河北夏季低涡暴雨的统计研究

Statistical study on summer's low eddy rainstrorm weather in Hebei

对河北省22个国家基准站和基本站及北京、天津1991-2000年10年的夏季低涡暴雨个例进行了统计与合成分析,划分了河北夏季低涡暴雨的天气概念模型,对燕山南麓及太行山东麓的低涡暴雨特征进行了研究。对高空形势场、低空风场、暴雨落区及强度等方面的分析表明,造成该地区暴雨的低涡系统主要为西北涡,其次为东蒙冷涡,影响最小的是西南涡。西北涡主要影响太行山南部地区,东蒙冷涡主要影响燕山南麓,以7、8月份较多;西南涡暴雨仅发生在7月份。70%的西北涡暴雨,南方有台风或热带气旋出现。经向型西北涡的水汽源地主要是黄海和东海;纬向型西北涡和经向型东蒙冷涡的水汽源地主要是南海和孟加拉湾。500 hPa中纬度经向型的环流形势更有利于低涡暴雨的持续性,降雨强度也更大;暴雨区一般出现在700 hPa低涡暖切变附近,最大风速区的左侧。

With statistical and synthetic analysis on the examples of low eddies rainstorm weathers in 22 national meteorological stations of Hebei Province, Beijing and Tianjin, from 1991 through 2000, the weather conceptual model of the low eddies rainstorm is divided, and the features of low eddies rainstorm weathers in eastern foot of Taihang Mountain and southern foot of Yanshan Mountain are studied. Through the analysis of the situation and torrent at high and low latitude, wind field in lower troposphere, rainfall area and intensity, it is indicated that the low eddies system causing rainstorm in this area is primarily the northwest eddies, and secondly the east-Mongolia cold eddies, the influence of southwest eddies is slight. Northwest eddies affect mostly south of Taihang Mountain, and east-Mongolia cold eddies primarily affect southern foot of Yanshan Mountain, mostly at July and August. The southwest eddies rainstorm only take place in July. 70% of northwest eddies rainstorm accompany with typhoon or tropical cyclone at south. The vapour source is the Yellow Sea or the East China Sea in northwest vortex meridional circulation. And it is the South China Sea or the Bay of Bengal in northwest vortex zonal circulation and east - Mongolia cold vortex meridional circulation. Midlatitude meridional circulations at 500 hPa are advantageous to the rainstorm continuously and heavily. The general emergence of the rainstorm area is near the worm sheer line of low eddies, the left side of the biggest wind velocity area at 700 hPa.