East Greenland Current

Last updated January 21, 2023

The East Greenland Current (EGC) is a cold, low-salinity current that extends from Fram Strait (~80N) to Cape Farewell (~60N). The current is located off the eastern coast of Greenland along the Greenland continental margin.^[1] The current cuts through the Nordic Seas (the Greenland and Norwegian Seas) and through the Denmark Strait.^[2] 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,^[2] and it is a major freshwater sink for the Arctic.^[3]

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 Arctic. 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. This current sends Atlantic water (AW) into the Fram Strait, and because it is more dense than 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.^[3] 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.^[4]

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 waters north of Iceland unhindered. It is important to note that these recirculated deep water masses in the Greenland Sea Gyre 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^[4] in the upper part of the EGC (<500 m) with inter-annual maximums of 20–30 cm/s.^[5] It was estimated in 1991 by Hopkins et al.^[1] that the transport of water southward ranged from 2–32 sverdrups. 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.^[3]^[6]

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.^[2] 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.^[7] 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.^[7]

Atmospheric forcings also have a strong impact on Arctic Sea Ice export through the EGC. The North Atlantic Oscillation (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.^[8]

Current research

Current research in the EGC is largely focused on freshwater fluxes (in the ocean and also as sea ice). 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 formation 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.^[9] 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,^[10] however, Rudels et al.^[11] disproved this theory and said it must be due to solid sea ice melt and precipitation in the central Greenland Sea.

Related Research Articles

<span class="mw-page-title-main">North Atlantic Deep Water</span> Deep water mass formed in the North Atlantic Ocean

North Atlantic Deep Water (NADW) is a deep water mass formed in the North Atlantic Ocean. Thermohaline circulation of the world's oceans involves the flow of warm surface waters from the southern hemisphere into the North Atlantic. Water flowing northward becomes modified through evaporation and mixing with other water masses, leading to increased salinity. When this water reaches the North Atlantic it cools and sinks through convection, due to its decreased temperature and increased salinity resulting in increased density. NADW is the outflow of this thick deep layer, which can be detected by its high salinity, high oxygen content, nutrient minima, high ¹⁴C/¹²C, and chlorofluorocarbons (CFCs).

A mediterranean sea is, in oceanography, a mostly enclosed sea that has limited exchange of water with outer oceans and with water circulation dominated by salinity and temperature differences rather than winds or tides. The eponymous Mediterranean Sea, for example, is almost completely enclosed by Europe, Asia, and Africa.

<span class="mw-page-title-main">Ocean current</span> Directional mass flow of oceanic water generated by external or internal forces

An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, shoreline configurations, and interactions with other currents influence a current's direction and strength. Ocean currents are primarily horizontal water movements.

Physical oceanography is the study of physical conditions and physical processes within the ocean, especially the motions and physical properties of ocean waters.

Thermohaline circulation (THC) is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes. The adjective thermohaline derives from thermo- referring to temperature and -haline referring to salt content, factors which together determine the density of sea water. Wind-driven surface currents travel polewards from the equatorial Atlantic Ocean, cooling en route, and eventually sinking at high latitudes. This dense water then flows into the ocean basins. While the bulk of it upwells in the Southern Ocean, the oldest waters upwell in the North Pacific. Extensive mixing therefore takes place between the ocean basins, reducing differences between them and making the Earth's oceans a global system. The water in these circuits transport both energy and mass around the globe. As such, the state of the circulation has a large impact on the climate of the Earth.

<span class="mw-page-title-main">Labrador Sea</span> Arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland

The Labrador Sea is an arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland. The sea is flanked by continental shelves to the southwest, northwest, and northeast. It connects to the north with Baffin Bay through the Davis Strait. It is a marginal sea of the Atlantic.

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 Atlantic Ocean. However, definitions of the Arctic Ocean and its seas tend to be imprecise or arbitrary. In general usage the term "Arctic Ocean" would exclude the Greenland Sea. In oceanographic studies the Greenland Sea is considered part of the Nordic Seas, along with the Norwegian Sea. The Nordic Seas are the main connection between the Arctic and Atlantic oceans and, as such, could be of great significance in a possible shutdown of thermohaline circulation. In oceanography the Arctic Ocean and Nordic Seas are often referred to collectively as the "Arctic Mediterranean Sea", a marginal sea of the Atlantic.

