Has the Western Pacific Subtropical High Extended Westward since the Late 1970s?

Abstract

revious studies reported that the summer western Pacific subtropical high (WPSH) has extended westward since the late 1970s and the change has affected summer rainfall over China and tropical cyclone prevailing tracks in the western North Pacific. The authors show that the 500-hPa geopotential height in the midlatitudes of the Northern Hemisphere has trended upward in the warming climate and the westward extension of the WPSH quantified with the 500-hPa geopotential height is mainly a manifestation of the global rising trend. That is, the summer 500-hPa WPSH has not remarkably extended westward since the late 1970s when the global trend is removed. It is suggested that the index that indicates the west?east shift of the summer 500-hPa WPSH should be redefined and that further investigation is needed to understand the observed climate change in the summer rainfall over China and tropical cyclone prevailing tracks in the western North Pacific.