The Oceanic Eddy Heat Transport

Abstract

The rectified eddy heat transport is calculated from a global high-resolution ocean general circulation model. The eddy heat transport is found to be strong in the western boundary currents, the Antarctic Circumpolar Current, and the equatorial region. It is generally weak in the central gyres. It is also found to be largely confined to the upper 1000 m of the ocean model. The eddy heat transport is separated into its rotational and divergent components. The rotational component of the eddy heat transport is strong in the western boundary currents, while the divergent component is strongest in the equatorial region and Antarctic Circumpolar Current. In the equatorial region, the eddy heat transport is due to tropical instability waves, while in the western boundary currents and the Antarctic Circumpolar Current the large eddy heat transports arise from the meandering of the currents. Stammer's method for estimating the eddy heat transport from an eddy diffusivity derived from mixing length arguments, using altimetry data and the climatological temperature field, is tested and fails to reproduce the model's directly evaluated eddy heat transport in the equatorial regions, and possible reasons for the discrepancy are explored. However, in the Antarctic Circumpolar Current region and to a lesser extent in the western boundary currents, the model's eddy heat transport is shown to have some qualitative agreement with his estimate.