View source for Oceanography

{{Short description|Scientific study of the ocean}}
{{For|the scientific journal|Oceanography (journal){{!}}''Oceanography'' (journal)|Ocean Science (journal){{!}}''Ocean Science'' (journal)}}
{{Use dmy dates|date=September 2019}}
[[File:Thermohaline Circulation 2.png|thumb|[[Thermohaline circulation]]]]

'''Oceanography''' ({{etymology|grc|''{{wikt-lang|grc|ὠκεανός}}'' ({{grc-transl|ὠκεανός}})|[[ocean]]||''{{wikt-lang|grc|γραφή}}'' ({{grc-transl|γραφή}})|[[writing]]}}), also known as '''oceanology''', '''sea science''', '''ocean science''', and '''marine science''', is the scientific study of the [[ocean]], including its [[Physical oceanography|physics]], [[Chemical oceanography|chemistry]], [[Biological oceanography|biology]], and [[Marine geology|geology]].  

It is an [[Earth science]], which covers a wide range of topics, including [[ocean current]]s, [[Wind wave|waves]], and [[geophysical fluid dynamics]];  [[flux]]es of various chemical substances and physical properties within the ocean and across its boundaries; [[ecosystem]] dynamics; and [[plate tectonics]] and [[seabed]] geology. 

Oceanographers draw upon a wide range of disciplines to deepen their understanding of the world’s oceans, incorporating insights from [[astronomy]], [[biology]], [[chemistry]], [[geography]], [[geology]], [[hydrology]], [[meteorology]] and [[physics]].

==History==
[[File: Gulf stream map.gif|thumb|[[Benjamin Franklin]]'s 1770 map of the [[Gulf Stream]]]]

===Early history===
Humans first acquired knowledge of the waves and currents of the [[sea]]s and [[ocean]]s in pre-historic times. Observations on [[tide]]s were recorded by [[Aristotle]] and [[Strabo]] in 384–322 BC.<ref>{{Cite web|title=A History Of The Study Of Marine Biology ~ MarineBio Conservation Society|date=17 June 2018|url=https://www.marinebio.org/creatures/marine-biology/history-of-marine-biology/|access-date=2021-05-17|language=en-US}}</ref> Early exploration of the oceans was primarily for [[cartography]] and mainly limited to its surfaces and of the animals that fishermen brought up in nets, though depth soundings by lead line were taken.

The Portuguese campaign of Atlantic navigation is the earliest example of a systematic scientific large project, sustained over many decades, studying the currents and winds of the Atlantic.

The work of [[Pedro Nunes]] (1502–1578) is remembered in the navigation context for the determination of the loxodromic curve: the shortest course between two points on the surface of a sphere represented onto a two-dimensional map.<ref name="mathshistory.st-andrews.ac.uk">[https://mathshistory.st-andrews.ac.uk/Biographies/Nunes/ Pedro Nunes Salaciense] at the [[MacTutor History of Mathematics archive]] (retrieved 13/06/2020)</ref><ref>W.G.L. Randles, "Pedro Nunes and the Discovery of the Loxodromic Curve, or How, in the 16th Century, Navigating with a Globe had Failed to Solve the Difficulties Encountered with the Plane Chart", Revista da Universidade Coimbra, 35 (1989), 119–30.</ref> When he published his "Treatise of the Sphere" (1537), mostly a commentated translation of earlier work by others, he included a treatise on geometrical and astronomic methods of navigation. There he states clearly that Portuguese navigations were not an adventurous endeavour:

''"nam se fezeram indo a acertar: mas partiam os nossos mareantes muy ensinados e prouidos de estromentos e regras de astrologia e geometria que sam as cousas que os cosmographos ham dadar apercebidas (...) e leuaua cartas muy particularmente rumadas e na ja as de que os antigos vsauam"'' (were not done by chance: but our seafarers departed well taught and provided with instruments and rules of astrology (astronomy) and geometry which were matters the cosmographers would provide (...) and they took charts with exact routes and no longer those used by the ancient).<ref>Pedro Nunes Salaciense, Tratado da Esfera, cap. 'Carta de Marear com o Regimento da Altura' p.2 - https://archive.org/details/tratadodaspherac00sacr/page/n123/mode/2up (retrieved 13/06/2020)</ref>

His credibility rests on being personally involved in the instruction of pilots and senior seafarers from 1527 onwards by Royal appointment, along with his recognized competence as mathematician and astronomer.<ref name="mathshistory.st-andrews.ac.uk"/>
The main problem in navigating back from the south of the [[Canary Islands]] (or south of [[Boujdour]]) by sail alone, is due to the change in the regime of winds and currents: the [[North Atlantic gyre]] and the Equatorial counter current <ref>http://ksuweb.kennesaw.edu/~jdirnber/oceanography/LecuturesOceanogr/LecCurrents/LecCurrents.html (retrieved 13/06/2020)</ref> will push south along the northwest bulge of Africa, while the uncertain winds where the Northeast trades meet the Southeast trades (the doldrums) <ref>https://kids.britannica.com/students/assembly/view/166714 (retrieved 13/06/2020)</ref> leave a sailing ship to the mercy of the currents. Together, prevalent current and wind make northwards progress very difficult or impossible. It was to overcome this problem and clear the passage to India around Africa as a viable maritime trade route, that a systematic plan of exploration was devised by the Portuguese. The return route from regions south of the Canaries became the '[[Volta do mar|volta do largo' or 'volta do mar]]'. The 'rediscovery' of the [[Azores|Azores islands]] in 1427 is merely a reflection of the heightened strategic importance of the islands, now sitting on the return route from the western coast of Africa (sequentially called 'volta de Guiné' and 'volta da Mina'); and the references to the [[Sargasso Sea]] (also called at the time 'Mar da Baga'), to the west of the [[Azores]], in 1436, reveals the western extent of the return route.<ref name="ReferenceA">Carlos Calinas Correia, A Arte de Navegar na Época dos Descobrimentos, Colibri, Lisboa 2017; {{ISBN|978-989-689-656-0}}</ref> This is necessary, under sail, to make use of the southeasterly and northeasterly winds away from the western coast of Africa, up to the northern latitudes where the westerly winds will bring the seafarers towards the western coasts of Europe.<ref>{{cite web |url=https://upload.wikimedia.org/wikipedia/commons/1/18/Map_prevailing_winds_on_earth.png |title=Map|website=upload.wikimedia.org|access-date=2020-09-15}}</ref>

