Rare Sudden Stratosphere Warming Events in the Southern Hemisphere in 2024

In July and August 2024, two rare consecutive stratospheric sudden warming (SSW) events, SW07 and SW08 occurred in the Southern Hemisphere. These events were marked by a rapid Antarctic temperature increase of nearly 17°C at 10 hPa within a few days and a significant deceleration of the stratospheric polar vortex (SPV). In particular, SW07 represents the earliest warming event recorded in the satellite era. Both events meet the criteria for minor SSWs and set new historical temperature records. The analysis reveals that planetary wave anomalies, dominated by nonlinear processes driven by strong tropospheric blocking highs and stratospheric preconditions, played a crucial role in SW07. Additionally, the rapid downward propagation of negative SAM into the troposphere, induced by SW07, created a favorable circulation background for planetary wave perturbations before SW08. These perturbations enhanced ozone transport from low-latitudes ozone to the pole, warming the atmosphere through the absorption of solar shortwave radiation and providing a warm background conducive to triggering SW08.