Variability in deep Western Boundary Current transports:: Preliminary results from 26.5°N in the Atlantic

Transport fluctuations of the deep limb of the Meridional Overturning Circulation (MOC) near the western boundary are presented from a line of inverted echo sounders, bottom pressure sensors, and a deep current meter east of Abaco Island, Bahamas, at 26.5 degrees N from September 2004 through September 2005. The mean southward flow between 800 dbar and 4800 dbar was 39 x 10(6) m(3) s(-1), with a northward recirculation of 28 x 10(6) m(3) s(-1), leaving a net southward flow of 11 x 10(6) m(3) s(-1) as the through-flow of the Deep Western Boundary Current (DWBC). The mean southward DWBC flow essentially equals previous values that were measured at the same location by arrays of current meters deployed from 1986 to 1992. DWBC transport spectra indicate that barotropic and baroclinic changes have very similar energy levels at most periods less than 10 days and that barotropic changes dominate at periods of 10 - 80 days.