Antarctic Ocean, the ocean situated about, or within, the Antarctic Circle. The Great Southern Ocean is that part of the ocean which surrounds the world in one continuous band between the latitude of 40° S. and the Antarctic Circle. This band is only partially interrupted by the southern prolongation of South America. The northern portions of this band are often called the South Atlantic, South Indian, and South Pacific, while the southern portions are usually called the Antarctic Ocean. The average depth of the continuous ocean which surrounds south polar land is about two miles; it gradually shoals towards Antarctic land, which in some places is met with a short distance within the Antarctic Circle. The Challenger found 1800 fathoms near the Antarctic Circle south of Kerguelen, but Ross records a much greater depth in the same latitude south of the Sandwich group. Only three navigators, Cook, Weddell, and Ross, have crossed the 70th parallel south. Of several other expeditions that have crossed the Antarctic Circle, the most notable was the Challenger in 1874, the only steam-vessel that had visited these seas. The majority of Antarctic voyagers have discovered land south of the 60th parallel, Cook in 71° S. and 107° W. Bellingshausen discovered Peter Island and Alexander Land, D’Urville discovered Adelie Land. Wilkes found land extending from the 100th to the 160th meridian of E. long. between the parallels of 65° and 67° S. Ross discovered Victoria Land, and in February 1841 sailed along its coasts within sight of the high mountain ranges, 7000 to 10,000 feet above the sea, as far as 78° S. The mountain range here terminated in an active volcano, Mount Erebus, 12,000 feet in height. His farther progress was stopped by an icy barrier 150 to 200 feet in height, along which he sailed to the east for 300 miles. The depth off this ice-barrier was 260 fathoms, so that it was just in the condition to generate those large, flat-topped, tabular icebergs, which are the characteristic feature of the Antarctic regions. Where the coast is steep and high, there is no true ‘ice-barrier,’ the ice being only 6 or 10 feet above the sea, extending many miles from the shore. Till 1895 Ross and D'Urville alone succeeded in setting foot on land within the Antarctic Circle. This land was of volcanic origin; but there is no doubt a large extent of continental land around the South Pole, for the Challenger dredged up granites, mica-schists, sandstones, and other continental rocks close to the ice-barrier. The present writer estimates the area of the Antarctic continent at 3,000,000 square miles. Vegetation was found on it in 1895: land animals have not been seen. Whales, grampuses, seals, penguins, petrels, albatrosses, and other oceanic birds abound. Diatoms are very abundant in the surface-waters, and their dead frustules form a pure white deposit called diatom ooze, about the latitude of 60°, outside the blue muds which surround the continent. Life is abundant in the surface-waters, and at the bottom of the ocean. The mean temperature both of the air and sea, south of 63° S., is even in summer below the freezing-point of sea-water. Between 60° and 63° S., a sensible rise takes place, temperatures as high as 38° F. being recorded both of sea and air in March. The Challenger found a cold layer of water sandwiched between a warm one on the surface and a warm one at the bottom; the surface layer was 37°.2; the cold layer at eighty fathoms was 32°.5; the temperature of the warm bottom layer was not accurately determined, but it was probably about 33° F. It is remarkable that the bottom temperature at 50° S. (33°.5 F.) is little different from the bottom water all over the Indian and other oceans. The return currents of dense, warm, tropical water from the Indian, Atlantic, and Pacific Oceans, which run southward along the eastern shores of America, Africa, and Australia, sink on reaching a latitude of from 45° to 56° S., and flow north at the bottom to supply the loss in the tropics by surface-currents and evaporation, and south, to supply the place of the ice-cold water drifted northwards. The barometric pressure within the Antarctic Regions appears to be low, considerably under 29,000 inches. The winds blow cyclonically towards the Pole from the Southern Ocean, carrying with them much moisture. The fall of rain and snow is estimated as about equal to a rainfall of 30 inches annually. All our knowledge of the Antarctic is confined to the summer months of December, January, and February. Fully equipped German and British expeditions were arranged to start in 1901.
See POLAR EXPLORATION; M'Cormack, Voyages in Antarctic and Arctic Seas (1884); Mackinder, Ross and the Antarctic; Burn-Murdoch, From Edinburgh to the Antarctic (1894); K. Fricker, The Antarctic Regions (trans. 1900).