对流边界层顶部夹卷速度参数化的模拟研究

A Laboratory and Numerical Simulation of the Entrainment Rate on the Top of CBL

提出一个关于夹卷速度的新参数化方案 ,即混合层顶部夹卷速度We 可由对流边界层特征量W 、θ 、zi及覆盖逆温强度 θ+ z确定 .对流槽实验模拟的测量结果证实了该参数化方案的合理性 ,并由实验数据拟合得出了参数化方案中的系数 .数值模拟结果表明此方案可直接预报对流边界层高度zi,并能很好地预报出zi 的变化过程 。

Based on resemblance analysis, a new parameterizati on suggests that the entrainment rate can be determined by turbulent characteristi cs of convective boundary layer, depth of mixed layer and potential temperature gradient of the capping inversion layer. The laboratory simulations in a water c onvection tank prove that it is reasonable. Numerical simulations show that this parameterization can be used in the numerical models and predict the calculated height of the mixed layer satisfactorily.