资源环境科技发展态势分析平台

This study investigates seasonality of interdecadal changes in the Northwest Pacific (WNP)-mean latitude-longitude covariability of tropical cyclogenesis location (TCGL). It is found that the latitude-longitude covariability of WNP-mean TCGL has experienced seasonally distinct interdecadal shifts since 1998, weakening in summer and strengthening in autumn. Since significant westward shift of WNP-mean TCGL exists in both summer and autumn, but robust poleward shift is only detected in autumn. The linchpin of such seasonal difference is the subtropical WNP sea-surface temperature (SST) warming in the key region of 125°–140°E, 15°–30°N, where numbers of typhoons increase in autumn but not in summer. Two main factors are responsible for the SST warming in the key region: the interdecadal trend of local SST and the Central Pacific La Niña-teleconnected warming. However, neither condition occurs in summer, highlighting the importance of seasonal difference in climatological background when interpreting climatic changes in typhoons.