The secrecy involving the Portuguese navigations, with the death penalty for the leaking of maps and routes, concentrated all sensitive records in the Royal Archives, completely destroyed by the [[1755 Lisbon earthquake|Lisbon earthquake of 1775]]. However, the systematic nature of the Portuguese campaign, mapping the currents and winds of the Atlantic, is demonstrated by the understanding of the seasonal variations, with expeditions setting sail at different times of the year taking different routes to take account of seasonal predominate winds. This happens from as early as late 15th century and early 16th: [[Bartolomeu Dias]] followed the African coast on his way south in August 1487, while [[Vasco da Gama]] would take an open sea route from the latitude of [[Sierra Leone]], spending three months in the open sea of the South Atlantic to profit from the southwards deflection of the southwesterly on the Brazilian side (and the Brazilian current going southward - Gama departed in July 1497); and [[Pedro Álvares Cabral]] (departing March 1500) took an even larger arch to the west, from the latitude of Cape Verde, thus avoiding the summer monsoon (which would have blocked the route taken by Gama at the time he set sail).<ref>Carlos Viegas Gago Coutinho, A Viagem de Bartolomeu Dias, Anais (Clube Militar Naval) May 1946</ref> Furthermore, there were systematic expeditions pushing into the western Northern Atlantic (Teive, 1454; Vogado, 1462; Teles, 1474; Ulmo, 1486).<ref>Carlos Viegas Gago Coutinho, As Primeiras Travessia Atlanticas - lecture, Academia Portuguesa de História, 22/04/1942 - in: Anais (APH) 1949, II serie, vol.2</ref>

The documents relating to the supplying of ships, and the ordering of sun declination tables for the southern Atlantic for as early as 1493–1496,<ref>Luís Adão da Fonseca, Pedro Álvares Cabral - Uma Viagem, INAPA, Lisboa, 1999, p.48</ref> all suggest a well-planned and systematic activity happening during the decade long period between [[Bartolomeu Dias]] finding the southern tip of Africa, and Gama's departure; additionally, there are indications of further travels by Bartolomeu Dias in the area.<ref name="ReferenceA" /> The most significant consequence of this systematic knowledge was the negotiation of the [[Treaty of Tordesillas]] in 1494, moving the line of demarcation 270 leagues to the west (from 100 to 370 leagues west of the Azores), bringing what is now Brazil into the Portuguese area of domination. The knowledge gathered from open sea exploration allowed for the well-documented extended periods of sail without sight of land, not by accident but as pre-determined planned route; for example, 30 days for [[Bartolomeu Dias]] culminating on [[Mossel Bay]], the three months Gama spent in the South Atlantic to use the Brazil current (southward), or the 29 days Cabral took from Cape Verde up to landing in [[Monte Pascoal]], Brazil.

The [[Danish Arabia expedition (1761–67)|Danish expedition to Arabia]] 1761–67 can be said to be the world's first oceanographic expedition, as the ship [[HDMS Grønland (1756)|''Grønland'']] had on board a group of scientists, including naturalist [[Peter Forsskål]], who was assigned an explicit task by the king, [[Frederick V of Denmark|Frederik V]], to study and describe the marine life in the open sea, including finding the cause of [[Milky seas effect|mareel]], or milky seas. For this purpose, the expedition was equipped with nets and scrapers, specifically designed to collect samples from the open waters and the bottom at great depth.<ref>{{cite book |last1=Wolff |first1=Torben |title=Danish Expeditions on the Seven Seas |date=1969 |publisher=Rhodos |location=Copenhagen}}</ref>

Although [[Juan Ponce de León]] in 1513 first identified the [[Gulf Stream]], and the current was well known to mariners, [[Benjamin Franklin]] made the first scientific study of it and gave it its name. Franklin measured water temperatures during several Atlantic crossings and correctly explained the Gulf Stream's cause. Franklin and Timothy Folger printed the first map of the [[Gulf Stream]] in 1769–1770.<ref name="NOAA_Franklin">{{Cite web|url=http://oceanexplorer.noaa.gov/library/readings/gulf/gulf.html|archive-url=https://web.archive.org/web/20051218185445/http://oceanexplorer.noaa.gov/library/readings/gulf/gulf.html|url-status=dead|title=1785: Benjamin Franklin's 'Sundry Maritime Observations'|archive-date=December 18, 2005}}</ref><ref>Wilkinson, Jerry. [http://www.keyshistory.org/gulfstream.html History of the Gulf Stream] 1 January 2008</ref>

