DISTRIBUTION OF CO{sub 2} IN SATURN'S ATMOSPHERE FROM CASSINI/CIRS INFRARED OBSERVATIONS

Journal Article · Sun Oct 20 04:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/776/2/73· OSTI ID:22270757

Abbas, M. M.; LeClair, A. ^[1]; Woodard, E.; Young, M.; Stanbro, M. ^[2]; Flasar, F. M.; Achterberg, R. K.; Bjoraker, G.; Brasunas, J.; Jennings, D. E. ^[3]

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1. NASA-Marshall Space Flight Center, Huntsville, AL 35812 (United States)
2. University of Alabama in Huntsville, Huntsville, AL 35899 (United States)
3. NASA-Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

This paper focuses on the CO{sub 2} distribution in Saturn's atmosphere based on analysis of infrared spectral observations of Saturn made by the Composite Infrared Spectrometer aboard the Cassini spacecraft. The Cassini spacecraft was launched in 1997 October, inserted in Saturn's orbit in 2004 July, and has been successfully making infrared observations of Saturn, its rings, Titan, and other icy satellites during well-planned orbital tours. The infrared observations, made with a dual Fourier transform spectrometer in both nadir- and limb-viewing modes, cover spectral regions of 10-1400 cm{sup –1}, with the option of variable apodized spectral resolutions from 0.53 to 15 cm{sup –1}. An analysis of the observed spectra with well-developed radiative transfer models and spectral inversion techniques has the potential to provide knowledge of Saturn's thermal structure and composition with global distributions of a series of gases. In this paper, we present an analysis of a large observational data set for retrieval of Saturn's CO{sub 2} distribution utilizing spectral features of CO{sub 2} in the Q-branch of the ν{sub 2} band, and discuss its possible relationship to the influx of interstellar dust grains. With limited spectral regions available for analysis, due to low densities of CO{sub 2} and interference from other gases, the retrieved CO{sub 2} profile is obtained as a function of a model photochemical profile, with the retrieved values at atmospheric pressures in the region of ∼1-10 mbar levels. The retrieved CO{sub 2} profile is found to be in good agreement with the model profile based on Infrared Space Observatory measurements with mixing ratios of ∼4.9 × 10{sup –10} at atmospheric pressures of ∼1 mbar.

• OSTI ID: 22270757
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 776; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
ATMOSPHERIC PRESSURE
CARBON DIOXIDE
COSMIC DUST
FOURIER TRANSFORM SPECTROMETERS
GASES
INFRARED SPECTRA
INFRARED SPECTROMETERS
INTERSTELLAR GRAINS
MIXING RATIO
PHOTOCHEMISTRY
RADIANT HEAT TRANSFER
SATELLITE ATMOSPHERES
SATURN PLANET