Aeolian erosion and roughness of the snow surface in Adélie Land : observations and numerical approach

• Main Author: Amory, Charles
• Other Authors: Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Université Grenoble Alpes, Hubert Gallée
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2016
• Subjects: Aeolian erosion; Antarctica; Snow surface roughness; Observations; Modeling; Modélisation; Rugosité de la surface neigeuse; Érosion éolienne; Antarctique; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Antarctic; East Antarctica; Terre Adélie; Terre-Adélie; The Antarctic; Antarc*; Antarctique*; Ice Sheet
• Online Access: https://tel.archives-ouvertes.fr/tel-01472936; https://tel.archives-ouvertes.fr/tel-01472936/document; https://tel.archives-ouvertes.fr/tel-01472936/file/AMORY_2016_archivage_2.pdf

The Antarctic ice sheet surface mass balance (SMB; the result of the balance between accumulation and ablation terms) has a direct influence on variations in the global mean sea level. In the context of climate change, atmospheric models are needed to improve its current and future estimation.Intense surface winds over the coastal slopes of East Antarctica are responsible for aerodynamic entrainment of snow at the surface, which has a significant influence on the BMS. Transport of snow by the wind also produces aeolian erosion features aligned parallel to the prevailing winds at the time of their formation. The spatial distribution of these features is a major determinant of surface roughness. On the other hand, surface roughness is an obstacle to flow and directly affects the surface wind field and, by extension, aeolian snow transport.The work presented here is based on observations and numerical modeling of aeolian snow erosion in a coastal stretch of Adélie Land, East Antarctica. First, the regional atmospheric model MAR, which includes a detailed representation of aeolian transport processes, was run at a spatial resolution of 5 km over a zone including Adélie Land and model results were compared with meteorological observations made over one month in summer, including continuous measurements of the wind and the aeolian snow mass flux. Aeolian snow mass fluxes modeled by MAR were highly sensitive to parameterization of surface roughness, and a single calibration of this parameter was not enough to simulate the surface wind field at two measurement points located only 100 km apart with the same accuracy. Consequently, roughness-erosion interactions were analyzed at the scale of individual aeolian erosion events using observations. The results of this analysis underlined that (i) the barrier effect generated by aeolian erosion features had an inhibiting impact on the aeolian snow mass flux and (ii) that the barrier effect can be strongly reduced by the ability of aeolian erosion features to realign with the ...