A Record‐Breaking Cyclone Over the Southern Ocean in 2022

• Published in: Geophysical research letters Vol. 50; no. 14
• Main Authors: Lin, Peiyi, Zhong, Rui, Yang, Qinghua, Clem, Kyle R., Chen, Dake
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.07.2023; Wiley
• Subjects: Amplification; Atmospheric conditions; Climate and weather; Climate change; Climate change influences; Cryosphere; Cyclones; Environmental impact; Extratropical cyclones; Heat flux; Heat transfer; Latent heat; Latent heat release; Marine ecosystems; Oceans; Pressure anomalies; Sea level; Sea level pressure; Severe weather; Skills; Weather; Weather forecasting; South Pacific; Southern Ocean
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL104012

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. Plain Language Summary Extreme extratropical cyclones cause severe weather events, significantly impacting humans, infrastructure, the oceans, the cryosphere, and ecosystems. These cyclones will increase when the large‐scale environment variables become more favorable for their development. Our study analyzed how a record‐breaking cyclone developed under the interplay of several atmospheric conditions: the extreme cyclone developed within a low‐pressure anomaly over the South Pacific, and the dynamical and thermodynamical processes cooperate to promote its explosive intensification. Furthermore, extreme cyclones in the Southern Ocean are increasing in recent years and the increasing trend in the Amundsen‐Bellingshausen Seas appears related to changes in the local environment. Our findings contribute to the improvement of forecast skills and highlight the close relationship between the increase of extreme cyclones and the environment under the influence of climate change. Key Points The strongest cyclone ever recorded worldwide since 1980 occurred in the Amundsen‐Bellingshausen Seas (ABS) in October 2022 The event formed from an interplay of dynamical and thermodynamical processes, including strong upper‐level forcing and latent heat release This cyclone is representative of a significant increase in extreme cyclones over the Southern Ocean in recent years, especially in the ABS