Stratified ekman boundary layer models

“Ekman” layers are proposed for use in geophysical fluid dynamic models which involve no arbitrary “eddy viscosity”. These layers are single slabs which conserve buoyancy and momentum rather than energy, and use a slab Richardson (or Froude) number criterion for closure. With a geostrophic velocity U and Coriolis parameter f, the “Ekman transport” of a layer on a rigid surface is close to 0.0018 U2 /f, independent of the stratification. With a wind stress τ and water density ρ, the Ekman transport of a free surface layer is the usual τ/(fρ).