Arctic Basin

(also Polar Basin or Central Arctic Basin), the deepwater area of the Arctic Ocean, bounded on the south by the edge of the continental shelf of Eurasia and North America. Area, about 5.3 million sq km.

The Arctic Basin is dissected by three underwater mountain ranges: Gakkel’ (minimum depth, 400 m), Lomonosov (954 m), and Mendeleev and by rises (Al’fa and Chukchi) into the Nansen (maximum depth, 5,449 m), Amundsen (4,321 m), Makarov (3,940 m), Podvodnik (3,285 m), von Toll (2,780 m), Canadian (3,838 m) and the North Pole (2,288 m) underwater depressions. The bottom is covered with a layer of silt 0.5–2.5 km thick.

The climate is harsh, with an average January temperature between -30° and -34°C and an average June temperature of about 0°C. The Arctic Basin is covered year round with packed floating glaciers, mostly permanent (pack ice).

The temperature of the uppermost layer of water is about - 1.8°C; salinity decreases to 30–32 parts per thousand (‰.) with the influx of river waters and melted ice in summer. This layer is underlain by more dense, warm Atlantic water, which enters north of Spitsbergen and spreads throughout the Arctic Basin at depths from 150–200 to 800 m. The temperature of this Atlantic water is about 1°C; its salinity is 34.5‰ and higher.

In the eastern part of the Arctic Basin, Pacific Ocean waters, entering from the Bering Sea and extending to the Lomonosov Ridge, are found at depths of 50–100 m. Their temperature is about -1.4°C, and salinity is about 33‰.

At depths below 800 m the Arctic Basin is filled with bottom water, with a temperature of about - 1°C and salinity of over 34.5‰.

The water and ice circulation is determined by the wind and by the exchange of waters with the Atlantic and Pacific oceans. A stable anticyclonal circulation of ice and surface waters develops in the Canadian region of the Arctic Basin. The ice and water flow of the Transarctic Current, moving from the Bering Sea to Greenland, predominates in the rest of the Arctic Basin. The average velocity of ice drift and of the permanent currents of the Arctic Basin is 2–4 km in a 24-hour period. Seventy varieties of phytoplankton— predominantly diatomic algae—and about 80 different forms of zooplankton have been discovered in the waters of the Arctic Basin. The animal population, consisting of walruses, seals, and polar bears, lives mainly in the peripheral areas of the Arctic Basin.