Sensitivity of western Pacific subtropical high to regional sea surface temperature changes

Abstract

The western Pacific subtropical high (WPSH) exerts significant influence on the climate of the Pacific region and East Asia. In this study, we systematically examined the responses of the WPSH intensity and position to regional sea surface temperature (SST) changes using idealized SST patch experiments with a climate model. Our findings reveal that the WPSH intensity is most sensitive to northern tropical SST during the boreal summer. Specifically, warming in the tropical Indian Ocean, eastern Pacific, and tropical North Atlantic contributes to a strengthening of the WPSH, whereas warming in the tropical western Pacific leads to its weakening. SST warming enhances local convergence and convection, which can modify the WPSH intensity via modulating the strength of tropical zonal circulation. Additionally, it is found that the SST-induced enhancement (weakening) of the WPSH is always accompanied with a westward extension (eastward retreat) of the WPSH. Furthermore, the response of the WPSH to tropical SST changes exhibits nonnegligible nonlinearity, which indicates the importance of multi-ocean interaction in determining the WPSH response to global surface warming.