A Baroclinic Prognostic Numerical Model Of The Circulation In The Gulf Of Mexico

Considered in a two-layer prognostic model of the circulation in the Gulf of Mexico. This two-layer model represents the simplest finite difference approximation to the continuously stratified real ocean. The equations of momentum, which are considered for each layer, include horizontal and vertical exchange of momentum, Coriolis effect, non-linear advection of momentum and the effect of topography. In the model, however, the topography is restricted to the lower layer. The associated vorticity equations are formed and the baroclinic and barotropic modes are separated. The baroclinic and barotropic vorticity prediction equations are then put into finite difference form utilizing centered differences with a double step in time. The Du Fort-Frankel scheme is used for the lateral diffusion of vorticity terms and the resulting system of finite difference equations are solved using the Gauss-Seidel method with successive over-relaxation. Laplacian flow is initially specified in the upper layer and the lower layer is considered at rest. The model is spun up to a quasi-steady state which is in turn used as the initial state for the subsequent computations. A one-year prediction is then made of the baroclinic and barotropic modes of circulation in the Gulf of Mexico during which time the input through the Yucatan Strait is varied seasonally. (Author).