Circulation and transports in the Newfoundland Basin, western subpolar North Atlantic

The southwestern part of the subpolar North Atlantic east of the Grand Banks of Newfoundland and Flemish Cap is a crucial area for the Atlantic Meridional Overturning Circulation. Here the exchange between subpolar and subtropical gyre takes place, southward flowing cold and fresh water is replaced by northward flowing warm and salty water within the North Atlantic Current (NAC). As part of a long-term experiment, the circulation east of Flemish Cap has been studied by seven repeat hydrographic sections along 47 degrees N (2003-2011), a 2 year time series of current velocities at the continental slope (2009-2011), 19 years of sea surface height, and 47 years of output from an eddy resolving ocean circulation model. The structure of the flow field in the measurements and the model shows a deep reaching NAC with adjacent recirculation and two distinct cores of southward flow in the Deep Western Boundary Current (DWBC): one core above the continental slope with maximum velocities at mid-depth and the second farther east with bottom-intensified velocities. The western core of the DWBC is rather stable, while the offshore core shows high temporal variability that in the model is correlated with the NAC strength. About 30 Sv of deep water flow southward below a density of sigma=27.68 kg m(-3) in the DWBC. The NAC transports about 110 Sv northward, approximately 15 Sv originating from the DWBC, and 75 Sv recirculating locally east of the NAC, leaving 20 Sv to be supplied by the NAC from the south

Vermischung und Energieflüsse im Tiefen Westlichen Randstrom des Nordatlantiks Eine Abschätzung aus hydrographischen Messdaten

Diapycnal diffusivity and energy dissipation along the western boundary of the North Atlantic have been inferred from more than 100 profiles of combined LADCP and CTD measurements collected at four different latitudes in the North Atlantic. Both diffusivity and dissipation were elevated at all four sites. Repeated measurements in the Deep Western Boundary Current (DWBC) at 47N and at 16N yield a velocity dependent energy dissipation rate for high core velocities, and a velocity independent background. Combined with the vertical energy flux direction and the lack of tidal signals the velocity dependence indicates that interaction between mean flow and bottom topography is the dominant process for the elevated mixing. Semi-diurnal energy fluxes in horizontal direction have been estimated from repeated measurements at 16N, 47N, and 49N. Integrated energy flux at 47N and 49N is directed along the shelf, while it is in uphill direction at 16N

Mixing and Energy Flux Estimates from Hydrographic Measurements in the Deep Western Boundary Current of the North Atlantic

Diapycnal diffusivity and energy dissipation along the western boundary of the North Atlantic have been inferred from more than 100 profiles of combined LADCP and CTD measurements collected at four different latitudes in the North Atlantic. Both diffusivity and dissipation were elevated at all four sites. Repeated measurements in the Deep Western Boundary Current (DWBC) at 47N and at 16N yield a velocity dependent energy dissipation rate for high core velocities, and a velocity independent background. Combined with the vertical energy flux direction and the lack of tidal signals the velocity dependence indicates that interaction between mean flow and bottom topography is the dominant process for the elevated mixing. Semi-diurnal energy fluxes in horizontal direction have been estimated from repeated measurements at 16N, 47N, and 49N. Integrated energy flux at 47N and 49N is directed along the shelf, while it is in uphill direction at 16N

Current meter measurements from five moorings in the subpolar North Atlantic east of the Grand Banks of Newfoundland

The southwestern part of the subpolar North Atlantic east of the Grand Banks of Newfoundland and Flemish Cap is a crucial area for the Atlantic Meridional Overturning Circulation. Here the exchange between subpolar and subtropical gyre takes place, southward flowing cold and fresh water is replaced by northward flowing warm and salty water within the North Atlantic Current (NAC). As part of a long-term experiment, the circulation east of Flemish Cap has been studied by seven repeat hydrographic sections along inline image (2003-2011), a 2 year time series of current velocities at the continental slope (2009-2011), 19 years of sea surface height, and 47 years of output from an eddy resolving ocean circulation model. The structure of the flow field in the measurements and the model shows a deep reaching NAC with adjacent recirculation and two distinct cores of southward flow in the Deep Western Boundary Current (DWBC): one core above the continental slope with maximum velocities at mid-depth and the second farther east with bottom-intensified velocities. The western core of the DWBC is rather stable, while the offshore core shows high temporal variability that in the model is correlated with the NAC strength. About 30 Sv of deep water flow southward below a density of sigma-theta = 27.68 kg/m**3 in the DWBC. The NAC transports about 110 Sv northward, approximately 15 Sv originating from the DWBC, and 75 Sv recirculating locally east of the NAC, leaving 20 Sv to be supplied by the NAC from the south