Interdecadal Changes of Characteristics of Tropical Cyclone Rapid Intensification Over Western North Pacific

This study investigates the interdecadal variations of rapid intensification (RI) of tropical cyclones (TCs) over Western North Pacific (WNP) during 1960-2016, TC variabilities associated with RI and the possible mechanisms for such variations are also explored. Two RI-active periods (P1:1960-1972, P3:2000-2016) and one RI-inactive period (P2:1973-1999) are identified using Regime Shift Detection method based on the RI-TC ratio data. RI spatial distributions all exhibit a common Main Development Region. Significant different characteristics of the TC genesis and lifetime maximum intensity location are observed between RITCs and Non-RI TCs and in each period. The majority of RITCs starts with initial intensity at 35-80 kts, and P2 shows an obvious displacement of these TC occurrences. The longitudinal distributions of RI ratio demonstrate totally different patterns. The higher SST and relative humidity, as well as stronger VWS, lead to the highest RI ratio in P3. TCs in P2 have less chance to undergo RI due to the eastward extension of monsoon trough associated with a more eastward movement of TC occurrence away from MDR. The environmental conditions are obviously unfavorable for RI in the Western WNP in P2, as well as in P1. Our findings imply that the TC variabilities are affected by the decadal variations of RI events and the changes in TC occurrence along with the RI-favored environmental fields all contribute to the RI variations at interdecadal scales.