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{{Distinguish|Sea|World Ocean}}{{Further|Seawater}}{{pp-move-indef}}{{Other use}}{{short description|A body of water that composes much of a planet's hydrosphere}}File:Clouds over the Atlantic Ocean.jpg|thumb|Surface view of the Atlantic OceanAtlantic Ocean{{Five oceans}}An ocean ({{Etymology|grc|, transc. Okeanós}}WEB,weblink Ὠκεανός, Perseus Project, Perseus Digital Library, May 17, 2012, ) is a body of water that composes much of a planet's hydrosphere.WEB,weblink WordNet Search — ocean, Princeton University, February 21, 2012, On Earth, an ocean is one of the major conventional divisions of the World Ocean. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans.WEB,weblink ocean, n, Oxford English Dictionary, February 5, 2012, WEB,weblink ocean, Merriam-Webster, February 6, 2012, The word "ocean" is often used interchangeably with "sea" in American English. Strictly speaking, a sea is a body of water (generally a division of the world ocean) partly or fully enclosed by land,WEB,weblink WordNet Search — sea, Princeton University, February 21, 2012, though "the sea" refers also to the oceans.Saline water covers approximately {{convert|361,000,000|km2|abbr=on}} and is customarily divided into several principal oceans and smaller seas, with the ocean covering approximately 71% of Earth's surface and 90% of the Earth's biosphere.WEB, NOAA – National Oceanic and Atmospheric Administration – Ocean,weblink, 2012-11-08, The ocean contains 97% of Earth's water, and oceanographers have stated that less than 5% of the World Ocean has been explored. The total volume is approximately 1.35 billion cubic kilometers (320 million cu mi) with an average depth of nearly {{convert|3700|m|ft|sp=us}}.WEB, Qadri, Syed, Volume of Earth's Oceans, The Physics Factbook, 2003,weblink 2007-06-07, JOURNAL, Charette, Matthew, Smith, Walter H. F., The volume of Earth's ocean, Oceanography, 2010, 23, 2, 112–114, 10.5670/oceanog.2010.51,weblink 27 September 2012, As the world ocean is the principal component of Earth's hydrosphere, it is integral to life, forms part of the carbon cycle, and influences climate and weather patterns. The World Ocean is the habitat of 230,000 known species, but because much of it is unexplored, the number of species that exist in the ocean is much larger, possibly over two million.NEWS, Mapping an ocean of species, Drogin, Bob,weblink August 2, 2009, August 18, 2009, Los Angeles Times, The origin of Earth's oceans is unknown; oceans are thought to have formed in the Hadean eon and may have been the cause for the emergence of life.Extraterrestrial oceans may be composed of water or other elements and compounds. The only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System. Early in their geologic histories, Mars and Venus are theorized to have had large water oceans. The Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, and a runaway greenhouse effect may have boiled away the global ocean of Venus. Compounds such as salts and ammonia dissolved in water lower its freezing point so that water might exist in large quantities in extraterrestrial environments as brine or convecting ice. Unconfirmed oceans are speculated beneath the surface of many dwarf planets and natural satellites; notably, the ocean of the moon Europa is estimated to have over twice the water volume of Earth. The Solar System's giant planets are also thought to have liquid atmospheric layers of yet to be confirmed compositions. Oceans may also exist on exoplanets and exomoons, including surface oceans of liquid water within a circumstellar habitable zone. Ocean planets are a hypothetical type of planet with a surface completely covered with liquid.WEB, Titan Likely To Have Huge Underground Ocean {{!, Mind Blowing Science |url= | |accessdate=2012-11-08 }}WEB, Ocean-bearing Planets: Looking For Extraterrestrial Life In All The Right Places,weblink, 2012-11-08,


The word ocean comes from the figure in classical antiquity, Oceanus ({{IPAc-en|oʊ|ˈ|s|iː|ə|n|ə|s|}}; }} Ōkeanós,Ὠκεανός, Henry George Liddell, Robert Scott, A Greek-English Lexicon, at Perseus project {{IPA-el|ɔːkeanós|pron}}), the elder of the Titans in classical Greek mythology, believed by the ancient Greeks and Romans to be the divine personification of the sea, an enormous river encircling the world.The concept of Ōkeanós has an Indo-European connection. Greek Ōkeanós has been compared to the Vedic epithet ā-śáyāna-, predicated of the dragon Vṛtra-, who captured the cows/rivers. Related to this notion, the Okeanos is represented with a dragon-tail on some early Greek vases.Matasović, Ranko, A Reader in Comparative Indo-European Religion Zagreb: Univ of Zagreb, 2016. p. 20.

Earth's global ocean

(File:World ocean map.gif|right|thumb|upright=1.1|Various ways to divide the World Ocean |alt=Rotating series of maps showing alternate divisions of the oceans)

