浙江热带气旋登陆前移动速度变化分析

利用1949~2004年登陆浙江的35个热带气旋的资料,计算了热带气旋登陆前24h和6h的速度和移速变率。结果表明,登陆浙江的热带气旋60%在登陆前移速加快,28.6%移速基本不变,11.4%移速减慢。从热带气旋登陆前的形势场、引导气流及它的结构和强度变化等方面进行分析,发现500hPa形势场的调整和引导气流的大小对热带气旋移速的变化起主导作用;热带气旋主流入通道的变化、热带气旋之间的互旋等与其移速变化有关。登陆前,热带气旋移速与其强度有一定的关系。

Moving Velocity Variation of Landfalling Tropical Cyclones before Landing in Zhejiang Province

There are 35 landfalling tropical cyclones in Zhejiang Province from 1949 to 2004.The average moving velocities and acceleration during 24 hours and 6 hours before landing are calculated.The results show that 60% of landfalling tropical cyclones move faster before landing;28.4% move at the same speed,and 11.4% move more slowly.Analyzed are the atmospheric circulation,the steering flow, the structure and intensity changes of tropical cyclones before landing,so to find the reason why tropical cyclones move at different velocities before landing.It is found that the moving velocity of a tropical cyclone is closely correlated with the 500 hPa circulation pattern and the steering flow and is also related to the variation of the main inflow path,the mutual rotation of tropical cyclones and moving velocity variation.