Distribution of Reynolds stress carried by mesoscale variability in the Antarctic Circumpolar Current

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Abstract
Satellite altimeter data collected by the U.S. Navy's Geosat Exact Repeat Mission were used to investigate turbulent stress resulting from the variability of surface geostrophic currents in the Antarctic Circumpolar Current. The altimeter measured sea level along the subsatellite track. The variability of the along‐track slope of sea level is directly proportional to the variability of surface geostrophic currents in the cross‐track direction. We used the two components of the slope at points where the satellite ground tracks cross to calculate orthogonal components of the current's variability. Because the grid of crossover points is dense at high latitudes, the satellite data could be used for mapping the temporal and spatial variability of the current. Two and a half years of data were used to compute the statistical structure of the variability, leading to a better understanding of the role of variability in the dynamics of the current. The statistics included the probability distribution functions for each component of the current, the time‐lagged auto correlation functions of the variability, and the Reynolds stress produced by the variability. The results demonstrate that stress is correlated with bathymetry. In some areas the distribution of negative stress indicate that eddies contribute to an acceleration of the mean flow, strengthening the hypothesis that baroclinic instability makes important contributions to strong oceanic currents.