2016年7月山西一次大暴雨天气过程的多尺度系统相互作用分析  

Multi-scale System Interaction Research of a Torrential Rainfall Process in Shanxi in July 2016

作　　者：王思慜[1] 赵桂香[1] 赵瑜[1] 申李文[1] 

机构地区：[1]山西省气象台,山西太原030006

出　　处：《干旱气象》2017年第5期857-867,共11页Journal of Arid Meteorology

基　　金：国家自然科学基金项目"黄河中游地区突发性大暴雨MCC结构特征研究"(4147505)

摘　　要：利用常规气象观测资料、加密自动站资料以及卫星云图、雷达回波等产品,对2016年7月18—20日山西一次大暴雨天气过程的多尺度天气系统及其相互作用特征进行分析。结果表明:(1)500 h Pa与地面图上东高西低的环流形势稳定维持,中尺度低涡切变线造成强烈的辐合上升运动,低空急流向山西源源不断地输送水汽,造成山西持续出现大暴雨天气。(2)卫星云图及雷达回波显示,此次过程由槽前斜压叶状云系发展成的涡旋云系造成,对应的雷达回波为积状云与层状云的混合性回波,层状云中不断有对流单体发展、合并、加强、消亡,整个过程可分为2个阶段:第1阶段以带状回波为主,其上多对流回波,出现了雷暴和短时强降水;第2阶段回波强度减小,对流性质减弱,但回波存在不断生消和停滞少动等特点,造成长时间稳定性降水。(3)天气尺度系统的稳定维持是中尺度系统稳定存在、持续发展加强的主要原因,主要表现在对中尺度低涡的阻挡作用和对低涡维持所需冷空气的持续供应;其中中-α尺度低涡则制约更小尺度系统即中-β尺度或中-γ尺度辐合系统的形成和维持,而这些小尺度系统是此次暴雨大暴雨天气的直接制造者。Based on conventional observation data,meteorological data observed by automatic encrypted weather stations,satellite images and radar mosaic products,the heavy rainfall occurring in Shanxi from 18 to 20 July in 2016 was analyzed. The results are as follows：（1） The continuously heavy rainfall in Shanxi was caused by the steady circulation situation on 500 h Pa and ground,the strong convergence and vertical updraft was caused by a meso-scale shear line and more moisture was transported to Shanxi by low level jet.（2） The process was caused by the vortex structure cloud which was developed by the baroclinic leaf cloud. The radar echoes showed convective cloud and the stratiform cloud,and there were several convection cells development,merging,strengthening and disappearing in the stratiform cloud. The whole process could be divided into two stages,at the first stage,it was mainly the zonal echo with several convective echoes on it,which caused thunderstorms and short-time strong rainfall. During the second stage,the radar echo intensity decreased and convection activity abated,while the radar echoes kept growing and decaying and long lasting,which resulted long time stable rainfall.（3） During the rainstorm process,the stable maintaining of synoptic-scale system made the meso-scale system stable,sustained developing and strengthening through the block role of the meso-scale low vortex and the continuous supply of the cold air. The formation and maintenance mechanism of the meso-β-scale or meso-γ-scale convergence system were restricted by the meso-α-scale low vortex system,and these smaller scale systems were the direct factors of the heavy rainfall.

关 键 词：大暴雨 不同尺度系统 涡旋云系 复杂回波 

分 类 号：P458.121.1[天文地球—大气科学及气象学]