Interaction of the Gulf Stream and Deep Western Boundary Current where they cross

Abstract

The long‐timescale variability of the Deep Western Boundary Current (DWBC) where it crosses under the Gulf Stream is analyzed using a 3‐year array of bottom current meters and inverted echo sounders. The relationship of this variability to fluctuations in the upper layer Gulf Stream is specifically addressed. At periods shorter than a year the DWBC variability shows no relationship to the local Gulf Stream, 100‐day fluctuations show a pulsing of the DWBC transport, whereas longer‐period fluctuations are indicative of a meandering‐type variability. By contrast, on timescales greater than a year, variations in the orientation 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, which is in contrast to earlier modeling results.