Oceanic divisions

{{further|Borders of the oceans}}(File:Layers of Ocean (1).svg|thumb|1. Epipelagic zone: surface – 200 meters deep 2. Mesopelagic zone: 200 m – 1000 m 3. Bathypelagic zone: 1000 m – 4000 m 4. Abyssopelagic zone: 4000 m – 6000 m 5. Hadal zone (the trenches): 6000 m to the bottom of the ocean)Though generally described as several separate oceans, the global, interconnected body of salt water is sometimes referred to as the World Ocean or global ocean.WEB, Ocean,weblink, 2012-11-08, "WEB,weblink Distribution of land and water on the planet, UN Atlas of the Oceans, dead,weblink" title="">weblink 2016-03-03, The concept of a continuous body of water with relatively free interchange among its parts is of fundamental importance to oceanography.JOURNAL, Spilhaus, Athelstan F., July 1942, Maps of the whole world ocean, 32, 3, 431–5, 10.2307/210385, Geographical Review, 210385, The major oceanic divisions – listed below in descending order of area and volume – are defined in part by the continents, various archipelagos, and other criteria.WEB, Volumes of the World's Oceans from ETOPO1,weblink National Oceanic and Atmospheric Administration, NOAA, 2015-03-07, bot: unknown,weblink" title="">weblink 2015-03-11, WEB, CIA World Factbook,weblink Central Intelligence Agency, CIA, 2015-04-05, {| class="wikitable sortable" style="margin: 0.2em auto; text-align: right"! class="unsortable" width=22 | # !! Ocean !! class="unsortable" width=350 | Location !! Area(km{{smallsup|2}})(%) !! Volume(km{{smallsup|3}})(%) !! Avg. depth(m) !! Coastline(km)
1 align=left Pacific Ocean > Separates Asia and Oceania from the Americas[NB] {{nts46.6 >669880000}}50.1 align=center 3970}} {{nts|135663}}
2 align=left Atlantic Ocean > Separates the Americas from Europe and Africa {{nts23.5 >310410900}}23.3 align=center 3646}} {{nts|111866}}
3 align=left Indian Ocean > Washes upon Indian subcontinent and separates Africa and Australia (continent)>Australia {{nts19.5 >264000000}}19.8 align=center 3741}} {{nts|66526}}
4 align=left Southern Ocean > Sometimes considered an extension of the Pacific, Atlantic and Indian Oceans, which encircles Antarctica {{nts6.1 >71800000}}5.4 align=center 3270}} {{nts|17968}}
5 align=left Arctic Ocean > Sometimes considered a sea or estuary of the Atlantic, which covers much of the Arctic and washes upon northern North America and Eurasia {{nts4.3 >18750000}}1.4 align=center 1205}} {{nts|45389}}
! colspan=3 | Total – World Ocean! style="text-align: right;" | {{nts|361900000}}100! style="text-align: right;" | {{nts|1335000000}}100! {{nts|3688}}! style="text-align: right;" | {{nts|377412}}
{| class="wikitable"|+Seas and Bays!Sea!Location!Area(sq. km)!#|Arabian Sea|Between the Arabian peninsula and the Indian subcontinent|3,862,000|1
|Bay of Bengal|Between the Indian subcontinent and the malaysia peninsula|2,173,000|2
{{longitem|NB: Volume, area, and average depth figures include NOAA ETOPO1 figures for marginal South China Sea.Sources: Encyclopedia of Earth,WEB, Pacific Ocean,weblink Encyclopedia of Earth, 2015-03-07, WEB, Atlantic Ocean,weblink Encyclopedia of Earth, 2015-03-07, WEB, Indian Ocean,weblink Encyclopedia of Earth, 2015-03-07, WEB, Southern Ocean,weblink Encyclopedia of Earth, 2015-03-10, WEB, Arctic Ocean,weblink Encyclopedia of Earth, 2015-03-07, International Hydrographic Organization,WEB,weblink Limits of Oceans and Seas, 3rd edition, 1953, International Hydrographic Organization, 7 February 2010, Regional Oceanography: an Introduction (Tomczak, 2005),BOOK, Matthias, Tomczak, J. Stuart, Godfrey, Regional Oceanography: an Introduction, 2, 2003, Daya Publishing House, Delhi, 978-81-7035-306-5,weblink Encyclopædia Britannica,WEB,weblink 'Arctic Ocean' – Encyclopædia Britannica, 2012-07-02, As an approximation, the Arctic Ocean may be regarded as an estuary of the Atlantic Ocean., and the International Telecommunication Union.WEB, Recommendation ITU-R RS.1624: Sharing between the Earth exploration-satellite (passive) and airborne altimeters in the aeronautical radionavigation service in the band 4 200–4 400 MHz (Question ITU-R 229/7),weblink International Telecommunication Union, ITU Radiotelecommunication Sector (ITU-R), 2015-04-05, The oceans occupy about 3.35×108 km2 of area. There are 377412 km of oceanic coastlines in the world., |style=line-height: 1.4em; margin: 1em 0 1.4em 1em; font-size: 0.9em;}}Oceans are fringed by smaller, adjoining bodies of water such as seas, gulfs, bays, bights, and straits.

Global system

File:World Distribution of Mid-Oceanic Ridges.gif|right|upright=1.35|thumb|World Distribution of Mid-Oceanic Ridges; USGSUSGSFile:Tectonic plate boundaries.png|thumb|right|upright=1.15|Three main types of plate boundaries.]]The mid-ocean ridges of the world are connected and form a single global mid-oceanic ridge system that is part of every ocean and the longest mountain range in the world. The continuous mountain range is {{convert|65000|km|mi|abbr=on}} long (several times longer than the Andes, the longest continental mountain range).WEB, What is the longest mountain range on earth?,weblink Ocean Facts, NOAA, 17 October 2014,

