梅雨锋致洪暴雨β中尺度涡旋的数值试验和结构分析

Numerical Simulation Study of Meso-β Scale Vortex System in Meiyu Front

运用 PSU/NCAR的 MM5 V2的嵌套模式 ,对 1 998年 7月的武汉致洪暴雨过程作了成功的数值模拟。并运用模式输出的高分辨率资料对引起此次特大暴雨的 β中尺度涡旋系统的结构作了诊断分析。分析了涡旋系统在 3个不同时期的三维结构特征 ,特别是得到与暴雨雨团相联系的β中尺度垂直环流分布特征。指出涡旋系统的水平范围在 90 km左右 ,涡旋环流只在对流层中层 ( 85 0 h Pa～ 65 0 h Pa)比较明显 ,与涡旋相伴的是一个在狭窄区域内物理量高度集中 ,并向垂直方向发展的暖心正涡度柱。

In this paper, by using MM5 V2 model, we have successfully simulated a heavy rain process that occurred in Wuhan area in July,1998 has been simulated. Based on the high resolution output data, the diagnostic analysis is conducted to disclose the structure of meso β scale vortex system in three different periods. The results show that the horizontal scale of the system is within 90 km, and the circulation is evident only in the low midlevel troposphere(850 hPa～650 hPa), and the most important feature is its warm core positive vorticity column with accumulation of various thermodynamic and dynamic variables.