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Southern Ocean

2007 Schools Wikipedia Selection. Related subjects: Antarctica; General
Geography

   Earth's five oceans
     * Atlantic Ocean
     * Arctic Ocean
     * Indian Ocean
     * Pacific Ocean
     * Southern Ocean

   The Southern Ocean, also known as the South Polar Ocean (and formerly
   the Antarctic Ocean), is the body of water encircling the continent of
   Antarctica. It is the world's fourth largest ocean and the latest to be
   defined, having been accepted by a decision of the International
   Hydrographic Organization (IHO) in 2000, though the term has long been
   traditional among mariners. This change reflects the recent findings in
   oceanography of the importance of ocean currents.

   Of the 68 member nations, 28 responded to the IHO's survey in 2000, and
   all responding members except Argentina agreed to define a new ocean.
   The name Southern Ocean was selected with 18 votes, beating the
   alternative Antarctic Ocean. Half of the votes were cast for ending the
   ocean at the imaginary 60 degrees south line of latitude (with no land
   interruptions at this latitude), with the other 14 votes cast for other
   definitions as far north as 35 degrees south.

   Other sources such as the National Geographic Society continue to show
   the Atlantic, Pacific and Indian Oceans as extending to Antarctica.
   Southern Ocean

Geography

   The Southern Ocean is oceanographically defined as an ocean connected
   with the Antarctic Circumpolar Current, which circulates around
   Antarctica. It includes Amundsen Sea, Bellingshausen Sea, part of the
   Drake Passage, Ross Sea, a small part of the Scotia Sea, and Weddell
   Sea. The total area is 20,327,000 square kilometers (7,848,000 mi²)

Features

   The Southern Ocean is located in the Southern Hemisphere possessing
   typical depths between 4,000—5,000 meters (13,000 to 16,000 ft) deep
   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 up to 800 meters (2,600 ft), compared to a global
   mean of 133 meters (436 ft).

   Solstice to solstice in line with the sun's seasonal influence, the
   Antarctic ice pack fluctuates from an average minimum of 2.6 million
   square kilometers (1.0 million mi²) in March to about 18.8 million
   square kilometers (7.2 million mi²) in September, more than a sevenfold
   increase in area.

   The Antarctic Circumpolar Current moves perpetually eastward—chasing
   and joining itself, and at 21,000 kilometers (13,000 mi) in length— it
   is the world's longest ocean current, transporting 130 million cubic
   meters (4.6 billion ft³) of water per second—100 times the flow of all
   the world's rivers.

   Its greatest depth is 7,235 meters (23,737 ft) at the southern end of
   the South Sandwich Trench, at 60°00'S, 024°W

Climate

   The packice zone pulsates over the year.
   Enlarge
   The packice zone pulsates over the year.

   Sea temperatures vary from about −2 to 10  °C (28 to 50 °F). 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 Celsius; at some coastal points
   intense persistent drainage winds from the interior keep the shoreline
   ice-free throughout the winter.

Natural hazards

   Icebergs can be found at any time of year throughout the ocean. Some
   may have drafts up to several hundred meters; smaller icebergs, iceberg
   fragments and sea ice (generally 0.5 to 1 meter thick) are also a
   problem for ships. The deep continental shelf is floored by glacial
   deposits varying widely over short distances. High winds and large
   waves during much of the year, along with ship ice, especially
   May-October make the area even more dangerous. The remoteness of the
   region makes sources of search and rescue scarce.

Environment

Current issues

   Increased solar ultraviolet radiation resulting from the Antarctic
   ozone hole has reduced marine primary productivity ( phytoplankton) by
   as much as 15% and is damaging the DNA of some fish. Illegal,
   unreported, and unregulated fishing, especially the landing of an
   estimated five to six times more Patagonian toothfish than the
   regulated fishery, likely affects the sustainability of the stock.
   There is also a high incidental mortality of seabirds resulting from
   long-line fishing for toothfish.

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:
     * The International Whaling Commission prohibits commercial whaling
       south of 40 degrees south (south of 60 degrees south between 50
       degrees and 130 degrees west). Japan regularly does not recognize
       this provision in regards to its whaling permit and whaling for
       scientific research and occasionally carries out whale hunts in the
       region.
     * The Convention for the Conservation of Antarctic Seals has limited
       seal hunting.
     * The Convention on the Conservation of Antarctic Marine Living
       Resources regulates fishing in the region.

   Many nations prohibit mineral resource exploration and exploitation
   south of the fluctuating Polar Front, which is in the middle of the
   Antarctic Circumpolar Current and serves as the dividing line between
   the very cold polar surface waters to the south and the warmer waters
   to the north.

   Since the Antarctic Treaty covers the portion of the globe south of
   sixty degrees south, claims to Antarctica and all islands in the
   Southern Ocean are suspended.

Economy

   Fisheries in 1998-99 between 1 July and 30 June landed 119,898 tonnes,
   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 1998-99 season landed five to six
   times more Patagonian toothfish than the regulated fishery. In the
   1998-99 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 were expected during the
   1999-2000 season.

Ports and harbors

   Few ports or harbors exist on the southern (Antarctic) coast of the
   Southern Ocean since ice conditions limit use of most of them 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 Antarctic Treaty observers.

   The major ones that are operational include: Esperanza Base, Villa Las
   Estrellas,Chile, Mawson Station, McMurdo Station, Palmer Station, Scott
   Base, and offshore anchorages in Antarctica

   Retrieved from " http://en.wikipedia.org/wiki/Southern_Ocean"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
