Prof. William K Dewar

Dept of Earth, Ocean and Atmospheric Science

Florida State University

Email: wdewar@fsu.edu

Research Interests: Meso-scale/Large scale interactions, submeso-scale/meso-scale interactions, ocean energetics and mixing.

On Wind-Driven General Circulation Energetics

Abstract

The energetics of the wind-driven circulation are examined in a combined theoretical and numerical study. Based on a multiple scale analysis, we find the mesoscale field is strongly affected by the ventilated thermocline, but no feedback from the eddies to the large scale is found. We then analyze the western boundary region arguing that the associated currents divide between coastal jets, which are conservative of energy, and open ocean, separated jet extensions where the mesoscale is energized by the mean field.

It is in this separated jet zone where we argue the primary loss of general circulation energy to the mesoscale takes place. This division of the general circulation is then tested by an analysis of a regional primitive equation 1/12- degree numerical model of the North Atlantic. The predictions of the theory are supported by the numerical results. The model analysis also shows wind forcing, although essential for establishing the interior circulation, is a relatively weak energy source compared to the energy fluxes occurring in the interior. Thus, the general circulation is characterized as recirculating energy in the manner of a Fofonoff gyre.