The method of extracting current profiles from layered ocean models, applied to an oscillatory internal Kelvin wave with friction damping along the coast

The method of extracting current profiles from vertically integrated hydrodynamic models for fluids with uniform density is extended and formulated for a multi-layered ocean model with constant density in each layer. Current profiles are extracted from an oscillatory internal Kelvin wave with friction damping along the coast, and the influence of eddy viscosity with geographical latitude is investigated. The critical latitude singularity of the oscillatory equations of motion, where the inertial frequency equals that of the oscillatory motion, has no apparent effect on the horizontal distribution of the two-dimensional current. The current profile becomes extremely sensitive to the magnitude and the vertical variation of the eddy viscosity. The constant eddy viscosity in each layer produces most inaccuracy near the sea bed and across the internal interface, but can satisfy current consistency far from the critical latitude. At the critical latitude a linear increase of the eddy viscosity with height above the sea bed is essential in the near bed region in order to obtain depth-averaged currents consistent with the two-dimensional current. © 1997 Elsevier Science Ltd