邯郸地区一次登陆台风大暴雨过程观测分析

受登陆台风"海棠"减弱后低压与东移锋面云系的共同影响,2005年7月21日夜间到23日早晨邯郸地区出现了大范围的暴雨天气。本文从天气形势、水汽输送特征、云系演变特征和大气不稳定条件等方面进行分析,探讨了这次登陆台风暴雨天气的成因。结果表明,台风低压、稳定少变的副热带高压以及500 hPa低槽相互作用,共同造成了这次暴雨天气过程,高纬弱冷空气南下,与台风携带的暖湿空气相遇,加之太行山地形的影响,造成暖湿空气抬升,使得冀南地区产生中尺度对流云团,进而发生强降水。地面自动站以及加密站风场资料分析指出,低空偏北风与偏东风之间的中尺度辐合线对暴雨发生有重要作用,其出现的时间和位置决定了中尺度暴雨天气的发生时间和位置。在水汽输送方面,西部山区的暴雨区水汽主要来源于南海和东海,而东部平原地区的大暴雨,其水汽主要来源于南海。简单的层结分析表明,暴雨区上空存在对流不稳定和对称不稳定共存的现象,两者共同为系统发展和暴雨发生提供了不稳定条件。

Observational Analysis for a Torrential Rain Caused by a Landfall Typhoon

By the landfall Typhoon Haitang and propagating eastward frontal systems,torrential rains appear near Handan and its adjacent area from the evening of July 21 to the morning of July 23,2005.By analyzing the synoptic features,characteristics of water vapor transportation,evolution of FY2-C infrared satellite images and stratification features,the cause of the torrential rain is discussed.The results show that,interactions among the tropical low,stable subtropical high and troughs on 500 hPa leads to the torrential rain.Cold air masses propagate southwards from middle to high latitudes and meet with the warm and moist air masses transported by the tropical low,then the latter are lifted by its cold counterpart and the Taihang Mountains and mesoscale convections generate in the vicinity of Handan.The analysis of wind vectors from automatic surface observations shows that the mesoscale convergence line between the northerlies and the easterlies in lower troposphere is very important to the torrential rain,which determines the locations and timings of the torrential rain.The water vapor supply of the torrential rain in the western part of Handan is mainly from South China Sea and East China Sea,while the supply in the eastern part of the city is mainly from South China Sea.At last,simple stratification analysis shows that convective instability and conditional symmetric instability may coexist above the torrential rain zones,which provide instable energy for the torrential rains.