Subpolar North Atlantic western boundary density anomalies and the meridional overturning circulation

Changes in the Atlantic Meridional Overturning Circulation (MOC) have traditionally been linked to the strength of subpolar North Atlantic deep water formation. However, there is no clear observational evidence nor agreement between models about how changes in deep water formation and export influence the MOC. Using the 2014-2018 observations from the Overturning in the Subpolar North Atlantic Program (OSNAP), we show that winter convection in the interior basin impacts western boundary density changes in the Irminger Sea, however that impact is diminished in the Labrador Sea. Regardless of the strength of the western boundary's response to convection in the interior, our results demonstrate that, in contrast to the subtropics, density anomalies in the Deep Western Boundary Current (DWBC) are not strongly associated with the subpolar MOC variability. Therefore, a careful reconsideration of the linkage between DWBC changes, intensity of deep water formation and MOC variability is warranted.