Abstract
<jats:p>Abstract. The Amundsen Sea Low (ASL) is a regional atmospheric circulation feature that significantly influences the climate of West Antarctica through its impact on the meridional wind field. An observed deepening of the ASL over the satellite era has raised concerns about the possibility of more extreme ASL conditions through the end of the twenty-first century. Here we use ERA5 reanalysis and passive microwave satellite observations to examine the impact of extreme ASL events on West Antarctica during the period 1979–2025. In total, we identify 13 extremely strong and 8 extremely weak events that vary geographically based on magnitude. Strong events tend to be concentrated poleward and centered in the vicinity of the Amundsen Sea while weak events are found farther north and display large zonal spatial heterogeneity. Composite maps of surface anomalies suggest that the location of extreme events serve to explain a regional dipole in surface temperatures and sea ice concentration, both of which are co-located with anomalous wind velocities modulated by ASL strength. Given the link between the regional ASL and additional large-scale modes of atmospheric variability in the Southern Hemisphere, we also investigate extreme ASL events in relation to the Southern Annular Mode, El Niño Southern Oscillation, and Zonal Wave 3. We find that nearly all extremely strong events occur when the three modes of variability are positively in-phase; there is less agreement during extremely weak ASL events. We assess future ASL variability and extremes using CESM2 model output under middle- and high-emission scenarios. Future projections indicate a higher proportion of extremely strong ASL events relative to weak events through the end of the 21st century, suggesting an increased likelihood of more extreme meridional conditions across West Antarctica in the near future.</jats:p>