across the border region, as well as within the urban areas themselves. City lights help outline the most populated areas in settlements around the world, and can be used to explore relative population densities, changing patterns of urban/suburban development, transportation networks, spatial relationship to geographic features, and more. The data also provides insight into parameters such as surface roughness for input into local and regional climate modeling and studies of light pollution. The ground resolution of night-time astronaut photography from the ISS is typically an order of magnitude greater than current Defense Meteorological Satellite Program (DMSP) data, and therefore can serve as a "zoom lens" for selected urban areas. Current handheld digital cameras in use on the ISS, optimized for greater light sensitivity, provide opportunities to obtain new detailed imagery of atmospheric phenomena such as airglow, aurora, and noctilucent clouds in addition to documenting urban patterns. ISS astronauts have taken advantage of increasingly sensitive digital cameras to document the world at night in unprecedented detail. In addition, the capability to obtain time-lapse imagery from fixed cameras has been exploited to produce dynamic videos of both changing surface patterns around the world and atmospheric phenomena. We will profile some spectacular images of human settlements over the South-Central U.S., and contrast with other images from around the world. More data can be viewed at http://eol.jsc.nasa.gov/Videos/CrewEarthObservationsVideos/. US-Mexico border is obvious by the different

  12. Distributions of TEC Fluctuations and Losses of Lock Associated with Equatorial Plasma Bubbles

    Science.gov (United States)

    Nakata, H.; Kikuchi, H.; Tsugawa, T.; Otsuka, Y.; Takano, T.; Shimakura, S.; Shiokawa, K.; Ogawa, T.

    2009-12-01

    Equatorial plasma bubbles (EPBs) are local depletions of the electron density in the ionosphere. Due to field-aligned irregularities (FAIs) with various spatial scales, EPBs affect wide-band radio waves and cause scintillations in GPS navigation system. Strong scintillation can cause a GPS receiver to lose lock on GPS signals because of rapid variations of signal amplitude and phase, and limit the availability of carrier phase measurements. Since the scintillation is caused by Fresnel diffraction, the spatial scale of FAIs that causes the scintillation of GPS signals is about 2-300 m. Therefore, loss of phase lock (LOL) on GPS signals is a reference of hundred-meter-scale FAIs. As EPBs are also associated with fluctuations of the total electron content (TEC), the enhancement of Rate of TEC change index (ROTI) occurs around EPBs. Assuming that the altitude of the ionosphere is about 400 km, the velocity of the pierce point of the GPS radio wave at the ionospheric altitude is approximately 70 m/s around the zenith. Thus, ROTI averaged during 5 minutes is a reference of ten-kilometer-scale fluctuations. In this study, we analyzed LOL and 5-min. ROTI associated with EPBs to examine the spatial and temporal scales of electron density disturbances associated with EPBs. We selected 11 EPBs from 630-nm airglow images obtained by all-sky imager at Sata, Japan, in 2001. LOL and ROTI are obtained from GPS data from GPS Earth Observation Network (GEONET) of Japan, which consists of more than 1000 GPS receivers. As a result, it is shown that both LOL and the enhancement of ROTI are observed in 8 events out of 11 events. The distributions of LOL are approximately consistent with the areas in which the ionospheric electron density is depleted. The enhancements of ROTI are observed in the vicinities of EPBs. The enhancement of ROTI expands especially in the west side of EPBs. After the EPBs pass through, therefore, LOLs are vanished but the enhancements of ROTI last a while. This

  13. 铟镓砷焦平面阵列在微光夜视应用中的潜力及前景%The Potential and Prospect of Indium Gallium Arsenide Focal Plane Array Applied to Low Light Level Night Vision

    Institute of Scientific and Technical Information of China (English)

