A reduced gravity, primitive equation model of the upper equatorial ocean
This paper describes a fourth-order finite difference model of the equatorial ocean that is designed to study dynamic and thermodynamic processes on time scales of a decade or less. It is a primitive equation model employing the reduced gravity assumption so that the deep ocean is at rest below the active upper ocean. The model consists of a surface mixed layer and an active layer below, which is divided into an arbitrary number of numerical layers by means of a sigma coordinate. The model can be used in an unstratified version, when temperature acts as a passive tracer, as well as in the full stratified version. The numerical formulation of the model is described in detail. Experiments comparing three different horizontal smoothers: Shapiro filter, Laplacian friction, and biharmonic friction are presented. It is concluded that, at the level needed to maintain computational stability, the Shapiro filter damps the fields least; in addition, it is faster and easier to implement when the horizontal finite difference grid is stretched.
scientific article; zbMATH DE number 4085326