The Norwegian Current is one of two dominant arctic inflows of water. It can be traced from near Shetland, north of Scotland, otherwise from the eastern North Sea at depths of up to 100 metres. It finally passes the Opening into the Barents Sea, a large outcrop of the Arctic Ocean. Compared to its partial source the North Atlantic Current it is colder and less salty; the other sources are the less saline North and Baltic seas and the Norwegian fjords and rivers. It is considerably warmer and saltier than the Arctic Ocean, which is freshened by precipitation and ice in and around it. Winter temperatures in the flow are typically between 2 and 5 °C — the co-parent North Atlantic flow, a heat remnant of its Gulf Stream chief contributor, exceeds 6 °C.

Lincoln Sea is a body of water in the Arctic Ocean, stretching from Cape Columbia, Canada, in the west to Cape Morris Jesup, Greenland, in the east. The northern limit is defined as the great circle line between those two headlands. It is covered with sea ice throughout the year, the thickest sea ice in the Arctic Ocean, which can be up to 15 m (49 ft) thick. Water depths range from 100 m (330 ft) to 300 m (980 ft). Water and ice from Lincoln Sea empty into Robeson Channel, the northernmost part of Nares Strait, most of the time.

Bottom water is the lowermost water mass in a water body, by its bottom, with distinct characteristics, in terms of physics, chemistry, and ecology.

The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately 14,060,000 km² (5,430,000 sq mi) and is known as the coldest of all the oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea. It has been described approximately as an estuary of the Atlantic Ocean. It is also seen as the northernmost part of the all-encompassing World Ocean.

The Fram Strait is the passage between Greenland and Svalbard, located roughly between 77°N and 81°N latitudes and centered on the prime meridian. The Greenland and Norwegian Seas lie south of Fram Strait, while the Nansen Basin of the Arctic Ocean lies to the north. Fram Strait is noted for being the only deep connection between the Arctic Ocean and the World Oceans. The dominant oceanographic features of the region are the West Spitsbergen Current on the east side of the strait and the East Greenland Current on the west.

The West Spitsbergen Current (WSC) 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. The warm and salty WSC flows north through the eastern side of Fram Strait, while the East Greenland Current (EGC) flows south through the western side of Fram Strait. The EGC is characterized by being very cold and low in salinity, but above all else it is a major exporter of Arctic sea ice. Thus, the EGC combined with the warm WSC makes the Fram Strait the northernmost ocean area having ice-free conditions throughout the year in all of the global ocean.

The Arctic dipole anomaly is a pressure pattern characterized by high pressure on the arctic regions of North America and low pressure on those of Eurasia. This pattern sometimes replaces the Arctic oscillation and the North Atlantic oscillation. It was observed for the first time in the first decade of 2000s and is perhaps linked to recent climate change. The Arctic dipole lets more southern winds into the Arctic Ocean resulting in more ice melting. The summer 2007 event played an important role in the record low sea ice extent which was recorded in September. The Arctic dipole has also been linked to changes in arctic circulation patterns that cause drier winters in Northern Europe, but much wetter winters in Southern Europe and colder winters in East Asia, Europe and the eastern half of North America.

The Great Salinity Anomaly (GSA) originally referred to an event in the late 1960s to early 1970s where a large influx of freshwater from the Arctic Ocean led to a salinity anomaly in the northern North Atlantic Ocean, which affected the Atlantic meridional overturning circulation. Since then, the term "Great Salinity Anomaly" has been applied to successive occurrences of the same phenomenon, including the Great Salinity Anomaly of the 1980s and the Great Salinity Anomaly of the 1990s. The Great Salinity Anomalies were advective events, propagating to different sea basins and areas of the North Atlantic, and is on the decadal-scale for the anomalies in the 1970s, 1980s, and 1990s.

In oceanography, a front is a boundary between two distinct water masses. The formation of fronts depends on multiple physical processes and small differences in these lead to a wide range of front types. They can be as narrow as a few hundreds of metres and as wide as several tens of kilometres. While most fronts form and dissipate relatively quickly, some can persist for long periods of time.

The East Iceland Current (EIC) is a cold water ocean current that forms east of Greenland at 72°N, 11°W as a branch of the East Greenland Current that merges with the Irminger Current flowing southward until it meets the northeast part of Iceland. It quickly rotates in a counterclockwise direction and flows eastward along the Iceland-Faeroe Ridge before turning north and flowing into the Norwegian Sea. The EIC flows at an average rate of 6 centimeters per second, with a maximum velocity of 10 centimeters per second occurring as the current turns eastward.

