Impact of Freshwater in the East Greenland Current on Overturning in the Subpolar North Atlantic

Accurately representing the density structure in the subpolar North Atlantic is crucial for a correct representation of overturning circulation, yet some high-resolution models tend to overestimate the density of the subpolar gyre due to their biases in salinity. This study investigates the impact of freshwater input via the East Greenland Current (EGC) on subpolar overturning using an eddy-permitting (1/12º) regional configuration of MITgcm. A suite of sensitivity experiments modifies the freshwater flux at the northern boundary, altering the volume of freshwater entering the subpolar North Atlantic. Results show that increased freshwater input through the EGC weakens overturning and reduces density of the overturning maximum, while decreased freshwater flux strengthens overturning, particularly in the Labrador Sea. The response to freshening is close to linear, while after a certain threshold, further increases in EGC salinity no longer strengthen overturning. The overturning response is evident from the first years of the experiment, highlighting the strong influence of Arctic freshwater anomalies on the subpolar circulation.