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‘Southern Ocean’ recognized as globe’s fifth ocean


The National Geographic magazine has recognised the ‘Southern Ocean’ as the world’s fifth ocean June 8, 2021 hoping others will soon follow suit.


GS-I: Geography (World relief features, Oceanography)

Dimensions of the Article:

  1. National Geographic Society
  2. International Hydrographic Organization (IHO)
  3. About the Southern Ocean
  4. Antarctic Circumpolar Current

National Geographic Society

  • The National Geographic Society (NGS), headquartered in Washington, D.C., United States, is one of the largest non-profit scientific and educational organizations in the world with interests in geography, archaeology, and natural science, the promotion of environmental and historical conservation, and the study of world culture and history.
  • The NGS also publishes other magazines, books, school products, maps, and Web and film products in numerous languages and countries.
  • The Society has helped sponsor many expeditions and research projects over the years.

International Hydrographic Organization (IHO)

  • The International Hydrographic Organization (IHO) is an intergovernmental organization representing hydrography, and as of 2021 the IHO comprises of 94 Member States.
  • A principal aim of the IHO is to ensure that the world’s seas, oceans and navigable waters are properly surveyed and charted.
  • It does this through the setting of international standards, the co-ordination of the endeavors of the world’s national hydrographic offices, and through its capacity building program.
  • The IHO enjoys observer status at the United Nations, where it is the recognized competent authority on hydrographic surveying and nautical charting.
  • When referring to hydrography and nautical charting in Conventions and similar Instruments, it is the IHO standards and specifications that are normally used.
  • The IHO develops hydrographic and nautical charting standards. These standards are subsequently adopted and used by its member countries and others in their surveys, nautical charts, and publications.
  • The almost universal use of the IHO standards means that the products and services provided by the world’s national hydrographic and oceanographic offices are consistent and recognizable by all seafarers and for other users. Much has been done in the field of standardization since the IHO was founded.

About the Southern Ocean

  • The National Geography cartographers have now identified the Southern Ocean as the fifth ocean on the planet. Other four Oceans are: Atlantic, Pacific, Indian, and Arctic Oceans.
  • Most of the waters that surround Antarctica out to 60 degrees south latitude, excluding the Drake Passage and Scotia Sea, constitute the newly acknowledged Southern Ocean.
  • The Southern Ocean is the only ocean ‘to touch three other oceans (Pacific, Atlantic and Indian Ocean) and to completely embrace a continent rather than being embraced by them’.
  • It is also defined by its Antarctic Circumpolar Current that was formed 34 million years ago. The current flows from west to east around Antarctica.

Antarctic Circumpolar Current

  • Antarctic Circumpolar Current (ACC) is the only current in the global ocean to close upon itself in a circumpolar loop.
  • This trait makes the ACC the most important current in the Earth’s climate system because it links the Atlantic, Pacific and Indian Oceans and is the primary means of inter-basin exchange of heat, carbon dioxide, chemicals, biology and other tracers.
  • The ACC is created by the combined effects of strong westerly winds across the Southern Ocean, and the big change in surface temperatures between the Equator and the poles.
  • Ocean density increases as water gets colder and as it gets more salty. The warm, salty surface waters of the subtropics are much lighter than the cold, fresher waters close to Antarctica.
  • The depth of constant density levels slopes up towards Antarctica. The westerly winds make this slope steeper, and the ACC rides eastward along it, faster where the slope is steeper, and weaker where it’s flatter.
ACC | ferrebeekeeper

-Source: India Today, Down to Earth Magazine

November 2023