The Nordic Seas are located north of Iceland and south of Svalbard. They have also been defined as the region located north of the Greenland-Scotland Ridge and south of the Fram Strait-Spitsbergen-Norway intersection. Known to connect the North Pacific and the North Atlantic waters, this region is also known as having some of the densest waters, creating the densest region found in the North Atlantic Deep Water. The deepest waters of the Arctic Ocean are connected to the worlds other oceans through Nordic Seas and Fram Strait. There are three seas within the Nordic Sea: Greenland Sea, Norwegian Sea, and Iceland Sea. The Nordic Seas only make up about 0.75% of the World's Oceans. This region is known as having diverse features in such a small topographic area, such as the mid oceanic ridge systems. Some locations have shallow shelves, while others have deep slopes and basins. This region, because of the atmosphere-ocean transfer of energy and gases, has varying seasonal climate. During the winter, sea ice is formed in the western and northern regions of the Nordic Seas, whereas during the summer months, the majority of the region remains free of ice.

Atlantification is the increasing influence of Atlantic water in the Arctic. Warmer and saltier Atlantic water is extending its reach northward into the Arctic Ocean. The Arctic Ocean is becoming warmer and saltier and sea-ice is disappearing as a result. The process can be seen on the figure on the far right, where the sea surface temperature change in the past 50 years is shown, which is up to 5 degrees in some places. This change in the Arctic climate is most prominent in the Barents Sea, a shallow shelf sea north of Scandinavia, where sea-ice is disappearing faster than in any other Arctic region, impacting the local and global ecosystem.

Irminger Rings (IRs) are mesoscale ocean eddies that are formed off the West coast of Greenland and travel southwestwards through the Labrador Sea. Most IRs are anti-cyclonic. There is considerable interest in researching IRs, because they have been hypothesized to influence deep convection in the Labrador sea, and therefore the formation of deep water.

References

1 2 Hopkins, T (1991). "The GIN Sea—A synthesis of its physical oceanography and literature review 1972–1985". Earth-Science Reviews. 30 (3–4): 175–318. Bibcode:1991ESRv...30..175H. doi:10.1016/0012-8252(91)90001-V.
1 2 3 Woodgate, Rebecca A.; Fahrbach, Eberhard; Rohardt, Gerd (1999). "Structure and transports of the East Greenland Current at 75°N from moored current meters". Journal of Geophysical Research. 104 (C8): 18059–18072. Bibcode:1999JGR...10418059W. doi: 10.1029/1999JC900146 .
1 2 3 Schlichtholz, P. and M.N. Houssais (1999). "An investigation of the dynamics of the East Greenland Current in Fram Strait based on a simple analytical model". Journal of Physical Oceanography. 29 (9): 2240–2265. Bibcode:1999JPO....29.2240S. doi: 10.1175/1520-0485(1999)029<2240:AIOTDO>2.0.CO;2 . ISSN 1520-0485.
1 2 Aagaard, K., and L.K. Coachman, 1968: The East Greenland Current north of Denmark Strait, Part I, Arctic, 21, 181-200.
↑ Bersch, M., 1995: On the circulation of the northeastern North Atlantic. Deep-Sea Research Part I: Oceanographic Research Papers, 42, 1583-1607.
↑ Foldvik, A; Aagaard, K; Torresen, T (1988). "On the velocity field of the East Greenland Current". Deep-Sea Research Part A: Oceanographic Research Papers. 35 (8): 1335. Bibcode:1988DSRA...35.1335F. doi:10.1016/0198-0149(88)90086-6.
1 2 Martin, T; Wadhams, P (1999). "Sea-ice flux in the East Greenland Current". Deep-Sea Research Part II: Topical Studies in Oceanography. 46 (6–7): 1063. Bibcode:1999DSRII..46.1063M. doi:10.1016/S0967-0645(99)00016-8.
↑ Tsukernik, Maria; Deser, Clara; Alexander, Michael; Tomas, Robert (2009). "Atmospheric forcing of Fram Strait sea ice export: a closer look". Climate Dynamics. 35 (7–8): 1349–1360. Bibcode:2010ClDy...35.1349T. doi: 10.1007/s00382-009-0647-z .
↑ Jones, E; Anderson, L; Jutterstrom, S; Swift, J (2008). "Sources and distribution of fresh water in the East Greenland Current". Progress in Oceanography. 78 (1): 37–44. Bibcode:2008PrOce..78...37J. doi:10.1016/j.pocean.2007.06.003.
↑ Aagaard, K.; Carmack, E. C. (1989). "The Role of Sea Ice and Other Fresh Water in the Arctic Circulation". Journal of Geophysical Research. 94 (C10): 14485. Bibcode:1989JGR....9414485A. doi:10.1029/JC094iC10p14485.
↑ Rudels, B; Bjork, G; Nilsson, J; Winsor, P; Lake, I; Nohr, C (2005). "The interaction between waters from the Arctic Ocean and the Nordic Seas north of Fram Strait and along the East Greenland Current: results from the Arctic Ocean-02 Oden expedition". Journal of Marine Systems. 55 (1–2): 1–30. Bibcode:2005JMS....55....1R. doi:10.1016/j.jmarsys.2004.06.008. Archived from the original on 2011-07-24.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[multiple5-1] 1 2 Hopkins, T (1991). "The GIN Sea—A synthesis of its physical oceanography and literature review 1972–1985". Earth-Science Reviews. 30 (3–4): 175–318. Bibcode:1991ESRv...30..175H. doi:10.1016/0012-8252(91)90001-V.

