WP2.2 – Ocean circulation variability in the western subpolar North Atlantic

The Deep Western Boundary Current (DWBC) constitutes the deep limb of the climate modulating Atlantic Meridional Overturning Circulation (AMOC). Deep water formation occurs in the Labrador Sea situated between Canada and Greenland and in the Norwegian-Greenland Sea through wintertime heat loss; the newly formed deep water components unite in the DWBC and flow southward. At the exit of the Labrador Sea, at about 53°N, the different components of the DWBC have merged into a narrow current of only about 150km width. Since 1997, the current, which extends from the surface to the seafloor in more than 3km depth, is measured at selected locations across its full width. This project analyses the 21 years of water velocity, temperature and salinity data, that now is available. The emphasis will be on connecting the long term observations with the large-scale changes in the subpolar North Atlantic.


  • Analyzing long term variability in the DWBC and possible trends
  • Deriving indices to capture the ocean state and evolution from observations and help to verify model data
  • Investigating the connections between the DWBC and the large-scale wind and buoyancy forcing


  • Analysis of ship data, anchored sensor data and satellite data
  • Comparisons of observations with model simulations
Overview map of the subpolar North Atlantic, with superimposed schematic paths of the Gulf Stream/North Atlantic Current (red) and components of the Deep Western Boundary Current (blue), plus transport estimates (in 106 m3 sec-1) for the respective current components (colored boxes). The inset at the bottom right illustrates a typical configuration of the moored sensors at 53°N superimposed over the outflow (coloured contours) and density field (black lines to indicate different water layers) obtained from shipboard measurements (image from Zantopp et al. 2017, Geomar Kiel).


Johannes Karstensen, Geomar, Kiel

Martin Visbeck, Geomar, Kiel


Patricia Handmann, Geomar, Kiel

Marilena Oltmanns, Geomar, Kiel

Sunke Schmidtko, Geomar, Kiel