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Applicant -- Martian past and current surface-atmosphere interactions: Insight using HiRISE/MRO and CRISM/MRO measurements

Wednesday, May 31, 2017

The presence of an atmosphere has induced varied surface-atmosphere interactions on Mars and has created diverse surface morphology features (e.g., dust devil tracks, Recurring Slope Lineae, gullies, dunes, stratified outcrops of clay-rich materials). Those interactions have been conducted by different agents responsible for the surface evolution: H2O, CO2 and wind. Their study is essential to evaluate the potential sources of H2OCO2 and aerosols, their quantity and the atmospheric gases and aerosols vertical and latitudinal transfer fluxes in order to get new constraints on the past and current Mars climate. Those interactions are visible from the grain to regional scales and can be studied by remote sensing technique from orbit. The High Resolution Imaging Science Experiment (HiRISE) and the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on-board the Mars Reconnaissance Orbiter (MRO) are appropriate instruments to characterize, track and quantify surface-atmosphere interactions. Firstthe camera HiRISE enable us to identify fine surface changes thanks to its high spatial resolution (down to 30 cm/pixel)Moreoverits color filters in the visible range enable us to evaluate the changes of the materials brightness and colors linked to the surface properties. Second, the VNIR spectro-imager CRISM enables us to characterize the brightness and the angular distribution of the surface scatteringthanks to its simultaneous multi-angular hyperspectral images. Thanks to this dataset, quantitative information about the surface physical properties can be estimated (e.g., grain size, morphology). However, from orbit, HiRISE and CRISM observe the surface under variable atmospheric aerosol quantities that represent an obstacle in VNIR remote sensing of the martian surface. In order to correct the atmospheric dust scattering contamination of the HiRISE and CRISM reflectance measurements, wedeveloped innovative data processingThis meticulous data analysis of the HiRISE and CRISM data enables me to quantitatively estimate the surface brightness (i.e., albedo)the angular distribution of the surface scattering (i.e., phase function) and the surface colors in order to evaluate the surface material composition and microtexture. These new data are high level products which enable me to get new constraints on the origin, mechanism, duration and impact of the surface-atmosphere interactions on surface evolution and the martian climate. During my presentation, I will present you some direct applications.

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