[multiple-2] 1 2 3 Woodgate, Rebecca A.; Fahrbach, Eberhard; Rohardt, Gerd (1999). "Structure and transports of the East Greenland Current at 75°N from moored current meters". Journal of Geophysical Research. 104 (C8): 18059–18072. Bibcode:1999JGR...10418059W. doi: 10.1029/1999JC900146 .

[multiple3-3] 1 2 3 Schlichtholz, P. and M.N. Houssais (1999). "An investigation of the dynamics of the East Greenland Current in Fram Strait based on a simple analytical model". Journal of Physical Oceanography. 29 (9): 2240–2265. Bibcode:1999JPO....29.2240S. doi: 10.1175/1520-0485(1999)029<2240:AIOTDO>2.0.CO;2 . ISSN 1520-0485.

[multiple4-4] 1 2 Aagaard, K., and L.K. Coachman, 1968: The East Greenland Current north of Denmark Strait, Part I, Arctic, 21, 181-200.

[5] Bersch, M., 1995: On the circulation of the northeastern North Atlantic. Deep-Sea Research Part I: Oceanographic Research Papers, 42, 1583-1607.

[6] Foldvik, A; Aagaard, K; Torresen, T (1988). "On the velocity field of the East Greenland Current". Deep-Sea Research Part A: Oceanographic Research Papers. 35 (8): 1335. Bibcode:1988DSRA...35.1335F. doi:10.1016/0198-0149(88)90086-6.

[multiple6-7] 1 2 Martin, T; Wadhams, P (1999). "Sea-ice flux in the East Greenland Current". Deep-Sea Research Part II: Topical Studies in Oceanography. 46 (6–7): 1063. Bibcode:1999DSRII..46.1063M. doi:10.1016/S0967-0645(99)00016-8.

[8] Tsukernik, Maria; Deser, Clara; Alexander, Michael; Tomas, Robert (2009). "Atmospheric forcing of Fram Strait sea ice export: a closer look". Climate Dynamics. 35 (7–8): 1349–1360. Bibcode:2010ClDy...35.1349T. doi: 10.1007/s00382-009-0647-z .

[9] Jones, E; Anderson, L; Jutterstrom, S; Swift, J (2008). "Sources and distribution of fresh water in the East Greenland Current". Progress in Oceanography. 78 (1): 37–44. Bibcode:2008PrOce..78...37J. doi:10.1016/j.pocean.2007.06.003.

[10] Aagaard, K.; Carmack, E. C. (1989). "The Role of Sea Ice and Other Fresh Water in the Arctic Circulation". Journal of Geophysical Research. 94 (C10): 14485. Bibcode:1989JGR....9414485A. doi:10.1029/JC094iC10p14485.

[11] Rudels, B; Bjork, G; Nilsson, J; Winsor, P; Lake, I; Nohr, C (2005). "The interaction between waters from the Arctic Ocean and the Nordic Seas north of Fram Strait and along the East Greenland Current: results from the Arctic Ocean-02 Oden expedition". Journal of Marine Systems. 55 (1–2): 1–30. Bibcode:2005JMS....55....1R. doi:10.1016/j.jmarsys.2004.06.008. Archived from the original on 2011-07-24.

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

[11]