Future Antarctic snow accumulation trend is dominated by atmospheric synoptic-scale events

Dalaiden, Quentin [UCL] Goosse, Hugues [UCL] Lenaerts, Jan T. M. [Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, CO, USA] Cavitte, Marie [UCL] Henderson, Naomi [Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA]

Over the last century, the increase in snow accumulation has partly mitigated the total dynamic Antarctic Ice Sheet mass loss. However, the mechanisms behind this increase are poorly understood. Here we analyze the Antarctic Ice Sheet atmospheric moisture budget based on climate reanalysis and model simulations to reveal that the interannual variability of regional snow accumulation is controlled by both the large-scale atmospheric circulation and short-lived synoptic-scale events (i.e. storm systems). Yet, when considering the entire continent at the multi-decadal scale, only the synoptic-scale events can explain the recent and expected future snow accumulation increase. In a warmer climate induced by climate change, these synoptic-scale events transport air that can contain more humidity due to the increasing temperatures leading to more precipitation on the continent. Our findings highlight that the multi-decadal and interannual snow accumulation variability is governed by different processes, and that we thus cannot rely directly on the mechanisms driving interannual variations to predict long-term changes in snow accumulation in the future.