East Greenland Current
Encyclopedia
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
current that extends from Fram Strait
Fram Strait
The Fram Strait is a passage from the Arctic Ocean to the Greenland Sea and Norwegian Sea, between Greenland and Spitsbergen. It is named after the Norwegian ship Fram. The Fram Strait is the major connection between the Arctic Ocean and the world ocean....
(~80N) to Cape Farewell
Cape Farewell
Cape Farewell can mean:* Cape Farewell, New Zealand, northernmost point of the South Island.* Cape Farewell, Greenland, southernmost point in the territory of Greenland....
(~60N). The current is located off the eastern coast of Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
along the Greenland continental margin. The current cuts through the Nordic Seas (Greenland Sea
Greenland Sea
The Greenland Sea is a body of water that borders Greenland to the west, the Svalbard archipelago to the east, Fram Strait and the Arctic Ocean to the north, and the Norwegian Sea and Iceland to the south. The Greenland Sea is often defined as part of the Arctic Ocean, sometimes as part of the...
, Norwegian Sea
Norwegian Sea
The Norwegian Sea is a marginal sea in the North Atlantic Ocean, northwest of Norway. It is located between the North Sea and the Greenland Sea and adjoins the North Atlantic Ocean to the west and the Barents Sea to the northeast. In the southwest, it is separated from the Atlantic Ocean by a...
and Icelandic Sea) and through the Denmark Strait
Denmark Strait
The Denmark Strait or Greenland Strait |Sound]]) is an oceanic strait between Greenland and Iceland...
. The current is of major importance because it directly connects the Arctic to the Northern Atlantic, it is a major contributor to sea ice export out of the Arctic, and it is a major freshwater sink for the Arctic.
Water properties
The EGC is composed of a mixture of three distinct water masses. The water masses are Polar Water, Atlantic Water, and Deep Water. These water masses can be clearly seen throughout the EGC's tract southward, however, the upper layer water masses do change some due to atmospheric interaction along with inflow from other water sources in the Nordic Seas. The top 150 meters of the EGC is considered polar water and it is cold and low in salinity. The lowness in salinity has a lot to do with freshwater run off from sea ice melting, river runoff, and Pacific water flux and it is cold due to air-sea interactions while in the ArcticArctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
. Typical characteristics for the EGC Polar water are a temperature between 0 °C and –1.7 °C (e.g. freezing point of low-salinity sea water), and the salinity varies greatly from 30 psu (near the surface) to 34 psu at a 150 meter depth. The layer beneath the Polar Water is known as the Atlantic Water layer. It extends down to about 1000 m. This layer is defined as having relatively warm temperatures and saline waters. The temperatures are normally above 0 °C and have a salinity of 34 psu at 150 meters and it increases to about 35 psu at 1000 meters. The Atlantic water that is seen in the EGC comes from two different sources. The first source of Atlantic Water originates from westward directed Atlantic water in the West Spitsbergen Current
West Spitsbergen Current
The West Spitsbergen Current is a warm, salty current that runs poleward just west of Spitsbergen, , in the Arctic Ocean. The WSC branches off the Norwegian Atlantic Current in the Norwegian Sea. The WSC is of importance because it drives warm and salty Atlantic Water into the interior Arctic...
. This current sends Atlantic water (AW) into the Fram Strait
Fram Strait
The Fram Strait is a passage from the Arctic Ocean to the Greenland Sea and Norwegian Sea, between Greenland and Spitsbergen. It is named after the Norwegian ship Fram. The Fram Strait is the major connection between the Arctic Ocean and the world ocean....
, and because it is more dense then the surface Polar water it sinks to an intermediate depth. The second source of AW in the EGC originates from recirculated AW in the Arctic. This is AW that has entered the Arctic via the North Atlantic and has been circulating in the Arctic and is now being pushed out of the Arctic via the EGC. The layer beneath the Atlantic Water is simply referred to as the Deep Water where the salinity and temperatures are relatively constant. This level typically extends from 1000 meters to the bottom of the ocean. The temperatures in this bottom level are normally below 0 °C and the salinity is around 34.9 psu.
The deep water masses (>1600 m) are recirculated within the Greenland Sea due to the Jan Mayen Fracture Zone. Here, the deep water encounters the Jan Mayen Ridge and are deflected eastward towards the interior of the Greenland Sea Gyre. The upper layers are able to pass into the Iceland Sea unhindered. It is important to note that these recirculated deep water masses in the Greenland Sea Gyre
Gyre
A gyre in oceanography is any large system of rotating ocean currents, particularly those involved with large wind movements. Gyres are caused by the Coriolis Effect; planetary vorticity along with horizontal and vertical friction, which determine the circulation patterns from the wind curl...
will be recirculated into the EGC once again in the future near Fram Strait.
