Department of Earth, Ocean, and Atmospheric Science, Florida State University
"Mixing in the Antarctic Circumpolar Current"

Abstract:

Relatively light surface water and dense bottom water spread away from Antarctica, raising the question of the closure of the global ocean circulation cell. To help answer this, RAFOS float data were collected during the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES). The large-scale mid-depth circulation and eddy diffusivities in the southeast Pacific Ocean and Scotia Sea sectors between 110W and 45W of the Antarctic Circumpolar Current (ACC) were observed with a deep Lagrangian experiment. The mean flow, adjusted to a common 1400-m depth, shows the presence of jets in the time-averaged sense with speeds of 6 cm/s in the southeast Pacific Ocean and upward of 13 cm/s in the Scotia Sea. The cross-ACC diffusivity in the southeast Pacific Ocean is reduced, 690 +- 150 m2/s and 1000 +- 200 m2/s at shallow and deep levels, respectively, due to the action of jets. These results are used to estimate cross-ACC eddy-driven circulation.