Intercomparison of Quasi-Geostrophic Simulations of the Western North Atlantic Circulation with Primitive Equation Results

Abstract

Abstract The purpose of this paper is to compare two numerical models of vastly different complexity and computational requirements, which have been used recently in a number of midlatitude ocean simulations. Specifically, the two-layer quasi-geostrophic (QG) model of Holland (1978) is compared with the five-level primitive equation (PE) model of Semtner and Mintz (1977) for a wind-driven multi-gyre ocean, with effects of bottom topography and thermal forcing included. The dominant feature of the circulation predicted in the previous PE calculations is a strong free jet, with intense mesoscale transients which are maintained by baroclinic instability. The configuration of the QG experiment is designed to approximate closely that of the PE experiment, while retaining as much of the simplicity of the Holland (1978) model as possible. The QG model spins up to a state of statistical equilibrium, which is characterized by a meandering jet and by mid-ocean mesoscale eddies with periods and wavelengths much like...