Dynamics
The general movement of the EGC is southward along the eastern Greenland continental margin. The currents are quite strong with annual averages of 6–12 cm/s in the upper part of the EGC (<500 m) with inter-annual maximums of 20–30 cm/s. It was estimated in 1991 by Hopkins et al. that the transport of water southward ranged from 2–32 sverdrupSverdrup
The sverdrup, named in honour of the pioneering oceanographer Harald Sverdrup, is a unit of measure of volume transport. It is used almost exclusively in oceanography, to measure the transport of ocean currents. Its symbol is Sv. Note that the sverdrup is not an SI unit, and that its symbol...
s. That is quite a large variation that they attributed to the widely varying strength of the Atlantic Water flow at intermediate depths. More recent estimations of water transport in the top layers (<800 m) of the EGC is between 3 and 4 sverdrups.
Export of Arctic Sea ice
One of the most important aspects of the East Greenland Current is the amount of sea ice it exports into the North Atlantic Ocean. It is a major pathway for sea ice to leave the Arctic. It is estimated that more than 90% of the Arctic Sea Ice exported from the Arctic takes place within the East Greenland Current. The volume of ice exported on an annual scale is a strong function of multiple atmospheric variables (wind, temperature, etc.) and oceanic variables and dynamics. There is a maximum of ice-flux export from October through December and a minimum from January to March. This interannual variability occurs because during the summer months the sea ice melts back quite a bit, and it results in a lot of drifting sea ice that can be easily exported through Fram Strait during the windy times of October through December. During the winter months, the sea ice refreezes together and thus the ability to have numerous sea ice drifts decreases due to the increase in overall sea ice extent. Essentially open water drifting decreases substantially during the winter months. The volume export ranges greatly from year to year. It can be as high as 5000 km3/year and as low as 1000 km3/year.Atmospheric forcings also have a strong impact on Arctic Sea Ice export through the EGC. The North Atlantic Oscillation
North Atlantic oscillation
The North Atlantic oscillation is a climatic phenomenon in the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level between the Icelandic low and the Azores high. Through east-west oscillation motions of the Icelandic low and the Azores high, it controls the...
(NAO)/Arctic Oscillation (AO) has a profound impact on the wind field over the Arctic. During high NAO/AO indexes the cyclonic wind field over the Arctic becomes very strong, this transports more ice out through Fram Strait and into the EGC. During low NAO/AO indexes the cyclonic wind field is quite small and thus the transport out of the Fram Strait diminishes greatly.
Current research
Current research for the EGC is focused on freshwater fluxes. Because the EGC runs through the Greenland Sea and eventually through the Labrador Sea (as the West Greenland Current) it can have strong implications for the strengthening and or weakening of deep water formations in the Greenland and Labrador Seas. The Meridional Overturning Circulation is a density driven circulation in which a small perturbation in the density field could easily slow down or speed up the deep water formation in the Nordic Seas. Jones et al. note that there are three different freshwater sources for the EGC: Pacific water, river runoff, and sea-ice meltwater. They find that the biggest contributor to the freshening of the EGC is due to river runoff, followed by Pacific water, and a distant last is sea-ice meltwater (nearly negligible). They find that even though these sources freshen the EGC, these specific sources do not penetrate very well into the central Greenland Sea where the deep convection takes place. They then decide that there must be some other freshwater influence in the central Greenland Sea. They believe it may be from solid sea ice being transported to the central Greenland Sea and then melting. Solid sea ice is very mobile, and winds can easily direct its flow along with ocean currents. Previous thoughts were that the recirculation of the EGC in the Greenland Sea via the Jan Mayen Fracture Zone helps lead to a freshening of the central Greenland Sea, however, Rudels et al. disproved this theory and said it must be due to solid sea ice melt and precipitation in the central Greenland Sea.See also
- Ocean currentOcean currentAn ocean current is a continuous, directed movement of ocean water generated by the forces acting upon this mean flow, such as breaking waves, wind, Coriolis effect, cabbeling, temperature and salinity differences and tides caused by the gravitational pull of the Moon and the Sun...
- Labrador CurrentLabrador CurrentThe Labrador Current is a cold current in the North Atlantic Ocean which flows from the Arctic Ocean south along the coast of Labrador and passes around Newfoundland, continuing south along the east coast of Nova Scotia...
- Baffin Island CurrentBaffin Island CurrentBaffin Island Current is an ocean current running south down the western side of Baffin Bay in the Arctic Ocean, along Baffin Island. Its sources are the West Greenland Current and outflow from the Arctic Ocean. Its speed is approximately per day.- See also :* Labrador Current* East Greenland...
- West Greenland CurrentWest Greenland CurrentThe West Greenland Current is a weak cold water current that flows to the north along the west coast of Greenland. The current results from the movement of water flowing around the southernmost point of Greenland caused by the East Greenland Current....
- PiteraqPiteraqA Piteraq is a cold Katabatic wind which originates on the Greenlandic icecap and sweeps down to the east coast. Piteraqs are most common in the fall and winter. Wind speeds typically reach 50 to 80 m/s. On February 6, 1970 the community Tasiilaq was hit by very strong Piteraq causing severe...