    潘京生; 孙建宁; 金戈; 任玲; 毛汉祺; 顾燕; 郭一亮; 苏德坦

    2014-01-01

    得益于夜气辉在短波红外(SWIR)0.9~1.7μm波段的自然辐射数十倍强于夜天空在可见光和近红外(NIR)0.4~0.9μm波段的辐射,SWIR成像成为应用于微光条件下的成像探测的最佳选择,由晶格匹配In0.53Ga0.47As/InP制作InGaAs焦平面阵列(Focal Plane Array,FPA),灵敏于0.9~1.7μm波段,在整个响应波段具有超过70%的量子效率,和室温非制冷工作的极低的暗电流。通过减薄基底,还可将InGaAs FPA的短波限延伸至可见光波段的0.4μm。最近几年,超低暗电流、低读出噪声、大面阵和小像素尺寸的InGaAs FPA的开发取得了实质性的进展,特别是暗电流得到了数量级的降低,InGaAs FPA探测器已经显露出应用于微光夜视的极大潜力,并且还通过采用更复杂的温度相关的非均匀校正算法实现了无TEC的低功耗工作,基于超低噪声的密集阵列InGaAs FPA的SWIR成像技术有望成为新一代夜视技术的一个重要组成部份。%The shortwave infrared(SWIR)spectral irradiance in the 0.9μm to 1.7μm band which caused by night airglow is several ten times stronger than the irradiance in the visible and near infrared realm of 0.4μm to 0.9μm of the night sky, so SWIR imaging is the best choice for the imaging detection under low light level condition. The Indium Gallium Arsenide(InGaAs)focal plane array(FPA)sensors based on lattice matched In0.53Ga0.47As/InP is sensitive to SWIR light whose wavelength is from 0.9μm to 1.7μm, matching the spectral irradiance caused by night airglow, and have exceeded quantum efficiency of 70%over whole response spectral range, as well as with very low dark current while working at room temperature. Removing the InP substrate from the FPA allows extending cutoff wavelength to visible region of 0.4μm. The work on InGaAs FPA with ultra low dark current, low readout noise, large format and small pixel size has been progressing substantially in

  14. Thermal structure and CO distribution for the Venus mesosphere/lower thermosphere: 2001-2009 inferior conjunction sub-millimeter CO absorption line observations

    Science.gov (United States)

    Clancy, R. Todd; Sandor, Brad J.; Moriarty-Schieven, Gerald

    2012-02-01

    Sub-millimeter 12CO (346 GHz) and 13CO (330 GHz) line absorptions, formed in the mesosphere and lower thermosphere of Venus (70-120 km), have been mapped across the nightside Venus disk during 2001-2009 inferior conjunctions, employing the James Clerk Maxwell Telescope (JCMT). Radiative transfer analysis of these thermal line absorptions supports temperature and CO mixing profile retrievals, as well as Doppler wind fields (described in the companion paper, Clancy et al., 2012). Temporal sampling over the hourly, daily, weekly and interannual timescales was obtained over 2001-2009. On timescales inferred as several weeks, we observe changes between very distinctive CO and temperature nightside distributions. Retrieved nightside CO, temperature distributions for January 2006 and August 2007 observations display strong local time, latitudinal gradients consistent with early morning (2-3 am), low-to-mid latitude (0-40NS) peaks of 100-200% in CO and 20-30 K in temperature. The temperature increases are most pronounced above 100 km altitudes, whereas CO variations extend from 105 km (top altitude of retrieval) down to below 80 km in the mesosphere. In contrast, the 2004 and 2009 periods of observation display modest temperature (5-10 K) and CO (30-60%) increases, that are centered on antisolar (midnight) local times and equatorial latitudes. Doppler wind derived global (zonal and should be SSAS) circulations from the same data do not exhibit variations correlated with these CO, temperature short-term variations. However, large-scale residual wind fields not fit by the zonal, SSAS circulations are observed in concert with the strong temperature, CO gradients observed in 2006 and 2007 (Clancy et al., 2010). These short term variations in nightside CO, temperature distributions may also be related to observed nightside variations in O 2 airglow (Hueso, H., Sánchez-Lavega, A., Piccioni, G., Drossart, P., Gérard, J.C., Khatuntsev, I., Zasova, L., Migliorini, A. [2008]. J

  15. Laboratory Study of O2(b1Σ g+, υ = 1) Collisional Removal at Thermospheric Temperatures

    Science.gov (United States)

    Wouters, E. R.; Pejaković, D. A.; Phillips, K. E.; Kalogerakis, K. S.

