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Circulation générale et photochimie dans l'atmosphère de Titan

Abstract : For twenty years, the atmosphere of Titan has been intensively observed and studied. A lot of questions about this complex system still need to be adressed, especially about the interactions between microphysics of the haze, photochemistry and atmospheric dynamics. To better understand the atmosphere of Titan before the arrival of the Cassini-Huygens mission, we developed a two-dimensional photochemical general circulation model. A three-dimensional description of the ultraviolet flux was used to get a realistic ultraviolet field at every latitude and season, and an up-to-date review of the hydrocarbon photochemistry was done. We introduced the transport by meridional winds and horizontal transient eddies in a two-dimensional (latitude-altitude) photochemical and transport model, which, along with a purely dynamic study and a sensitivity study, demonstrated the role of dynamical transport on the latitudinal variations of the stratospheric composition, as observed by the Voyager I mission. Comparison between the different observations and our results is fairely good, but the uncertainties on chemical data remain a main source of difficulties. We investigated the radiative retroaction of the variations of the composition on the temperature field. The coupled version of the general circulation model will be a powerful tool to investigate the new data obtained with the Cassini-Huygens mission.
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Contributor : Sébastien Lebonnois <>
Submitted on : Wednesday, March 19, 2008 - 3:06:54 PM
Last modification on : Thursday, December 10, 2020 - 12:37:14 PM
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  • HAL Id : tel-00265537, version 1


Sébastien Lebonnois. Circulation générale et photochimie dans l'atmosphère de Titan. Astrophysique [astro-ph]. Université Paul Sabatier - Toulouse III, 2000. Français. ⟨tel-00265537⟩



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