[[File:Rennel map 1799.png|left|thumb|1799 map of the currents in the [[Atlantic Ocean|Atlantic]] and [[Indian Ocean]]s, by [[James Rennell]]]]
Information on the currents of the [[Pacific Ocean]] was gathered by explorers of the late 18th century, including [[James Cook]] and [[Louis Antoine de Bougainville]]. [[James Rennell]] wrote the first scientific textbooks on oceanography, detailing the current flows of the [[Atlantic Ocean|Atlantic]] and [[Indian Ocean|Indian]] oceans. During a voyage around the [[Cape of Good Hope]] in 1777, he mapped ''"the [[Agulhas Current|banks and currents at the Lagullas]]"''. He was also the first to understand the nature of the intermittent current near the [[Isles of Scilly]], (now known as Rennell's Current).<ref>{{cite DNB|wstitle=Rennell, James|volume=48}}</ref> 

The tides and currents of the ocean are distinct. 
Tides are the rise and fall of [[sea level]]s created by the combination of the [[Gravity|gravitational]] forces of the [[Moon]] along with the Sun (the Sun just in a much lesser extent) and are also caused by the [[Earth]] and [[Moon]] orbiting each other. An ocean current is a continuous, directed movement of [[Seawater|seawater generated]] by a number of forces acting upon the water, including wind, the [[Coriolis effect]], [[breaking wave]]s, [[cabbeling]], and temperature and [[Salinity|salinity differences]].<ref>{{Cite web |last=US Department of Commerce |first=National Oceanic and Atmospheric Administration |title=Tides and Currents |url=https://oceanservice.noaa.gov/navigation/tidesandcurrents/#:~:text=Tides%20involve%20water%20moving%20up,other%20facts%20that%20drive%20currents. |access-date=2024-04-25 |website=oceanservice.noaa.gov |language=EN-US}}</ref>

Sir [[James Clark Ross]] took the first modern sounding in deep sea in 1840, and [[Charles Darwin]] published a paper on [[reef]]s and the formation of [[atoll]]s as a result of the [[Second voyage of HMS Beagle|second voyage of HMS ''Beagle'']] in 1831–1836. [[Robert FitzRoy]] published a four-volume report of ''Beagle''{{'}}s three voyages. In 1841–1842 [[Edward Forbes]] undertook dredging in the [[Aegean Sea]] that founded marine ecology.

The first superintendent of the [[United States Naval Observatory]] (1842–1861), [[Matthew Fontaine Maury]] devoted his time to the study of marine meteorology, [[navigation]], and charting prevailing winds and currents. His 1855 textbook ''Physical Geography of the Sea'' was one of the first comprehensive oceanography studies. Many nations sent oceanographic observations to Maury at the Naval Observatory, where he and his colleagues evaluated the information and distributed the results worldwide.<ref>Williams, Frances L. ''Matthew Fontaine Maury, Scientist of the Sea.'' (1969) {{ISBN|0-8135-0433-3}}</ref>

=== Modern oceanography ===
Knowledge of the oceans remained confined to the topmost few fathoms of the water and a small amount of the bottom, mainly in shallow areas. Almost nothing was known of the ocean depths. The British [[Royal Navy]]'s efforts to chart all of the world's [[coast]]lines in the mid-19th century reinforced the vague idea that most of the ocean was very deep, although little more was known. As exploration ignited both popular and scientific interest in the polar regions and [[Africa]], so too did the mysteries of the unexplored oceans.

[[File:Challenger.jpg|right|thumb|{{HMS|Challenger|1858|6}} undertook the first global marine research expedition in 1872.]]
The seminal event in the founding of the modern science of oceanography was the 1872–1876 [[Challenger expedition|'' Challenger'' expedition]]. As the first true oceanographic cruise, this expedition laid the groundwork for an entire academic and research discipline.<ref name="NOAA">[http://oceanexplorer.noaa.gov/explorations/03mountains/background/challenger/challenger.html Then and Now: The HMS Challenger Expedition and the 'Mountains in the Sea' Expedition], Ocean Explorer website (NOAA), accessed 2 January 2012</ref> In response to a recommendation from the [[Royal Society]], the [[British Government]] announced in 1871 an expedition to explore world's oceans and conduct appropriate scientific investigation. [[Charles Wyville Thomson]] and [[John Murray (oceanographer)|Sir John Murray]] launched the [[Challenger expedition|''Challenger'' expedition]]. {{HMS|Challenger|1858|2}}, leased from the Royal Navy, was modified for scientific work and equipped with separate laboratories for [[natural history]] and [[chemistry]].<ref name="Rice">{{cite book|last=Rice|first=A. L.|title=Understanding the Oceans: Marine Science in the Wake of HMS Challenger|publisher=[[Routledge]]|date=1999|pages=27–48|chapter=The Challenger Expedition|isbn=978-1-85728-705-9|chapter-url=https://books.google.com/books?id=F5agn3NSzEoC&pg=PA27}}</ref> Under the scientific supervision of Thomson, ''Challenger'' travelled nearly {{convert|70000|nmi|km}} surveying and exploring. On her journey circumnavigating the globe,<ref name="Rice"/> 492&nbsp;deep sea soundings, 133&nbsp;bottom dredges, 151&nbsp;open water trawls and 263&nbsp;serial water temperature observations were taken.<ref>''Oceanography: an introduction to the marine environment'' (Peter K. Weyl, 1970), p. 49</ref> Around 4,700&nbsp;new species of marine life were discovered. The result was the ''Report Of The Scientific Results of the Exploring Voyage of H.M.S. Challenger during the years 1873–76''. Murray, who supervised the publication, described the report as "the greatest advance in the knowledge of our planet since the celebrated discoveries of the fifteenth and sixteenth centuries". He went on to found the academic discipline of oceanography at the [[University of Edinburgh]], which remained the centre for oceanographic research well into the 20th century.<ref>{{cite web|url=http://www.geos.ed.ac.uk/public/JohnMurray.html|title=Sir John Murray (1841–1914) – Founder Of Modern Oceanography|publisher=Science and Engineering at The University of Edinburgh|access-date=7 November 2013|url-status=dead|archive-url=https://web.archive.org/web/20130528123837/http://www.geos.ed.ac.uk/public/JohnMurray.html|archive-date=28 May 2013}}</ref> Murray was the first to study marine trenches and in particular the [[Mid-Atlantic Ridge]], and map the sedimentary deposits in the oceans. He tried to map out the world's ocean currents based on salinity and temperature observations, and was the first to correctly understand the nature of [[coral reef]] development.

