Structure and variability of the shelf break East Greenland Current

The East Greenland Current is a major conduit for dense overflow water and Arctic-origin freshwater to be transported from the Nordic Seas to the North Atlantic via the Denmark Strait. North of the strait the current divides into two branches, one located near the shelf break and the other situated in the basin. To date there have been limited measurements of the time-varying hydrographic and velocity structure of either branch, despite their importance to the circulation system of the subpolar North Atlantic. Here we use data from a high-resolution mooring array deployed between Iceland and Greenland north of the Denmark Strait, from summer 2011 to summer 2012, to quantify the temporal and spatial variability of the shelf break branch of the East Greenland Current. The two dominant modes of variability of the current are pulsation and meandering around its mean state. In addition to the variability of the along-stream flow, strong and persistent along-shore winds cause substantial responses in the cross-stream flow in the form of coastal upwelling and downwelling. Both can be important in terms of freshwater exchange between the shelf and the interior. The overflow water is composed of two distinct water masses: Atlantic Water that has recirculated in the Nordic Seas and colder Arctic-origin Atlantic Water. We find that the structure of the current varies depending on which water mass dominates, suggesting a coupling between the dynamics of the current and the water masses it transports.