    2003-12-01

    In the Earth's thermosphere, energy transfer from O(1D) to O2 generates oxygen molecules in the υ = 0 and 1 levels of the O2(b1Σg+) state. The emissions in the O2(b1Σ g+ - X3Σ g-) system (Atmospheric Band) present a major component of the Earth's airglow. Interpretation of the measured intensities of O2 Atmospheric Band emissions can yield altitude profiles of oxygen atom density and local temperature in the lower thermosphere. To achieve this goal accurate laboratory measurements of the collisional removal rate coefficients of O2(b, υ = 1) and their temperature dependence are essential. Atmospheric observations suggest that the relevant colliders for the removal of O2(b, υ = 1) in the lower thermosphere are O2 and O(3P). We report measurements of the rate coefficients for the collisional removal of O2(b, υ = 1) by O2, N2, and CO2, at temperatures in the range 300--1000 K. A state-specific two-laser technique is used, in which the visible output of the first laser directly excites O2 to O2(b, υ = 1), and the ultraviolet output of the second laser probes the O2(b, υ = 1) population by resonantly enhanced multiphoton ionization via the υ= 4 level of the d1Π g Rydberg state. The temporal evolution of the O2(b, υ = 1) population is monitored by varying the time delay between the two laser pulses. The rate coefficient of the collisional removal of O2(b, υ = 1) by O2 increases monotonically with temperature from about 1.5 x 10-11 cm3 s-1 to about 6*E-11 cm3 s-1 in the range 300--1000 K. Experiments with colliders N2 and CO2 determine the upper limits for the removal rate coefficients of O2(b, υ = 1) by N2 and CO2 to be 2 orders of magnitude smaller. This work extends previous studies of O2(b, υ = 1) at room and low temperatures.1,2 We are currently planning experiments to investigate the collisional removal of O2(b, υ = 1) by O atoms. This study was supported by the NSF's Grant ATM-0209229. The participation of K. Phillips in this project was funded by

  16. Subauroral red arcs as a conjugate phenomenon: comparison of OV1-10 satellite data with numerical calculations

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    Full Text Available This study compares the OV1-10 satellite measurements of the integral airglow intensities at 630 nm in the SAR arc regions observed in the northern and southern hemisphere as a conjugate phenomenon, with the model results obtained using the time-dependent one-dimensional mathematical model of the Earth ionosphere and plasmasphere (the IZMIRAN model during the geomagnetic storm of the period 15–17 February 1967. The major enhancements to the IZMIRAN model developed in this study are the inclusion of He+ ions (three major ions: O+, H+, and He+, and three ion temperatures, the updated photochemistry and energy balance equations for ions and electrons, the diffusion of NO+ and O2+ ions and O(1D and the revised electron cooling rates arising from their collisions with unexcited N2, O2 molecules and N2 molecules at the first vibrational level. The updated model includes the option to use the models of the Boltzmann or non-Boltzmann distributions of vibrationally excited molecular nitrogen. Deviations from the Boltzmann distribution for the first five vibrational levels of N2 were calculated. The calculated distribution is highly non-Boltzmann at vibrational levels v > 2 and leads to a decrease in the calculated electron density and integral intensity at 630 nm in the northern and southern hemispheres in comparison with the electron density and integral intensity calculated using the Boltzmann vibrational distribution of N2. It is found that the intensity at 630 nm is very sensitive to the oxygen number densities. Good agreement between the modelled and measured intensities is obtained provided that at all altitudes of the southern hemisphere a reduction of about factor 1.35 in MSIS-86 atomic oxygen densities is included in the IZMIRAN model with the non-Boltzmann vibrational distribution of N2

  17. Expected first-order effects of a notional equatorial ring on Earth's night sky: a geometric consideration

    Science.gov (United States)

    Hancock, L. O.

    2013-12-01

    : a schema of ring effects on the southern sky: (i) extinction of extra-terrestrial light between celestial equator and horizon; (ii) brightening of extra-terrestrial light via light-through-dust effects near the southern horizon; and (iii) reflection of sunlight from celestial equator to horizon. These effects would be modulated by season (due to ring self-shadowing) and hour of the night (because of Earth's shadow). We suggest that the expected effects are not "missing" at all - similar effects are well known to observers but are taken to be fully accounted for by skyglow, airglow and light pollution, qualitatively similar phenomena that certainly exist. We conclude that ground-based observers' non-identification of an equatorial ring is not a counter-indicator of a ring's existence. As far as this consideration goes, the question of an Earth ring system is open.

