Suggested Revisions to Certain Boundary Layer Parameterization Schemes Used in Atmospheric Circulation Models

Abstract

The results from some of the latest experimental and theoretical studies of the planetary boundary layer (PBL) ire used to revise certain better known schemes (Clarke, 1970b; Deardorff, 1972b) of parameterizing the boundary layer in general circulation models (GCM's). For high-resolution models, our proposed scheme is based on the surface layer similarity theory relations derived by Businger et al. (1971) from the Kansas tower data. For low-resolution GCM'S, the proposed scheme is based on the generalized PBL-similarity theory with the various similarity functions evaluated from the best available numerical models of the boundary layer. The usual practice of specifying a single value for the roughness parameter (z0) for all the land surfaces in a GCM is questioned. The specified z0 value at each grid point should actually reflect the roughness characteristics of the surface represented by it.