Tropospheric response to an 'ozone depletion'-like polar stratospheric cooling

By following the setup of Kushner and Polvani (2006) in a simplified dynamical model, we add a polar stratospheric cooling in the springtime to mimic the ozone depletion, and try to investigate the role of polar vortex breakdown, also known as stratospheric final warming (SFW), in the tropospheric response to stratospheric changes. Overall, the circulation anomaly associated with such cooling bears a remarkable resemblance to the Southern Hemisphere climate trends due to ozone depletion, including poleward shift of the tropospheric jet and poleward expansion of the Hadley cell. We then categorize the 80 members into those SFWs are delayed, and those SFWs are not, and calculate the response separately. The response for the years in which SFWs are delayed are very similar to the total one, while the stratosphere is only characterized by the localized cooling for those years in which SFWs are not delayed, without any clear downward influence. This suggests that ozone depletion affects the Southern Hemisphere climate through delaying the SFWs. We also find that interannual variability in the stratospheric and tropospheric circulation can be organized by the timing of SFWs, similar to the observed climate trends.