Influence of the Wind Stress Curl on the Eddy Saturation Behavior of the ACC in a Barotropic Perspective

Abstract

The size of zonal transport of the Antarctic Circumpolar Current (ACC) is almost independent of the variations in westerly winds over the Southern Ocean; this phenomenon is called eddy saturation. The eddy saturation has been studied in both barotropic and baroclinic contexts in the presence of topography, yet many aspects of its dynamics remain elusive. We focus here on barotropic eddy saturation, which occurs in a narrow band of wind stresses where topographic-barotropic instability takes place. As a result, barotropic eddy saturation is highly sensitive to the specific geometry of bottom topography and to the boundary conditions. Here, we investigate whether the amplitude of the wind stress curl relative to that of a constant background wind stress can also modulate barotropic eddy saturation by modifying the global vorticity budget of a doubly periodic quasigeostrophic flow. We report that the zonal transport and the eddy saturation regime are sensitive to the wind stress curl and explore the underlying dynamics.