The Upper Branch of the AMOC in the Subpolar North Atlantic in Model and Observation

Tilia Breckenfelder1,2, Monika Rhein1,2, Achim Roessler3, Erik Behrens4, Claus W Boning5, Arne Biastoch5 and Christian Mertens3, (1)MARUM, University of Bremen, Bremen, Germany, (2)University of Bremen, Institute of Environmental Physics, Bremen, Germany, (3)University of Bremen, Bremen, Germany, (4)National Institute of Water and Atmospheric Research (NIWA), Wellington, New Zealand, (5)GEOMAR Helmholtz Centre for Ocean Research Kiel, FB1 Ocean Circulation and Climate Dynamics, Kiel, Germany
Abstract:
The North Atlantic Current (NAC) is the northward extension of the Gulfstream. As the upper branch of the Atlantic Meridional Overturning Circulation (AMOC), the NAC brings warm and salty tropical/subtropical water into the subpolar gyre and thereby determines to a large extent the climate of Western Europe. Although the importance of the NAC is widely known, continuous measurements of the NAC transports and its variability away from the western boundary in the subpolar gyre are rare and too short to study longer-term fluctuations.

To further understand the processes behind the NAC transport and its variability, the NAC circulation in the high-resolution North Atlantic (1/20°) VIKING20 model is analyzed and compared with shipboard measurements and moored transport time series of the NAC along the Mid-Atlantic Ridge (MAR).