The Antarctic Ocean or Antarctic Ocean or icy ocean the Antarctic is the stretch of water which surrounds the the Antarctic. It is in surface fourth ocean, and the last defined, since it is a decision of the international hydrographic Organization (OHI) which accepted in 2000 the name of Antarctic Ocean, used for a long time by the sailors (one also employed “Antarctic Ocean”). This decision reflects the recent discoveries on the importance of the oceanic currents.

Certain sources continue to consider that the oceans Atlantique, Pacifique and Indien extend to the Antarctic continent. Only 28 of the 193 consulted States answered the questionnaire of the OHI into 2000,18 only voter for the new name of Antarctic Ocean. 14 answers were favorable to limit the ocean to the parallel 60° S, 14 other answers proposing of the limits which could reach until 35° S, latitude in the south of the equator equal to that of the Mediterranean in the northern hemisphere.

Geography

From an oceanographical point of view, the Antarctic Ocean is defined like an ocean traversed by the circumpolar current the Antarctic, which circulates around the Antarctic continent.

The Antarctic Ocean includes/understands several bay S or Mer S, like the Mer of Amundsen, the Mer of Bellingshausen, the Mer of Ross, the Mer of Weddell, as well as part of the Passage Drake and Mer of Scotia. Its total surface area is of 20.327.000 km ², the length of the coasts which bathe it of 17.968 km.

The point of maximum contracting is the passage of Drake. The polar face (Antarctic convergence) is the best natural definition of the Antarctic Ocean; it is an area distinct in the middle of the circumpolar current the Antarctic which separates very cold surface water in the south, from hotter water in north; the face and the current extend all around the Antarctic continent, reaching 60°S near New Zealand and close to 48°S in the extreme south of the Atlantic Ocean, which coincides with the maximum of the winds of west.

The extension of the ice-barrier presents an annual pulsation.

Limits

Contrary to the other oceans, which are defined like stretches of water limited by continents, the Antarctic Ocean is the only one with being defined as a water mass which surrounds a continent; this ring extends to the south from 60° from southern latitude, on 360° of longitude (limits suggested by the international hydrographic Organization).

This limit was proposed in 2000; before that, the water covered by the Antarctic Ocean was regarded as the southern parts of the oceans Atlantique, Indien and Pacifique, even if the term existed for a certain time already. The limit of 60° of southern latitude corresponds in addition to the grounds concerned with the Traité on the Antarctic and on which the sovereignty of any country is not recognized.

This definition is not universal; in Australia the Antarctic Ocean includes/understands not only the zone defined by the OHI, but includes also all the maritime extent located between the Antarctic and the southern parts of Australia and New Zealand. It is represented thus on the charts. The coasts of Tasmanie and the south of Australia are then bathed by the Antarctic Ocean and not by the Indian Ocean .

Chart showing the Australian definition of the Antarctic Ocean (pdf)

Ocean floor

The Antarctic Ocean is deep, of 4  000 with 5  000 m on the majority of its extent, with only some major zones. The continental shelf the Antarctic is generally narrow. The maximum depth is reached with the pit of the Sandwich islands of the South, by 7.235 m of depth.

Islands

From the nature of its ocean floor, the Antarctic Ocean contains few islands, settings besides those which border the continent the Antarctic itself. One can however quote:

Formation

Even if its ocean floor is not it, the Antarctic Ocean is certainly youngest of the oceans, since its existence goes back to only 30 million years, when the Antarctic and the South America separated, opening the Drake passage and giving rise to the circumpolar current the Antarctic.

Climate

The temperature of the sea varies between approximately -2 °C and 10 °C. Cyclonic storms are propagated towards the east around the continent and are frequently intense because of the contrast of temperature between the ice and the open ocean. The oceanic zone which extend between the surroundings from 40°S and the polar circle the Antarctic undergo the strongest winds known on the Earth. In winter, the ocean freezes beyond 65°S in the Pacifique sector, and of 55°S in the Atlantique sector, lowering the temperatures of surface well below 0°C; in certain points of the coast of the permanent winds catabatic coming from the ground maintain the littoral free of ice all the winter.

