High-altitude CO 2 clouds on Mars: OMEGA and HRSC observations

• Main Authors: Määttänen, Anni, Montmessin, Franck, Gondet, B., Hoffmann, H., Scholten, F., Hauber, E., Gonzalez-Galindo, F., Forget, F., Bibring, J.-P., Bertaux, Jean-Loup, Neukum, G.
• Other Authors: PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Deutsches Zentrum für Luft- und Raumfahrt (DLR), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Freie Universität Berlin
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2009
• Subjects: [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]; [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP]; polar night
• Online Access: https://hal.archives-ouvertes.fr/hal-00484879; https://hal.archives-ouvertes.fr/hal-00484879/document; https://hal.archives-ouvertes.fr/hal-00484879/file/7023.pdf

International audience The Martian climate hosts a rare phenomenon of condensation of the bulk atmosphere. CO 2 condenses on the polar ice caps, but also forms clouds in the atmosphere. The existence of low-level, convective CO 2 clouds in the polar night was indirectly discovered by MOLA [1,2] and modeled in some studies [3-5]. Recently several satellite instruments [6-9] have observed CO 2 clouds also near the equator, but at high altitudes where the temperatures are low enough for CO 2 condensation. Montmessin et al. [7] identified spectroscopically from MEx/OMEGA observations these high-altitude clouds to be composed of CO2 ice crystals by modeling the CO2 ice spectral signature that was observed in a deep CO 2 gas absorption band at around 4.3 μm. In this work we have used the OMEGA [10] and HRSC [11] observations to map the occurrences of the high-altitude CO 2 clouds and their properties. We have also compared the observations to the predictions of the LMD Mars Global Climate Model (LMD-MGCM) [12] and in particular its improved version that extends to the upper atmosphere [13].