Physical properties

{{further|Seawater}}The total mass of the hydrosphere is about 1.4 quintillion tonnes ({{val|1.4|e=18}} long tons or {{val|1.5|e=18}} short tons), which is about 0.023% of Earth's total mass. Less than 3% is freshwater; the rest is saltwater, almost all of which is in the ocean. The area of the World Ocean is about 361.9 million square kilometers (139.7 million square miles), which covers about 70.9% of Earth's surface, and its volume is approximately 1.335 billion cubic kilometers (320.3 million cubic miles). This can be thought of as a cube of water with an edge length of {{convert|1101|km|mi|sp=us}}. Its average depth is about {{convert|3688|m|ft|sp=us}}, and its maximum depth is {{convert|10994|m|mi|sp=us}} at the Mariana Trench.NEWS,weblink Scientists map Mariana Trench, deepest known section of ocean in the world, 23 March 2012, 7 December 2011, The Telegraph, Telegraph Media Group, Nearly half of the world's marine waters are over {{convert|3000|m|ft|sp=us}} deep. The vast expanses of deep ocean (anything below {{convert|200|m|ft|sp=us|disp=or}}) cover about 66% of Earth's surface.WEB, Drazen, Jeffrey C., Deep-Sea Fishes, School of Ocean and Earth Science and Technology, the University of Hawaiʻi at Mānoa,weblink 2007-06-07, This does not include seas not connected to the World Ocean, such as the Caspian Sea.The bluish ocean color is a composite of several contributing agents. Prominent contributors include dissolved organic matter and chlorophyll.JOURNAL, Paula G., Coble, Marine Optical Biogeochemistry: The Chemistry of Ocean Color, Chemical Reviews, 2007, 107, 2, 402–418, 10.1021/cr050350, 17256912, Mariners and other seafarers have reported that the ocean often emits a visible glow which extends for miles at night. In 2005, scientists announced that for the first time, they had obtained photographic evidence of this glow.WEB,weblink Mystery Ocean Glow Confirmed in Satellite Photos, Robert Roy, Britt, October 4, 2005, It is most likely caused by bioluminescence.WEB,weblink A glowing sea, courtesy of algae, November 21, 2005, Holladay, April, USA Today, WEB,weblink Sea's eerie glow seen from space, October 5, 2005, New Scientist, WEB,weblink The Incredible Glowing Algae, Casey, Amy, NASA Earth Observatory, NASA, August 8, 2003,

Oceanic zones

(File:Oceanic divisions.svg|upright=1.8|thumb|The major oceanic zones, based on depth and biophysical conditions |alt=Drawing showing divisions according to depth and distance from shore)Oceanographers divide the ocean into different vertical zones defined by physical and biological conditions. The pelagic zone includes all open ocean regions, and can be divided into further regions categorized by depth and light abundance. The photic zone includes the oceans from the surface to a depth of 200 m; it is the region where photosynthesis can occur and is, therefore, the most biodiverse. Because plants require photosynthesis, life found deeper than the photic zone must either rely on material sinking from above (see marine snow) or find another energy source. Hydrothermal vents are the primary source of energy in what is known as the aphotic zone (depths exceeding 200 m). The pelagic part of the photic zone is known as the epipelagic.The pelagic part of the aphotic zone can be further divided into vertical regions according to temperature.The mesopelagic is the uppermost region. Its lowermost boundary is at a thermocline of {{convert|12|C|F}}, which, in the tropics generally lies at {{convert|700|-|1000|m|ft|sp=us}}. Next is the bathypelagic lying between {{convert|10|and|4|C|F}}, typically between {{convert|700|-|1000|m|ft|sp=us}} and {{convert|2000|-|4000|m|ft|sp=us}}, lying along the top of the abyssal plain is the abyssopelagic, whose lower boundary lies at about {{convert|6000|m|ft|sp=us}}. The last zone includes the deep oceanic trench, and is known as the hadalpelagic. This lies between {{convert|6000|-|11000|m|ft|sp=us}} and is the deepest oceanic zone.The benthic zones are aphotic and correspond to the three deepest zones of the deep-sea. The bathyal zone covers the continental slope down to about {{convert|4000|m|ft|sp=us}}. The abyssal zone covers the abyssal plains between 4,000 and 6,000 m. Lastly, the hadal zone corresponds to the hadalpelagic zone, which is found in oceanic trenches.The pelagic zone can be further subdivided into two subregions: the neritic zone and the oceanic zone. The neritic zone encompasses the water mass directly above the continental shelves whereas the oceanic zone includes all the completely open water.In contrast, the littoral zone covers the region between low and high tide and represents the transitional area between marine and terrestrial conditions. It is also known as the intertidal zone because it is the area where tide level affects the conditions of the region.If a zone undergoes dramatic changes in temperature with depth, it contains a thermocline. The tropical thermocline is typically deeper than the thermocline at higher latitudes. Polar waters, which receive relatively little solar energy, are not stratified by temperature and generally lack a thermocline because surface water at polar latitudes are nearly as cold as water at greater depths. Below the thermocline, water is very cold, ranging from −1 Â°C to 3 Â°C. Because this deep and cold layer contains the bulk of ocean water, the average temperature of the world ocean is 3.9 Â°C. {{citation needed|date=December 2015}}If a zone undergoes dramatic changes in salinity with depth, it contains a halocline. If a zone undergoes a strong, vertical chemistry gradient with depth, it contains a chemocline.The halocline often coincides with the thermocline, and the combination produces a pronounced pycnocline.


File:Ocean gravity map.gif|right|thumb|upright=1.6|Map of large underwater features (1995, alt=False color photoThe deepest point in the ocean is the Mariana Trench, located in the Pacific Ocean near the Northern Mariana Islands. Its maximum depth has been estimated to be {{convert|10971|m|ft|sp=us}} (plus or minus 11 meters; see the Mariana Trench article for discussion of the various estimates of the maximum depth.) The British naval vessel Challenger II surveyed the trench in 1951 and named the deepest part of the trench the "Challenger Deep". In 1960, the Trieste successfully reached the bottom of the trench, manned by a crew of two men.

