Numerical simulation and diagnosis analysis on a region torrential rain event

Based on a torrential rain event occurred on the 15th July 2003 in Shannxi, China,the circumfluence situation , the flow field , vapor condition, dynamic condition and energy were analyzed and simulated. The results show that the MM5 model can successfully simulate the torrential rain, circulation properties and physical factors. Results show also that the occurrence of heavy rainfall had obvious dynamic-thermodynamic structural feature: strong divergence column and intensive vorticity column were coupling developed; the extremely intensive ascendant motion was inter-coupled with saturated air column.