浙江热带气旋气候特征及其与环境场的关系

Climatic Characteristics of Tropical Cyclones in Zhejiang and Relationship with Environmental Factors

根据1950～2006年共57年的热带气旋(TC)年鉴资料对影响浙江热带气旋的气候特征进行了统计,结果表明,在影响我国和登陆我国热带气旋频数呈减少趋势的背景下,影响浙江和登陆浙江的热带气旋频数呈增加趋势,20世纪90年代以来,这种相反态势尤为明显。影响和登陆浙江TC频数均存在准15年和准25年的长周期,短周期则分别为准5年和准8年。影响浙江TC平均源地较影响我国TC平均源地偏北和偏东,90年代以来,影响浙江TC平均源地偏西、偏北。通过对热带气旋集中活动期(7～9月)的东亚环流形势进行分析发现,影响浙江TC偏多和偏少年,东亚高、中、低各层环流场特征几乎相反。

With the 57-year Tropical Cyclone（TC） data from 1950 to 2006,the climatic characteristics of TCs influencing Zhejiang are analyzed.The results indicate that since the 1990s,the TCs influencing or landing Zhejiang show a increasing trend,which is different from the decreasing trend of TCs influencing or landing on the whole China.In TCs both influencing and landing on Zhejiang there exist variation with the long periods being quasi-15 years and quasi-25 years,and the short periods being the quasi-5 years and quasi-8 years,respectively.The average source region is more northward and eastward for TCs influencing Zhejiang than those influencing China,which is more westward and northward than normal from the 1990s.In addition,the East Asian circulation factors during July and September are analyzed,and the results show that the structure of the circulation system in the years with more TCs influencing Zhejiang is much different from the years with less TCs influencing Zhejiang.