重庆“9·4”特大暴雨天气过程数值模拟分析

NUMERICAL SIMULATION ANALYSIS OF A HEAVY RAINFALL IN CHONGQING AREA ON 4 SEPTEMBER 2004

本文利用MM5中尺度数值预报模式对2004年9月4日发生在重庆的特大暴雨天气过程进行了模拟。模拟结果表明,模拟降水的落区和量级效果较好,通过对造成此次暴雨天气的中尺度天气系统西南涡的分析,模拟结果是西南涡的强度和中心与实况分析都是一致的。结合高低层的物理量场分析形成暴雨发生条件和落区分布的物理概念模型,水汽的输送和辐合从低层到高层是沿着西南气流的方向向东倾斜,落区的分布与中高层500 hPa^300 hPa的风场辐合相关性非常好,降水强度与垂直速度的强度和上升高度有关。

A heavy rainfall on 4 September, 2004 in Chongqing area is simulated by MM5 mesoscale numerical model. The simulation results show that the rainfall area and quantity are simulated quite well. It shows that the simulation density and center of southwest vortex are nearly the same as the weather analysis,according to analysis the mesoscale weather system generates the heavy rainfall. A physical concept model of the generation condition of heavy rainfall and rainfall area distribution is found according to physical quantity analysis of high-low level. The vapor＇s transportation and convergence from low level to high level is inclined to east along with the southeast current. The rain distribution relates to mid-high level such as 500hPa-300 hPa,and rain intensity relates to the density and hight of vertical current.