Analyses on Rainstorm Characteristics in Middle and South of Shanxi Province during 18-19 August 2010

A rainstorm occurred in Shanxi Province during 18-19 August 2010 are analyzed based on the encrypted data at automatic station,FY-2C product,and observational data.The results show that:(1) The rainstorm is affected jointly by cutting low,trough and subtropical high.There are well consistency between the absolute value of TBB and precipitation at rainstorm stations.(2) In this process,the rainstorm area are very scattered.There are six centers which have typical β-and γ-mesoscale characteristics.The rainstorm center have three patterns such as double,single and isolate peak.(3) Analysis of automatic wind field data shows that there are three patterns such as vortex precipitation,shear precipitation and convergent precipitation.There are apparent difference with intensity and duration of precipitation.The rainstorm area is related to its corresponding position with subtropical high.(4) Diagnosis of index A shows that the rainstorm is caused by high humidity air and strong cold air from high latitude area.Under the background of unstable stratification,the high humidity air is constantly elevated height along the edge of subtropical high.In the upper-level of troposphere,the conversion is a main factor which made vorticity developed and vertical motion constantly strengthen.