Transport of Nordic Seas Overflow Water into and Within the Irminger Sea: An Eddy-Resolving Simulation and Observations

摘要

Results from a climatologically forced, eddy-resolving (1/12 deg) Atlantic simulation using the Hybrid Coordinate Ocean Model help clarify some presently unresolved connections between volume transports of Nordic Seas overflow water at key locations in the northernmost North Atlantic Ocean. The model results demonstrate that, in addition to the known westward flow through the Charlie Gibbs Fracture Zone (CGFZ), some Iceland Scotland overflow water (ISOW) flows westward through gaps in the Reykjanes Ridge north of the CGFZ into the Irminger Sea, and some flows southward along the eastern flank of the Mid-Atlantic Ridge into the West European Basin. These results provide insights into the well-known inconsistency between observed westward transport of ISOW through the CGFZ (2.4 Sv) and the transports upstream at Southeast of Iceland section (3.2 Sv) and downstream in the western Irminger Sea (4.5 Sv). Although the portion of the simulated ISOW that flows through CGFZ is about 500 m deeper than observed, the model results also show two ISOW pathways of this flow into the Irminger Sea, one northward along the western flank of the Reykjanes Ridge and the other westward before turning north-eastward on the western side of the Irminger Basin. Comparisons with the long-term moored instrument database in the Irminger Sea show that the model-based mean circulation is in reasonable agreement with observed volume transports of overflow water and that it gives approximately correct temperature and salinity characteristics.