广州机场终端区“4.30”飑线过程的诊断分析和数值模拟

Diagnostic analysis and numerical simulation of the squall line event in Guangzhou airport terminal area on 30 April 2013

利用常规观测资料、多普勒天气雷达观测资料、风廓线雷达资料及NCEP/NCAR再分析资料,对2013年4月30日发生在广州白云机场终端区的飑线过程进行了诊断分析和数值模拟。结果表明:此次过程是由高空槽东移带动地面弱冷空气南下造成的;高分辨率WRF(Weather Research and Forecasting)模式较好地模拟出了这次飑线的形态和发展变化过程;飑线内部有较明显的倾斜气流,发展阶段内部以上升气流为主,成熟阶段强的上升运动主要位于600 h Pa以上,中低层则由于拖曳作用有显著的下沉气流;此次飑线过程有明显的地面冷池和雷暴高压配合,飑线的强度变化与地面冷池的变化存在明显相关,发展阶段雷暴高压出现在整个飑线的下方及后部,在成熟阶段其下方的正变压与后部的负变压呈对称结构。

Based on the conventional observation data, Doppler radar observation data, wind profiler radar data and NCEP/NCAR reanalysis data, a squall line event occurred in Guangzhou Baiyun airport terminal area on 30 April 2013 was analyzed and simulated. Results show that the weather event is caused by the east movement of the upper trough, which drives weak surface cold air southward. The shape and intensity changes of squall line simulated by WRF （Weather Research and Forecasting ） model are quite in agreement with the observations.There are obvious tilted updraft in the squall line.In the stage of development, there are updraft in the whole squall line, while in the mature stage, the updraft above 600 hPa and the downdraft in middle and low levels as a result of drag effect of heavy rain. There are obvious surface cold pool and thunderstorm high during the squall line process, and there is an obvious correlation between intensity change of squall line and change of cold pool. In the stage of development, the thunderstorm high locates in the low and back parts of the whole squall line, while in the mature stage, the positive pressure change in the low part and the negative pressure change in the back part are symmetrical.