37th DPS Meeting, 4-9 September 2005
Session 41 Titan 1
Oral, Wednesday, September 7, 2005, 4:30-6:00pm, Music Concert Hall

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[41.03] Titan's stratospheric composition from Cassini/CIRS observations

A. Coustenis (LESIA, Paris-Meudon Obs., France), B. Conrath (CRSR, Cornell University, USA), R. Achterberg (SSAI, NASA/GSFC, USA), D. Jennings, G. Bjoraker, M. Flasar, C. Nixon, P. Romani, R. Samuelson (NASA/GSFC, Greenbelt, MD, USA), B. Bézard, E. Lellouch, R. Courtin, E. Lellouch, A. Marten, S. Vinatier, Th. Fouchet (LESIA, Paris-Meudon Obs., France), P. Irwin, N. Teanby (AOPP, Clarendon Lab., U. Oxford, UK), M. Abbas (NASA/MSFC, SD50 NSSTC, USA), CIRS Investigation Team

We have analyzed data recorded by the Composite Infrared Spectrometer (CIRS) aboard the Cassini mission during the recent Titan fly-bys (October 2004- June 2005). The spectra characterize various regions on Titan from south to north pole with a large spectrum of emission angles. We study the emission observed in the 3 CIRS detectors (covering roughly the 10-1500 cm-1 spectral range with a 0.53 cm-1 apodized resolution at best). The composite spectrum shows several molecular signatures : hydrocarbons, nitriles and 3 oxygen components. We have used temperature profiles 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 and some of their isotopes in Titan's stratosphere. Information is retrieved on the meridional variation of the trace constituents. We will compare these mixing ratios with values retrieved two Titan seasons ago by V1 and V2 IRIS observations, with more recent disk-averaged Infrared Space Observatory (ISO) results and with the latest Cassini-Huygens inferences from other instruments in an attempt to tie our findings to the seasonal phenomena on Titan.


Flasar, F. M., Achterberg R. K., Conrath B. J., Gierasch, P. J., Kunde V. G., Nixon C. A., Bjoraker G. L., Jennings D. E., Romani P. N., Simon-Miller A. A., Bézard B., Coustenis A., Irwin P. G. J., Teanby, N. A., Brasunas J., Pearl J. C., Segura, M. E., Carlson, R., Matmoukine, A., Schinder, P. J., Barucci A., Courtin R., Fouchet T., Gautier D., Lellouch E., Marten A., Prangé, R., Vinatier, S., Strobel, D. F., Calcutt S. B., Read P. L., Taylor, F. W., Bowles, N., Samuelson R. E., Orton G. S., Spilker L. J., Owen T. C., Spencer, J. A., Showalter, M. R., Ferrari, C., Abbas M. M., Raulin F., Edgington, S., Ade P., Wishnow, E. H. 2005. Titan’s atmospheric temperatures, winds, and composition. Science, 308, 975-978.

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