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Incertitudes photochimiques dans les modèles de l'atmosphère de Titan : Revue et conséquences

Abstract : Theoretical models of Titan's atmosphere require a detailed and accurate description of all important processes relevant to its photochemistry. Particularly sensitive to the imprecision attached to the different kinetic parameters they enclose, such modeling studies inevitably present an overall uncertainty, which is even supposed to be contributing mostly to the discrepancies between observations and computed predictions. As in any other scientific experiment, a rigorous evaluation of their overall uncertainty is therefore crucial if we are to place confidence in the modeled results. Yet, traditional sensitivity studies, which simply vary each parameter in turn and disregard any inherent nonlinearity, do not estimate it correctly.
The objective of this thesis is to develop photochemical models of Titan's neutral atmosphere (0D and 1D) and to assess for the first time the overall imprecision in computed results arising from uncertainties in the photochemical parameters used. Through a comprehensive cross-examination of extensive photochemical rates database, we review the different photochemical sources of uncertainties in Titan's atmosphere modeling. By adequately treating enclosed nonlinearities through a Monte-Carlo procedure, we are then able to assess their effect on the computed results. Our original calculations establish that this effect could be so significant as to challenge any comparisons with observations and any potential conclusions subsequently inferred, and advocate for substantial efforts in promoting experimental studies which would greatly assist in developing planetary atmospheric models that more accurately -and usefully- reproduce observations.
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Contributor : Eric Hébrard <>
Submitted on : Wednesday, April 4, 2007 - 5:32:53 PM
Last modification on : Saturday, March 13, 2021 - 3:32:24 AM
Long-term archiving on: : Wednesday, April 7, 2010 - 1:04:40 AM


  • HAL Id : tel-00140071, version 1


Eric Hébrard. Incertitudes photochimiques dans les modèles de l'atmosphère de Titan : Revue et conséquences. Océan, Atmosphère. Université Paris-Diderot - Paris VII, 2006. Français. ⟨tel-00140071⟩



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