Variation of Active Tropical Cyclone Season in the Western North Pacific

Abstract:

The variation of active tropical cyclone (TC) season in the western North Pacific (WNP) is analyzed using the quantile analysis of TC formation dates. The length of the active TC season is highly dependent on its start date that has large interannual variation. The variation of start TC season is closely associated with the sea surface temperature (SST) over the Indian Ocean (IO) and the eastern Pacific (EP). When the IO and EP SSTs are warm (cold) in the winter and early-spring, anomalous downdraft (updraft) and anticyclonic (cyclonic) circulation are induced around the WNP, resulting in the delay (advance) of start of the active TC season.