Numerical Simulations of Stratified Rotating Flow over Finite Amplitude Topography

Abstract

A primitive equation numerical ocean model is used to investigate the response of an basic flow, initially horizontally and vertically uniform, to the presence of an isolated seamount at the center of a 4000-m-deep periodic channel. The model is configured with 5-km horizontal resolution and 15 constant-density layer in the vertical. The Coriolis parameter, fluid stratification, coefficient of lateral friction, and length scale or the topography are held constant while the men downstream flow speed and height of the obstacle vary up to an extreme case of a 20 cm s?1 current impinging on a 3500 seamount. The results include the familiar anticyclonic vortex straddling the topograhy while a cyconic vortex propagates downgstream. Both advective and vorticity interaction effects are noted in the experiment with the extent of perturbations to the density field being influenced by variations in the mean flow speed and obstacle height. Possible modifications to the model are discussed in relation to observed conditions at Fieberling Guyot, a Pacific Ocean seamount whose geometric parameters are approximated by the model topography.