Southern Ocean Surface Characteristics from FGGE Buoys

Abstract

In this analysis of satellite-tracked drifting surface buoys released in the Southern Ocean, buoy velocities are averaged along trajectories for 90 days to determine the mean circulation, and eddy kinetic energy is computed using perturbations about the 90-day mean. The 90-day mean is based upon wind-driven circulation theory, Southern Ocean wind spectra, cumulative averages of mean buoy velocity and energy, and plots of the resulting mean circulation. Excluding the Antarctic Circumpolar Current (ACC), the spatial distribution of the eddy kinetic energy is consistent with previous distributions, based upon spatially averaged ship drift and surface drifting buoy data, reported in the literature. In the ACC, values of eddy kinetic energy are generally lower than found elsewhere. The analysis indicates that the spatial structure of perturbations about the 90-day mean is zonally extended and meridionally compressed. The meridional compression may be due to β, which acts as the restoring force for planetary waves that contribute to the perturbation energy using the temporal averaging method described here.