southern ocean

from CIA World Factbook 2006
Southern Ocean

Introduction

   Background:  A large body of recent oceanographic research has shown
                that the Antarctic Circumpolar Current (ACC), an ocean
                current that flows from west to east around Antarctica,
                plays a crucial role in global ocean circulation. The
                region where the cold waters of the ACC meet and mingle
                with the warmer waters of the north defines a distinct
                border - the Antarctic Convergence - which fluctuates
                with the seasons, but which encompasses a discrete body
                of water and a unique ecologic region. The Convergence
                concentrates nutrients, which promotes marine plant
                life, and which in turn allows for a greater abundance
                of animal life. In the spring of 2000, the
                International Hydrographic Organization decided to
                delimit the waters within the Convergence as a fifth
                world ocean - the Southern Ocean - by combining the
                southern portions of the Atlantic Ocean, Indian Ocean,
                and Pacific Ocean. The Southern Ocean extends from the
                coast of Antarctica north to 60 degrees south latitude,
                which coincides with the Antarctic Treaty Limit and
                which approximates the extent of the Antarctic
                Convergence. As such, the Southern Ocean is now the
                fourth largest of the world's five oceans (after the
                Pacific Ocean, Atlantic Ocean, and Indian Ocean, but
                larger than the Arctic Ocean). It should be noted that
                inclusion of the Southern Ocean does not imply
                recognition of this feature as one of the world's
                primary oceans by the US Government.

Geography

     Location:  body of water between 60 degrees south latitude and
                Antarctica

    Geographic  60 00 S, 90 00 E (nominally), but the Southern Ocean
  coordinates:  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

           Map  Antarctic Region
   references:

         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
                bodies

        Area -  slightly more than twice the size of the US
  comparative:

    Coastline:  17,968 km

      Climate:  sea temperatures vary from about 10 degrees Celsius to
                -2 degrees Celsius; 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

      Terrain:  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 icepack grows from an average minimum of 2.6
                million square kilometers in March to about 18.8
                million square kilometers in September, better than a
                sixfold 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

     Elevation  lowest point: -7,235 m at the southern end of the South
     extremes:  Sandwich Trench
                highest point: sea level 0 m

       Natural  probable large and possible giant oil and gas fields on
    resources:  the continental margin, manganese nodules, possible
                placer deposits, sand and gravel, fresh water as
                icebergs; squid, whales, and seals - none exploited;
                krill, fishes

       Natural  huge icebergs with drafts up to several hundred meters;
      hazards:  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 region is remote from
                sources of search and rescue

 Environment -  increased solar ultraviolet radiation resulting from
       current  the Antarctic ozone hole in recent years, reducing
       issues:  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; large amount of incidental mortality of
                seabirds resulting from long-line fishing for toothfish
                note: the now-protected fur seal population is making a
                strong comeback after severe overexploitation in the
                18th and 19th centuries

 Environment -  the Southern Ocean is subject to all international
 international  agreements regarding the world's oceans; in addition,
   agreements:  it is subject to these agreements specific to the
                Antarctic 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)
                note: many nations (including the US) prohibit mineral
                resource exploration and exploitation south of the
                fluctuating Polar Front (Antarctic Convergence) 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

   Geography -  the major chokepoint is the Drake Passage between South
         note:  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

     Economy -  Fisheries in 2003-04 landed 136,262 metric tons, of
     overview:  which 87% (118,166 tons) was krill and 8% (11,182 tons)
                Patagonian toothfish, compared to 142,555 tons in
                2002-03 of which 83% (117,728 tons) was krill and 12%
                (16,479 tons) Patagonian toothfish (estimated fishing
                from the area covered by the Convention of the
                Conservation of Antarctic Marine Living Resources
                (CCAMLR), which extends slightly beyond the Southern
                Ocean area). International agreements were adopted in
                late 1999 to reduce illegal, unreported, and
                unregulated fishing, which in the 2000-01 season
                landed, by one estimate, 8,376 metric tons of
                Patagonian and Antarctic toothfish. In the 2004-05
                Antarctic summer 28,202 tourists, most of them seaborne
                (approximately 97%), visited the Southern Ocean and
                Antarctica, compared to 14,762 in 1999-2000.


Transportation

     Ports and  McMurdo, Palmer, and offshore anchorages in Antarctica
    terminals:  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 Antarctic
                Treaty observers (see Article 7); 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,
                Chile, China, France, Germany, Greece, India, Italy,
                NZ, Norway, Russia, South Africa, Spain, and the UK
                (2005)

Transportation  Drake Passage offers alternative to transit through the
       - note:  Panama Canal


Transnational
Issues

    Disputes -  Antarctic Treaty defers claims (see Antarctica entry),
international:  but Argentina, Australia, Chile, France, NZ, Norway,
                and UK assert claims (some overlapping), including the
                continental shelf in the Southern Ocean; several states
                have expressed an interest in extending those
                continental shelf claims under the United Nations
                Convention on the Law of the Sea (UNCLOS) to include
                undersea ridges; the US and most other states do not
                recognize the land or maritime claims of other states
                and have made no claims themselves (the US and Russia
                have reserved the right to do so); no formal claims
                exist in the waters in the sector between 90 degrees
                west and 150 degrees west





                                        
    

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