References of "Gunson, Michael R"
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See detailAtmospheric Trace Molecule Spectroscopy (ATMOS) experiment version 3 data retrievals
Irion, Fredrick W.; Gunson, Michael R.; Toon, Geoff C. et al

in Applied Optics (2002), 41(33), 6968-6979

Version 3 of the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment data set for some 30 trace and minor gas profiles is available. From the IR solar-absorption spectra measured during four Space ... [more ▼]

Version 3 of the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment data set for some 30 trace and minor gas profiles is available. From the IR solar-absorption spectra measured during four Space Shuttle missions (in 1985, 1992, 1993, and 1994), profiles from more than 350 occultations were retrieved from the upper troposphere to the lower mesosphere. Previous results were unreliable for tropospheric retrievals, but with a new global-fitting algorithm profiles are reliably returned down to altitudes as low as 6.5 km (clouds permitting) and include notably improved retrievals of H2O, CO, and other species. Results for stratospheric water are more consistent across the ATMOS spectral filters and do not indicate a net consumption of H-2 in the upper stratosphere. A new sulfuric-acid aerosol product is described. An overview of ATMOS Version 3 processing is presented with a discussion of estimated uncertainties. Differences between these Version 3 and previously reported Version 2 ATMOS results are discussed. Retrievals are available at http://atmos.jpl.nasa.gov/atmos. (C) 2002 Optical Society of America. [less ▲]

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See detailATMOS version 3 water vapor measurements: Comparisons with observations from two ER-2 Lyman-alpha hygrometers, MkIV, HALOE, SAGE II, MAS, and MLS
Michelsen, Hope A.; Manney, Gloria L.; Irion, Fredrick W. et al

in Journal of Geophysical Research. Atmospheres (2002), 107(D3),

[1] We have compared a new version of Atmospheric Trace Molecule Spectroscopy Experiment (ATMOS) retrievals (version 3) of stratospheric and mesospheric water vapor with observations from shuttleborne ... [more ▼]

[1] We have compared a new version of Atmospheric Trace Molecule Spectroscopy Experiment (ATMOS) retrievals (version 3) of stratospheric and mesospheric water vapor with observations from shuttleborne, satelliteborne, balloonborne, and aircraftborne instruments. These retrievals show agreement to within 5% with the MkIV observations in the middle and lower stratosphere. ATMOS agrees with the National Oceanic and Atmospheric Administration (NOAA) Lyman-alpha hygrometer to within 5% except for features with spatial scales less than the vertical resolution of ATMOS (such as the lower stratospheric seasonal cycle). ATMOS observations are 10-16% lower than measurements from the Harvard Lyman-alpha hygrometer in the lower stratosphere and are 7-14% higher than those from the Microwave Limb Sounder (MLS; prototype version 0104) throughout most of the stratosphere. Agreement is within 7% with the Millimeter-Wave Atmospheric Sounder (MAS; version 20) in the middle and upper stratosphere, but differences are closer to 13% in the lower stratosphere. Throughout the stratosphere, agreement is within 8% with the Halogen Occultation Experiment (HALOE; version 19). ATMOS data from 1994 show agreement with the Stratospheric Aerosol and Gas Experiment II (SAGE II; version 6) values to within 8% in the middle stratosphere, but ATMOS observations are systematically higher than those from SAGE II by as much as 41% in the lower stratosphere. In contrast, ATMOS 1985 values are systematically similar to50% lower than SAGE II values from sunset occultations in the lower stratosphere near 70 hPa but appear to be in better agreement with sunrise occultations. Version 3 retrievals in the upper stratosphere and lower mesosphere are typically 5-10% lower than version 2 values between 1 and 0.05 hPa. This reduction improves agreement with HALOE, MAS, and MLS upper atmospheric observations, but ATMOS values still tend to be higher than values from these instruments in the middle mesosphere. Agreement among the instruments compared here (except for SAGE II) is generally within 15% in the middle to lower stratosphere and mesosphere and within 10% in the middle to upper stratosphere. At altitudes near 30 km, all instruments (including SAGE II) agree to within 10%. [less ▲]

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See detailATMOS/ATLAS-3 measurements of stratospheric chlorine and reactive nitrogen partitioning inside and outside the November 1994 Antarctic vortex
Rinsland, Curtis P.; Gunson, Michael R.; Salawitch, R. J. et al

in Geophysical Research Letters (1996), 23(17), 2365-2368

Partitioning between HCl and ClONO2 and among the main components of the reactive nitrogen family (NO, NO2, HNO3, ClONO2, N2O5, and HO2NO2) has been studied inside and outside the Antarctic stratospheric ... [more ▼]

