37th DPS Meeting, 4-9 September 2005
Session 51 Titan II
Oral, Thursday, September 8, 2005, 2:00-3:50pm, Music Concert Hall

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[51.03] Photochemical modeling of Titan's atmosphere: Constraints from Cassini-Huygens

V. Vuitton, R. V. Yelle (University of Arizona)

Cassini and Huygens measurements provided new data on Titan's atmospheric characteristics and chemical composition. New constraints on methane mixing ratio, aerosol distribution and eddy diffusion coefficients are now available. This, along with advances in our knowledge of photolytic and kinetic rates, triggered our development of a new 1-D photochemical model of Titan's neutral hydrocarbon chemistry. The net production and loss rates of the major hydrocarbons are reassessed and their condensation rates are reinvestigated. The implications for the presence of liquids on Titan's surface are discussed. Constituent vertical profiles are also compared to the Ion Neutral Mass Spectrometer and Cassini InfraRed Spectrometer measurements performed in the upper and lower atmosphere, respectively. The H2 escape rate from Titan's upper atmosphere was retrieved from the Ion Neutral Mass Spectrometer measurements. This is a sensitive indicator of the photolysis rates in the stratosphere. This helps constraining the aerosol distribution and opacity, which along with the eddy diffusion coefficient controls the altitude and rate of photolysis of C2H2, C2H4 and C4H2. Sensitivity studies of these parameters on the vertical profiles are presented.

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.