In the late 19th century, other [[Western culture|Western]] nations also sent out scientific expeditions (as did private individuals and institutions). The first purpose-built oceanographic ship, ''Albatros'', was built in 1882. In 1893, [[Fridtjof Nansen]] allowed his ship, ''Fram'', to be frozen in the Arctic ice. This enabled him to obtain oceanographic, meteorological and astronomical data at a stationary spot over an extended period.
 
[[File:Ocean currents 1911.jpg|thumb|[[Ocean current]]s (1911)]]
[[File:John Francon Williams FRGS commemorative plaque, Clackmannan Cemetery 2019.jpg|thumb|left|Writer and geographer [[John Francon Williams]] FRGS commemorative plaque, [[Clackmannan]] Cemetery 2019]]
In 1881 the geographer [[John Francon Williams]] published a seminal book, ''Geography of the Oceans''.<ref>[[John Francon Williams|Williams, J. Francon]] (1881) [https://books.google.com/books?id=FyMIAQAAIAAJ&q=%22The+Geography+of+the+Oceans%22 ''The Geography of the Oceans: Physical, Historical, and Descriptive''] George Philip & Son.
</ref><ref>''Geography of the Oceans'' by John Francon Williams, 1881, {{OCLC|561275070}}</ref><ref>[[John Francon Williams]] commemorated (article) (''Alloa Advertiser'', retrieved 26 September 2019): https://www.alloaadvertiser.com/news/17928655.long-awaiting-tribute-pioneering-writer-buried-clacks/</ref> Between 1907 and 1911 [[Otto Krümmel]] published the ''Handbuch der Ozeanographie'', which became influential in awakening public interest in oceanography.<ref>{{cite web|author=Otto Krümmel|date=1907|title=Handbuch der Ozeanographie|url=https://archive.org/stream/handbuchderozean02bogu#page/n5/mode/2up <!-- Abstract: http://openlibrary.org/books/OL14010853M/Handbuch_der_ozeanographie -->|publisher=J. Engelhorn}}</ref> The four-month 1910 [[North Atlantic]] expedition headed by [[John Murray (oceanographer)|John Murray]] and [[Johan Hjort]] was the most ambitious research oceanographic and marine zoological project ever mounted until then, and led to the classic 1912 book ''The Depths of the Ocean''.

The first acoustic measurement of sea depth was made in 1914. Between 1925 and 1927 the "Meteor" expedition gathered 70,000 ocean depth measurements using an echo sounder, surveying the Mid-Atlantic Ridge.

In 1934, [[Easter Ellen Cupp]], the first woman to have earned a PhD (at Scripps) in the United States, completed a major work on [[diatoms]]<ref>{{Cite news |date=1934-05-10 |title=Women passes test; become oceanographer |pages=13 |work=The Whittier News |url=https://www.newspapers.com/clip/118426106/women-passes-test-become-oceanographer/ |access-date=2023-02-11}}</ref> that remained the standard taxonomy in the field until well after her death in 1999. In 1940, Cupp was let go from her position at Scripps. Sverdrup specifically commended Cupp as a conscientious and industrious worker and commented that his decision was no reflection on her ability as a scientist. Sverdrup used the instructor billet vacated by Cupp to employ Marston Sargent, a biologist studying marine algae, which was not a new research program at Scripps. Financial pressures did not prevent Sverdrup from retaining the services of two other young post-doctoral students, [[Walter Munk]] and [[Roger Revelle]]. Cupp's partner, Dorothy Rosenbury, found her a position teaching high school, where she remained for the rest of her career. (Russell, 2000)

Sverdrup, Johnson and Fleming published ''[[The oceans|The Oceans]]'' in 1942,<ref>{{cite book|last1=Sverdrup|first1=Harald Ulrik|author-link1=Harald Sverdrup (oceanographer)|last2=Johnson|first2=Martin Wiggo|author-link2=Martin W. Johnson|last3=Fleming|first3=Richard H.|title=The Oceans, Their Physics, Chemistry, and General Biology|date=1942|publisher=[[Prentice-Hall]]|location=New York|url=http://ark.cdlib.org/ark:/13030/kt167nb66r/}}</ref> which was a major landmark. ''The Sea'' (in three volumes, covering physical oceanography, seawater and geology) edited by M.N. Hill was published in 1962, while [[Rhodes Fairbridge]]'s ''Encyclopedia of Oceanography'' was published in 1966.

The Great Global Rift, running along the Mid Atlantic Ridge, was discovered by [[Maurice Ewing]] and [[Bruce Heezen]] in 1953 and mapped by Heezen and [[Marie Tharp]] using bathymetric data; in 1954 a mountain range under the Arctic Ocean was found by the Arctic Institute of the USSR. The theory of seafloor spreading was developed in 1960 by [[Harry Hammond Hess]]. The [[Ocean Drilling Program]] started in 1966. Deep-sea vents were discovered in 1977 by [[Jack Corliss]] and [[Robert Ballard]] in the submersible {{ship|DSV|Alvin}}.<ref>{{Cite web |title=Bathyscaphe {{!}} Definition, History, & Facts {{!}} Britannica |url=https://www.britannica.com/technology/bathyscaphe |access-date=2025-01-18 |website=www.britannica.com |language=en}}</ref>

In the 1950s, [[Auguste Piccard]] invented the [[bathyscaphe]] and used the [[bathyscaphe]] {{ship|Bathyscaphe|Trieste||2}} to investigate the ocean's depths. The United States [[nuclear submarine]] {{USS|Nautilus|SSN-571|2}} made the first journey under the ice to the North Pole in 1958. In 1962 the FLIP (Floating Instrument Platform), a {{convert|355|ft|m|adj=on|0}} spar buoy, was first deployed.

