Iceland–Scotland Overflow Water (ISOW) is a major deep water mass flowing from the Norwegian Sea into the North Atlantic. Traditionally depicted as a counter-clockwise deep boundary current, new Lagrangian observations and model simulations reveal a more complex reality. This study shows ISOW spreads into the interior towards the Labrador and Irminger basins after passing the Charlie-Gibbs Fracture Zone, and also identifies a previously unobserved southward pathway along the Mid-Atlantic Ridge. Deep-reaching eddies and meanders of the North Atlantic Current influence the pathway partitioning. These findings necessitate a revised understanding of ISOW pathways.

Sijia Zou, Amy Bower, Heather Furey, M. Susan Lozier, Xiaobiao Xu