The Southern Ocean extends from the coast of Antarctica north to 60 degrees south latitude, where it joins the Atlantic, Indian, and Pacific Oceans. The Southern Ocean is the second-smallest of the world's five oceans. (The Pacific, Atlantic, and Indian Oceans are larger; the Arctic Ocean smaller.) Its extent was formally defined by the International Hydrographic Organization in 2000, and coincides with the Antarctic Treaty Limit.
|the five Oceans|
65 00 S, 0 00 E (nominally), but the Southern Ocean has the unique distinction of being a large circumpolar body of water totally encircling the continent of Antarctica; this ring of water lies between 60 degrees south latitude and the coast of Antarctica, and encompasses 360 degrees of longitude
Sea temperatures vary from about 10°C to -2°C. Cyclonic storms travel eastward around the continent and frequently are intense because of the temperature contrast between ice and open ocean. The ocean area from about latitude 40 south to the Antarctic Circle has the strongest average winds found anywhere on Earth. In winter the ocean freezes outward to 65 degrees south latitude in the Pacific sector and 55 degrees south latitude in the Atlantic sector, lowering surface temperatures well below 0 degrees Centigrade; at some coastal points intense persistent drainage winds from the interior keep the shoreline ice-free throughout the winter.
The Southern Ocean is deep, 4,000 to 5,000 meters over most of its extent with only limited areas of shallow water. The antarctic continental shelf is generally narrow and unusually deep, its edge lying at depths of 400 to 800 meters (the global mean is 133 meters). The Antarctic ice pack grows from an average minimum of 2.6 million square kilometers in March to about 18.8 million square kilometers in September, more than a sevenfold increase in area. The Antarctic Circumpolar Current (21,000 km in length) moves perpetually eastward; it is the world's largest ocean current, transporting 130 million cubic meters of water per second -- 100 times the flow of all the world's rivers.
Probable large and possible giant oil and gas fields on the continental margin, manganese nodules, possible placer deposits, sand and gravel, fresh water as icebergs, squid, whales, and sealss - none exploited; krill, fishes
Huge icebergs with drafts up to several hundred meters; smaller bergs and iceberg fragments; sea ice (generally 0.5 to 1 meter thick) with sometimes dynamic short-term variations and with large annual and interannual variations; deep continental shelf floored by glacial deposits varying widely over short distances; high winds and large waves much of the year; ship icing, especially May-October; most of the region is remote from sources of search and rescue
Environment - current issues
increased solar ultraviolet radiation resulting from the Antarctic ozone hole in recent years, reducing marine primary productivity (phytoplankton) by as much as 15% and damaging the DNA of some fish; illegal, unreported, and unregulated fishing in recent years, especially the landing of an estimated five to six times more Patagonian toothfish than the regulated fishery, which is likely to affect the sustainability of the stock; high incidental mortality of seabirds resulting from long-line fishing for toothfish
Environment - international agreements
The Southern Ocean is subject to all international agreements regarding the world's oceans. In addition, it is subject to these agreements specific to the region: International Whaling Commission (prohibits commercial whaling south of 40 degrees south [south of 60 degrees south between 50 degrees and 130 degrees west]); Convention on the Conservation of Antarctic Seals (limits sealing); Convention on the Conservation of Antarctic Marine Living Resources (regulates fishing)
Geography - note
The major chokepoint is the Drake Passage between South America and Antarctica. The Polar Front (Antarctic Convergence) is the best natural definition of the northern extent of the Southern Ocean; it is a distinct region at the middle of the Antarctic Circumpolar Current that separates the very cold polar surface waters to the south from the warmer waters to the north; the Front and the Current extend entirely around Antarctica, reaching south of 60 degrees south near New Zealand and near 48 degrees south in the far South Atlantic coinciding with the path of the maximum westerly winds.
Economy - overview
Fisheries in 1998-1999 (1 July to 30 June) landed 119,898 metric tons, of which 85% was krill and 14% Patagonian toothfish. International agreements were adopted in late 1999 to reduce illegal, unreported, and unregulated fishing, which in the 1998-1999 season landed five to six times more Patagonian toothfish than the regulated fishery. In the 1998-1999 Antarctic summer 10,013 tourists, most of them seaborne, visited the Southern Ocean and Antarctica, compared to 9,604 the previous year. Nearly 16,000 tourists are expected during the 1999-2000 season.
Ports and harbors
McMurdo, Palmer, and offshore anchorages in Antarctica
Transportation - note
The Drake Passage offers an alternative to transit through the Panama Canal
Disputes - international
The Antarctic Treaty defers claims (see Antarctic Treaty); sections (some overlapping) are claimed by Argentina, Australia, Chile, France, New Zealand, Norway, and the UK; most other nations (including the US) do not recognize the maritime claims of other nations and have made no claims themselves (although the US reserves the right to do so); no formal claims have been made in the sector between 90 degrees west and 150 degrees west.