Interdecadal variation of tropical cyclone activity in association with summer monsoon,sea surface temperature over the western North Pacific

Based on geographic division over the western North Pacific(WNP),the interdecadal relationships between summer monsoon,sea surface temperature(SST) and tropical cyclones activity(including number,track and intensity) are examined.In the past several decades,the western Pacific subtropical high(WPSH) and tropical westerlies contribute to the interdecadal variation of TC number in the northwest and southeast of WNP respectively.The increased TC occurrence density to the east of Philippines related to TC track appears during the 1990s,in terms of both steer flow induced by WPSH and genesis location.From the interdecadal viewpoint,the tendency of TC intensity,measured by averaged accumulated cyclone energy,does well agree with that of SST,implying that SST plays an important role in TC intensity.