Widespread longitudinal snow dunes in Antarctica shaped by sintering

Abstract

The surface of Antarctica is continuously shaped by erosion, blowing snow and deposition, resulting in diverse aeolian bedforms akin to those observed in subtropical sand deserts. However, although dunes are universally recognized as a climate and environmental proxy, the properties of snow dunes are not well understood. Here, using satellite images covering most of Antarctica, we report the widespread occurrence (>95% of the area studied) of linear dunes that are between 100 and 1,000 m in length and aligned with the local resultant snow drift direction (61% are longitudinal dunes). On the basis of sand dune theory, we suggest that these snow dunes grow by elongation, often under unidirectional wind regimes. 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 remove snowfall. These characteristics result from specific meteorological conditions that distinguish Antarctica from other snow-covered regions, and may shift with future climate changes. We suggest that snow sintering not only influences Antarctic aeolian landform evolution but also regulates the amount of snow sublimated during transport, an uncertain term in the ice-sheet mass balance. Linear aeolian dunes aligned in the direction of snow drift are widespread across Antarctica, indicating a limited supply of mobile snow particles controlled by snow sintering, according to an analysis of satellite imagery.