Antarctic Intermediate Water circulation in the tropical and subtropical South Atlantic

The low salinity of the Antarctic Intermediate Water (AAIW) extends eastward across the South Atlantic just south of the equator (3-4°S). Evidence of a weak eastward flow just north of the equator (1-2°N) is also shown. Lateral and vertical homogenization of properties in the AAIW is found at the equator between 2°S and 2°N. Observations suggest enhanced mixing within the equatorial baroclinic deformation radius. The South Atlantic tropical gyre is shown to consist of the following three cells: one cyclonic cell centered at about 7°S, another centered at about 19°S in the west and 23°S in the east, and one anticyclonic cell centered at about 13°S. These cells are associated with a westward extension at 10°S of high salinity and low oxygen which originates in the eastern tropical South Atlantic and a front in these properties at about 15°S in the west and about 20°S in the east. -from Authors