一次梅雨锋大暴雨过程的数值模拟分析

Synoptic Analysis and Numerical Simulation of Heavy Rainstorm Process Caused by a Meiyu Front

利用区域大气数值模式RAMS 6.0,模拟了2008年6月9-10日发生在我国长江中下游地区的一次梅雨锋大暴雨过程。结果表明,模式能较好地再现这次大暴雨过程以及中小尺度系统的生消演变。在这次大暴雨过程中,高低空流场的恰当配置、三支气流在长江中下游的汇合及低涡沿切变线东移等都为大暴雨的形成提供了有利的大尺度环流背景。低涡内生成的一系列中尺度对流系统沿梅雨锋稳定地向东北偏东方向移动并发展,是造成这次长江中下游地区大暴雨的动力机制。孟加拉湾到我国西南地区稳定的南支低槽和副热带高压外围发展旺盛的西南气流输送,为这次暴雨过程提供了充沛的水汽。

Rainstorm process occurred the mid-and lower-reaches of Changjiang River was caused by a Meiyu front on 9-10June 2008.The rainstorm process was analyzed and simulated by the regional atmosphere model RAMS 6.0（Region Atmosphere Modeling System）.The results of RAMS reproduced the firstborn and development of mesoscale system in the rainstorm process.The occurrance and development of the mesoscale system during the rainstrom processe were studied.The results showed that the rainstorm process connected with the appropriate configuration of upper-and low-level jet stream.Southwest Vortex moved eastward along the shear line,which provided a favorable large-scale circulation background for the formation of rainstorm;a series of mesoscale convective systems stably moved to northeast direction and developing along the Meiyu front,it was the dynamic mechanism of the heavy rainstorm in this region;the stable trough of Bay of Bengal and the southwesterly water vapor tranport of strong developing outside the subtropical high provided the material conditions for the heavy rainstorm process.