Summer Westerly Wind Intensification Weakens Southern Ocean Seasonal Cycle Under Global Warming

• Published in: Geophysical Research Letters
• Main Authors: Yiwen Zhang, Changlin Chen, Shineng Hu, Guihua Wang, Kay McMonigal, Sarah M. Larson
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2024
• Subjects: Geophysics. Cosmic physics; QC801-809; Southern Ocean
• Online Access: https://doi.org/10.1029/2024GL109715; https://doaj.org/article/13f8c0a55605401a9833a92ca61e2dec

Abstract Since the 1950s, observations and climate models show an amplification of sea surface temperature (SST) seasonal cycle in response to global warming over most of the global oceans except for the Southern Ocean (SO), however the cause remains poorly understood. In this study, we analyzed observations, ocean reanalysis, and a set of historical and abruptly quadrupled CO2 simulations from the Coupled Model Intercomparison Project Phase 6 archive and found that the weakened SST seasonal cycle over the SO could be mainly attributed to the intensification of summertime westerly winds. Under the historical warming, the intensification of summertime westerly winds over the SO effectively deepens ocean mixed layer and damps surface warming, but this effect is considerably weaker in winter, thus weakening the SST seasonal cycle. This wind‐driven mechanism is further supported by our targeted coupled model experiments with the wind intensification effects being removed.