How Do Weakening of the Stratospheric Polar Vortex in the Southern Hemisphere Affect Regional Antarctic Sea Ice Extent?
Shaoyin Wang, Jiping Liu, Xiao Cheng, Tobias Kerzenmacher, Yongyun Hu, Fengming Hui, Peter Braesicke
Abstract
Abstract In the Southern Hemisphere, variability of the stratospheric polar vortex is an important driver of surface climate. In this study, we explore the influence of weakening and strengthening of the polar vortex on regional Antarctic sea ice in observations and model simulations. We propose a two‐stage mechanism that translates stratospheric harbingers to sea ice changes: (a) it starts with polar vortex variability that is highly correlated with the Amundsen Sea Low (ASL); through modulation of the ASL and thus surface winds, (b) weak polar vortex leads to statistically significant decrease of sea ice over the Ross Sea and increase of sea ice around the Antarctic Peninsula, and vice versa. The two‐stage mechanism can be detected in observations and state‐of‐the‐art model simulations, confirming a robust chain of response. This study underlines the importance of stratosphere‐troposphere coupling on the Antarctic sea ice variability and its seasonal predictability.