Oceanic maritime currents

(File:Ocean currents 1943.jpg|thumb|right|upright=1.15|Oceanic surface currents (U.S. Army, 1943).)File:M2 tidal constituent.jpg|thumb|right|upright=1.15|Amphidromic points showing the direction of tidestidesOceanic maritime currents have different origins. Tidal currents are in phase with the tide, hence are quasiperiodic; they may form various knots in certain places,{{clarify|date=September 2017}} most notably around headlands. Non-periodic currents have for origin the waves, wind and different densities.The wind and waves create surface currents (designated as “drift currents”). These currents can decompose in one quasi-permanent current (which varies within the hourly scale) and one movement of Stokes drift under the effect of rapid waves movement (at the echelon of a couple of seconds).).Étude de la dérive à la surface sous l’effet du vent, Observation and estimation of Lagrangian, Stokes and Eulerian currents induced by wind and waves at the sea surface, F. Ardhuin, L. Marié, N. Rascle, P. Forget, and A. Roland, 2009: J. Phys. Oceanogr., vol. 39, n° 11, pp. 2820–2838. The quasi-permanent current is accelerated by the breaking of waves, and in a lesser governing effect, by the friction of the wind on the surface.Mesure de l’effet de frottement à la surface de la mer, "Tangential stress beneath wind-driven air-water interfaces", M. L. Banner and W. L. Peirson, J. Fluid Mech., vol. 364, pp. 115–145, 1998.This acceleration of the current takes place in the direction of waves and dominant wind. Accordingly, when the sea depth increases, the rotation of the earth changes the direction of currents in proportion with the increase of depth, while friction lowers their speed. At a certain sea depth, the current changes direction and is seen inverted in the opposite direction with current speed becoming null: known as the Ekman spiral. The influence of these currents is mainly experienced at the mixed layer of the ocean surface, often from 400 to 800 meters of maximum depth. These currents can considerably alter, change and are dependent on the various yearly seasons. If the mixed layer is less thick (10 to 20 meters), the quasi-permanent current at the surface adopts an extreme oblique direction in relation to the direction of the wind, becoming virtually homogeneous, until the Thermocline.Courants mesurés près de la surface, The drift current from observations made on the bouee laboratoire, Joseph Gonella, 1971: Cahiers Océanographiques, vol. 23, pp. 1–15.In the deep however, maritime currents are caused by the temperature gradients and the salinity between water density masses.In littoral zones, breaking waves are so intense and the depth measurement so low, that maritime currents reach often 1 to 2 knots.


(File:Thermohaline Circulation 2.png|A map of the global thermohaline circulation; blue represent deep-water currents, whereas red represent surface currents|thumb|upright=0.9|left |alt=World map with colored, directed lines showing how water moves through the oceans. Cold deep water rises and warms in the central Pacific and in the Indian, whereas warm water sinks and cools near Greenland in the North Atlantic and near Antarctica in the South Atlantic.)Ocean currents greatly affect Earth's climate by transferring heat from the tropics to the polar regions. Transferring warm or cold air and precipitation to coastal regions, winds may carry them inland. Surface heat and freshwater fluxes create global density gradients that drive the thermohaline circulation part of large-scale ocean circulation. It plays an important role in supplying heat to the polar regions, and thus in sea ice regulation. Changes in the thermohaline circulation are thought to have significant impacts on Earth's energy budget. In so far as the thermohaline circulation governs the rate at which deep waters reach the surface, it may also significantly influence atmospheric carbon dioxide concentrations.For a discussion of the possibilities of changes to the thermohaline circulation under global warming, see shutdown of thermohaline circulation.The Antarctic Circumpolar Current encircles that continent, influencing the area's climate and connecting currents in several oceans.One of the most dramatic forms of weather occurs over the oceans: tropical cyclones (also called "typhoons" and "hurricanes" depending upon where the system forms).


{{further|Marine biology|Marine life}}The ocean has a significant effect on the biosphere. Oceanic evaporation, as a phase of the water cycle, is the source of most rainfall, and ocean temperatures determine climate and wind patterns that affect life on land. Life within the ocean evolved 3 billion years prior to life on land. Both the depth and the distance from shore strongly influence the biodiversity of the plants and animals present in each region.BOOK, Biology: Concepts & Connections, Chapter 34: The Biosphere: An Introduction to Earth's Diverse Environment, section 34.7,weblink As it is thought that life evolved in the ocean, the diversity of life is immense, including: In addition, many land animals have adapted to living a major part of their life on the oceans. For instance, seabirds are a diverse group of birds that have adapted to a life mainly on the oceans. They feed on marine animals and spend most of their lifetime on water, many only going on land for breeding. Other birds that have adapted to oceans as their living space are penguins, seagulls and pelicans. Seven species of turtles, the sea turtles, also spend most of their time in the oceans.URLHTTP://WWW.SOEST.HAWAII.EDU/OCEANOGRAPHY/COURSES/OCN623/SPRING2012/NON_CO2_GASES.PDF, titleDissolved Gases other than Carbon Dioxide in Seawater,, accessdate2014-05-05, WEB, urweblink title Dissolved Oxygen and Carbon Dioxide, website, publisher, date, WEB, firstFloor, lastAnthoni, urweblink titleComposition of seawater,, date, accessdate2014-05-05, ">

Gases {| class"wikitable" cellpadding"5" style"margin:auto;"URLHTTP://WWW.SOEST.HAWAII.EDU/OCEANOGRAPHY/COURSES/OCN623/SPRING2012/NON_CO2_GASES.PDF, titleDissolved Gases other than Carbon Dioxide in Seawater,, accessdate2014-05-05, WEB, urweblink title Dissolved Oxygen and Carbon Dioxide, website, publisher, date, WEB, firstFloor, lastAnthoni, urweblink titleComposition of seawater,, date, accessdate2014-05-05,

