一次飑线过程的数值模拟及诊断分析

Numerical simulation and diagnosis analysis of a squall line case

利用NCAR、NCEP和FSL/NOAA等共同研制的WRF中尺度数值模式,对2009年6月3日河南地区发生的一次飑线过程进行数值模拟,并利用模式输出的高分辨率资料对该次过程进行诊断分析。结果表明:WRF模式成功地再现了高低空环流形势演变及强对流的分布发展特征,高空冷涡后部冷空气南下,近地层较暖,形成了上冷下暖的位势不稳定层结及地面辐合线是这次强对流和飑线天气过程的触发机制。强对流发生时,该地区出现的低空增温增湿、低空急流的爆发及低层急流核向东南快传、高空急流轴稳定在强对流天气发生地上空,对流有效位能积累和释放随时间的演变过程及垂直螺旋度大值中心等对此次强对流天气过程有较好的指示意义。

A squall line case on June 3,2009 in He′nan province was simulated by the WRF mesoscale numerical model developed by NACR,NCEP and FSL/NOAA etc.,and it was diagnosed by fine resolution data from WRF model.The results indicate that WRF model successfully reveals the circulation＇s evolution and the distribution characteristics of the severe convection weather.The cold air in the back of the upper cold vortex is southbound and warmer near ground surface,so the upper-layer cold and lower-layer warm potential instability stratification and the ground convergence line are formed.All these are the trigger mechanism of the severe convection and the squall line weather process.The strong instability of low level,the outbreak of low level jet（LLJ） and the core of the LLJ moving southeastward quickly,convective available potential energy（CAPE） and vertical helicity high center are indicative to the strong convection weather.