Numerical Simulation And Genesis Analysis Of The Rainstorm On29～30July2007in The West Part Of Henan Province

The storm which happened on29-30July2007leaded to great casualties and property lose at the west part of Henan province. This storm had the characteres of short-time、flood-causing、hazard-formation and mesoscale. The prediction of this storm was unsuccessful before it’s happen, this precipitation process need to be summarized and analyzed in order to proveded reference to the forecast of the storm and improve the forecast accuracy and betimes.By using the conventional observation data, NCEP reanalysis data, radar data and satellite data, the rainstorm weather process which occurred on29-30July2007is analyzed and simulated by using mesoscale model WRF(V3),The result shows that the rainstorm weather process was caused by the southwest air current front of the trough and Subtropical High. Before the rainstorm, the upper air circulation of500hPa shows the feature of two troughs and one ridge, the location of Subtropical High was steady, there was obvious shear on the700hPa and low jet exist around the falling area of the storm at the same time.The analysis of the satellite data shows that the precipitation cloud has obvious mesoscale characteristics in two rain stages, the producing of the rainstorm and the development of mesoscale cloud has direct relation.The Doppler radar data shows that the mesoscale convective cloud is the main reason of local heavy rainfall, there are obvious mesoscale convective exist, the meso-yconvergence was find in the radar velocity images, the local strong echo continuously arise in the combination reflectivity, these are all helpful to the form of rainstorm.The rainstorm process was simulated by using mesoscale numerical model WRF(V3), the simulation result of the first stage of the rainstorm is the precipitation is close to the observation, but the rainfall area is further west compared to the observation, based on the simulation result, an analysis was give to the water vapor flux, vertical motion,potential vorticity,moist potential vorticity and vertical helicity.The analysis and the numerical simulation to the rainstorm which happen at the west part of Henan province on29-30July2007shows that, the sufficient water vapor transportation, mesoscale strong convective and low-level jet is the key point of the form of rainstorm. The numerical simulation can simulate the precipitation greatly, but the rainfall area has some deviation. much more influence factors were needed to improve the accuracy and reliability of the simulation. In the future, the radar data、ragional automatic station and automatic rainfall station should be put into the simulation to perfect the initial fields if the condition allowed.