Dynamics of aeolian sedimentation waves at the surface of Martian and terrestrial glaciers: Morphologicand spectroscopic observation, numerical modeling of mass transfer by sublimation/condensation

• Main Author: Herny, Clémence
• Other Authors: Laboratoire de Planétologie et Géodynamique UMR 6112 (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Ecole Centrale de Nantes (ECN), Olivier Bourgeois
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2015
• Subjects: Ice cap; mass transfer; ice; Antarctica; wind; mass balance; Calotte polaire; transfert de masse; glace; mégadune; Mars; Antarctique; vent; sublimation; condensation; bilan de masse; [SDU]Sciences of the Universe [physics]; [PHYS]Physics [physics]; Antarctic; Antarc*; Antarctique*
• Online Access: https://theses.hal.science/tel-01324984; https://theses.hal.science/tel-01324984/document; https://theses.hal.science/tel-01324984/file/Herny_These_TEL.pdf

Mass and energy balance of terrestrial and Martian ice sheets are driven by complex interactions between the atmosphere and the cryosphere that could lead to the formation of sedimentation waves at the surface of ice sheets. Here we explore the role of sublimation and condensation of water vapor in the development of these sedimentation waves. We use complementary data set acquired by Mars orbiters, to show that the surface of the Martian North Polar Cap displays two superimposed sets of sedimentation waves with differing wavelengths that grow and migrate downwind or upwind in response to the development of periodic accumulation /ablation patterns controlled by katabatic winds. These sedimentation waves have similarities with Antarctic snow megadunes. In addition, we designed a numerical model to explore the coupled interaction between the sublimation/condensation of water vapor and a steady unidirectional atmospheric flow on a wavy icy surface. The maximum of water vapor flux coincides with the maximum shear stress, whose location relative to the crest is dependent of the wavelength and fluid characteristics. For a maximum of flux located upwind, mass transfer rates are smaller on the downwind sides. These results are the same for sublimation (ablation) and condensation (accumulation). During a given simulation, the ice waves do not experience simultaneous accumulation and ablation as it would be the case, for instance, for aeolian sand dunes. These results mean that if the accumulation rate is greater than the ablation rate the waves will migrate upwind.Our observations and simulations are in accordance with the hypothesis that the Martian sedimentation waves couldmigrate downwind or upwind due to an asymmetric accumulation rate between their upwind sides and their downwind sides over a Martian year. Le bilan de masse et d’énergie des calottes polaires martiennes et terrestres est contrôlé par des interactions complexes entre l’atmosphère et la cryosphère qui peuvent aboutir à la formation d’ondes de ...