Modifications to the Representation of the Surface Layer Processes in thePhillips Laboratory Global Spectral Model

摘要

This report documents the recommended modifications to the ways by which surfacelayer processes have been represented in the Phillips Laboratory Global Spectral Model (PL-GSM). First, new formulas for surface layer exchange coefficients and a new method of defining roughness lengths over water replace the earlier version. Second, the scope of surface energy balance is expanded to include latent energy of phase transformation of water at the surface. The logic and order of executing the corresponding numerical procedure is accordingly modified. A number of other minor changes in either definition or computation that are found desirable or necessary are also made. The report starts with a description of the recommended changes element by element that includes isolated analysis of the individual changes. It then presents analyses of static comparisons of the outputs from various versions of the representation and concludes with the final recommendation.