Study of tracer distribution in the Drake Passage

On each cruise the same set of 21 hydrographic stations with characteristic spacing <20 nautical miles was visited. The results of the three surveys display a characteristic zonation of water masses in the region, which is defined by four hydrographic fronts.

The net geostrophic transport of the Antarctic Circumpolar Current (ACC) across SR1b, computed with reference to the deepest common depth of each pair of adjacent stations, is similar in all three cruises, 144 Sv in February 1995, 131 Sv in February 1996, and 134 Sv in February 1998, and compares well with earlier computations of the ACC transport across Drake Passage. A close comparison of the vertical distributions of water properties on SR1b reveals changes in the structure of the ACC that are linked to undersampled current mesoscale activity, as suggested by infrared satellite images contemporary to the cruises.