Southern Ocean

Southern Ocean The Southern Ocean as the fourth-largest of the five oceans.

The Southern Ocean, also known as the Great Southern Ocean, the Antarctic Ocean and the South Polar Ocean.

Area:

Total: 20.327 million sq. km 
note: includes Amundsen Sea, Bellingshausen Sea, part of the Drake Passage, Ross Sea, a small part of the Scotia Sea, Weddell Sea, and other tributary water.

Natural resources:

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 seals - none exploited; krill, fish.

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 tooth fish than the regulated fishery, which is likely to affect the sustainability of the stock; large amount of incidental mortality of seabirds resulting from long-line fishing for tooth fish.

note: the now-protected fur seal population is making a strong comeback after severe overexploitation in the 18th and 19th centuries.

Ports and terminals:

Mc-Murdo, Palmer, and offshore anchorages in Antarctica
Note: few ports or harbors exist on southern side of Southern Ocean; ice conditions limit use of most to short periods in midsummer; even then some cannot be entered without icebreaker escort; most Antarctic ports are operated by government research stations and, except in an emergency, are not open to commercial or private vessels; vessels in any port south of 60 degrees south are subject to inspection by observers under Article 7 of the Antarctic Treaty; The Hydrographic Committee on Antarctica (HCA), a special hydrographic commission of International Hydrographic Organization (IHO), is responsible for hydrographic surveying and nautical charting matters in Antarctic Treaty area; it coordinates and facilitates provision of accurate and appropriate charts and other aids to navigation in support of safety of navigation in region; membership of HCA is open to any IHO Member State whose government has acceded to the Antarctic Treaty and which contributes resources and/or data to IHO Chart coverage of the area; members of HCA are Argentina, Australia, Brazil, Chile, China, Ecuador, France, Germany, Greece, India, Italy, NZ, Norway, Russia, South Africa, Spain, UK, and US (2007).

Terrain:

the Southern Ocean is deep, 4,000 to 5,000 m 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 m (the global mean is 133 m); the Antarctic icepack grows from an average minimum of 2.6 million sq. km in March to about 18.8 million sq. km in September, better than a six fold 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.

lowest point: -7,235 m at the southern end of the South Sandwich Trench.

Natural hazards:

huge icebergs with drafts up to several hundred meters; smaller bergs and iceberg fragments; sea ice (generally 0.5 to 1 m thick) with sometimes dynamic short-term variations and with large annual and inter annual 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 region is remote from sources of search and rescue

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 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.