HR: 13:55h
AN: P23C-02 INVITED     [Abstracts]
TI: Spring Sublimation of the Seasonal Condensates on Mars from Omega/Mars Express
AU: * Schmitt, B
EM: Bernard.Schmitt@obs.ujf-grenoble.fr
AF: Laboratoire de Planétologie de Grenoble, CNRS/UJF, Bât. D de Physique, BP 53, Grenoble Cedex 9, 38041 France
AU: Douté, S
EM: doute@obs.ujf-grenoble.fr
AF: Laboratoire de Planétologie de Grenoble, CNRS/UJF, Bât. D de Physique, BP 53, Grenoble Cedex 9, 38041 France
AU: Langevin, Y
EM: langevin@ias.u-psud.fr
AF: IAS, Univ. Paris Sud, Bât. 121, Orsay, 91405 France
AU: Forget, F
EM: forget@lmd.jussieu.fr
AF: LMD, Univ. Paris 6, 4 place Jussieu, Paris, 75252 France
AU: Bibring, J
EM: bibring@ias.u-psud.fr
AF: IAS, Univ. Paris Sud, Bât. 121, Orsay, 91405 France
AU: Bellucci, G
EM: bellucci@ifsi.rm.cnr.it
AF: IFSI, INAF, Via del Fosso del Cavaliere, Roma, 00133 Italy
AU: Altieri, F
EM: altieri@ifsi.rm.cnr.it
AF: IFSI, INAF, Via del Fosso del Cavaliere, Roma, 00133 Italy
AU: Poulet, F
EM: poulet@ias.u-psud.fr
AF: LMD, Univ. Paris 6, 4 place Jussieu, Paris, 75252 France
AU: Gondet, B
EM: Gondet@ias.u-psud.fr
AF: LMD, Univ. Paris 6, 4 place Jussieu, Paris, 75252 France
AB: The formation and sublimation of the seasonal deposits on Mars surface are major elements controlling its atmospheric circulation and its climate. A complex competition occurs between sublimation of CO₂ frost, inter-hemispheric transports and snow deposition/condensation in the opposite polar regions. Water is released by different sources (caps, condensates, soil) but their locations and contributions are not yet well known. Before the Mars Express mission the evolution of the seasonal condensations have been essentially monitored by following the albedo and temperature changes of the surface (TES, MOC/MGS). Since January 2004 the OMEGA imaging spectrometer allows us to directly monitor the abundance, physical state and distribution of the CO₂, water and dust components of the martian frosts and ices through their visible and near-infrared spectral signatures. In particular, the monitoring of the evolution of the frost composing the seasonal caps provides strong constraints on the microphysics of the sublimation/condensation/deposition processes of volatiles as well as on their seasonal cycle. The abundance of the dust co-deposited with ices should also constrain the dust loading and transport processes. We present the latitudinal evolution of the composition and physical state of the ices composing the seasonal deposits from the north pole to the crocus line, as seen by OMEGA. Then we describe the temporal evolution of the spatial distribution of CO₂ frost and H₂O ice during spring sublimation of the northern seasonal condensates. In particular a wide annulus of a thin layer of dusty water ice forms at the fringe of the recessing CO₂ seasonal cap and moves towards higher latitudes as sublimation progress. All this information allows us to draw a coupled microphysical and latitudinal evolution sketch of the seasonal frosts. Implications and constraints on Mars GCMs will be analyzed.
DE: 5410 Composition (1060, 3672)
DE: 5422 Ices
DE: 5462 Polar regions
DE: 5464 Remote sensing
SC: Planetary Sciences [P]
MN: Fall Meeting 2005