Linking Surface and Sub-Surface Variability in Drake Passage

The Antarctic Circumpolar Current (ACC) is the largest current in the world, with a mean transport of 134 Sv, and it provides a significant barrier to the oceanic transfer of heat from mid-latitudes to polar regions. Infrequent full-depth hydrographic sections have shown large variability in the transport of the ACC and the position of its constituent fronts. The many sources of satellite remote-sensing data, with much more frequent sampling, offer another vista on such variability. The question we address here is how the spatial patterns and modes of variability recorded from satellite data relate to the observations from ships. In this paper, we confine our studies to height and temperature data from sensors that are unaffected by clouds, and thus provide near-complete records along the same. The seasonal variations in temperature are deeper south of 60degS, whereas the interannual variations, associated with meandering fronts, occur further north and are deeper. The variability signal from altimetry lies further north again.