Altimeter Data Analysis of the Antarctic Circumpolar Current
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The first two years of TOPEX/POSEIDON altimeter measurements of the Southern Ocean, between 30° S and 65° S were analyzed in order two study the mesoscale characteristics of the basin. Objective maps of sea level anomalies were computed for each cycle, showing synoptic view of the mesoscale activity of the study area. These maps underlined a population of mesoscale eddies, with a typical diameter of 100-200 Km in the sector 10° - 50° E and 30° _ 60° W, possibly shed from the meanders of the Antarctic Circumpolar Current. The rings seem to move southward confined to a rather narrow corridor (about 400Km). Sea level variability maps were computed to characterize the mesoscale activity in the study area. The highest values of more 25 cm are found between 10° - 60° E and near 50° W at a latitude of 40° - 50° S. A high variability area extends to at least 60° - 65° S. The TOPEX/POSEIDON cross-over data were used to resolve both magnitude and direction of residual geostrophic velocities. The time series are then used to determine surface eddy statistics in the Southern Ocean, hence the spatial distribution in the surface Reynolds stresses (u’2, v’2, u’v’). According with the information available so far, we found that the complex spatial distribution of surface eddy momentum flux is strongly influenced by bottom topography and the position of the mean current.
KeywordsSouthern Ocean Altimeter Data Antarctic Circumpolar Current Mesoscale Eddy Drake Passage
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