A COUPLED HYDRODYNAMIC BOTTOM BOUNDARY-LAYER MODEL OF EKMAN FLOW ON STRATIFIED CONTINENTAL SHELVES

This paper describes a hydrodynamic model with turbulent energy closur e that uses a simplified wave-current interaction model of the bottom boundary layer to compute bed drag coefficients. The coupled model is used to investigate the interaction of the upper and lower boundary la yers with the geostrophic core flow for simple shelf geometry and forc ing, and to evaluate the effects of increased bottom friction on coast al hydrodynamics for summer and winter stratification. The thickness o f the bottom boundary layer predicted by the model ranges from 10 to 3 5 m and is consistent with observations from the California shelf. The increased bottom friction calculated by the coupled model in intermed iate water depths increases bottom Ekman veering (leftward in the Nort hern Hemisphere) by as much as 10-degrees if stratification is strong, thus enhancing downwelling and upwelling. Currents along isobaths in shallow water are uniformly decreased by as much as 25% in the coupled model for both summer and winter initial stratification.