Understanding the Formation of the Reduced Warming Pattern in the Pacific Sector of the Southern Ocean

Abstract

Sea surface temperature (SST) warming patterns exhibit a reduced warming band in the Pacific Sector of the Southern Ocean (PSSO) in response to global warming, known as the Southern Ocean reduced (SOR) warming pattern. This study utilizes data from 30 climate models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6), under the 1% CO2 increase per year (1pctCO2) scenario. Through factor decomposition, we identify the radiation forcing, wind cooling in evaporation, and oceanic heat flux as the essential contributors to multi-model ensemble (MME) mean distribution and inter-model uncertainty of the SOR pattern. It is crucial to highlight that the significant impact of the intensified westerlies on the formation of the SOR pattern involves both the wind cooling effect and the wind-driven oceanic dynamics, in both the MME mean distribution and inter-model uncertainty aspects. Our findings suggest that improving the simulation skills of the westerly winds could lead to more precise projection of Southern Ocean warming.