黄河中下游一次MCC和中-β尺度强对流云团相互作用暴雨过程综合分析

Synthetic Diagnostic Analysis on a Rainstorm Process Caused Interaction of MCC and Meso-β Scale Severe Convective Cell in Mid-and Lower-Reaches of Yellow River

利用卫星云图、多普勒雷达资料、地面加密观测资料和NCEP再分析资料等,对2007年7月29日山西和河南交界地带发生的一次暴雨过程进行了大尺度环境场和中尺度影响系统的综合分析。结果表明:暴雨是由MCC、中-β尺度强对流云团、以及MCC和中-β尺度强对流云团合并造成的;低空急流和边界层东北风是MCC生成和发展的触发机制之一;气流呈顺时旋转的次级环流圈生成,为MCC的生成和发展提供了动力条件;黄河下游范围更大、气流呈逆时针旋转的环流圈生成,对上游次级环流圈具有阻挡和稳定作用;伴随MCC云顶红外亮温TBB≤-62℃面积的减小,位于MCC上游的切变线上同时激发了中-β尺度强对流云团的发展;地面风场切变线、配合地面小高压舌的动向,以及地面中尺度低压的生成和能量比低值舌的活动,对MCC和中-β尺度强对流云团的生成和发展具有指示作用。

Using the satellite image data,Doppler radar data,the conventional observation data,the surface intensive observationdata and NCEP reanalyzeddata,the large-scale environment field and mesoscale influence systems of the floodingrainstorm process in common boundary of Shanxi and Henan on July 29～30,2007 is analyzed. The results show that the rainstorm is caused by MCC,the meso-β scale severe convection cloud clusters,as well as MCC and the meso-β scale severe convection cloud cluster merger.The low jet stream and northeast wind at boundary layer are one of the triggeringmechanisms for generation and development of MCC.The secondary circulation circleis generated when the air current is clockwise rotation to provid the dynamic conditions for the generation and development of MCC.The generation of the secondary circulation circle has the meso-α scale in downstream when the air current the counterclockwise rotation which is of the impediment and the stabilization tothesecondary circulation circlein upstream.The high pressure of surface mesoscale moves to the south triggeredthe generation and developmentof MCC in the shear line,it is located in thefront ofthe mesoscale high pressure.The severe precipitation of MCC brings triggered the meso-β scale severe convection cell development in the shear line that located at the upstream of MCC.The cyclone perturbation,the motion trendof thesmall high-pressuretongue,as well as the generation of mesoscale low pressureon the surface pressure field,has the instruction function to the developmentof meso-β scale severe convective cell.