Where does meltwater from the Arctic and Greenland Ice Sheet go?

Fresh water emanating from the melting of the Greenland Ice Sheet and input from the Arctic may cause rapid shifts in our climate system by stratifying the subpolar North Atlantic and slowing the overturning circulation. Previous research has demonstrated that the fresh water accumulates in a coastal current along the Southeast Greenland Shelf, but where it goes as it approaches Cape Farewell at the southern tip of Greenland is unknown. This NSF-funded research project will follow the pathways and fate of the fresh water by deploying surface drifters and profiling floats near Cape Farewell and developing a high-resolution ocean circulation model of the region. Our goal is to determine whether this fresh water mixes offshore, or stays along the coast along the West Greenland Shelf.

Motivation

The current melting of the Arctic pack-ice and the Greenland Ice Sheet is introducing enough fresh water into the subpolar North Atlantic to significantly alter the Atlantic Meridional Overturning Circulation (AMOC).

The three branches of the East Greenland Current System: (1) the East Greenland Coastal Current (EGCC), (2) the East Greenland Current (EGC), and (3) the Deep Western Boundary Current (DWBC). How connected the eastern and western branches of the coastal current are is currently unknown and is the subject of this project.

Much of this fresh water accumulates in the southward-flowing East Greenland Coastal Current, but where and how this current interacts with the boundary currents and deep basins of the subpolar North Atlantic is not known.

In this project, we are testing the hypothesis that much of the relatively fresh, buoyant water is flushed offshore as the coastal current rounds Cape Farewell at the southern tip of Greenland. Here, some of the strongest winds in the global ocean likely cause significant exchange between the shelf and open ocean. If mixed offshore, these waters could slow the AMOC by capping the subpolar North Atlantic and reducing convection.

See our recent paper in Science Advances on this topic here.

Observations

In summer 2021, we sailed on the R/V Armstrong to deploy the first set of drifters and floats. In total, there were 38 surface drifters and 4 profiling floats. The animation below shows the pathways of the surface drifters (circles shaded according to their measured salinity) and profiling floats (pink squares and salinity data to the right) after we deployed them. Surface winds from the ERA5 Reanalysis Product (Hersbach et al. 2020) are shown in the top right. Vertical salinity profiles from the four floats are shown in the bottom right, with depth on the y-axis and time on the x-axis. Another round of drifters and floats will be deployed from the R/V Armstrong in summer 2022.

Models

A vertical section cutting across the East Greenland Shelf, with the coastline to the left. The viewer is looking northward with depth in meters on the y-axis and distance offshore in kilometers on the x-axis. The time-averaged current velocities (purple shading) from a year-long, high-resolution model are directed out of the page, or to the south. The East Greenland Coastal Current is apparent from 0-25 km offshore, and the inshore edge of the East Greenland Current is present at the shelfbreak, or ~40-50 km offshore. The planned deployment locations in the East Greenland Coastal Current of the surface drifters (drogued at 15 m) are shown in the magenta crosses, and the target depth at 100 m of the profiling float is shown in the magenta circle.

We are in the process of running a new model for the region. It will be a high-resolution MITgcm run of the subpolar North Atlantic, focused on the Cape Farewell region. Please stay tuned for more updates to this page.

People

This project is a partnership between the Woods Hole Oceanographic Institution and the Johns Hopkins University. We are also partnering with the Ocean Observatories Initiative (OOI) and the Overturning in the Subpolar North Atlantic Program (OSNAP) to deploy the instrumentation on existing research cruises to the region. The material on this site is based on work supported by the National Science Foundation under Grant Numbers 2047952 and 2048496.

Nicholas Foukal

Principal Investigator
Assistant Scientist

Contact: nfoukal@whoi.edu
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Robert Pickart

Principal Investigator
Senior Scientist

Contact: rpickart@whoi.edu
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Renske Gelderloos

Principal Investigator
Associate Research Scientist

Contact: rgelder2@jhu.edu
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