台风活动与陕西极端暴雨的相关特征分析

ACTIVITY OF TYPHOONS AND EXTREME RAINSTORMS IN SHANXI PROVINCE

利用1970～2003年35年间出现在陕西的极端暴雨与近海台风活动的资料,对其进行时空分布统计分析和天气学、动力学诊断以及卫星云图等综合分析,结果表明:两者的相关率接近87%;7、8两个月台风影响最为显著。与华北、东北地区比较,陕西的极端暴雨以远距离影响的台风活动为主。影响台风有两类,一类是台风在台湾岛附近登陆或以北海域活动的,其水汽、能量主要以850hPa层输送尤为明显,这类台风云系与暴雨区之间的晴空区明显。另一类是台风在海南、广东或广西一带登陆或移动,该类水汽、能量主要以700hPa层输送最为显著。当台风在125°E以西,且在13～33°N的范围内活动时,该类台风活动对陕西的强降水作用明显,是造成陕西极端暴雨的一个重要的因素。300hPa高空急流的先兆性对陕西极端暴雨具有一定的预报意义。影响台风的位置与影响云系对极端暴雨落区预报有帮助。

Based on the data of extreme rainstorms in Shanxi and near-coast typhoon movements in the past 35 years from 1970 to 2003, analyzing the time-space distribution statistics, synoptic meteorology, dynamical diagnosis and cloud image feature, this paper indicates that： the correlation rate is close to 87% and the typhoon influence is most obvious in July and August. Compared to north and northeast China, extreme rainstorms in Shanxi are pivotally influenced by long-distance typhoon movements. There are two kinds of typhoons influencing the rainstorm in Shanxi Province. One makes landfall on or moves around the island of Taiwan which transports large amount of vapor and energy at 850 hPa, and the cloud image between the two regions is featured by cloudless sky. The other is near or makes landfall on Hainan island, Guangdong province or Guangxi province, transporting large amount of vapor and energy at 700 hPa, especially when typhoon is active to the west of 125°E and within 13-33°N. This kind of typhoon plays an important role in the rainstorm in Shanxi Province. 300-hPa-high jets are of some indication in forecasting extreme rainstorm weather. The cloud image and typhoon＇s activity are also precursory to the forecasting of extreme rainstorm weather when using the rule and characteristics.