[A-CG32] Extratropical oceans and atmosphere

[ACG32-13] Sea Surface Warming Maxima in the Western Boundary Current Regions in MIROC6 Large Ensemble Simulations

*Kaichi Morimoto¹, Satoru Okajima¹, Masaki Toda¹, Ryo Satoh¹, Takashi Kawamura¹, Yu Kosaka¹ (1.the University of Tokyo)

Keywords:Global warming, Attribution, Air-sea interaction

Observational data shows local maxima of sea surface temperature rise in the western boundary current regions of ocean basins in the 20th century. The present study investigates the mechanism behind this warming pattern using large ensemble experiments conducted with the MIROC6 climate model. We used the historical all-forcing and single-forcing experiments, each extended under the SSP2-4.5 scenario. Each experiment consists of 50 ensemble members. Simulated centennial changes highlight distinct warming maxima along the Agulhas Return Current, East Australian Current, and Brazil-Malvinas Current in the Southern Hemisphere. A weaker maximum is also found in the Kuroshio Extension region. Such localized intense sea surface temperature changes were observed not only in response to greenhouse gases but also to aerosols, and the response in the all-forcing experiment is largely explained by the sum of these two effects. Our heat budget analysis suggests a localized increase in heat release from the ocean to the atmosphere, implying the importance of internal oceanic processes.