Восточно-Гренландское течение: от Фрамского пролива до мыса Фаревелл

Current from Fram Strait to Cape Farewell off the eastern coat of Greenland

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. The current cuts through the Nordic Seas (the Greenland and Norwegian Seas) and through the Denmark Strait. 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, 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 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.

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 It was estimated in 1991 by Hopkins et al.

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. 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.

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. 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.