The East Greenland Current (EGC) flows southward along Greenland’s eastern coast, from the Fram Strait in the Arctic Ocean to Cape Farewell. It acts as a conduit, linking the Arctic with the North Atlantic Ocean. The EGC moves along the Greenland continental margin and through the Nordic Seas, including the Greenland and Norwegian Seas and the Denmark Strait. It serves as a primary pathway for water and ice exiting the Arctic.
Origin and Water Properties
The East Greenland Current forms from distinct water masses. The uppermost layer, extending to about 150 meters, consists of cold, low-salinity Polar Water, with temperatures ranging from 0°C to -1.7°C. Its salinity, varying from 30 psu near the surface to 34 psu at 150 meters, is reduced by freshwater from melting sea ice, river runoff, and Pacific water inflow.
Beneath this polar layer, a warmer, more saline Atlantic Water layer extends to about 1000 meters. Temperatures are above 0°C, with salinity increasing from 34 psu at 150 meters to 35 psu at 1000 meters. This Atlantic Water originates from two sources: westward-flowing Atlantic Water from the West Spitsbergen Current entering the Fram Strait and recirculated Atlantic Water from within the Arctic.
Below 1000 meters, Greenland Sea Deep Water is found, with temperatures between -0.8°C and -1.2°C and a salinity of 34.91 psu. These deeper water masses can be recirculated within the Greenland Sea due to features like the Jan Mayen fracture zone, which deflects them eastward into the Greenland Sea Gyre.
Driving Forces and Flow Patterns
The East Greenland Current’s movement is influenced by dynamic factors, including eddies. Eddies redistribute warm, salty Atlantic Water between the Arctic Ocean and deep convection areas in the central Greenland Sea. These rotating water masses contribute to the current’s variability.
The EGC also responds to large-scale atmospheric patterns, such as the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO). A high NAO/AO index intensifies a strong cyclonic wind field over the Arctic, increasing sea ice export through the Fram Strait into the EGC. Conversely, a low NAO/AO index results in a weaker wind field and a reduction in ice transport.
The current’s velocity ranges from annual averages of 6–12 cm/s in the upper 500 meters, with inter-annual maximums reaching 20–30 cm/s. The EGC transitions from a broad, uniform flow (barotropic) in the northern Fram Strait to a narrower, more stratified flow (baroclinic) further south. This change occurs as recirculating Atlantic Water increases the density difference across the shelf break, shaping the boundary current along the eastern Greenland shelf.
Global Climate Impact
The East Greenland Current holds significance for global climate through its role in transporting sea ice and freshwater. It acts as a conveyor of sea ice from the Arctic Ocean into the North Atlantic, with annual export volumes fluctuating from 1,000 to 5,000 km³ per year. This export influences ocean conditions and regional climates.
The current also distributes freshwater, which originates from melting glaciers, Arctic rivers, and sea ice. Freshwater content in the surface layers along Greenland’s eastern coast has increased, from about 1 meter in 2003 to 4 meters in 2015 in some areas. This influx can alter local ocean circulation within Greenland’s fjords, potentially impacting marine ecosystems by hindering nutrient-rich bottom waters from reaching surface layers where plankton thrive.
The EGC’s influence extends to Greenland’s glaciers, affecting their melt rates and stability. The increased melting of the Greenland Ice Sheet has doubled since 2003, contributing freshwater to the ocean. This freshwater input can interact with the Meridional Overturning Circulation (MOC), a global ocean current system that transports heat and influences climate. Moderate melting may not significantly alter the MOC, but a large influx of freshwater could slow it down, leading to regional warming changes and contributing to sea level rise in areas like the northeast North American coast.