SURFACE LAYER

The lowest few meters of the atmosphere where the velocity profile is approximated as having a constant horizontal frictional stress (using the surface value). In this layer, the wind profile from the top of the roughness length (typically 1 to 4 centimeters above the land surface) to the top of the surface layer is logarithmic and varies only with the roughness of the surface. Rougher surfaces (larger roughness lengths) have wind profiles which asymptotically approach a smaller wind speed at the top of the surface layer.