The Mean Circulation East of the Bahamas as Determined from a Recent Measurement Program and Historical XBT Data

Abstract

Observational evidence from a two-ship synoptic survey, from one-year-long current measurements at four sites, and from two independent long-term expendable-baththermograph (XBT) data sets is combined to describe the circulation east of the Bahamas. The results indicate that a weak Antilles Current actually exists at mid-depths, about 300?100 m, with a northward transport along this boundary of about 4 ? 106 m3 s?1. However, both the dynamic height fields and water mass distributions suggest that this current does not represent return flow from the gyre-wire Sverdrup recirculation but instead is part of the northwestern Gulf Stream recirculation system, west of about 50°W. The near-surface flow east of the Bahamas is more complicated and consists of two isolated anticyclonic circulation cells along the boundary. The most intense of these is centered just northeast of Abaco Island in the northern Bahamas; the southern, weaker cell is centered at about 24°N, 71°W. In the area just north of Puerto Rico a narrow band of water with characteristics originating in the southern and southeastern subtropical gyre is found. Dynamic height maps and water mass distributions imply that this flow passes through the island passages into the Caribbean. No evidence for significant seasonally reversing barotropic or baroclinic currents could be found in Antilles Current area.