! Gas !! Concentration of seawater, by mass (in parts per million), for the whole ocean !! % Dissolved gas, by volume, in seawater at the ocean surface
Carbon dioxide (CO2) >| 15%
Nitrogen (N2) >| 48%
Oxygen (O2) >| 36%
{| class="wikitable"Solubility of oceanic gases (in mL/L) with temperature at salinity of 33‰ and atmospheric pressureHTTP://OCW.MIT.EDU/COURSES/EARTH-ATMOSPHERIC-AND-PLANETARY-SCIENCES/12-742-MARINE-CHEMISTRY-FALL-2006/LECTURE-NOTES/LEC_11_GAS_EXCH.PDF, 12.742. Marine Chemistry. Lecture 8. Dissolved Gases and Air-sea exchange, 2014-05-05, ! Temperature !! O2 !! CO2 !! N2
0 Â°C >| 14.47
10 Â°C >| 11.59
20 Â°C >| 9.65
30 Â°C >| 8.26
URLHTTP://WWW.IPCC.CH/PUBLICATIONS_AND_DATA/AR4/WG1/EN/CH5S5-6.HTML, title5.6 Synthesis – AR4 WGI Chapter 5: Observations: Oceanic Climate Change and Sea Level,, date, accessdate2014-05-05, WEB, urweblink titleEvaporation minus precipitation, Latitude-Longitude, Annual mean, workERA-40 Atlas, publisherECMWF, url-statusdead, archivedate2014-02-02, archiveurweblink" title="">weblink WEB, titleAtmosphere, Weather, and Climate, publisher[Routledge], firstRoger Graham, lastBarry, first2Richard J., last2Chorley, date2003, page68, WEB, urweblink titleOcean Stratification,, date, accessdate2014-05-05, WEB, titleOcean Circulation: Wind-Driven and Thermohaline Processes, publisher[Cambridge University Press], firstRui Xin, lastHuang, date2010, JOURNAL, doi 10.1146/annurev-marine-120408-151453, pmid 21141660, title Sea Surface Temperature Variability: Patterns and Mechanisms, journal Annual Review of Marine Science, volume 2, pages 115–43, year 2010, last1 Deser, first1 C., last2 Alexander, first2 M. A., last3 Xie, first3 S. P., last4 Phillips, first4 A. S., url weblink bibcode 2010ARMS....2..115D, url-status dead, archiveurl weblink" title="">weblink archivedate 2014-05-14, WEB, urweblink workIntroduction to Physical Oceanography, titleChapter 6 – Temperature, Salinity, and Density – Geographical Distribution of Surface Temperature and Salinity,, date2009-03-23, accessdate2014-05-05, ">

Surface {| class"wikitable" cellpadding"5" style"margin:auto;"URLHTTP://WWW.IPCC.CH/PUBLICATIONS_AND_DATA/AR4/WG1/EN/CH5S5-6.HTML, title5.6 Synthesis – AR4 WGI Chapter 5: Observations: Oceanic Climate Change and Sea Level,, date, accessdate2014-05-05, WEB, urweblink titleEvaporation minus precipitation, Latitude-Longitude, Annual mean, workERA-40 Atlas, publisherECMWF, url-statusdead, archivedate2014-02-02, archiveurweblink" title="">weblink WEB, titleAtmosphere, Weather, and Climate, publisher[Routledge], firstRoger Graham, lastBarry, first2Richard J., last2Chorley, date2003, page68, WEB, urweblink titleOcean Stratification,, date, accessdate2014-05-05, WEB, titleOcean Circulation: Wind-Driven and Thermohaline Processes, publisher[Cambridge University Press], firstRui Xin, lastHuang, date2010, JOURNAL, doi 10.1146/annurev-marine-120408-151453, pmid 21141660, title Sea Surface Temperature Variability: Patterns and Mechanisms, journal Annual Review of Marine Science, volume 2, pages 115–43, year 2010, last1 Deser, first1 C., last2 Alexander, first2 M. A., last3 Xie, first3 S. P., last4 Phillips, first4 A. S., url weblink bibcode 2010ARMS....2..115D, url-status dead, archiveurl weblink" title="">weblink archivedate 2014-05-14, WEB, urweblink workIntroduction to Physical Oceanography, titleChapter 6 – Temperature, Salinity, and Density – Geographical Distribution of Surface Temperature and Salinity,, date2009-03-23, accessdate2014-05-05,

! Characteristic !! Oceanic waters in polar regions !! Oceanic waters in temperate regions !! Oceanic waters in tropical regions
Precipitation vs. evaporation > E > E >| E > P
Sea surface temperature in winter >| 20 to 25 Â°C
Average salinity >| 35‰ to 37‰
< 5 Â°C
Annual variation of air temperature >|
< 5ªC < 5 Â°C
Annual variation of sea temperature>water temperature 10 Â°C

Mixing time

{| class="wikitable" cellpadding="5" style="margin:auto;"weblink ! Constituent !! Residence time (in years)
| 200
| 600
| 1,300
| 4,100
| 20,000
| 110,000
| 1,000,000
| 11,000,000
| 12,000,000
| 13,000,000
| 68,000,000
| 100,000,000


