A Review on the Long Term Variations of Tropical Cyclone Activity in the Typhoon Committee Region

Abstract

ABSTRACT A review on the long term variations of tropical cyclone (TC) activity in the Typhoon Committee region was conducted based on the assessments of IPCC, IWTC and ESCAP/WMO Typhoon Committee and a number of recent publications. The results reveal strong inter-annual and inter-decadal variations in the TC activity over the western North Pacific (WNP). Analysis of available TC data since 1950s indicates that most of the TC datasets depict a decreasing trend, and some statistically significant, in the annual number of TCs and typhoons in the WNP. For TC intensity, differences in TC databases for the WNP do not allow a convincing detection of a long term trend in this basin. Climate model projections suggest a noticeable decrease in the frequency of the WNP TCs in the 21st century. Some of the model simulations also report an increase in the number of intense TCs and the TC potential intensity in the WNP in a warmer climate. Looking forward, data homogeneity in TC databases and uncertainties in model simulation are two main hurdles hindering the determination of the past and future trends of TC activity in this basin. Inter-agency co-operations are urgently required to improve the homogeneity and consistency of TC databases in the WNP. Continuous research would also be needed to further improve our understanding of the influence of natural variability and anthropogenic warming on the TC activity in the WNP.