Modeling of the Antarctic Ice Sheet Surface Mass Balance

• Main Author: Gential, Luc
• Other Authors: Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS), Université Joseph-Fourier - Grenoble I, Hubert Gallée([e-mail])
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2007
• Subjects: modélisation du climat; Modèle atmosphérique régional; échelle régionale; Antarctique; calotte glaciaire; bilan de masse en surface; désagrégation; Law Dome; transport de neige par le vent; précipitation; forçage orographique; niveau moyen des mers; climate modeling; regional scale; Antarctica; ice sheet; surface mass balance; disaggregation; blowing snow; orographic forcing; global mean sea level; [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Antarctic; Dome The; The Antarctic; Antarc*; Antarctique*; Ice Sheet; polar night
• Online Access: https://tel.archives-ouvertes.fr/tel-00189139; https://tel.archives-ouvertes.fr/tel-00189139/document; https://tel.archives-ouvertes.fr/tel-00189139/file/these_luc_gential_lgge.pdf

The Antarctic ice sheet surface mass balance (SMB, snow accumulation minus ablation) is sensitive to climate parameters and directly contributes to global mean sea level variations. Therefore, in the perspective of climate change, it is useful to develop tools that can simulate the physical processes involved in the Antarctic surface mass balance. The approach developed in this thesis consists in using a cascade of atmospheric models from large scale to local scale. Thus, a regional climate model (Modèle atmosphérique régional, hereinafter referred to as MAR), forced by European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis, provides a diagnostic physical-based rain- and snowfall disaggregation model with meteorological fields at the regional scale (typically 40-km resolution). In a first part, it is shown that the SMB calculated by MAR is in good agreement with observations in most regions. Nonetheless, runoff appears to be overestimated; the problem vanishes when introducing a dependency of albedo with solar zenithal distance. In a second part, it is shown that although the parameterizations invoked in the disaggregation model are fairly simple, the knowledge of small-scale topography (5-km resolution) is efficiently used to improve the spatial variability of precipitation - and therefore SMB - over coastal regions of Antarctica. Model validation is carried out with the help of snow height measurements provided by automatic weather stations. Over the coastal place of Law Dome, the net accumulation gradient is mostly due to orographic forcing of precipitation (rather than blowing snow). The disaggregation model dramatically underestimates precipitation over the Antarctic Plateau, where polar stratospheric clouds associated with radiative cooling could play a role in the formation of precipitation during the polar night. Le bilan de masse en surface (noté BMS l'accumulation de neige diminuée de l'ablation) de la calotte glaciaire antarctique est sensible aux paramètres climatiques et contribue ...