Physical characteristics

The Antarctic Ocean is deep (4 000 to 5.000 m in its greater part), and the zones low depth are limited. The continental shelf the Antarctic is generally narrow and unusually deep, with a coastal part reaching the depths from 400 to 800 m (the depth world mean is 133 m). The ice-barrier increases by a minimal average surface of 2,6 million square kilometers in March to approximately 18,8 million square kilometers in September, that is to say an increase in a factor 7 on the surface. The circumpolar current the Antarctic moves towards the east; it is the largest oceanic current: it transports 130 million cubic meters of water a second, that is to say 100 times more than the flow of all the rivers of the world.

Extreme rises

  • Not low: -7  235 m at the southern end of the pit of the Sandwich of the south, in 60°00' S, 024°W.
  • Not highest: sea level 0 Mr.

Natural resources

  • Oil fields and gases, probably large, perhaps giant, on the continental shelf
  • Nodules of manganese
  • Layers of possible ores
  • Sand and gravel
  • Fresh water in the form of icebergs
    • various
  • Cephalopods, whales, seals, krill and fish

Natural risks

Enormous icebergs with drafts reaching several hundred meters; smaller blocks and fragments of icebergs; freeze sea (generally thick of 0,5 with 1m) with sometimes of the dynamic variations in the short run and the annual variations and interannual important; deep continental shelf covered with drifts varying in an important way on short distances; very strong and vague winds very high most of the year; icing of the ships, in particular from May to October; the essence of the area is far away from the means of research and rescue.

Environment

Subjects of topicality

  • Increase in solar radiations in the ultra-violet due to the Antarctic hole in the layer of ozone, causes of a reduction of at least 15  % of the productivity marinades primary (Phytoplancton) and of damage to the DNA of certain fish.
  • Fishing illegal, not declared and not regulated, particularly the capture and the unloading of a proportion estimated in 1999 at 5 or 6 times the quota authorized of Légine southern ( Dissostichus eleginoides ), which threatens the durability of stock.
  • Important additional mortality of birds of sea due to fishing with the Trawl line of légine.
  • the population now protected from the seals with fur increases quickly after a serious overexploitation with 18th and 19th centuries.
  • the Antarctic Ocean, estimated to absorb 15% of the carbon dioxide rejections anthropic, saw a study lately revealing that the exchanges of gas were now with balance, meaning that its role of pump with carbon is saturated.

International agreements

The Antarctic Ocean is concerned with all international conventions which cover the oceans of the whole world, in particular: the Convention of the United Nations on the right of the sea (Montego Bay, 1982) and Convention international whale-boat (and in particular the sanctuary whaler of the Antarctic Ocean: prohibited commercial hunting for the whale in the south of 40°S - southern of 60°S between 50°W and 130°W)).

It is also is concerned with the agreements specific to the area: Convention for the protection of the seals of the Antarctic (London, 1972) (limit hunting for the seals); Convention on the conservation of fauna and the marine flora of the Antarctic (CCAMLR) (regulates fishing).

Economic situation

In 1998 - 1999 (July 1st at June 30th), the fisheries unloaded 119.898 tons, made up with 85% of Krill and 14% of Légine southern. International agreements were concluded at the end of 1999 to reduce illegal fishing, not declared and not regulated. In summer 1998-1999, 10.013 tourists, most of the time made by the sea, visited the Antarctic Ocean and the the Antarctic, to compare with the 9604 visitors of the previous year. Close to 16  000 tourists were awaited for the season 1999-2000.

Ports and dampings

Esperanza Bases, Mawson Station, McMurdo Station, Palmer Station, Scott Base, and dampings off the Antarctic.

Note : few ports and dampings exist in the southernmost part of the Antarctic Ocean; the conditions of ice limit the use of the majority of them to short periods in the middle of the summer; even then, some cannot be used without ice-breakers. The majority of the ports of the Antarctic are exploited by governmental research stations and, except urgency, are not opened with the private or commercial ships; the ships attending the ports in the south of 60°S can be controlled by observers of the Traité of the Antarctic.

Maritime transport

The Passage of Drake offers an alternative to the transit by the Panama Canal.

See too

External bonds

  • Site of the CCAMLR (Convention on the conservation of fauna and the marine flora of the Antarctic): www.ccamlr.org

Be-X-old: Паўднёвыакіян Simple: Southern Ocean Zh-min-nan: Lâm-ke̍k-iûⁿ

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