Parametrization of the Convective Atmospheric Boundary Layer and Its Applicationinto a Global Climate Model

摘要

In this paper the authors focus on vertical diffusion of heat and passive scalars(like moisture) in the convective atmospheric boundary layer. In the first part of the paper, a summary of the recent work by Holtslag and Moeng (1991) is given. In this work the heat and scalar flux equations are analyzed with data obtained from large-eddy-simulations. The findings can be used in a modified flux-gradient approach, which takes account for nonlocal convective vertical exchange using so-called counter-gradient transport and a nonlocal diffusivity coefficient. In the second part of the paper, the previous findings are simplified and applied in the latest version of the NCAR community climate model (CCM2). The impact of the non-local approach is illustrated in comparison with the usual local diffusion approach (Holtslag and Boville, 1992).