半个世纪来热带海洋风暴对中国大陆的影响

本文利用美国海军台风警报中心（JTWC）提供的1945～2002年热带风暴路径资料统计分析了西北太平洋（NWP）和中国南海（SCS）风暴生成及登陆中国大陆热带风暴的时空演变特征.季节变化上，NWP风暴登陆主要集中于6～11月，SCS风暴影响主要集中在6～9月，但后者登陆总数比前者少.西北太平洋风暴在东南沿海(27°N，120°E)附近登陆的频次最高，在此以北随纬度急剧下降.年际变化时间尺度上，登陆大陆的风暴年总数与来自南海的年风暴数成正比.登陆我国的热带风暴年频数有明显的区域差异和显著的2～7年振荡.长期趋势上，两个海域的风暴年生成频数和登陆大陆的年风暴频数在58年中总体呈线性增长趋势，其中登陆频数增长趋势相对缓慢，但近几年登陆风暴数与生成风暴数都表现出减少的趋势.生成频数和登陆频数都呈现出年代际变化，其年代转换发生在1960、1970年和1990年前后.

Statistic analysis of tropical cyclone impact on the China mainland during the last half century

The typhoon best track data provided by Joint Typhoon Warning Center (JTWC) was employed to analyze the temporal spatial variability of the landfall tropical cyclones over the China mainland, which generated over the Northwest Pacific (NWP) basin and the South China Sea (SCS) for the period 1945～2002 Seasonally, landfall cyclones concentrated from the NWP in June November are more than that from the SCS in June September. Along the China coast line, the highest landfall frequency of cyclones is located in the southeast coast (27°N, 120°E) and the frequency rapidly decreases north to it. The interannual variability shows that the annual total sum of landfall cyclones is proportional to that coming from the SCS. The wavelet analysis shows that regional yearly series of landfall cyclone frequency varies from 2 to 7 years on time scales. Long term linear trends indicate that the generation frequency of cyclone over the NWP and the SCS, as well as landfall cyclone frequency in China increase at different rates. On the other hand, a short term trend shows that decreasing trends of generation frequency and landfall frequency were observed in recent years. The short term trend implies that there are decadal variations in generation frequency and landfall frequency. Three transition points of the decadal variations appeared around the 1960, 1970, and 1990, respectively.