- Names
-
- Th. Appéré
- Title
- Cycle actuel de l’eau sur Mars : étude des dépôts saisonniers de l’hémisphère nord par télédétection hyperspectrale (OMEGA/Mars Express)
- Abstract
- Seasonal $CO_2$ and $H_2O$ ices play a major role in the current climate of Mars. Their condensation/sublimation cycle largely control the variations of atmospheric pressure and humidity. The aim of this thesis is to provide new observational constraints to the surface/atmosphere interactions during the retreat of the northern seasonal deposits. Using near infrared hyperspectral images from the OMEGA instrument (Mars Express), the extent of the seasonal $CO_2$ and $H_2O$ ices was mapped from winter solstice to summer solstice. A water ice annulus systematically surrounds the $CO_2$-rich seasonal deposits. It is an important source of water vapor during its sublimation. A water ice layer progressively covers the $CO_2$ ice. It results from two processes : accumulation of water ice grains previously embedded into $CO_2$ ice and laying onto the surface while $CO_2$ ice sublimes, and condensation of water vapor coming from the sublimating water ice annulus. Sudden increases of the $CO_2$ ice signatures are observed in the spiral troughs and scarps of the North permanent cap and in the circumpolar dark dunes field. It probably results from an enhancement of the katabatic winds due to transient low pressure systems. These dynamical processes result in an inhomogeneous accumulation of water frost onto the North permanent cap at the beginning of summer which could play a role in the present evolution of the cap. Knowledge of the water vapor sources location and of the surface/atmosphere interactions during northern winter and spring will improve climate models and our understanding of the current water cycle on Mars.
- Keywords
- spectroscopy, thermodynamics, bidirectional reflection, radiative transfer simulation, bidirectional reflectance spectra, visible, near-IR, thermal process, condensation, sublimation, kinetic, grain size, molecular solid, ice, snow, CO2, H2O, Mars, surface
- Content
- planetary sciences
- Document type
- phd thesis
- Year
- 2013
- Pages
- 1 - 354
- Pages number
- 354
- Editor
- IPAG
- Publisher
- Université Joseph Fourier
- Publisher city
- Grenoble, France
- Publication state
- published
- Comments
- PhD defence: 10 July 2012
- Identifiers
- File
- appere12-PhD-UJF.pdf
- Publications
-
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- Pommerol and Schmitt, 2008, J. Geophys. Res. E, 113, E10009
- Pommerol and Schmitt, 2008, J. Geophys. Res. E, 113, E12008
- Pommerol, 2009, 1 - 254
- Quirico and Schmitt, 1997, Icarus, 127, 354 - 378
- Schmitt et al., 1998, 227, 199 - 240