贵州02.6大暴雨的模拟与诊断分析

Simulation and Diagnostic Analysis of “02.6” Heavy Rain Event in Guizhou Province

利用MM5中尺度模式对贵州2002年6月18日00时～19日00时的暴雨天气过程进行了数值模拟，首先利用模式输出的基本物理量分析了相当位温、垂直速度，并计算垂直螺旋度以及湿位涡正压、斜压项，诊断分析发现：暴雨中心位于最大垂直速度中心附近；南北两支闭合经向垂直环流对于暴雨区的低空入流和高空出流具有非常重要的作用。螺旋度的变化对暴雨的强度变化有很好的指示性，暴雨区位于螺旋度等值线密集区靠正螺旋度区一例；贵州大暴雨与500hPa“漏斗”形MPV1高值区同位相变化，高低层MPV1“正负值区垂直叠加”的配置是暴雨发生、发展的有利形势。500hPa上MPV2正值区与对流性降水区对应很好，而且强度变化也一致。

A heavy rain event in Guizhou on June 18. 00-19：00 （UTC）, 2002, is simulated with meso-scale numerical model （MMS）. With the basic physical parameters from the model output, the potential equivalent temperature and vertical velocity are analyzed, and calculation of the helicity and the barotropic and baroclinic moist potential vorticity （MPV） are made. The diagnosis results are as follows. The center of the rainfall is adjacent to the maximum vertical velocity. The southern and northern meridional-vertical circulations are significant to the in- and out-flow on the lower and upper level, respectively. The change of the helicity is a good indicator for the evolution of the rainfall intensity. The heavy rainfall area lie in the dense part of helicity isograms. The occurrence, intensification and decay of the event is corresponding to that of the funnel-like MPV1 high value area. Moreover, the overlapping of the positive MPV1 at the upper-level and negative MPV1 at the low-level is advantageous to the appearance and development of the event. The positive MPV2 area at 500hPa is well corresponding to the convective rainfall area, and they have in phase changes.