Different Impacts of Tropical Sea Surface Temperature on Sea Ice Variability in the Amundsen Sea During Austral Summer and Winter

Abstract

Antarctic sea ice is undergoing significant changes associated with climate change. While previous studies have primarily examined temporal and spatial variations in Antarctic sea ice as a whole, this broad approach can obscure the specific dynamics of the marginal seas. Sea ice change in the Amundsen Sea is featured with complex mechanisms including at‐least ice shelf meltwater, regional atmosphere‐ice‐ocean interaction and Antarctic‐tropical teleconnection. A regional analysis of sea ice changes in the Amundsen Sea is therefore warranted. Using satellite‐derived sea ice concentration data and empirical orthogonal function (EOF) decomposition, we identify the leading modes of summer and winter sea ice concentration in the Amundsen Sea. In austral summer, the first EOF mode explains nearly 30% of the variance and reveals a decreasing trend in sea ice concentration in the Amundsen Sea, linked to atmospheric planetary wavetrains excited by reduced sea surface temperatures in the western Pacific. In austral winter, the first EOF mode accounts for an impressive 65% of the variance, characterized by uniform interannual variability. This winter season variability in Amundsen Sea ice cover is associated with the Pacific‐South America mode, influenced by a developing La Niña state. Understanding the specific sea ice change patterns and their underlying dynamics in the Amundsen Sea is critical for improving predictions of regional climate variability and assessing the broader impacts on Antarctic ice sheet stability, ocean circulation, and global sea level rise.