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Background:
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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:
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body of
water between 60 degrees south latitude and Antarctica
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Geographic coordinates:
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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:
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Antarctic
Region |
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Area:
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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:
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slightly
more than twice the size of the US |
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Coastline:
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17,968 km
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Climate:
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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:
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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:
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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:
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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:
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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:
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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:
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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:
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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:
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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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Ports and harbors:
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McMurdo,
Palmer, and offshore anchorages in Antarctica
note: few ports or harbors exist on the southern
side of the Southern Ocean; 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 (see Article 7) |
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Transportation - note:
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Drake
Passage offers alternative to transit through the Panama
Canal |
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Disputes - international:
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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 |
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This page was last updated on
20 October, 2005 |
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