Numerical Circulation Model for Wind Induced Flow

Based on a compilation of current data at the surface, the classical Ekman theory is inappropriate for calculating wind generated currents near the surface. The cause is found to be the assumption by Ekman of a vertical eddy viscosity, N_v, which is constant over a depth. A numerical model is described briefly, which allows for a variation of N_v over depth, z, as well as in the x and y directions. The model was developed using a Galerkin technique. The model can include a sharp, wind driven profile near the surface. The method is computationally reasonable, requiring about the same number of computations as a vertically averaged formulation. A relationship for choosing N_v versus depth is presented. Experimental data are compared to the numerical model results.