Increasing WNP tropical cyclone-related extreme precipitation over East Asia during boreal summer associated with PDO shift

Abstract

Over the past two decades, there has been a significant shift in tropical cyclone (TC) activity in the western North Pacific (WNP) basin during the boreal summer. Our analysis of data spanning from 1979 to 2021 reveals significant shifts in the WNP TC characteristics and rainfall pattern variation. To deepen our understanding of TC-related precipitation dynamics, we expressly address the difference between TC-related core precipitation (TCP) and remote precipitation (TRP). The results show that TRP significantly impacts the East Asian (EA) continent, especially on the Korean Peninsula. Notably, TCP exhibits decadal variability, with a pronounced negative correlation identified between it and the Pacific decadal oscillation (PDO) following a strong climate shift. This pivotal shift was marked by the PDO first transitioning to its negative phase in 1997, a notable change since 1979, resulting in a marked increase in TC-related extreme rainfall over the EA area. Concurrently, the rising sea surface temperatures (SSTs) over the WNP have intensified the western Pacific subtropical high (WPSH) circulation. The easterly steering flow associated with the WPSH then strengthened, leading to the continental migration of TC trajectories, thereby intensifying TC-related extreme precipitation.