Numerical Simulation and Diagnostic Analysis of a Heavy Rainfall Caused by Mesoscale-β System
Using MM5V3.5 mesoscale non-hydrostatic model, torrential rain occurring in the Shannxi Province during 8 to 9 June,2002 was simulated and analyzed. The main results are as follows: (1) Under the advantageous macroscale weather situation, the mesoscale-β system by developing along low-level-jet triggered by mesoscale-shear is the main influence system causing the heavy rainfall.(2)Furthermore,there are obvious dynamic-thermodynamic structural features in the developing phase of the mesoscale-β system. That is ,strong divergence column and intensive vorticity column are coupling developed,the intensive ascendant motion is intercoupled with saturated air column,there is a lot of accumulation of instable energy during the development of ascendant motion.MM5 model has the better performence to simulate the mesoscale systems and the torrential rainfall.So these conclusions will be helpful and provide references for the forecast of mesoscale storm rainfall.