From Greenland Fjords to the Labrador Sea: Mechanisms of Heat and Freshwater Transport in Mesoscale Eddy Active Ocean/Sea-ice Simulations

The increased presence of warm Atlantic water on the Greenland continental shelf and within glacial fjords has been connected to the accelerated melting of the Greenland Ice Sheet, particularly in the southwest and southeast continental shelf regions. Meltwater is transported into the Labrador Sea where it may disrupt deep convection, a process that has been linked to the variability of the Atlantic Meridional Overturning Circulation (AMOC). To study the transport of heat onto the continental shelf and freshwater into the Labrador Sea, we use coupled ocean/sea-ice simulations with horizontal resolutions that permit or resolve mesoscale eddies. We compare the on shelf transport of heat in two mesoscale eddy-permitting simulations. In both simulations, the region of greatest heat flux onto the shelf is southeast Greenland and south of the Denmark strait, where there is a seasonally persistent pattern of multi-day variability in the cross-shelf heat flux. This high-frequency variability is associated with Denmark Strait Overflow eddies propagating along the shelfbreak. Using mesoscale eddy-resolving simulations to compare the off-shelf transport of meltwater and impacts on the West Greenland Current, we find that vertically distributed meltwater results in an increase in total freshwater flux into the Labrador Sea. Eddy kinetic energy and baroclinic conversion in the West Greenland Current along the continental shelf break also increase with the addition of vertically distributed meltwater. Finally, we derive and test a box model to represent the mixing within fjords. This Fjord Box Model merges buoyant plume theory with the estuarine mixing that occurs along fjords. The Fjord Box Model provides a more realistic boundary condition for meltwater forcing in ocean models that cannot resolve fjords