相似环流背景下山西两次暴雨过程对比分析

Contrastive Analysis of Two Rainstorm Process in ShanxiProvince with Similar Circulation Background

利用常规和非常规气象观测资料，针对2012年山西境内出现的两次相似环流背景下的暴雨过程进行流型配置、物理量诊断、卫星、雷达、GPS／MET资料的综合分析。结果表明：（1）两次暴雨过程均发生在副高进退的环流背景下，两次暴雨过程槽、脊、涡位置接近，阻塞高压和冷涡强度相当。（2）副高特征线的位置和热力不稳两项有利条件决定了“7．27”强对流的特征，但口中尺度对流系统的欠缺、触发对流发生的系统尺度小以及对流发生环境的动力条件差，决定了“7．27”暴雨过程的局地性。（3）“7．21”区域性暴雨过程，8个13中尺度对流云团的生成发展与合并对山西北部M仪CS的形成、发展有贡献；“7．27”局地暴雨过程，4个B中尺度对流云团的生成发展与合并对山西中部MpCS的形成、发展有贡献。（4）两次暴雨过程，d或B中尺度切变线云系上均有1中尺度特征，“或卢中尺度切变线云系在发展阶段，均有多个具有独立回波核的对流单体有组织的排列组成，各对流单体的水平尺度均为v中尺度。不同的是“7．27”暴雨过程强对流单体伸展的高度更高，局地强降水的强度更强。（5）“7．21”暴雨过程，-53℃的冷云盖超前〉45dBz的冷锋云系雷达回波，强降水出现在TBB≤-530C等值线后部梯度的大值区；“7．27”暴雨过程，-53℃的冷云盖与40dBz的雷达回波区相重叠，强对流暴雨出现在40dBz雷达回波覆盖区与-53℃冷云盖相重叠的区域。相似环流背景下，同样是强对流降水暴雨过程，500hPa以下温度直减率的大小决定了局地强降水的强弱。水汽锋的形成及其位置是暴雨起报和暴雨落区预报的一个很好参考指标。

Based on conventional and unconventional similar circulation background in 2012 inShanxi province were configuration, physical diagnosis, and sate satellite, radar and observation data ,the two rainstorm process with the comprehensively analyzed at the aspects of circulation GPS/MET data. The results showed that ： （1） Both of the two rainstorm process occurred in the circulation background with the movement of subtropical high .The position oftrough, ridge and vortex and the strength of blocking high and cold vortex were similar in the two rainstorm process. （2） The severe convection character of the ＂7.27＂depended on two advantages that were the high characteristic lines and thermodynamic instability ,while the local character of the ＂7 posi 27＂ tion of subtropical rainstorm process depended on the lack of Mot CS, the small scale of the convection system and the poor dynamic conditions. （3） The generation, development and consolidation of the eight development of the Mot CS in northern Shanxi provin meso-β convective cloud？contributed to the generation and ce during the ＂7.21＂ regional rainstorm process, and, The generation, development and consolidation of the four meso- β convective cloud？contributed to the generation and development of the M β CS in central Shanxi province during the ＂7.27＂ local rainstorm process.（4） During the development period of the meso- α or meso- β shear line cloud that had meso-γ character , the convection cells which had independent echo nucleus and were meso- γ in horizontal were arrayed in organized in the two rainstorm process. But the severe convection cells extended higher and the local precipitation heavier in the ＂7.27＂ rainstorm process.（5） In the ＂7.21＂rainstorm process, the cold cover of value -53℃ came before the radar echo of cold front cloud system whose intensity was more than or equal to 45 dBz, and the heavy precipitation occurred in the great value area of gradient behind the isoline that the TBB was less than or equal to -53℃ In the ＂7.21＂rainstorm process, the cold cover of value -53℃ and the radar echo of value 40 dBz overlapped, and the sever convection rainstorm occurred in this area. It was the vertical laps of temperature below 500hPa that determined the strength of the local precipitation in the two sever convection rainstorm process with similar circulation background. The generation and position of the vapor front was a good reference to the start time and area of rainstorm forecast