台风Rananim登陆后引发强降水成因和暴雨分布的诊断分析

首先对2004年第14号台风Rananim登陆后造成的强降水过程按主要影响系统进行了划分,指出第一阶段的降水是由台风本身环流产生的,第二阶段的降水则是台风残留低压与中纬度西风带环流系统共同作用的结果。然后针对暴雨在台风登陆点南北两侧非对称分布的特点进行了重点分析,结果表明,台风暴雨的非对称分布与台风本身的非对称结构、南北两侧不同的水汽输送以及中尺度地形有密切关系。同时利用湿位涡分析方法诊断了台风暴雨时空分布特征,发现湿位涡负值中心与暴雨中心存在较好对应关系,而且其中心数值的绝对值大小与1 h降水强度存在正相关关系,从而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。

Analysis of heavy rain causes and distribution caused by the landfall typhoon "Rananim"

Based on the main influenced system,the heavy rain process caused by landfall typhoon Rananim(0414) was divided into two phases.It was showed that the first strong precipitation phase was affected by typhoon itself and for the second precipitation phase,the major casue was the result of interaction between the typhoon circulation and middle latitude weather system.Then focusing on the characteristic of asymmetrical distribution of rainfall at the side of landfall dot,the study was carried out and indicated that this phenomenon associated with asymmetrical structure of typhoon itself,different moisture transportation and meso-scale topography.At the same time,the moist potential vorticity(MPV) was applied to diagnose space-time distribution of rainfall,the results suggested that the corresponding relation between the negative value center of MPV and heavy rain area was better,and its absolute value had positive correlation to the intensity of one hour precipitation.It provided more valuable information for short range weather forecasting,the typhoon torrential rain especially.