福建登陆北上台风对杭州影响的对比分析

利用自动站观测资料、探空资料和全球预测系统（global forecast system，GFS）分析资料，结合统计分析、合成分析、对比分析以及物理量诊断等方法，对5个福建登陆北上并严重影响杭州的台风进行了分析，结果表明：（1）福建登陆北上影响杭州的5个台风可以分为两类，一类是福建登陆北上越过30°N（北上台风），另一类是刚进入浙南就减弱为低压（1010号莫兰蒂台风）。北上台风对杭州造成了大风和暴雨双重影响，而1010号莫兰蒂台风主要带来的是暴雨。（2）在北上台风对杭州产生较大影响时，其合成台风中心位于福建中部地区，东南风低空急流和偏南风低空急流显著，杭州处于台风环流第一象限两支急流的交汇处，利于产生暴雨、大风；而在1010号莫兰蒂台风对杭州产生较大影响时已减弱为热带低压环流，其北部倒槽与西风带冷空气相结合是产生特大暴雨的主要原因，低压环流与副高之间的偏南风急流也有利于暴雨形成。（3）两类台风虽然部分指数和空间热动力结构相近，但北上台风的水汽条件和动力条件更好，而1010号莫兰蒂台风在冷空气切入和斜压性增强作用下，具备更高的对流有效位能，出现对流性强降水的可能性更大。

Comparative analysis of Fujian-landfall and northward-moving typhoons regrading their influence on Hangzhou

In this study, the impact analysis of five Fujian-landfall and northward-moving typhoons on Hangzhou are examined based on automatic weather stations data, sounding data and the global forecast system (GFS) data with statistical analysis, composite analysis, comparative analysis and physical diagnostic analysis. The results are summarized as follows. (1) These five typhoons could be divided into two types after landfall. One is northward-moving typhoons that after landing on Fujian province keeps moving over 30°N. The other is the typhoon Meranti (1010) which weakened to low pressure as soon as it arrived southern Zhejiang province. The northward-moving type brought both gale and heavy rainfall to Hangzhou while typhoon Meranti (1010) mainly produced heavy rainfall. (2) It will have significant impact on Hangzhou when the center of northward-moving typhoon is located in the central part of Fujian province ,as the south-westerly and southerly low-level jets are significant and Hangzhou is located within the first quadrant of the typhoon circulation which is the junction of these two jets, it is beneficial for the formation of the gale and heavy rainfall. On the contrast, it will cause great influence on Hangzhou when typhoon Meranti (1010) has weakened into a tropical low. The typhoon inverted trough has an obvious combination with the cold air of the westerly belt. A southerly jet forms between the circulation of the tropical low and the subtropical high, which is favorable for the formation of the heavy rainfall. (3) These two types of typhoons have some similar indexes and structure. However, the northward-moving type contains richer saturated water vapor and more suitable dynamic condition than typhoon Meranti (1010). Besides, typhoon Meranti (1010) reserves more available potential energy owing to cold air enhancing the baroclinicity.