三个登陆浙江热带气旋数值试验及暴雨过程的湿位涡分析

首先利用非静力平衡中尺度数值模式MM5(V3)对2004年3个登陆浙江热带气旋的登陆过程进行了数值模拟试验,通过对路径、降水的对比验证表明,MM5模式对热带气旋的模拟是比较成功的。然后在模拟效果较好的基础上,利用高分辨的模拟结果,对台风暴雨过程的湿位涡进行了诊断分析,结果表明:3场台风暴雨的形成机制有显著差异,Rananim强降水是由其本身环流造成的,至于Mindulle和Haima的降水冷空气的侵入起到了重要作用。暴雨都发生在陡立密集区附近,对流层低层湿位涡负值中心与暴雨落区存在较好的对应关系,而其中心数值绝对值随时间的变化量与1h降水存在正相关关系,说明湿位涡负值中心可以作为降水时空分布的重要指标,为台风暴雨预报提供一种思路。

Numerical experiments of three landfall tropical cyclons and analysis of moist potential vorticity during their heavy rain processes

Numerical experiments were conducted on three landfall tropical cyclones(TCs) by use of PSU/NCAR nonhydrostatic mesoscale model(MM5).Verified against observations,the tracks and detailed mesoscale precipitation distributions were well reproduced.Using simulated information,the moist potential vorticity(MPV) was analyzed.The results show that there was marked distinction in the heavy rain cause of three TCs.The strong precipitation of Rananim was affected by typhoon itself and as to the others,the spreading into of cold air played an important role.The rainstorm occured in the stiff and dense section of moist isentropes,the corresponding relation between the negative center of MPV and heavy rain area was better,and the absolute value variation of MPV had positive correlation to the intensitiy of one hour precipitation,It provided more valuable information for short range weather forecasting,the typhoon torrential rain especially.