Factors Influencing Snowfall Accumulations during Atmospheric River Events Over the Antarctic Peninsula

Atmospheric Rivers (ARs) are long, narrow filaments of heat and moisture that are observed at middle and high latitudes. They can lead to intense rain/snow, greater cloud cover, increased temperatures, and changes in wind speed and direction. ARs are most frequent at middle latitudes and, on rare occasions, can reach polar regions. Using meteorological data from the ERA5, an analysis was conducted to determine how meteorological conditions (temperature, wind direction, and wind speed) vary across the Antarctic Peninsula during landfalling ARs. We specifically examined data between 2015 and 2019 at two ERA5 grid points closest to two automatic weather stations (AWS), AWS1 and AWS18 (shown below), on the Larsen C Ice Shelf. Results demonstrate that the orientation of atmospheric rivers may dictate the impacts that occur on the ice shelf. Due to the peninsula's topography, atmospheric rivers can be accompanied by upslope flow or downslope flow (i.e., foehn winds). Upslope flow favors large amounts of snowfall accumulation, which can help maintain the structural integrity of the ice shelf. Conversely, foehn winds during AR events favor warmer temperatures and less snowfall accumulation, which may favor surface melting and reduced ice sheet stability.