Lagrangian Observations of the Deep Western Boundary Current in the North Atlantic Ocean.

Abstract

Abstract In this study, the authors analyze the trajectories of 18 RAFOS floats, launched in the deep western boundary current (DWBC) between the Grand Banks and Cape Hatteras to investigate the kinematics and dynamics in the region where the DWBC crosses under the Gulf Stream, near 36°N (the “crossover region”). Floats deployed in the chlorofluorocarbon (CFC) maximum associated with upper Labrador Sea Water (depth ∼800 m) illustrate the entrainment process of this water mass into the Gulf Stream. The behavior of the floats (and fluid parcels) in the crossover region is strongly dependent on the meandering of the Gulf Stream. When the stream is close to its mean position, fluid parcels entrained from the upper DWBC travel along the northern edge of the stream. When a meander trough is present downstream of the entrainment location, DWBC fluid parcels cross the Gulf Stream and sometimes are expelled on the south side. This represents a previously unrecognized mechanism for transporting upper Labrador Sea W...