Tropical Cyclone Influence On China During The Past 20 Years

Previous studies have suggested that tropical cyclone (TC) intensity, frequency, locations of genesis and prevailing tracks over the Western North Pacific (WNP) may have changed in the backdrop of global warming. Since typhoons are one of the major natural disasters in China, changes in TC activity may lead to significant loss of life and damage. In this study, the newly defined TC activity index CAI (Cyclone Activity Index) is used to examine the variations of TC influence on China’s coastal regions and possible mechanisms. A marked reduction is revealed in the frequency of typhoons affecting China after 1996, while no significant trend is seen in the landfall typhoon frequency over the past 50 years. It is suggested that, the southern (southeastern) coastal areas suffer from less (more) TC influence. Of significance is that the value of CAI increases in Xiamen, Fuzhou, Wenzhou, Hangzhou and Shanghai in summer (June-October) (the former three cities significant at the 95% confidence level, the latter two significant at the 90% confidence test), On the contrary, a significant decrease of CAI is presented in Sanya and Haikou (significant at the 95% confidence test). Further analyses indicates that these variations are closely associated with the changes in the TC prevailing tracks and intensity.