斜压性与非线性Ekman抽吸的动力特征
BAROCLINICITY AND DYNAMICS OF NONLINEAR EKMAN PUMPING
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摘要: 本文利用Ekman动量近似研究了斜压性对Ekman层动力学的影响,得到了一些新的结果.大气斜压性对Ekman层的水平风速分布及近地面的风速矢的水平分量夹角有重要的改变作用.斜压边界层顶部的非线性Ekman抽吸(垂直运动)由三个不同的物理因子决定,第一、正压性的地面地转涡度,第二、斜压性作用产生的热成风涡度,第三、正压性的地面地转涡度与斜压性的热成风涡度的非线性相互作用.这些理论结果为边界层的参数化及数值模拟结果的解释提供物理基础.Abstract: In this paper,the influence of atmospheric barolinicity on the dynamics of boundary layer with the Ekman momentum approximation is studied.Some new results are obstained.The atmospheric baroclinicity plays an important role in altering the horizontal velocity of the Ekman layer and the angele between the latitude component of velocity and the longtitude one near the surface.There are three different physical factors affecting the nonlinear Ekman pumping (the vertical motion) at the top of baroclinic boundary layer:First,the barotropic geostrophic near the surface; Second,the thermal wind vorticity due to the atmospheric baroclinicity; Third,the nonlinear effect of joint of barotropic geostrophic vorticity and baroclinic thermal wind vorticity.These results may provide a better physical basis for parameterization of boundary layer and the interpretation of the numerical moding results.
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