Partitioning between HCl and ClONO2 and among the main components of the reactive nitrogen family (NO, NO2, HNO3, ClONO2, N2O5, and HO2NO2) has been studied inside and outside the Antarctic stratospheric vortex based on ATMOS profiles measured at sunrise during the 3-12 November 1994 ATLAS-3 Shuttle mission. Elevated mixing ratios of HCl in the lower stratosphere with a peak of similar to 2.9 ppbv (10(-9) parts per volume) were measured inside the vortex near 500 K potential temperature (similar to 19 km). Maximum ClONO2 mixing ratios of similar to 1.2, similar to 1.4, and similar to 0.9 ppbv near 700 K (similar to 25 km) were measured inside, at the edge, and outside the vortex, respectively. Model calculations reproduce the higher levels of HCl and NOx (NO + NO2) inside the lower stratospheric vortex both driven by photochemical processes initiated by low O3. The high HCl at low O3 results from chemical production of HCl via the reaction of enhanced Cl with CH4, limited production of ClONO2, and the descent of inorganic chlorine from higher altitudes. [less ▲]

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See detailValidation of hydrogen fluoride measurements made by the Halogen Occultation Experiment from the UARS platform
Russell, James M.; Deaver, Lance E.; Luo, Mingzhao et al

in Journal of Geophysical Research. Atmospheres (1996), 101(D6), 10163--10174

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See detailValidation of hydrogen chloride measurements made by the Halogen Occultation Experiment from the UARS platform
Russell, James M.; Deaver, Lance E.; Luo, Mingzhao et al

in Journal of Geophysical Research. Atmospheres (1996), 101(D6), 10151--10162

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See detailThe Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment: Deployment on the ATLAS Space Shuttle missions
Gunson, Michael R.; Abbas, M. M.; Abrams, M. C. et al

in Geophysical Research Letters (1996), 23(17), 2333-2336

The ATMOS Fourier transform spectrometer was flown for a fourth time on the Space Shuttle as part of the ATLAS-3 instrument payload in November 1994. More than 190 sunrise and sunset occultation events ... [more ▼]

The ATMOS Fourier transform spectrometer was flown for a fourth time on the Space Shuttle as part of the ATLAS-3 instrument payload in November 1994. More than 190 sunrise and sunset occultation events provided measurements of more than 30 atmospheric trace gases at latitudes 3-49 degrees N and 65-72 degrees S, including observations both inside and outside the Antarctic polar vortex. The instrument configuration, data retrieval methodology, and mission background are described to place in context analyses of ATMOS data presented in this issue. [less ▲]

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See detailHeterogeneous conversion of N2O5 to HNO3 in the post-Mount Pinatubo eruption stratosphere
Rinsland, Curtis P.; Gunson, Michaël R.; Abrams, M. C. et al

in Journal of Geophysical Research (1994), 99(D4), 8213-8219

Simultaneous stratospheric volume mixing ratio (VMR) profiles of dinitrogen pentoxide (N2O5) and nitric acid (HNO3) at sunrise between 25-degrees-N and 15-degrees-S latitude and profiles of HNO3 at sunset ... [more ▼]

Simultaneous stratospheric volume mixing ratio (VMR) profiles of dinitrogen pentoxide (N2O5) and nitric acid (HNO3) at sunrise between 25-degrees-N and 15-degrees-S latitude and profiles of HNO3 at sunset between 42-degrees-S and 53-degrees-S latitude have been derived from 0.01 cm-1 resolution infrared solar occultation spectra recorded 9 1/2 months after the massive eruption of the Mount Pinatubo volcano in the Philippine Islands. The measurements were obtained by the atmospheric trace molecule spectroscopy (ATMOS) Fourier transform spectrometer during the ATLAS 1 shuttle mission (March 24 to April 2, 1992). The measured HNO3 VMRs are higher at all altitudes and latitudes than corresponding values measured by the limb infrared monitor of the stratosphere (LIMS) instrument during the same season in 1979, when the aerosol loading was near background levels. The largest relative increase in the HNO3 VMR occurred near the equator at 30-km altitude, where the ATMOS/ATLAS 1 values are about a factor of 2 higher than the LIMS measurements. Two-dimensional model calculations show that the increase in HNO3 and the ATMOS/ATLAS 1 measurement of a steep decrease in the N2O5 VMR below 30 km can be explained by the enhanced conversion of N2O5 to HNO3 on the surfaces of the Mount Pinatubo sulfate aerosols. Our profile results demonstrate the global impact of the N2O5 + H2O --> 2HNO3 heterogeneous reaction in altering the partitioning of stratospheric odd nitrogen after a major volcanic eruption. [less ▲]

