Stratospheric Circulation in the Southern Hemisphere: links to tropical winds, ozone and Hunga Eruption

The Southern Hemisphere (SH) stratosphere circulation can be organized around the development of the low-latitude jet (LLJ) in the upper stratosphere during winter months. The LLJ is associated with weak planetary wave activity, reduced residual circulation, and connections to westerly anomalies of the middle and upper stratosphere during early and mid-winter. The 2022 Hunga eruption coinciding with an anomalously strong LLJ year. Additionally, the LLJ is linked to a persistent, strong polar vortex in the lower stratosphere during October–December. This strong vortex, primarily driven by dynamical processes in winter, is further associated with enhanced ozone losses in spring, with ozone feedback reinforcing the vortex as sunlight returns in October.