泰山地形对一次局地强降水过程动力作用的数值模拟分析

文章针对2005年9月2日发生在济宁郭楼镇的一次泰山背风下游区局地特大暴雨过程（438 mm/7 h），利用济南SA雷达资料和WRF中尺度数值模式资料，分析了泰山山区地形造成的对流层中低层大气动力过程及其对暴雨中尺度系统的影响，开展了地形敏感性数值试验。结果表明：对流层低层回流南下的东北气流受鲁中山区地形影响，水平方向发生绕流，垂直方向被迫抬升，从而在泰山背风向的暴雨区附近形成准定常的绕流汇合区和重力波扰动区，两项作用强迫的垂直运动，与天气系统辐合区共同作用触发该地区的对流活动，并使移入该地的对流系统增强和维持。改变地形后引起低层风场和散度场变化，进而影响降雨带中的强降水落区和强度，但对主雨带的分布无明显影响。

Numerical Simulation Analysis on Dynamic Effect of Taishan Mountain Terrain on Local Severe Rainfall

An extremely heavy rainfall event (435 mm/7 h) that happened in Guolou Town behind the leeward slope of Taishan Mountain on September 2, 2005 is simulated and analyzed by using WRF mesoscale numerical model data and the Jinan SA radar data, and sensitivity tests are carried out to study the influence of the terrain of Taishan Mountain in central Shandong Province on the dynamic process of atmosphere in mid low troposphere. The results show that because of the effect of Taishan Mountain, the northeast airflow becomes circum mountain airflow in the horizontal direction, and is lifted in the vertical direction. The quasi permanent convergence zone of the circum mountain flow and gravity wave disturbance zone are formed near the torrential rain area in the lee side of Taishan Mountain and triggers the severe convection together with the convergence zone of weather system, driving the severe convective system into this area intensify and maintain. If the terrain was changed, the wind field and divergence field in low level could get weakened, affecting the location and the intensity of the extremely severe precipitation, but not having distinct impact on the distribution of the main rain belt.