Antarctic extreme snowfall: A CloudSat and CALIPSO satellite perspective

Abstract

The Antarctic Ice Sheet is a critical component of the Earth’s climate system, with its role in global sea level regulation becoming increasingly significant in a warming climate. Snowfall is a key factor in ice mass balance, influencing the ice sheet’s contribution to sea level changes. Previous studies have shown that moisture intrusions can cause large snowfall events, but by focusing only on the most extreme moisture events impinging on the ice sheet, these studies only address specific regions of the ice sheet, omitting many potential mass-building snowfall events across other parts of the continent. This study examines extreme snowfall events (defined as greater than the 95th percentile) across each drainage basin in Antarctica. Using the new Combined CloudSat CALIPSO Snowfall (C3S) that leverages the snowfall detection capabilities of the CloudSat radar while mitigating errors caused by the radar blind zone with CALIPSO lidar observations, we find that top 5% of snowfall events in each basin account for nearly 40% of the total accumulation on the Antarctic ice sheet. Analyzing MERRA-2 reanalysis and automatic weather station data, we find that, unlike moderate snowfall, extreme events in many drainage basins exhibit sea level pressure dipoles that bring warm, moist air to the continent. This comprehensive analysis broadens the findings of recent work, by demonstrating that extreme snowfall events play a key role in Antarctic ice mass balance and are frequently connected to enhanced atmospheric moisture transport across the entire Antarctic ice sheet offering valuable insights for climate research and sea level rise projections.