Snow dunes orientation in East Antarctica

Wind drives the formation, shape and dynamics of aeolian snow dunes. Depending on the wind regime, different bedforms are formed such as as erosional shape (sastrugi) or linear dunes, which are straight or slightly sinuous dunes. Constraining the relationship between snow dunes and wind regimes, notably orientation, is essential for a better understanding of snow redistribution and therefore local surface mass balance. Snow dunes are widely spread in the windy polar regions and have an influence on the surface energy balance. However, relative to their sand analogues there have been few investigations relating snow bedforms orientation to wind direction. In Antarctica where snow bedforms are widely spread, wind direction has been inferred from sastrugi direction, but the relationship between the orientation of dunes and wind regime remains unclear.

In this study, we present a large-scale investigation of linear dune orientation in East Antarctica related to wind direction. We used optical Sentinel-2 images to identify linear dune fields location during summer with a 10-m resolution and retrieved their orientation. Inferring wind direction and speed from ERA5 reanalysis, at 0.25° resolution, we demonstrate that linear snow dunes are found even in areas with weak mean annual wind speed, providing some insights about the conditions of their formation. In addition, the comparison between wind direction statistics (prevailing direction and constancy) and dune orientations provides new insight into the relationship between linear snow dunes and the local wind regimes.