Re-examination of Trends Related to Tropical Cyclone Activity over the Western North Pacific Basin

In order to re-examine some trends related to tropical cyclones (TCs) over the western North Pacific since 1949, the unreliable maximum sustained wind (Vmax) recorded in the 1949--1978 TC best-track data from the Shanghai Typhoon Institute was modified based on the wind--pressure relationships (WPRs) in this study. Compared to the WPR scheme based on the cyclostrophic balance, the WPR scheme based on the gradient balance could give a better fit to TCs under higher wind speeds and could introduce smaller estimated errors for TCs locating at higher latitudes as well as TCs landing on the continent. After the Vmax modification based on minimum sea-level pressure and TC center latitude, the revised annual number of category 4--5 typhoons shows no long-term trend, while the potential destructiveness measured by power-dissipation index decreases slightly, and this trend is not significant in the period 1949--2008.