In 1968, [[Tanya Atwater]] led the first all-woman oceanographic expedition. Until that time, gender policies restricted women oceanographers from participating in voyages to a significant extent.

From the 1970s, there has been much emphasis on the application of large scale computers to oceanography to allow numerical predictions of ocean conditions and as a part of overall environmental change prediction. Early techniques included analog computers (such as the [[Ishiguro Storm Surge Computer]]) generally now replaced by numerical methods (e.g. [[Sea, Lake, and Overland Surge from Hurricanes|SLOSH]].) An oceanographic buoy array was established in the Pacific to allow prediction of [[El Niño]] events.

1990 saw the start of the [[World Ocean Circulation Experiment]] (WOCE) which continued until 2002. [[Geosat]] seafloor mapping data became available in 1995.

Study of the oceans is critical to understanding shifts in [[Earth's energy balance]] along with related global and regional changes in [[climate]], the [[Biosphere#Origin and use of the term|biosphere]] and [[biogeochemistry]]. The atmosphere and ocean are linked because of [[evaporation]] and [[precipitation (meteorology)|precipitation]] as well as [[thermal flux]] (and solar [[insolation]]). Recent studies have advanced knowledge on [[ocean acidification]], [[ocean heat content]], [[ocean currents]], [[sea level rise]], the [[oceanic carbon cycle]], the [[water cycle]], [[Arctic sea ice decline]], [[coral bleaching]], [[marine heatwave]]s, [[extreme weather]], [[coastal erosion]] and many other phenomena in regards to ongoing [[climate change (general concept)|climate change]] and [[climate feedback]]s.

In general, understanding the world ocean through further scientific study enables better [[stewardship]] and sustainable utilization of Earth's resources.<ref>{{Cite web|url=https://www.britannica.com/science/oceanography|title=Oceanography {{!}} science|website=Encyclopedia Britannica|language=en|access-date=2019-04-13}}</ref> The [[Intergovernmental Oceanographic Commission]] reports that 1.7% of the total national research expenditure of its members is focused on ocean science.<ref>Isensee, Kirsten. editor. Intergovernmental Oceanographic Commission. (2020). ''Global ocean science report 2020: charting capacity for ocean sustainability.'' Executive summary. {{ISBN|978-92-3-100424-7}}. [https://unesdoc.unesco.org/ark:/48223/pf0000375147.locale=en UNESCO Digital Library website] p. 16. Retrieved 21 September 2022.</ref>

==Branches==
[[File:Antarctic frontal-system hg.png|thumb|Oceanographic frontal systems on the [[Southern Hemisphere]]]]
[[File:Rosenstiel Applied Marine Physics Building.jpg|thumb|The Applied Marine Physics Building at the [[University of Miami]]'s [[Rosenstiel School of Marine, Atmospheric, and Earth Science]] on [[Virginia Key]], in September 2007]]
The study of oceanography is divided into these five branches:

===Biological oceanography===
{{Main|Biological oceanography}}

{{see also|Marine biology}}

Biological oceanography investigates the ecology and biology of marine organisms in the context of the physical, chemical and geological characteristics of their ocean environment.

===Chemical oceanography===
{{Main|Chemical oceanography}}

Chemical oceanography is the study of the [[chemistry]] of the ocean. Whereas chemical oceanography is primarily occupied with the study and understanding of seawater properties and its changes, [[ocean chemistry]] focuses primarily on the [[geochemical cycle]]s. The following is a central topic investigated by chemical oceanography.

====Ocean acidification====
{{Main|Ocean acidification}}

Ocean acidification describes the decrease in ocean [[PH#Seawater|pH]] that is caused by [[human impact on the environment|anthropogenic]] [[carbon dioxide]] ({{CO2}}) emissions into the [[Earth's atmosphere|atmosphere]].<ref name="cald03">{{Cite journal|last=Caldeira|first=K.|author2=Wickett, M. E.|date=2003|title=Anthropogenic carbon and ocean pH|url=http://pangea.stanford.edu/research/Oceans/GES205/Caldeira_Science_Anthropogenic%20Carbon%20and%20ocean%20pH.pdf |archive-url=https://web.archive.org/web/20070604185633/http://pangea.stanford.edu/research/Oceans/GES205/Caldeira_Science_Anthropogenic%20Carbon%20and%20ocean%20pH.pdf |archive-date=2007-06-04 |url-status=live|journal=[[Nature (journal)|Nature]]|volume=425|issue=6956|pages=OS11C–0385|doi=10.1038/425365a|pmid=14508477|bibcode=2001AGUFMOS11C0385C|s2cid=4417880}}</ref> Seawater is slightly [[alkalinity|alkaline]] and had a preindustrial [[pH]] of about 8.2. More recently, anthropogenic activities have steadily increased the [[carbon dioxide]] content of the atmosphere; about 30–40% of the added CO<sub>2</sub> is absorbed by the oceans, forming [[carbonic acid]] and lowering the pH (now below 8.1<ref name="EPA_Ocean_Acidity">{{cite web|title=Ocean Acidity|publisher=[[EPA]]|date=13 September 2013|url=https://www.epa.gov/climate-indicators/climate-change-indicators-ocean-acidity|access-date=1 November 2013}}</ref>) through ocean acidification.<ref name="Feely04">{{cite journal|last=Feely|first=R. A.|display-authors=etal|title=Impact of Anthropogenic CO<sub>2</sub> on the CaCO<sub>3</sub> System in the Oceans|journal=Science|volume=305|date=July 2004|pages=362–366|bibcode=2004Sci...305..362F|doi=10.1126/science.1097329 |pmid=15256664|issue=5682|s2cid=31054160}}</ref><ref name="Zeebe2008">{{cite journal|last1=Zeebe|first1=R. E.|last2=Zachos|first2=J. C.|last3=Caldeira|first3=K.|last4=Tyrrell|first4=T.|title=OCEANS: Carbon Emissions and Acidification|journal=Science|volume=321|issue=5885|date=4 July 2008|pages=51–52|doi=10.1126/science.1159124|pmid=18599765|s2cid=206513402}}</ref><ref name="GattusoHansson2011">{{cite book|author1=Gattuso, J.-P.|author2=Hansson, L.|title=Ocean Acidification|url=https://books.google.com/books?id=8yjNFxkALjIC|date=15 September 2011|publisher=[[Oxford University Press]]|isbn=978-0-19-959109-1|oclc=730413873}}</ref> The pH is expected to reach 7.7 by the year 2100.<ref name="AboutAntarctica"/>

