Can the Irminger Current impact restratification in the Irminger Sea?A Lagrangian model study on the fate of the Irminger Current water

The Irminger Sea is one of the few places in the North Atlantic where dense water masses are formed through deep convection. Next to atmospheric forcing, wintertime convection in the Irminger Sea interior can be impacted by the extent of restratification in the preceding year(s). In the Irminger Sea, the central basin is cold contrasted to the Irminger Current (IC), its cyclonic boundary current that carries warm and saline waters of subtropical origin. In this study, we investigated the potential impact of the IC on restratification of the Irminger Sea’s convection area, using a high-resolution regional model combined with Lagrangian particle tracking. We released particles over the upper 1500 meters of the IC in the eastern Irminger Sea and tracked them forward in time.

Of those the majority stayed within the Irminger Sea: 38% followed the boundary current circulation and 61% entered the interior Irminger Sea. Only one percent of the particles left the Irminger Sea through Denmark Strait and to the Iceland Basin. Of those entering the interior, about one half reaches the deep convection area (DCA). The seeded particles reach the DCA from the eastern side, seemingly steered by mesoscale variability. On their way to the DCA, the IC waters loose part of their buoyancy but on average remain lighter than waters in the DCA. This westward spread of warm and saline IC waters likely limits the region of deep convection to the western Irminger Sea by adding to the stratification in the eastern part of the basin. Understanding the processes driving the lateral buoyancy fluxes to the basin’s interior is important to understand variability in deep convection in the Irminger Sea.

Considering the Irminger Sea’s importance in overturning future changes in water mass properties could influence the variability in convection and with impact subpolar overturning.