Sensitivity of the Amundsen Sea Low to Stratospheric Ozone Depletion

Dramatic sea ice loss in the Amundsen and Bellingshausen Seas and regional warming in West Antarctica and the Antarctica Peninsula have been observed over the last few decades. Both of these changes are strongly influenced by the presence of the Amundsen Sea low (ASL), a climatological region of low pressure in the Amundsen Sea. Studies have demonstrated a deepening of the ASL, particularly in austral spring and to a lesser extent autumn, the former related to decreases in the underlying cyclone central pressures and the latter previously suggested to be due to stratospheric ozone depletion. This study further investigates the sensitivity of the ASL to stratospheric ozone depletion using geopotential height from a suite of chemistry–climate models (CCMs) as well as historical simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5). Overall, both model types capture the mean characteristics of the ASL, although they have notable positive height biases at 850 hPa and a subdued seasonal cycle in its longitudinal position. Comparing across model simulations, it is observed that there is a pronounced influence of stratospheric ozone depletion in the vicinity of the ASL in the stratosphere through the lower troposphere during austral summer, consistent with the positive phase of the southern annular mode. In the autumn, the authors note a weaker, secondary influence of stratospheric ozone depletion on the ASL only in the CMIP5 simulations.