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