Direct observations of the current structure east of the Bahamas

Quasisynoptic absolute velocity sections were obtained in the western North Atlantic to the east of the Bahamas on five cruises from 1992 to 1994, showing complex spatial and temporal variability of the currents throughout the water column. Lowered acoustic Doppler current profilers were used on all cruises; for comparison, an acoustically-tracked free-fall profiler was used on the August 1992 and June 1993 cruises. Where simultaneous profiles from both methods are available, depth-averaged differences are less than 0.01 m s(-1) in the ensemble mean and standard deviation. Though small, the mean difference appears to be statistically non-zero for one of the two Doppler profilers used; no cause has been found. The individual velocity sections show a banded structure of currents in the offshore direction with strong baroclinic and depth-averaged components extending over the full sampling domain. Two sections show a picture of the southward-flowing Deep Western Boundary Current (DWBC) differing from previous observations. During August 1992 and June 1993 the mean DWBC core was located more than 100 km offshore; in observations prior to 1990 it was usually near 50 km offshore. Net southward transport below 800 m integrated from the coast to 400 km offshore varied from 15 to 50 Sv with a mean of about 40 Sv (1 Sv = 1 x 10(6) m(3) s(-1)). Our mean is consistent with previous estimates; our sections add new evidence that the transport is highly variable to at least 400 km offshore.