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Aspects microphysiques de l'atmosphère martienne : de la poussière aux nuages de glace d'eau

Abstract : Because of the permanent and global effect of airborne dust on the radiative balance, the study of microphysical processes is of major interest for the Martian atmosphere. In addition, water ice clouds similar to terrestrial cirrus are frequently observed despite the low water vapor abundances. During my thesis work, a microphysical model has been developed to study the coupling between dust, ice crystals and water vapor. Being mainly focused on the vertical structure of the Martian haze, our efforts have yielded an interpretation of a photometric dataset, itself leading to a new estimation of ice crystals and dust microphysical properties. Our conclusions challenge the function commonly adopted to represent the size spectrum of Martian dust, an hypothesis corroborated by other size spectra of dust generally observed in Earth deserts. Besides, we have been able to conduct a thorough analysis of the impact of Martian nebulosity on the water cycle. Our implementation of a simplified microphysical scheme within a General Circulation Model has led to the quantification of the role of atmospheric water ice transport on the geographical distribution of water. This study follows one of the main scientific topic: understanding the evolution of water on Mars. Related to this topic, the study of the deuterium cycle is crucial to give consistent estimates of the amount of water that has escaped throughout Martian history. This cycle is partly controlled by a fractionation effect occuring within clouds that has been studied with our microphysical model. Our results give a consistent explanation of the puzzling observations of deuterium abundances at high altitudes.
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https://tel.archives-ouvertes.fr/tel-00010657
Contributor : Franck Montmessin <>
Submitted on : Monday, October 17, 2005 - 12:24:54 PM
Last modification on : Wednesday, December 9, 2020 - 3:11:27 PM
Long-term archiving on: : Friday, April 2, 2010 - 10:32:42 PM

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  • HAL Id : tel-00010657, version 1

Citation

Franck Montmessin. Aspects microphysiques de l'atmosphère martienne : de la poussière aux nuages de glace d'eau. Astrophysique [astro-ph]. Université Pierre et Marie Curie - Paris VI, 2002. Français. ⟨tel-00010657⟩

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