A zone of rapid salinity increase with depth is called a halocline. The temperature of maximum density of seawater decreases as its salt content increases. Freezing temperature of water decreases with salinity, and boiling temperature of water increases with salinity. Typical seawater freezes at around −2 Â°C at atmospheric pressure.WEB,weblink Can the ocean freeze? Ocean water freezes at a lower temperature than freshwater., NOAA, January 2, 2019, If precipitation exceeds evaporation, as is the case in polar and temperate regions, salinity will be lower. If evaporation exceeds precipitation, as is the case in tropical regions, salinity will be higher. Thus, oceanic waters in polar regions have lower salinity content than oceanic waters in temperate and tropical regions.BOOK, Chester, Roy, Jickells, Tim, Marine Geochemistry, 2012, Blackwell Publishing, 978-1-118-34907-6,weblink Salinity can be calculated using the chlorinity, which is a measure of the total mass of halogen ions (includes fluorine, chlorine, bromine, and iodine) in seawater. By international agreement, the following formula is used to determine salinity:Salinity (in ‰) = 1.80655 × Chlorinity (in ‰)The average chlorinity is about 19.2‰, and, thus, the average salinity is around 34.7‰ ">

Absorption of light {| class"wikitable" cellpadding"5" style"margin:auto;"|+Absorption of light in different wavelengths by ocean

! Color: Wavelength (nm) !! Depth at which 99 percent of the wavelength is absorbed (in meters) !! Percent absorbed in 1 meter of water
Ultraviolet (UV): 310 >| 14.0
Violet (V): 400 >| 4.2
Blue (B): 475 >| 1.8
Green (G): 525 >| 4.0
Yellow (Y): 575 >| 8.7
Orange (O): 600 >| 16.7
Red (R): 725 >| 71.0
Infrared (IR): 800 >| 82.0

Economic value

Many of the world's goods are moved by ship between the world's seaports.BOOK,weblink's+goods+are+moved+by+ship+between+seaports.#v=onepage&q=Many%20of%20the%20world's%20goods%20are%20moved%20by%20ship%20between%20seaports.&f=false, Marine Policy: An Introduction to Governance and International Law of the Oceans, Zacharias, Mark, 2014-03-14, Routledge, 9781136212475, en, Oceans are also the major supply source for the fishing industry. Some of the major harvests are shrimp, fish, crabs, and lobster.

Waves and swell

{{Further|Wind wave}}{{see also|Sea#Waves}}The motions of the ocean surface, known as undulations or waves, are the partial and alternate rising and falling of the ocean surface. The series of mechanical waves that propagate along the interface between water and air is called swell. {{Citation needed|date=May 2017}}

Extraterrestrial oceans

{{Further|Extraterrestrial liquid water|List of largest lakes and seas in the Solar System}}File:PIA19656-SaturnMoon-Enceladus-Ocean-ArtConcept-20150915.jpg|thumb|right|upright=1.35|Artist's conception of subsurface ocean of Enceladus confirmed April 3, 2014.JOURNAL, Iess, L., 4, Stevenson, D.J., Parisi, M., Hemingway, D., Jacobson, R.A., Lunine, J.I., Nimmo, F., Armstrong, J.w., Asmar, S.w., Ducci, M., Tortora, P., The Gravity Field and Interior Structure of Enceladus, 4 April 2014, Science (journal), ScienceScience (journal), Science(File:EuropaInterior1.jpg|thumb|right|Two models for the composition of Europa predict a large subsurface ocean of liquid water. Similar models have been proposed for other celestial bodies in the Solar System.)Although Earth is the only known planet with large stable bodies of liquid water on its surface and the only one in the Solar System, other celestial bodies are thought to have large oceans.WEB, Dyches, Preston, Chou, Felcia, The Solar System and Beyond is Awash in Water,weblink 7 April 2015, NASA, 8 April 2015,


The gas giants, Jupiter and Saturn, are thought to lack surfaces and instead have a stratum of liquid hydrogen; however their planetary geology is not well understood. The possibility of the ice giants Uranus and Neptune having hot, highly compressed, supercritical water under their thick atmospheres has been hypothesised. Although their composition is still not fully understood, a 2006 study by Wiktorowicz and Ingersall ruled out the possibility of such a water "ocean" existing on Neptune,JOURNAL, Wiktorowicz, Sloane J., Ingersoll, Andrew P., Liquid water oceans in ice giants, Icarus, 186, 2, 2007, 436–447, 0019-1035, 10.1016/j.icarus.2006.09.003, astro-ph/0609723, 2007Icar..186..436W, though some studies have suggested that exotic oceans of liquid diamond are possible.JOURNAL, Silvera, Isaac, Diamond: Molten under pressure, Nature Physics, 6, 1, 2010, 9–10, 1745-2473, 10.1038/nphys1491, 2010NatPh...6....9S,weblink The Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, though the water on Mars is no longer oceanic (much of it residing in the ice caps). The possibility continues to be studied along with reasons for their apparent disappearance. Astronomers now think that Venus may have had liquid water and perhaps oceans for over 2 billion years. M. Way et al. "Was Venus the First Habitable World of Our Solar System?" Geophysical Research Letters, Vol. 43, Issue 16, pp. 8376-8383.

