气流的垂直分布对地形雨落区的影响

The Effects of Vertical Distribution of the LowerLevel Flow on Precipitation Location

从大气运动的基本方程出发, 讨论了华北地区太行山东侧低空东风气流背景下不同垂直分布气流对降水落区的影响。认为: 当垂直于山体的气流随高度减小时, 地形的作用表现为迎风坡上水平辐合, 造成气旋式涡度增加, 产生风场切变, 因此对迎风坡降水产生明显的增幅作用。当气流的垂直分布随高度增加时, 迎风坡方向表现为反气旋涡度增强, 而在背风坡方向产生辐合作用, 造成气旋式涡度增加, 发生风场切变。

The dynamical effects of the topography on air flows with different vertical distributing have been studied. If a mountain is upright to air flow, the results are as follows: When lower level wind is stronger than upper wind, the divergence motion and wind shear come into being, and eddy will be enhanced, so the precipitation obviously amplitudes against to windward slope. To leeward slope, the situation is opposite. However, when upper wind is stronger than lower, there will be diverged motion on windward slope and eddy will be enhanced on leeward slope. The viewpoints are successfully utilized to explain the different precipitation distributing which happened in North China.