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Modélisation du transfert radiatif dans l'atmosphère martienne pour la détermination des propriétés spectrales de surface et la caractérisation des aérosols martiens à partir des données OMEGA

Abstract : Micrometric dust particles are always present in the martian atmosphere. This aerosol loading varies with time and location. Aerosols have a major impact on the martian climate as they modify the radiative equilibrium of the atmosphere. Suspended dust particles scatter incoming solar photons in the visible and near infrared wavelengths. The imaging spectrometer OMEGA has observed Mars in this wavelength range since January 2004. The analysis of OMEGA observations rapidly led to the identification of new minerals at the surface of Mars. These discoveries have changed our view of the martian history. This work focuses on the development of a radiative transfer model based on Monte-Carlo methods. The model makes it possible to separate the contribution of aerosols from that of the surface. It is used to study the optical and physical properties of dust aerosols and refine our comprehension of the surface. The first applications are dedicated to polar regions where the contribution of aerosols is large due to the long optical paths. Seasonal interactions between dust and surface ice, which were poorly understood, are investigated using OMEGA data. A method for mapping the optical depth of aerosols is developed for regions covered by CO2 ice at southern latitudes. We then extend our analysis to equatorial and mid-latitude regions. We demonstrate that dust raised during storms in these regions does not settle uniformly on the ground. We present the first applications of our model for improving the quantitative assessment of surface mineralogy from OMEGA data first, then from the CRISM experiment on-board MRO. CRISM, which started operating in November 2006, is complementary to OMEGA with its observations at a higher resolution.
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Contributor : Mathieu Vincendon <>
Submitted on : Monday, November 24, 2008 - 5:47:31 PM
Last modification on : Wednesday, September 16, 2020 - 4:42:28 PM
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Mathieu Vincendon. Modélisation du transfert radiatif dans l'atmosphère martienne pour la détermination des propriétés spectrales de surface et la caractérisation des aérosols martiens à partir des données OMEGA. Astrophysique [astro-ph]. Université Paris Sud - Paris XI, 2008. Français. ⟨tel-00341252⟩

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