西南低涡诱发贵州夏季暴雨预报研究

目的]研究西南低涡诱发贵州夏季暴雨的预报。方法]选取2.5°×2.5°NECP提供的北半球700 hPa 1971～2008年6～8月一天4个时次再分析资料,对贵州6～8月暴雨与西南低涡活动进行较为系统的研究,并给出西南低涡型贵州6～8月区域性暴雨预报思路。结果]西南低涡是造成贵州汛期（6～8月）,尤其是6、7月份暴雨的主要影响系统之一,该类暴雨的发生与西南低涡的移动路径、冷空气活动、500 hPa环境流场、850 hPa切变线、西南急流、副高脊线的位置及水汽条件、涡度场等有密切的关系。应用实况资料,采用相似方法和物理量诊断,建立客观的预报业务系统,并对该系统进行验证表明选取高空槽、西南低涡、垂直运动条件、西南急流、水汽条件等因子来作为贵州暴雨的预报因子是合理的;西南低涡中心位于主关键区（100°～105°E、25°～35°N）和次关键区（105°～108°E、25°～35°N）时,贵州当日最容易出现区域性暴雨降水,其中又以在主关键区出现暴雨的概率较大。结论]该研究为提高该类型暴雨预报水平和防灾、减灾提供依据。

Study on the Prediction of Summer Rainstorm Caused by Southwest Vortex

Objective] The aim was to study the prediction of summer rainstorm caused by southwest vortex.Method] Based on 2.5°×2.5° reanalysis data in four hours a day from June to August during 1971-2008 at 700 hPa in northern hemisphere provided by NECP,rainstorm and southwest vortex from June to August in Guizhou Province were studied systematically,and the forecast idea of rainstorm caused by southwest was obtained.Result] Southwest vortex was one of major influence systems of rainstorm in flood season(from June to August),especially in June and July;the occurrence of this kind of rainstorm was closely related to the moving path of southwest vortex,activity of cold air,environmental flow filed at 500 hPa,shear line at 850 hPa,southwest jet,position of subtropical high ridge,water vapour conditions,vorticity filed,etc.On the basis of factual data,objective forecast system was established and verified by means of similar method and physical diagnosis.The results showed that it was rational to choose upper trough,southwest vortex,conditions of vertical movement,southwest jet,water vapour conditions,etc.as forecast factors;when the center of southwest vortex was located in major key area(100°-105° E,25°-35° N) and secondary key area(105°-108 ° E,25°-35° N),regional rainstorm occurred most easily,especially in major key area with high frequency of rainstorm.Conclusion] The study could provide references for the improvement of prediction level of rainstorm caused by southwest vortex,disaster prevention and reduction.