Enhanced relationship between the tropical Atlantic SST and the summertime western North Pacific subtropical high after the early 1980s

Abstract

Abstract The western North Pacific subtropical high (WNPSH) in boreal summer shows a remarkable enhancement after the early 1980s. Whereas the sea surface temperature (SST) in the North Indian Ocean (NIO) and the equatorial eastern Pacific had been noted to have remarkable local or remote effects on enhancing the WNPSH, the influence of the Atlantic SST, so far, is hardly explored. This article reports a new finding: enhanced relationship between the tropical Atlantic (TA)‐SST and the WNPSH after the early 1980s. Regression study suggests that the warm TA‐SST produced a zonally overturning circulation anomaly, with descending over the equatorial central Pacific and ascending over the tropical Atlantic/eastern Pacific. The anomalous descending over the equatorial central Pacific likely induced low‐level anticyclonic anomaly to the west and therefore enhanced the WNPSH. One implication of this new finding is for predictability. The well‐known “spring predictability barrier” (i.e., the influence of El Niño–Southern Oscillation (ENSO) falls dramatically during boreal spring) does not apply to the TA‐SST/WNPSH relationship. The TA‐SST shows consistently high correlation starting from boreal spring when the ENSO influence continues declining. The TA‐SST extends the predictability of the WNPSH in boreal summer approximately one season earlier to boreal spring.