A simulation of snow megadunes along the Dumont d'Urville—Dome C transect, Antarctica

The polar regional climate model MAR (Modèle Atmosphérique Régional) has been used to simulate the formation of snow megadunes along the Dumont d'Urville - Dome C transect, Antarctica. MAR is coupled with a multi-layered snow model including the budget of energy and mass of snow and ice. The following processes are represented: the conduction of heat, the melting, percolation and refreezing of water, and the snow metamorphism, from wich the snow aldedo is parameterized. A blowing snow model is used in order to couple the snow model with MAR. In particular blown snow particles are viewed as snow flakes by the cloud microphysical scheme of MAR and the buoyancy calculations include the impact of air loading by blown snow. The 2D version of MAR is initialized with a typical atmospheric sounding. The simulated snow net accumulation is characterized by a wavy pattern along the transect. This pattern forms downwind a break of the ice sheet slope, 200 km far from the ice sheet margin! Fourier analyses indicate that the length of the waves is roughly a few tens of km, in agreement with that of snow megadunes observed along that transect.