2011年梅雨期湖北省首场暴雨天气过程分析

目的]分析2011年6月9日湖北入梅后首场暴雨过程。方法]利用常规观测资料以及每6 h一次的NCEP 0.5°×0.5°再分析资料、卫星资料和地面加密雨量站资料等,对2011年6月9日湖北入梅后首场暴雨过程进行了天气动力学诊断和中尺度分析,寻找湖北省梅雨期暴雨的中尺度对流系统结构特征、系统移动演变规律以及触发机制等。结果]这次暴雨过程是在有利的天气背景条件下产生的,此次暴雨过程是单阻型梅雨形势,500 hPa中高纬维持"两槽一脊"形势,无明显阻高,副高位置偏东偏弱,以高原冷空气为主;川东低涡东移、中低层切变线、干线和低空急流为降水发生提供了有利的水汽和动力条件;造成强降水的雨团有明显的中尺度系统特征,3个中β对流云团分别来自西南暖湿气流、700 hPa冷式切变尾部和850 hPa暖式切变顶部,经过在鄂东南合并加强,生成具有东北—西南走向的带状结构特征、维持少动的中β尺度对流系统(Mβcss),该云团是此次降水的直接制造者,通城强降水出现在云团合并发展最旺盛的地方。结论]该研究为梅雨期暴雨的预报提供理论依据。

Analysis of the First Heavy Rain in Hubei Province during Meiyu

Objective] The aim was to analyze the first fit of rainstorm in southeast Hubei on June 9,2011.Method] GFS reanalysis data with resolution 0.5°×0.5 °,routine-observational data,the intensive observations of automatic weather station data,satellite image as wel1 as satellite image were used in the analysis for the process of a heavy rain on June 9~10,2011 during Meiyu in Hubei Province.Result] The result showed that the heavy rainfall occurred under the favorable environmental conditions,but the single-obstruction situation during Meiyu was different from the typical double-obstruction one.The affecting systems were the trough at 45°N on 500 hpa caused the systems moving slowly in the middle and low troposphere.The strong convergence of water vapor and conditional convective instability were provided from the shear line on 700 hpa and 850hpa,the southwest jet flow and dry lines in the middle and low troposphere for heavy rainfall.Three rain clusters which brought heavy rainfall had the features of meso-scale β system,which came from warm and humid airflow,the tail of shear line on 700hpa and the head of shear line on 850 hpa.Through convergence and strengthening in Southeast region of Hubei Province,the ribbon structure from northeast to southwest was formed to maintain the meso-scale β system.The cloud was the direct producer of precipitation.Heavy rainfall occurred in strengthening phase of strong convection zone on Tongcheng city.Conclusion] The study provided theoretical reference for the report of rainstorm during Meiyu period.