GWDO参数化在内蒙古东部地区一次暴雨天气的模拟分析

文章以2011年7月24—26日发生在内蒙古东部地区大兴安岭山脉西侧、宝格达山脉南部的一次大到暴雨天气为例,利用WRF3.3.1中尺度模式对这一过程进行数值模拟,探讨地形重力波拖曳(GWDO)参数化方案对山区暴雨的模拟能力,以及本次暴雨的发生机制。通过模拟结果与实况对比分析后得出:①模式中考虑了GWDO参数化方案较好地模拟了此次强降雨的中心位置和落区及强度,根据暴雨过程中大尺度环流形势及其演变状况,较好地得出切变线暴雨以及地形重力波拖曳能导致上升运动加强,并使得暴雨范围相对集中。而未考虑此方案的控制试验没能模拟出此次暴雨,其在中心位置和降水强度方面都与实况差别较大。②通过流场、涡度场等物理量场的对比分析,比较合理地模拟出了地形对气流的影响,从而使山区暴雨的模拟效果更接近于实况。

Simulation Analysis of GWDO Parameterization on a Rainstorm in the Eastern Area of Inner Mongolia

The weather process that occurred on the west of Da Hinggan Mountains and the south of Baogeda in the eastern area of Inner Mongolia from July 24th to 26th was analyzed using the mesoscale numerical model WRF3.3.1. The capability on rainstorm in mountain areas by OGWD and the mechanism of this rainstorm process was discussed. The results showed that： （1） the center position of the heavy rainfall, falling area and intensity were better simulated in the model considering OGWD. According to the rainstorm of the large scale circulation and evolution status, that the shear line rainstorm and GWDO could cause that ascending motion of tile storm was strengthened was simulated better, and the failing area was concentrated relatively. In the model without consid- ering OGWD, the center position of the heavy rainfall and intensity were greatly different from the actual value. （2） The influence of topography on the wind was simulated more reasonably, through comparison and analysis of physical quantity fields, such as flow field and vorticity field, etc. So as to make the simulation results closer to the actual mountain storm.