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[22.01] Stratospheric composition of Titan from Cassini/CIRS observations

A. Coustenis, B. Bézard, E. Lellouch, Th. Fouchet (LESIA, Paris-Meudon Obs., France), B Conrath (CRSR, Cornell Univ., USA), R. Achterberg (SSAI, NASA/GSFC, USA), D. Jennings, M. Flasar (NASA/GSFC, USA), CIRS Investigation Team

We have analyzed data recorded by the Composite Infrared Spectrometer (CIRS) aboard Cassini mission during the first Titan fly-by. The spectra characterize essentially regions around Titan’s south pole and up to 5 S (with higher emission angles close to the equator) from the emission observed in the FP3 and FP4 detectors (covering the 580-1495 cm^-1 spectral range with a 0.26 cm^-1 unapodized resolution). The composite spectrum contains 1417 scans for FP3 and 1683 scans for FP4, corresponding to a total effective integration time of about 20 and 23 hours respectively. It shows a large variety of molecular signatures : hydrocarbons, nitriles and CO2. We have used a temperature profile retrieved by inversion of the emission observed in the methane nu4 band at 1304 cm^-1 and a line-by-line radiative transfer code to infer the abundances of the trace constituents at Titan's south pole. We compare these mixing ratios with values retrieved two Titan seasons ago by V1 and V2 IRIS observations and with more recent Infrared Space Observatory (ISO) results.

The author(s) of this abstract have provided an email address for comments about the abstract: Athena.Coustenis@obspm.fr

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.