An important element for the [[skeleton]]s of marine animals is [[calcium]], but [[calcium carbonate]] becomes more soluble with pressure, so carbonate shells and skeletons dissolve below the [[carbonate compensation depth]].<ref name="Pinet">{{cite book|last=Pinet|first=Paul R.|date=1996|title=Invitation to Oceanography|pages=126, 134–135|publisher=[[West Publishing Company]]|url=https://books.google.com/books?id=eAqQvGYap24C|isbn=978-0-314-06339-7}}</ref> Calcium carbonate becomes more soluble at lower pH, so ocean acidification is likely to affect marine organisms with calcareous shells, such as oysters, clams, sea urchins and corals,<ref name="PMEL">{{cite web|url=http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F|title=What is Ocean Acidification?|publisher=NOAA PMEL Carbon Program|access-date=15 September 2013|archive-date=2 September 2013|archive-url=https://web.archive.org/web/20130902071022/http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F|url-status=dead}}</ref><ref name="orr05">{{Cite journal|last=Orr|first=James C.|display-authors=etal|date=2005|title=Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms|url=http://www.ipsl.jussieu.fr/~jomce/acidification/paper/Orr_OnlineNature04095.pdf|archive-url=https://web.archive.org/web/20080625100559/http://www.ipsl.jussieu.fr/~jomce/acidification/paper/Orr_OnlineNature04095.pdf|archive-date=25 June 2008|journal=Nature|volume=437|issue=7059|pages=681–686|doi=10.1038/nature04095|pmid=16193043|bibcode=2005Natur.437..681O|s2cid=4306199}}</ref> and the carbonate compensation depth will rise closer to the sea surface. Affected [[plankton]]ic organisms will include [[pteropod]]s, [[coccolithophorid]]s and [[foraminifera]], all important in the [[food chain]]. In tropical regions, [[coral]]s are likely to be severely affected as they become less able to build their calcium carbonate skeletons,<ref name="Cohen2009">{{cite journal|last1=Cohen|first1=A.|last2=Holcomb|first2=M.|date=2009|title=Why Corals Care About Ocean Acidification: Uncovering the Mechanism|journal=Oceanography|volume=24|pages=118–127|doi=10.5670/oceanog.2009.102|issue=4|hdl=1912/3179|doi-access=free|bibcode=2009Ocgpy..22d.118C |hdl-access=free}}</ref> in turn adversely impacting other [[Coral reef|reef]] dwellers.<ref name="AboutAntarctica">{{cite web|url=http://www.antarctica.gov.au/about-antarctica/environment/climate-change/ocean-acidification-and-the-southern-ocean|title=Ocean acidification|date=28 September 2007|publisher=Department of Sustainability, Environment, Water, Population & Communities: Australian Antarctic Division |access-date=17 April 2013}}</ref>

The current rate of ocean chemistry change seems to be unprecedented in Earth's geological history, making it unclear how well marine ecosystems will adapt to the shifting conditions of the near future.<ref name="Hönisch2012">{{cite journal |last1=Hönisch |first1=Bärbel |author-link=Bärbel Hönisch |last2=Ridgwell |first2=Andy |last3=Schmidt |first3=Daniela N. |last4=Thomas |first4=E. |last5=Gibbs |first5=S. J. |last6=Sluijs |first6=A. |last7=Zeebe |first7=R. |last8=Kump |first8=L. |last9=Martindale |first9=R. C. |last10=Greene |first10=S. E. |last11=Kiessling |first11=W. |display-authors=4 |date=2012 |title=The Geological Record of Ocean Acidification |journal=[[Science (journal)|Science]] |volume=335 |issue=6072 |pages=1058–1063 |bibcode=2012Sci...335.1058H |doi=10.1126/science.1208277 |pmid=22383840 |last12=Ries |first12=J. |last13=Zachos |first13=J. C. |last14=Royer |first14=D. L. |last15=Barker |first15=S. |last16=Marchitto |first16=T. M. |last17=Moyer |first17=R. |last18=Pelejero |first18=C. |last19=Ziveri |first19=P. |last20=Foster |first20=G. L. |last21=Williams |first21=B. |hdl=1983/24fe327a-c509-4b6a-aa9a-a22616c42d49 |s2cid=6361097|url=https://dspace.library.uu.nl/bitstream/1874/385704/1/Geological_Record.pdf }}</ref> Of particular concern is the manner in which the combination of acidification with the expected additional stressors of higher [[ocean temperature]]s and [[hypoxia (environmental)|lower oxygen levels]] will impact the seas.<ref name="Gruber2011">{{cite journal|last=Gruber|first=N.|title=Warming up, turning sour, losing breath: ocean biogeochemistry under global change|journal=Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences|volume=369|issue=1943|date=18 April 2011|pages=1980–96|doi=10.1098/rsta.2011.0003|pmid=21502171|bibcode = 2011RSPTA.369.1980G |doi-access=free}}</ref>

===Geological oceanography===
{{Main|Marine geology}}

Geological oceanography is the study of the [[geology]] of the ocean floor including [[plate tectonics]] and [[paleoceanography]].