Natural satellites

A global layer of liquid water thick enough to decouple the crust from the mantle is thought to be present on the natural satellites Titan, Europa, Enceladus and, with less certainty, Callisto, GanymedeNEWS, Clavin, Whitney,weblink Ganymede May Harbor 'Club Sandwich' of Oceans and Ice, NASA, Jet Propulsion Laboratory, May 1, 2014, 2014-05-01, JOURNAL, Ganymede's internal structure including thermodynamics of magnesium sulfate oceans in contact with ice, Planetary and Space Science, 12 April 2014, Vance, Steve, Bouffard, Mathieu, Choukroun, Mathieu, Sotina, Christophe, 10.1016/j.pss.2014.03.011, 2014P&SS...96...62V, 96, 62–70, and Triton.ENCYCLOPEDIA, Encyclopedia of the Solar System, Triton, McKinnon, William B., Kirk, Randolph L., Academic Press, 2007, Lucy Ann Adams McFadden, Lucy-Ann Adams, Paul Robert Weissman, Torrence V. Johnson, 2nd, Amsterdam; Boston, 978-0-12-088589-3, 483–502, JOURNAL, Javier, Ruiz, Heat flow and depth to a possible internal ocean on Triton, Icarus, 166, 2, 436–439, December 2003, 10.1016/j.icarus.2003.09.009, 2003Icar..166..436R,weblink A magma ocean is thought to be present on Io. Geysers have been found on Saturn's moon Enceladus, possibly originating from an ocean about {{convert|10|km|sp=us}} beneath the surface ice shell.WEB, Platt, Jane, Bell, Brian, NASA Space Assets Detect Ocean inside Saturn Moon,weblink NASA, 2014-04-03, 2014-04-03, Other icy moons may also have internal oceans, or may once have had internal oceans that have now frozen.JOURNAL, 10.1016/j.icarus.2006.06.005, Hussmann, Hauke, Sohl, Frank, Spohn, Tilman, November 2006, Subsurface oceans and deep interiors of medium-sized outer planet satellites and large trans-neptunian objects, Icarus (journal), Icarus, 185, 1, 258–273,weblink 2006Icar..185..258H, {{sfnRef, Hussmann Sohl et al., 2006, }}Large bodies of liquid hydrocarbons are thought to be present on the surface of Titan, although they are not large enough to be considered oceans and are sometimes referred to as lakes or seas. The Cassini–Huygens space mission initially discovered only what appeared to be dry lakebeds and empty river channels, suggesting that Titan had lost what surface liquids it might have had. Later flybys of Titan provided radar and infrared images that showed a series of hydrocarbon lakes in the colder polar regions. Titan is thought to have a subsurface liquid-water ocean under the ice in addition to the hydrocarbon mix that forms atop its outer crust.

Dwarf planets and trans-Neptunian objects

File:Ceres Cutaway-en.svg|left|thumb|Diagram showing a possible internal structure of Ceres ]]Ceres appears to be differentiated into a rocky core and icy mantle and may harbour a liquid-water ocean under its surface.JOURNAL, McCord, Thomas B., Ceres: Evolution and current state, Journal of Geophysical Research, 110, E5, E05009, 2005, 10.1029/2004JE002244, 2005JGRE..11005009M, JOURNAL, Castillo-Rogez, J. C., McCord, T. B., Davis, A. G., Ceres: evolution and present state, Lunar and Planetary Science, XXXVIII, 2006–2007, 2007,weblink 2009-06-25, Not enough is known of the larger trans-Neptunian objects to determine whether they are differentiated bodies capable of supporting oceans, although models of radioactive decay suggest that Pluto,WEB, The Inside Story, Johns Hopkins University Applied Physics Laboratory, â€” NASA New Horizons mission site,weblink 2013, 2 August 2013, dead,weblink" title="">weblink 13 November 2014, Eris, Sedna, and Orcus have oceans beneath solid icy crusts approximately {{nowrap|100 to 180 km}} thick.


File:UpsilonAndromedae D moons.jpg|thumb|right|Rendering of a hypothetical large extrasolar moonextrasolar moonSome planets and natural satellites outside the Solar System are likely to have oceans, including possible water ocean planets similar to Earth in the habitable zone or "liquid-water belt". The detection of oceans, even through the spectroscopy method, however is likely extremely difficult and inconclusive.Theoretical models have been used to predict with high probability that GJ 1214 b, detected by transit, is composed of exotic form of ice VII, making up 75% of its mass,WEB,weblink Astronomers Find Super-Earth Using Amateur, Off-the-Shelf Technology, David A., Aguilar, 2009-12-16, Harvard-Smithsonian Center for Astrophysics, January 23, 2010, making it an ocean planet.Other possible candidates are merely speculated based on their mass and position in the habitable zone include planet though little is actually known of their composition. Some scientists speculate Kepler-22b may be an "ocean-like" planet.WEB,weblink Updates on Exoplanets during the First Kepler Science Conference, 2011-12-08, Abel, Mendez Torres, Planetary Habitability Laboratory at University of Puerto Rico at Arecibo, UPR Arecibo, Models have been proposed for Gliese 581 d that could include surface oceans. Gliese 436 b is speculated to have an ocean of "hot ice".NEWS,weblink Hot "ice" may cover recently discovered planet, Maggie, Fox, Reuters, May 16, 2007, May 18, 2012, Exomoons orbiting planets, particularly gas giants within their parent star's habitable zone may theoretically have surface oceans.Terrestrial planets will acquire water during their accretion, some of which will be buried in the magma ocean but most of it will go into a steam atmosphere, and when the atmosphere cools it will collapse on to the surface forming an ocean. There will also be outgassing of water from the mantle as the magma solidifies—this will happen even for planets with a low percentage of their mass composed of water, so "super-Earth exoplanets may be expected to commonly produce water oceans within tens to hundreds of millions of years of their last major accretionary impact."JOURNAL, Elkins-Tanton, 10.1007/s10509-010-0535-3, Formation of Early Water Oceans on Rocky Planets, 2010, Astrophysics and Space Science, 332, 2, 359–364, 1011.2710, 2011Ap&SS.332..359E,

