Spreading Patterns of the Labrador Sea Water and Nordic Seas Overflow Water in the North Atlantic

From a Eulerian perspective, moored current meter arrays and hydrographic surveys suggest a continuous southward-flowing Deep Western Boundary Current (DWBC) from the subpolar to the subtropical North Atlantic, as predicted by theory. From a Lagrangian perspective, however, most of the floats that have been released in the Labrador Sea Water (LSW) layer of the DWBC in the western subpolar North Atlantic do not flow around the Grand Banks of the Newfoundland and do not reach the subtropics. The question then arises as to whether the Nordic Seas Overflow water (NSOW) component of the DWBC exhibits a similar spreading pattern to the LSW or if it is more consistent with the Eulerian point of view. Here, we perform numerical float experiments in a high horizontal numerical simulation of the North Atlantic and show very different spreading patterns between the LSW and NSOW. Specifically, the floats released in the NSOW are more concentrated in the DWBC (than those released in the LSW) and is more consistent with the Eulerian perspective.