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See detailSECULAR EVOLUTION OF THE VERTICAL COLUMN ABUNDANCES OF CHCLF2 (HCFC-22) IN THE EARTH'S ATMOSPHERE INFERRED FROM GROUND-BASED IR SOLAR OBSERVATIONS AT THE JUNGFRAUJOCH AND AT KITT-PEAK, AND COMPARISON WITH MODEL-CALCULATIONS
Zander, Rodolphe ULiege; Mahieu, Emmanuel ULiege; Demoulin, Philippe ULiege et al

in Journal of Atmospheric Chemistry (1994), 18(2), 129-148

Series of high-resolution infrared solar spectra recorded at the International Scientific Station of the Jungfraujoch, Switzerland, between 06/1986 and 11/1992, and at Kitt Peak National Observatory ... [more ▼]

Series of high-resolution infrared solar spectra recorded at the International Scientific Station of the Jungfraujoch, Switzerland, between 06/1986 and 11/1992, and at Kitt Peak National Observatory, Tucson, Arizona (U.S.A.), from 12/1980 to 04/1992, have been analyzed to provide a comprehensive ensemble of vertical column abundances of CHClF2 (HCFC-22; Freon-22) above the European and the North American continents. The columns were derived from nonlinear least-squares curve fittings between synthetic spectra and the observations containing the unresolved 2nu6 Q-branch absorption of CHClF2 at 829.05 cm-1. The changes versus time observed in these columns were modeled assuming both an exponential and a linear increase with time. The exponential rates of increase at one-sigma uncertainties were found equal to (7.0 +/- 0.35)%/yr for the Junfraujoch data and (7.0 +/- 0.23)%/yr for the Kitt Peak data. The exponential trend of 7.0%/yr found at both stations widely separated in location can be considered as representative of the global increase of the CHClF2 burden in the Earth's atmosphere during the period 1980 to 1992. When assuming two realistic vertical volume mixing ratio profiles for CHClF2 in the troposphere, one quasi constant and the other decreasing by about 13% from the ground to the tropopause, the concentrations for mid-1990 were found to lie between 97 and 111 pptv (parts per trillion by volume) at the 3.58 km altitude of the Jungfraujoch and between .97 and 103 pptv at Kitt Peak, 2.09 km above sea level. Corresponding values derived from calculations using a high vertical resolution-2D model and recently compiled HCFC-22 releases to the atmosphere, were equal to 107 and 105 pptv, respectively, in excellent agreement with the measurements. The model calculated lifetime of CHClF2 was found equal to 15.6 years. The present results are compared critically with similar data found in the literature. On average, the concentrations found here are lower by 15-20% than those derived from in situ investigations; this difference cannot be explained by the absolute uncertainty of +/- 11% assigned presently to the infrared remote measurements. [less ▲]

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See detailThe 1985 chlorine and fluorine inventories in the stratosphere based on atmos observations at 30-degrees north latitude
Zander, Rodolphe ULiege; Gunson, Michael R.; Farmer, Crofton B. et al

in Journal of Atmospheric Chemistry (1992), 15(2), 171-186

The set of high-resolution infrared solar observations made with the Atmospheric Trace Molecule Spectroscopy (ATMOS) - Fourier transform spectrometer from onboard Spacelab 3 (30 April-1 May 1985) has been ... [more ▼]

The set of high-resolution infrared solar observations made with the Atmospheric Trace Molecule Spectroscopy (ATMOS) - Fourier transform spectrometer from onboard Spacelab 3 (30 April-1 May 1985) has been used to evaluate the total budgets of the odd chlorine and fluorine chemical families in the stratosphere. These budgets are based on volume mixing ratio profiles measured for HCl, HF, CH3Cl, ClONO2, CCl4, CCl2F2, CCl3F, CHClF2, CF4, COF2, and SF6, near 30-degrees north latitude. When including realistic concentrations for species not measured by ATMOS, i.e., the source gases CH3CCl3, and C2F3Cl3 below 25 km, and the reservoirs ClO, HOCl and COFCl between 15 and 40 km (five gases actually measured by other techniques), the 30-degrees-N zonal 1985 mean total mixing ratio of chlorine, Cl, was found to be equal to (2.58 +/- 0.10) ppbv (parts per billion by volume) throughout the stratosphere, with no significant decrease near the stratopause. The results for total fluorine indicate a slight, but steady, decrease of its volume mixing ratio with increasing altitude, around a mean stratospheric value of (1.15 +/- 0.12) ppbv. Both uncertainties correspond to one standard deviation. These mean springtime 1985 stratospheric budgets are commensurate with values reported for the tropospheric Cl and F concentrations in the early 1980s, when allowance is made for the growth rates of their source gases at the ground and the time required for tropospheric air to be transported into the stratosphere. The results are discussed with emphasis on conservation of fluorine and chlorine and the partitioning among source, sink, and reservoir gases throughout the stratosphere. [less ▲]

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