Arctic to the North Atlantic connectivity using Montgomery Potential on neutral density surfaces

How Arctic waters end up in the North Atlantic? We have examined ocean connectivity for neutral density surfaces by developing Montgomery Potential for the NEMO ocean model. The method is coded in Python, enabling calculating geostrophic flow on pseudo-neutral density surfaces. We have analysed global NEMOv4.2 at 1/12 degree runs for the 2008-2021 period for ocean connectivity from the Arctic to the North Atlantic. We have also mapped water-mass pathways by releasing on neutral density surfaces 25.8-28.2 in the Laptev Sea, in the Denmark and Davis Straits, near the Flemish Cap and on the West European Shelf, then by tracking particles forward and backward. The transient times from the Laptev Sea to the Great Banks are of about 6 years; across the Atlantic – another 6 yrs; and the Laptev Sea to the West European Shelf is of about 16 years in total. The model transient times were compared to those from the observed Technetium spread to the Western Barents Sea and to the regions around Greenland. This presented work has been funded from the European Union's project EPOC, EU grant 101059547 and UKRI grant 10038003, EC Horizon Europe project OptimESM “Optimal High Resolution Earth System Models for Exploring Future Climate Changes”, grant 101081193 and UKRI grant 10039429, and from the UK NERC projects LTS-M BIOPOLE (NE/W004933/1), CANARI (NE/W004984/1) and UK LTS-S Atlantic Climate & Environment Strategic Science –ATLANTIS. For the EU projects the work reflects only the authors' view; the European Commission and their executive agency are not responsible for any use that may be made of the information the work contains. We acknowledge the use of ARCHER UK National Supercomputing and JASMIN.