Analyzing the characteristics of vortex heavy rainfall in Henan during 16`19 July 2010

Based on the conventional meteorological observations, the regional automatic stations, Doppler radar and NCEP reanalysis data, characteristics of two vortex heavy rainfalls occurred in Henan during 16 and 19 July 2010 were analyzed. The result shows that the interaction between the warm and wet air flowing on the edge of Subtropical High and the spreading south cold air benefits the formation of western Huanghuai meso-scale vorticity; while the warm and wet air on the edge of Typhoon and Subtropical High flows up north in a far distance to provid abundant water vapor for rainfalls. The coupled dynamic structure between high-level divergence and low-level convergence near the center of vortex is in favor of the development of vertical ascending motion, which also increases the convergence and lifting of water vapor. The thermal instability structures are different during the two vortex-storm process: Convective instability and conditional symmetric instability coexisted during the 7.17 process, and the convective instability is the atmospheric major character; While in the 7.19 process, the frontal zone was strong and deep, the Conditional symmetric instability is the atmospheric major character, which leaded a relatively weak rainfall. Analysis of vorticity suggests that the peak values of local vorticity transfers down from the top, and vertical transport is the major contribution of local vorticity increasement.