The Western Boundary Undercurrent off the Bahamas

Abstract

Abstract Two tritium sections through the deep western boundary current east of the Bahamas taken in late 1980 and early 1981 are presented. Tritium from the bomb tests in the late 1950s and early 1960s is used to identify recently formed deep waters in the sections. High concentrations are found in the North Atlantic Deep Water. Low tritium values occur in the Labrador Sea Water found above the core of this deep water. This is consistent with the suggestion by Talley and McCartney that this water mass has not been ventilated at the temperatures observed in these sections since the mid-1950s. Tritium in the sections is correlated with maxima in potential vorticity. This is inconsistent with deep convection as a direct source for the water mass. The potential vorticity maxima may be associated with plume dynamics near the overflow regions or with the dynamics of the deep western boundary current. The sections are south of the section discussed by Jenkins and Rhines where high tritium concentrations were fo...