Observations of circulation and transport in the northwestern subpolar North Atlantic

Labrador Sea and Newfoundland Basin in the northwestern subpolar North Atlantic are a key region for the Atlantic Meridional Overturning Circulation. Warm and salty water is imported from the subtropics and in return cold and fresh water is carried along the continental slope by a system of deep boundary currents and eventually exported to subtropics east of Newfoundland. Here we use hydrographic and current measurements from a total of 15 cruises that were carried out between 2003 and 2015. The data set comprises 602 stations along a closed triangle from Flemish Cap off the Grand Banks of Newfoundland to Cape Farewell at the southern tip of Greenland to the Mid-Atlantic Ridge at 47N and back to Flemish Cap. The major currents that exchange heat and freshwater in this area are the North Atlantic Current (NAC) that flows through a chain of semi-permanent eddies towards the Mid-Atlantic Ridge, the deep Labrador or deep western boundary current (DWBC), and the East Greenland Current (EGC). These currents are crossed several times by the three sections of the triangle. The results show mean transports and pathways of the major currents: The DWBC carrying cold water along the continental slope of North America and its recirculation toward the Labrador Sea. They show the bottom reaching NAC and its recirculation at 47N and in the Northwest Corner as well as the NAC crossing the Mid-Atlantic Ridge. South of Greenland the EGC show a surface intensified core and a bottom intensified core. Further a strong deep reaching recirculation is found off shore of the EGC.