Non-water surface liquids

Oceans, seas, lakes and other bodies of liquids can be composed of liquids other than water, for example the hydrocarbon lakes on Titan. The possibility of seas of nitrogen on Triton was also considered but ruled out.ENCYCLOPEDIA, Encyclopedia of the Solar System, Triton, McKinnon, William B., Kirk, Randolph L., Academic Press, 2007, Lucy Ann Adams McFadden, Lucy-Ann Adams, Paul Robert Weissman, Torrence V. Johnson, 2nd, Amsterdam; Boston, 978-0-12-088589-3, 485, There is evidence that the icy surfaces of the moons Ganymede, Callisto, Europa, Titan and Enceladus are shells floating on oceans of very dense liquid water or water–ammonia.JOURNAL, 2008AGUFM.P21A1346C, 2008, 1346, 21, The Titan Saturn System Mission, American Geophysical Union, Fall Meeting, Coustenis, A., 4, Lunine, J., Lebreton, J., Matson, D., Erd, C., Reh, K., Beauchamp, P., Lorenz, R., Waite, H., Sotin, C., Tssm Jsdt, T., the Titan system, rich in organics, containing a vast subsurface ocean of liquid water, JOURNAL, 10.1016/j.icarus.2010.02.020, Icarus, 208, 2, 2010, 896–904, Shell thickness variations and the long-wavelength topography of Titan, F., Nimmo, B. G., Bills, observations can be explained if Titan has a floating, isostatically-compensated ice shell, 2010Icar..208..896N, JOURNAL, 0910.0032, Elastic ice shells of synchronous moons: Implications for cracks on Europa and non-synchronous rotation of Titan, Peter M., Goldreich, Jonathan L., Mitchell, 10.1016/j.icarus.2010.04.013, Icarus, 209, 2, 2010, 631–638, A number of synchronous moons are thought to harbor water oceans beneath their outer ice shells. A subsurface ocean frictionally decouples the shell from the interior, 2010Icar..209..631G, WEB,weblink Study of the ice shells and possible subsurface oceans of the Galilean satellites using laser altimeters on board the Europa and Ganymede orbiters JEO and JGO, 2011-10-14, WEB,weblink Tidal heating and the long-term stability of a subsurface ocean on Enceladus, 2011-10-14, Earth is often called the ocean planet because it is 70% covered in water.JOURNAL, The ocean planet, 2011-10-03, 12349465, 7, 2, People Planet, 6–9, Hinrichsen, D, WEB,weblink Irrigating Crops with Seawater, August 1998, Scientific American, Extrasolar terrestrial planets that are extremely close to their parent star will be tidally locked and so one half of the planet will be a magma ocean.JOURNAL, 0906.1204, Chemistry of Silicate Atmospheres of Evaporating Super-Earths, Laura, Schaefer, Bruce, Jr., Fegley, The Astrophysical Journal Letters, 2009, 703, 2, L113–L117, 10.1088/0004-637X/703/2/L113, 2009ApJ...703L.113S, It is also possible that terrestrial planets had magma oceans at some point during their formation as a result of giant impacts.WEB,weblink Fluid Dynamics of a Terrestrial Magma Ocean, V. S., Solomatov, 2000, Hot Neptunes close to their star could lose their atmospheres via hydrodynamic escape, leaving behind their cores with various liquids on the surface.JOURNAL,weblink Atmospheric Loss of Sub-Neptune's and Implications for Liquid Phases of Different Solvents on Their Surfaces, J.J., Leitner, H., 4, Lammer, P., Odert, M., Leitzinger, M.G., Firneis, A., Hanslmeier, EPSC Abstracts, 4, EPSC2009-542, 2009, European Planetary Science Congress, Where there are suitable temperatures and pressures, volatile chemicals that might exist as liquids in abundant quantities on planets include ammonia, argon, carbon disulfide, ethane, hydrazine, hydrogen, hydrogen cyanide, hydrogen sulfide, methane, neon, nitrogen, nitric oxide, phosphine, silane, sulfuric acid, and water.Tables 3 and 4 in WEB,weblink Many Chemistries Could Be Used to Build Living Systems, William, Bains, Astrobiology, 4, 2, 2004, Supercritical fluids, although not liquids, do share various properties with liquids. Underneath the thick atmospheres of the planets Uranus and Neptune, it is expected that these planets are composed of oceans of hot high-density fluid mixtures of water, ammonia and other volatiles.JOURNAL,weblink Water-ammonia ionic ocean on Uranus and Neptune?, S., Atreya, P., Egeler, K., Baines, Geophysical Research Abstracts, 8, P11A–0088, 2006, 2005AGUFM.P11A0088A, The gaseous outer layers of Jupiter and Saturn transition smoothly into oceans of supercritical hydrogen.JOURNAL, Guillot, T., A comparison of the interiors of Jupiter and Saturn, Planetary and Space Science, 1999, 47, 10–11, 1183–200, 1999P&SS...47.1183G, astro-ph/9907402, 10.1016/S0032-0633(99)00043-4,weblink WEB, Lang, Kenneth R., 2003,weblink Jupiter: a giant primitive planet, NASA, 2007-01-10, The atmosphere of Venus is 96.5% carbon dioxide, which is a supercritical fluid at its surface.

See also

{{div col|colwidth=18em}} On other bodies: {{div col end}}



Further reading

  • Matthias Tomczak and J. Stuart Godfrey. 2003. Regional Oceanography: an Introduction. (see the site)
  • Pope, F. 2009. From eternal darkness springs cast of angels and jellied jewels. in The Times. November 23. 2009 pp. 16–17.

External links

{{commons}}{{Wiktionary}} {{List of seas|state=uncollapsed}}{{physical oceanography|expanded=other}}{{Physical Earth}}

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