黄河中下游地区一次暴雨过程的数值模拟和诊断

利用非静力中尺度模式WRF V3.2.1及其输出的高时空分辨率资料,对2007年7月29~30日发生在黄河中下游地区的暴雨天气过程进行了数值模拟和诊断分析。结果表明:(1)广义位温的大值中心区与相对湿度90%的高湿区相一致,暴雨区上空的广义位温等值线呈漏斗状从对流层中高层向低层伸展,在漏斗的底部,其垂直梯度也相应增大,暴雨中心位于广义位温的大梯度区;(2)P坐标下,对流涡度矢量垂直分量(Cz)与降水量随时间演变二者呈现反位相,且Cz极值的出现滞后降水峰值1 h左右;对流涡度矢量垂直分量的垂直积分的发展演变与降水落区、强度的发展变化相对应,对强降水落区、强度的发展变化具有指示意义。

The Numerical Simulation and Diagnostic Analysis of a Rainstorm Process in the Middle and Lower Reaches of the Yellow River

Based on PSU/NCAR nonhydrostatic mesoscale model WRF V3.2.1 and its output data with high spatial and temporal reso-lution,the heavy rainfall process which occurred in the middle and lower reaches of the Yellow River from 29 to 30 July 2007 was simu-lated and analyzed.The results are as follows：（1 ）The center of maximum values of generalized potential temperature was consistent with the area of relative humidity more than 90%.Over the rainstorm area,the funnelform isolines of generalized potential temperature sloped and extended from the middle and upper troposphere to the lower level,and the vertical gradient of generalized potential temper-ature increased accordingly under the bottom of the funnel,the storm center was located in the big gradient area of generalized potential temperature.（2）In pressure coordinates,the vertical component （Cz ）of convective vorticity vector was opposite to the rainfall with time evolution,and the extreme value of Cz lagged the peak precipitation about an hour.The development of the vertical integration of Cz was corresponding to the rainfall area and the rainfall intensity change,which showed that it had some indication to the rainfall area and precipitation intensity.