A Description of The Mynn Surface-layer Scheme

Abstract

The surface-layer scheme controls the degree of coupling between the model surface and the atmosphere. Traditionally, surface-layer schemes have been developed to be paired with certain planetary boundary layer (PBL) schemes, but this singular pairing is too narrow in scope for modern physics suites, since the surface-layer physics should also be well integrated with the land-surface model (LSM), gravity-wave drag scheme, and ocean wave model. The expansion of model complexity, such as the inclusion of subgrid-scale landuse variations, vertically distributed sources of drag [e.g., wind farm drag (Fitch et al. 2013), small-scale gravity wave drag (Steeneveld et al. 2008) and topographic form drag (Beljaars et al. 2004)], requires that the surface-layer scheme be developed within a broader context so assumptions made across all model components are physically consistent.