边界层特征参数对边界层顶垂直速度的影响

Effects of Boundary Layer Characteristic Parameters on the Vertical Velocity at the Top of Planetary Boundary Layer

本文从正斜压及有层结时的边界层相似理论及阻力定律出发，由边界层顶垂直速度与地面湍应力的关系求出了层结、粗糙度、它们的水平梯度及地转风的水平梯度、斜压性对W的影响的解析式，可用于模式计算。计算结果表明层结影响可使W差1－2个量级，不稳定时粗糙度影响也使W差几倍。除地转涡度决定W外，地转风、层结稳定度和粗糙度及其水平梯度也起了重要作用，还讨论了斜压性的影响。

By using the similarity theory and resistance law of PBL in barotropic and baroclinic conditions,we have derived a formula for the vertical velocity w at the top of the PBL which includes the effects ofstratification, roughness, their horizontal gradients, the gradient of geostrophic wind speed andbaroclinity based on the relation between w and eddy stress in the surface layer. The equation can beused in the model computation. The results show that the effects of the stratification can change w byone or two orders of magnitude, the effect of the roughness during unstable conditions can change w byseveral times, the horizontal gradients of the geostrophic wind, stratification parameter and theroughness all may contribute to the w besides geostrophic vorticity. The effect of baroclinity is also dis-cussed.