Analysis on the Multi-Scale Characteristics of the Rainstorm in Shanxi Province on 29 July 2011

Based on the NCEP reanalyzed data(1° × 1°),infrared radiation bright temperature,Doppler radar data and the total column water vapor content data,the multi-scale characteristics of the regional rainstorm which occurred in Shanxi on 28 ~ 29 July 2011 were analyzed.Results were as follows:(1) The collapsing of Ural blocking high,westerly trough moving eastward,the advance and retreat of the subtropical high were the circulation characteristics of the rainstorm;(2) The vortex shear line on 850 hPa,warm shear line on 700 hPa and the cold front on surface were the meso-α-scale system triggering rainstorm occurrence;(3) The radar echo more than 30 dBZ lied between the surface cold front and the 700 hPa shear line,and moved eastward with them going to east;(4)The lower level vortex shear line was guided to northeast by the strong southwest airflow on 500 hPa,while the rainfall area always followed the shear line;(5) During the rainstorm process,there were nine active meso-β-scale convective cloud clusters totally in Shanxi Province,and five of them entered in Shanxi one after the other and triggered the rainstorms in southwestern Shanxi nearby the shear lines of extreme wind of automatic stations.While the rainstorm in southeastern Shanxi was the result of mergence and development of three meso-β-scale convective cloud clusters,and the meso-γ-scale cyclone directly leaded to the occurrence of the local torrential rain;(6) The rainstorm occurred in the south and east areas of the water vapor front,as well as in the side of the high value area of the total column water vapor content.The formation of the water vapor front was 17 hours ahead of precipitation occurrence,and at least 24 hours ahead of the rainstorm appearence,which had a great significance in short-range and short-time weather forecast.