The Research Of The Hailstrom Weather Form Mechanism In Guangxi Region

Based on the NCEP reanalyzed data, MM5 numerical simulation data and the Doppler radar products, a severe hailstorm process occurred in north of Guangxi Province of China on April 9, 2006 is analyzed to search the cause of the hailstorm of Guangxi.By analysised on the moisture field, energy field and high lever jet and low lever jet stream, we discovered that the dry and warm lid existed previous to the strong convection process is favorable to storing of the convective available potential energy (CAPE). The increase of vertical wind shear promoted the exchanges of the high lever and low lever to unveil the dry and warm lid, to trigger the convection.In order to determine the best simulation program, we changed different parameter to carry on the numerical experimentation. The comparisons analysis for changing for planetary boundary layer indicated that different PBLs can effect on the trend of the rain belt and the distributed of the heavy rain center.Changing cumulus parameterization schemes indicated that different CPSs can change the position of the rain belt and rain center. The explicit moisture schemes have little effects on the rain belt and rain center, but significant effects on the precipitation intensity. When we added the upper air and surface observation data, the simulation was more approaching to the real state.Base on simulated the meso scale Convection system successfully, the output data of MM5 was analysised. It was found that the middle lever was very dry before convection. The lifting movement that destroied the middle dry level, Is advantageous to strong convection exploding. Around the convection occurs,the atmosphere is gravitational stability, conditionally unstable possibly is the important mechanism which the strong convection explodes. The transport downward of the potential vortices of high lever arouse the low lever vortices changes, and lead to the convergence of low lever and divergence of high lever, it keeps and strengthens the strong convection.During the hailstrom, there was a warm heart whose intensity related to the convection. When the convection strong, the warm hart strong, and the convection weak, .the warm hart weak. When the hailstorm happens, there were strong convection between 600hPa and 400hPa, the strong convective center was stand above 0~C lever 100hPa approximately.Doppler radar products were analysied to find that the hailstorm process was caused by a squall line from southwest to northeast.The strong storm center stand above 5km, there is a weak echo on the low lever. Strom centerascended incline and whirl clockwise from low lever to high lever. The vertical integrated liquid and VAD Wind profile products have significance Instructs to hailstorm forecast.