Change in precipitation as a response to the Amundsen Sea Low characteristics in region of West Antarctica

Climate change has led to the shrinkage of ice sheets and glaciers, contributing to sea level rise, particularly in regions like West Antarctica. Over the past several decades, this area has experienced one of the most pronounced increases in temperature and precipitation. Projections suggested increase in extreme precipitation by the end of the 21st century. Together with the expected deepening of the Amundsen Sea Low (ASL), these changes play a significant role in Antarctic ice sheet's mass in the future. This study aims to analyze a spatio-temporal precipitation variability and its extreme values in West Antarctica as a response to ASL characteristics. To analyze the relationships, we used a number of parameters describing ASL (average pressure field, the central pressure, the relative pressure at the center, longitude of the ASL, and the distance to the ASL center), and parameters for precipitation (daily totals and the 95th percentile) derived from the historical European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 reanalysis data. The study is focused on natural zones along the coast corresponding to glacial basins such as Getz Ice Shelf, Thwaites Glacier, Pine Island glaciers, and Abbot Ice Shelf. Relationships between precipitation and ASL characteristics were assessed using Spearman rank correlation coefficients in each grid cell of the studied domain. Overall, the highest 95th percentile values, approximately 35 mm, were observed along the western coast of the Antarctic Peninsula. These values decreased to 15 mm along the remaining coastline of West Antarctica and further to 5 mm over the continental areas. Extreme precipitation had well-detected seasonality, with maximum precipitation totals during the austral autumn/spring seasons. In average, extreme precipitation events covered approximately 4.7–4.9% of basin areas. Over the last 30 years, the tendencies of extreme precipitation intensified the observed spatial differences: the 95th percentile increased over more humid areas with a trend of 4 mm/decade and decreased in continental regions by 2 mm/decade. The meridional position of ASL impacts weather and precipitation over the region much more than changes in its latitudinal remoteness to the coast. The ASL movement towards the west caused decreased precipitation near the Amundsen Sea and increased over the Antarctic Peninsula. Extreme precipitation was more sensitive to changes in ASL location than total precipitation. This study will contribute to understanding the occurrence of extreme precipitation events under climate change.