  18. NCU-SWIP Space Weather Instrumentation Payload - Intelligent Sensors On Efficient Real-Time Distributed LUTOS

    Science.gov (United States)

    Yeh, Tse-Liang; Dmitriev, Alexei; Chu, Yen-Hsyang; Jiang, Shyh-Biau; Chen, Li-Wu

    The NCU-SWIP - Space Weather Instrumentation Payload is developed for simultaneous in-situ and remote measurement of space weather parameters for cross verifications. The measurements include in-situ electron density, electron temperature, magnetic field, the deceleration of satellite due to neutral wind, and remotely the linear cumulative intensities of oxygen ion air-glows at 135.6nm and 630.0nm along the flight path in forward, nader, and backward directions for tomographic reconstruction of the electron density distribution underneath. This instrument package is suitable for micro satellite constellation to establish nominal space weather profiles and, thus, to detect abnormal variations as the signs of ionospheric disturbances induced by severe atmospheric weather, or earth quake - mantle movement through their Lithosphere-Atmosphere-Ionosphere Coupling Mechanism. NCU-SWIP is constructed with intelligent sensor modules connected by common bus with their functionalities managed by an efficient distributed real-time system LUTOS. The same hierarchy can be applied to the level of satellite constellation. For example SWIP's in a constellation in coordination with the GNSS Occultation Experiment TriG planned for the Formosa-7 constellation, data can be cross correlated for verification and refinement for real-time, stable and reliable measurements. A SWIP will be contributed to the construction of a MAI Micro Satellite for verification. The SWIP consists of two separate modules: the SWIP main control module and the SWIP-PMTomo sensor module. They are respectively a 1.5kg W120xL120xH100 (in mm) box with forward facing 120mmPhi circular disk probe on a boom top edged at 470mm height and a 7.2kg W126xL590x372H (in mm) slab containing 3 legs looking downwards along the flight path, while consuming the maximum electricity of 10W and 12W. The sensors are 1) ETPEDP measuring 16bits floating potentials for electron temperature range of 1000K to 3000K and 24bits electron

  19. Multi-wavelength imaging observations of plasma depletions over Kavalur, India

    Directory of Open Access Journals (Sweden)

    H. S. S. Sinha

    small regions in the northern part of the image and then in about 90 min time, they attain their peak brightness and encompass the entire field-of-view in about 2 hrs 30 min. In some cases, brightness patterns contain one or two well developed plasma depletions within them. (f The brightness patterns reported here differ from the earlier observations in that they do not show any differential behaviour in the direction of movement before and after the midnight, and that they are present for extended periods of time as large as 6 hrs.

    Key words. Atmospheric composition and structure (air-glow and aurora; Ionosphere (equatorial ionosphere; ionospheric irregularities

  20. Obituary: Herbert Gursky, 1930-2006

    Science.gov (United States)

    Doschek, George; Dahlburg, Jill

    2007-12-01

    imaging telescope (EIT) on the ESA/NASA Solar and Heliospheric Observatory. These experiments have shed considerable light on how solar activity affects the near-Earth environment with many potential space weather applications. In high-energy astronomy, Dr. Gursky made many contributions. He provided scientific oversight for the Advanced Research and Global Observation Satellite (ARGOS) Space Test Program spacecraft that contained five NRL instruments: the Unconventional Stellar Aspect (USA) experiment, the Global Imaging Monitor of the Ionosphere (GIMI), the High Resolution Airglow/Aurora Spectroscopy (HIRAAS) experiment, the Extreme Ultraviolet Imaging Photometer (EUVIP), and the Coherent Electromagnetic Radio Tomography (CERTO) instrument. He continued his interest in X-ray astronomy with the USA experiment, which obtained observations of many celestial sources such as galactic binary X-ray sources and pulsars. Always with an eye toward applications, Dr. Gursky was interested in using X-ray sources, specifically X-ray pulsars, as precise clocks to provide spacecraft with autonomous timing and navigation. Dr. Gursky also supported research in gamma ray astrophysics, such as the development of NRL's Oriented Scintillation Spectrometer Experiment (OSSE) for the NASA Compton Gamma Ray Observatory (CGRO) satellite, and analysis of solar flare gamma ray spectra obtained from the NASA Solar Maximum Mission. In atmospheric science, Dr. Gursky particularly encouraged practical applications of basic research. He recognized the importance of remote sensing for space weather, which resulted in the development at NRL of operational ultraviolet sensors on Defense Meteorological Satellite Program (DMSP) spacecraft that are now providing environmental data products to the Air Force Space Weather Agency. He initiated a program in middle atmosphere research that has been enormously successful and has spawned numerous experimental and theoretical advances, such as the Middle Atmosphere