A Record-Breaking Cyclone Over the Southern Ocean in 2022

In October 2022, an extreme cyclone developed in the South Pacific Ocean with a sea level pressure of 900 hPa, becoming the strongest extratropical cyclone in the satellite era. Using ERA5 reanalysis data, we investigated its development mechanisms and examined long-term changes in the occurrence of extreme cyclones over the Southern Ocean. Our findings indicate that the cyclone formed within a low-pressure anomaly over the South Pacific. Its explosive development was initiated by upper-level dynamic forcing and driven by low-level latent heat release, which had been preconditioned by surface heat flux. Extreme cyclones have increased significantly in the Amundsen-Bellingshausen Seas (ABS) and the South Indian Ocean since 1980. The large-scale environmental variables in the ABS also showed a consistent trend toward more favorable conditions for cyclone intensification. Understanding these extreme cyclone events will help to overcome the uncertainty in projections of climate change impacts and improve weather forecast skills.