一次广西暴雨过程的数值模拟及低涡系统分析

应用WRF中尺度数值模式对2008年6月12日广西地区的一次大暴雨过程进行了模拟,利用模式输出资料,对引发这次大暴雨的西南低涡的演变情况及其物理场特征进行了分析。结果表明,低涡暴雨的发生具有明显的不均匀性,暴雨主要出现在低涡东侧暖区切变线附近;暴雨过程中充沛的水汽主要来源于孟加拉湾和中国南海,水汽的辐合不仅是涡旋区降水的必要条件,还是低涡发展加强的一个有利因素;强降水与强上升运动及正涡度区有很好的对应关系,低涡低层有强不稳定能量积聚也是造成此次大暴雨的重要原因之一。

NUMERICAL SIMULATION AND DIAGNOSIS OF A HEAVY RAINFALL IN GUANGXI

The mesoscale model WRF is used to simulate the process of a heavy rainfall occurred in the Guangxi during 12—13 June 2008.The results show that the occurrence of this heavy rain was triggered by southwest vortex which presented obvious inhomogeneity.Heavy rain primarily occurred on the side of warm wind shear which locates over the east of the vortex center.The diagnostic analyses indicate that the vapor mainly came from the Bay of Bengal and South China Sea.Moisture convergence was not only a necessary condition for precipitation in the vortex area,but also a favorable factor to strengthen the vortex.Heavy rainfall had a good correspondence with strong upward motion and positive vorticity area.Accumulation of instability energy at low level of the vortex is also one of the causes for the heavy rain.