Mean full-depth summer circulation and transports at the northern periphery of the Atlantic Ocean in the 2000s

A mean state of the full-depth summer circulation in the Atlantic Ocean in the region in between Cape Farewell (Greenland), Scotland and the Greenland-Scotland Ridge (GSR) is assessed by combining 2002-2008 yearly hydrographic measurements at 59.5 degrees N, mean dynamic topography, satellite altimetry data and available estimates of the Atlantic-Nordic Seas exchange. The mean absolute transports by the upper-ocean, mid-depth and deep currents and the Meridional Overturning Circulation (MOC sigma = 16.5 +/- 2.2 Sv, at sigma(0) = 27.55) at 59.5 degrees N are quantified in the density space. Inter-basin and diapycnal volume fluxes in between the 59.5 degrees N section and the GSR are then estimated from a box model. The dominant components of the meridional exchange across 59.5 degrees N are the North Atlantic Current (NAC, 15.5 +/- 0.8 Sv, sigma(0) < 27.55) east of the Reykjanes Ridge, the northward Irminger Current (IC, 12.0 +/- 3.0 Sv) and southward Western Boundary Current (WBC, 32.1 +/- 5.9 Sv) in the Irminger Sea and the deep water export from the northern Iceland Basin (3.7 +/- 0.8 Sv, sigma(0) > 27.80). About 60% (12.7 +/- 1.4 Sv) of waters carried in the MOC sigma upper limb (sigma(0) < 27.55) by the NAC/IC across 59.5 degrees N (21.1 +/- 1.0 Sv) recirculates westward south of the GSR and feeds the WBC. 80% (10.2 +/- 1.7 Sv) of the recirculating NAC/IC-derived upper-ocean waters gains density of sigma(0) > 27.55 and contributes to the MOC sigma lower limb. Accordingly, the contribution of light-to-dense water conversion south of the GSR (similar to 10 Sv) to the MOC sigma lower limb at 59.5 degrees N is one and a half times larger than the contribution of dense water production in the Nordic Seas (similar to 6 Sv).