INTERACTION OF THE GULF-STREAM AND DEEP WESTERN BOUNDARY CURRENT WHERE THEY CROSS

The long-timescale variability of the Deep Western Boundary Current (D WBC) where it crosses under the Gulf Stream is analyzed using a 3-year array of bottom current meters and inverted echo sounders. The relati onship of this variability to fluctuations in the upper layer Gulf Str eam is specifically addressed. At periods shorter than a year the DWBC variability shows no relationship to the local Gulf Stream, 100-day f luctuations show a pulsing of the DWBC transport, whereas longer-perio d fluctuations are indicative of a meandering-type variability. By con trast, on timescales greater than a year, variations in the orientatio n and transport of the DWBC are directly related to such fluctuations in the local Gulf Stream. The coupling reveals that the DWBC is forced by changes in the Gulf Stream rather than causing such variations, wh ich is in contrast to earlier modeling results.