Arctic Circumpolar Boundary Current (ACBC): The main water transformations in the Arctic Mediterranean Sea take place in a boundary current of Atlantic Water, which enters the Arctic across the Greenland–Scotland Ridge.
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After entering, it flows around the Arctic Ocean before exiting as the East Greenland Current, primarily via the Denmark Strait. On route, it experiences many branchings and mergings. The details of its journey around the Arctic are summarized by Rudels et al. :
The circulation is dominated by the movement of warm Atlantic Water entering across the eastern part of the Greenland–Scotland Ridge into the Norwegian Sea. It flows along the Norwegian coast as the Norwegian Atlantic Current. When it reaches the latitude of the Bear Island Channel, its first major bifurcation occurs. A substantial fraction flows eastward and enters the Barents Sea, while the main part continues northward as the West Spitsbergen Current. Several branches are deflected westward from the current: north of the Greenland Sea basin, north of the Boreas basin and in Fram Strait. Only a smaller part of the West Spitsbergen Current eventually enters the Arctic Ocean and flows eastward along the Eurasian continental slope. North of the Kara Sea the boundary current meets the branch that turned east and entered the Barents Sea north of Norway. This branch reaches the Arctic Ocean by crossing the Barents Sea and the northern part of the Kara Sea. The combined boundary current continues eastward a short distance before it again splits. Branches leave the continental slope along bathymetric features, particularly along the Nansen-Gakkel Ridge, the Lomonosov Ridge and the Mendeleyev Ridge. However, a part of the boundary current follows the continental slope around the entire Arctic Ocean.
As this part recrosses the Lomonosov Ridge into the Eurasian Basin it meets and mixes with the other branches as they converge east of the Morris Jesup Plateau. The waters exit the Arctic Ocean through Fram Strait, where they combine with the recirculating waters of the West Spitsbergen Current to continue southward along the Greenland continental slope as the East Greenland Current. The boundary current again diverges at bathymetric features, in this case the Greenland Fracture Zone and the Jan Mayen Fracture Zone, and branches from the boundary current enter the interior of the Boreas Basin and the Greenland Sea Basin. Exchanges in both directions occur, and the East Greenland Current is resupplied with water masses formed in the subpolar seas. The main part of the boundary current exits the Arctic Mediterranean through the 600 m deep Denmark Strait, but its denser fractions are deflected eastward along the Jan Mayen Fracture Zone and along the Iceland shelf slope and eventually enter the Norwegian Sea. The upper part of these waters then returns to the North Atlantic through the 850 meter deep Faeroe-Shetland Channel.
- Physical Oceanography Index
- B. Rudels, H. J. Friedrich, and D. Quadfasel. The Arctic Circumpolar Boundary Current. DSR II, 46: 1023–1062, 1999.