Legend:  Definition  Field Listing  Rank Order
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Background: |
A decision by the International Hydrographic Organization in the
spring of 2000 delimited a fifth world ocean - the Southern Ocean -
from 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. 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).
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Location: |
body of water between 60 degrees south latitude and Antarctica
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Geographic coordinates: |
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 |
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Map references: |
Antarctic
Region |
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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 |
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Area - comparative: |
slightly more than twice the size of the US |
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Coastline: |
17,968 km |
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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 |
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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 |
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Elevation extremes: |
lowest point: -7,235 m at the southern end of the South
Sandwich Trench
highest point: sea level 0 m |
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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, fishes |
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Natural hazards: |
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 region is remote from sources of search and rescue |
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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; 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 |
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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 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
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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
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Economy - overview: |
Fisheries in 2000-01 (1 July to 30 June) landed 112,934 metric
tons, of which 87% was krill and 11% Patagonian toothfish.
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 2000-01 antarctic summer 12,248
tourists, most of them seaborne, visited the Southern Ocean and
Antarctica, compared to 14,762 the previous year. |
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Disputes - international: |
Antarctic Treaty defers claims (see Antarctica entry), 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 |
This page was last updated on 21 April,
2005
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