===Physical oceanography===
{{Main|Physical oceanography}}

Physical oceanography studies the ocean's physical attributes including temperature-salinity structure, mixing, [[ocean surface wave|surface waves]], internal waves, surface [[tide]]s, [[internal tides]], and [[ocean current|currents]]. The following are central topics investigated by physical oceanography.

====Seismic Oceanography====
{{Main|Seismic Oceanography}}

====Ocean currents====
{{Further|Ocean current}}
Since the early ocean expeditions in oceanography, a major interest was the study of ocean currents and temperature measurements. The [[tides]], the [[Coriolis effect]], changes in direction and strength of [[wind]], salinity, and temperature are the main factors determining ocean currents. The [[thermohaline circulation]] (THC) (''thermo-'' referring to [[temperature]] and ''-haline'' referring to [[salinity|salt content]]) connects the ocean basins and is primarily dependent on the [[Water (molecule)#Density of saltwater and ice|density of sea water]]. It is becoming more common to refer to this system as the 'meridional overturning circulation' because it more accurately accounts for other driving factors beyond temperature and salinity. 
*Examples of sustained currents are the [[Gulf Stream]] and the [[Kuroshio Current]] which are [[wind]]-driven [[western boundary currents]].

====Ocean heat content====
[[File:Oceans of Climate Change.ogv|thumbnail|right|[https://climate.nasa.gov/climate_reel/OceansClimateChange640360 Oceans of Climate Change] NASA]]
{{Further|Oceanic heat content}}
[[Oceanic heat content]] (OHC) refers to the extra heat stored in the ocean from changes in [[Earth's energy balance]]. The increase in the ocean heat play an important role in [[sea level rise]], because of [[thermal expansion]]. [[Ocean warming]] accounts for 90% of the energy accumulation associated with [[global warming]] since 1971.<ref>{{cite report |author= IPCC|author-link= Intergovernmental Panel on Climate Change|date= 2013|title= Climate Change 2013: The Physical Science Basis|url= http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SPM_FINAL.pdf |archive-url=https://web.archive.org/web/20141029034929/https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SPM_FINAL.pdf |archive-date=2014-10-29 |url-status=live|publisher= [[Cambridge University Press]]|page= 8}}</ref><ref>{{cite web |url=https://news.ucar.edu/132773/2020-was-record-breaking-year-ocean-heat |title=2020 was a record-breaking year for ocean heat - Warmer ocean waters contribute to sea level rise and strengthen storms |date=2021-01-13 |author=Laura Snider |publisher=[[National Center for Atmospheric Research]]}}</ref>

===Paleoceanography===
{{Main|Paleoceanography}}

Paleoceanography is the study of the history of the oceans in the geologic past with regard to circulation, chemistry, biology, geology and patterns of sedimentation and biological productivity. Paleoceanographic studies using environment models and different proxies enable the scientific community to assess the role of the oceanic processes in the global climate by the reconstruction of past climate at various intervals. Paleoceanographic research is also intimately tied to palaeoclimatology.

==Oceanographic institutions==
[[Image:Stazione zoologica Dohrn.jpg|thumbnail|Stazione Zoologica of Naples in the 1890s]]
{{see also|List of oceanographic institutions and programs}}
The earliest international organizations of oceanography were founded at the turn of the 20th century, starting with the [[International Council for the Exploration of the Sea]] created in 1902, followed in 1919 by the [[Mediterranean Science Commission]]. Marine research institutes were already in existence, starting with the [[Stazione Zoologica Anton Dohrn]] in Naples, Italy (1872), the Biological Station of Roscoff, France (1876), the Arago Laboratory in Banyuls-sur-mer, France (1882), the Laboratory of the Marine Biological Association in Plymouth, UK (1884), the Norwegian Institute for Marine Research in Bergen, Norway (1900), the Laboratory für internationale Meeresforschung, Kiel, Germany (1902). On the other side of the Atlantic, the [[Scripps Institution of Oceanography]] was founded in 1903, followed by the [[Woods Hole Oceanographic Institution]] in 1930, the [[Virginia Institute of Marine Science]] in 1938, the [[Lamont–Doherty Earth Observatory]] at [[Columbia University]] in 1949, and later the [[University of Washington#Organization|School of Oceanography]] at [[University of Washington]]. In [[Australia]], the [[Australian Institute of Marine Science]] (AIMS), established in 1972 soon became a key player in marine tropical research.

In 1921 the [[International Hydrographic Bureau]], called since 1970 the [[International Hydrographic Organization]], was established to develop hydrographic and nautical charting standards.

