Linear snow dune orientations in Antarctica

Antarctica stands out as one of the windiest regions on Earth, resulting in snow transport and various eolian bedforms akin to those observed in subtropical sand deserts. Unlike sand dunes, Antarctic have been only qualitatively described, and little is known about their spatial distribution, orientation and dynamics. Therefore, fundamental questions about the processes of deposition and accumulation of snow remain unanswered, impacting the understanding of snow redistribution, surface mass balance variability in Antarctica and, more generally, the eolian transport of a cohesive material. In this study, we present a continent-wide mapping of linear snow dune orientations in Antarctica. We used Sentinel-2 and Landsat-8 images with, respectively, a 10 m and 15 m resolution to retrieve the orientation of periodic topographic features. Using wind direction and speed from ERA-5 Reanalysis with a 0.25°x0.25° resolution, we show that, on length scales ranging from 30m to several kilometers, longitudinal dune is the predominant type of landform in Antarctica and that they form by elongation in the mean snow flux direction. The predominance of the elongating mode indicates a low availability of mobile snow particles. This limited availability prevails at the continental scale due to a subtle balance between snow sintering, which limits erosion, and strong winds which rapidly removes snowfall. Our findings highlight the importance of snow sintering, not only to shape unique landforms, but also to control the amount of snow exported by wind to the ocean, an uncertain term of the ice-sheet mass balance.