==Related disciplines==
{{div col}}
* {{annotated link|Biogeochemistry}}
* {{annotated link|Biogeography}}
* {{annotated link|Climatology}}
* {{annotated link|Coastal geography}}
* {{annotated link|Environmental science}}
* {{annotated link|Geophysics}}
* {{annotated link|Glaciology}}
* {{annotated link|Hydrography}}
* {{annotated link|Hydrology}}
* {{annotated link|Limnology}}
* {{annotated link|Meteorology}}
* {{annotated link|MetOcean}}
{{div col end}}

==See also==
{{portal|Oceans|Underwater diving}}
{{div col}}
* {{annotated link|Anoxic event}}
* {{annotated link|Anoxic waters}}
* {{annotated link|Argo (oceanography)}}
* {{annotated link|Astrooceanography}}
* {{annotated link|Bathymetric chart}}
* {{Annotated link|Cabled observatory}}
*{{annotated link|Ecological forecasting}}
* {{annotated link|List of ocean circulation models}}
* [[List of seas]]
* {{annotated link|List of submarine topographical features}}
* {{annotated link|Maritime archaeology}}
* {{annotated link|Marine current power}}
* {{annotated link|Marine engineering}}
* {{annotated link|Naval architecture}}
* {{annotated link|Ocean colonization}}
* {{annotated link|Oceans Act of 2000}}
* [[Ocean optics]]
* [[Ocean color]]
* {{annotated link|Offshore construction}}
* {{annotated link|Outline of oceanography}}
* {{annotated link|Planetary oceanography}}
* {{annotated link|Sea level}}
*[[Ocean chemistry]]
{{div col end}}

==References==
{{Reflist}}

===Sources and further reading===
* Boling Guo, Daiwen Huang. [http://www.worldscientific.com/worldscibooks/10.1142/9106 ''Infinite-Dimensional Dynamical Systems in Atmospheric and Oceanic Science''], 2014, World Scientific Publishing, {{ISBN|978-981-4590-37-2}}. [http://www.worldscientific.com/doi/suppl/10.1142/9106/suppl_file/9106_chap01.pdf Sample Chapter]
* Hamblin, Jacob Darwin (2005) [https://books.google.com/books?id=6jrUK226eRgC&dq=Hamblin+%22Oceanographers+and+the+Cold+War%22&pg=PP1 ''Oceanographers and the Cold War: Disciples of Marine Science'']. University of Washington Press. {{ISBN|978-0-295-98482-7}}
* Lang, Michael A., Ian G. Macintyre, and Klaus Rützler, eds. [http://www.sil.si.edu/smithsoniancontributions/MarineSciences/sc_RecordSingle.cfm?filename=SCMS-0038 ''Proceedings of the Smithsonian Marine Science Symposium.''] Smithsonian Contributions to the Marine Sciences, no. 38. Washington, D.C.: Smithsonian Institution Scholarly Press (2009)
* Roorda, Eric Paul, ed. ''The Ocean Reader: History, Culture, Politics'' (Duke University Press, 2020) 523 pp. [http://www.h-net.org/reviews/showrev.php?id=58118 online review]
* Steele, J., K. Turekian and S. Thorpe. (2001). ''Encyclopedia of Ocean Sciences.'' San Diego: Academic Press. (6 vols.) {{ISBN|0-12-227430-X}}
* Sverdrup, Keith A., Duxbury, Alyn C., Duxbury, Alison B. (2006). ''Fundamentals of Oceanography'', McGraw-Hill, {{ISBN|0-07-282678-9}}
* Russell, Joellen Louise. [https://library.ucsd.edu/dc/object/bb3962043d/_3_1.pdf Easter Ellen Cupp], 2000, Regents of the University of California.

==External links==
{{EB1922 Poster}}
{{Commons category|Oceanography}}
* [http://podaac.jpl.nasa.gov/ NASA Jet Propulsion Laboratory – Physical Oceanography Distributed Active Archive Center (PO.DAAC)]. A data centre responsible for archiving and distributing data about the physical state of the ocean.
* [http://www.scripps.ucsd.edu Scripps Institution of Oceanography]. One of the world's oldest, largest, and most important centres for ocean and Earth science research, education, and public service.
* [http://www.whoi.edu Woods Hole Oceanographic Institution (WHOI)]. One of the world's largest private, non-profit ocean research, engineering and education organizations.
* [http://www.bodc.ac.uk/ British Oceanographic Data Centre]. A source of oceanographic data and information.
* [https://web.archive.org/web/20060211015453/http://dapper.pmel.noaa.gov/dchart/ NOAA Ocean and Weather Data Navigator]. Plot and download ocean data.
* [http://www.vega.org.uk/video/programme/10 Freeview Video 'Voyage to the Bottom of the Deep Deep Sea' Oceanography Programme] by the [[Vega Science Trust]] and the [[BBC]]/[[Open University]].
* [http://atlas.investigadhoc.com/ Atlas of Spanish Oceanography] by [https://web.archive.org/web/20130602181200/http://investigadhoc.com/ InvestigAdHoc].
* [https://web.archive.org/web/20110927020036/http://stommel.tamu.edu/~baum/paleo/ocean/ Glossary of Physical Oceanography and Related Disciplines ] by Steven K. Baum, Department of Oceanography, Texas A&M University
* [http://barcelona-ocean.com/ Barcelona-Ocean.com ] {{Webarchive|url=https://web.archive.org/web/20141109094549/http://barcelona-ocean.com/ |date=9 November 2014 }}. Inspiring Education in Marine Sciences
* [https://web.archive.org/web/20180905125513/http://cfoo.co.za/seaatlas/index.php CFOO: Sea Atlas]. A source of oceanographic live data (buoy monitoring) and education for South African coasts.
* {{In Our Time|Oceanography|p00547lb}}
* [https://www.tags-ship.com/ Memorial website for USNS Bowditch, USNS Dutton, USNS Michelson and USNS H. H. Hess]

{{Earth science}}
{{Environmental science}}
{{physical oceanography|expanded=other}}
{{Physical geography topics}}
{{Underwater diving}}

{{Authority control}}

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