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Oceanography (), also known as oceanology and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...
dynamics;
ocean current An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth conto ...
s,
waves Waves most often refers to: * Waves, oscillations accompanied by a transfer of energy that travel through space or mass. * Wind waves, surface waves that occur on the free surface of bodies of water. Waves may also refer to: Music *Waves (ban ...
, and geophysical fluid dynamics;
plate tectonics Plate tectonics (from the la, label= Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of larg ...
and the geology of the sea floor; and fluxes of various chemical substances and physical properties within the ocean and across its boundaries. These diverse topics reflect multiple disciplines that oceanographers utilize to glean further knowledge of the world ocean, including
astronomy Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...
,
biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary ...
,
chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...
,
climatology Climatology (from Greek , ''klima'', "place, zone"; and , '' -logia'') or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. This modern field of stu ...
,
geography Geography (from Greek: , ''geographia''. Combination of Greek words ‘Geo’ (The Earth) and ‘Graphien’ (to describe), literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, an ...
,
geology Geology () is a branch of natural science concerned with Earth and other Astronomical object, astronomical objects, the features or rock (geology), rocks of which it is composed, and the processes by which they change over time. Modern geology ...
,
hydrology Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability. A practitioner of hydrology is call ...
,
meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...
and
physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which ...
. Paleoceanography studies the history of the oceans in the geologic past. An oceanographer is a person who studies many matters concerned with oceans, including marine
geology Geology () is a branch of natural science concerned with Earth and other Astronomical object, astronomical objects, the features or rock (geology), rocks of which it is composed, and the processes by which they change over time. Modern geology ...
,
physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which ...
,
chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...
and
biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary ...
.


History


Early history

Humans first acquired knowledge of the waves and currents of the
sea The sea, connected as the world ocean or simply the ocean, is the body of salty water that covers approximately 71% of the Earth's surface. The word sea is also used to denote second-order sections of the sea, such as the Mediterranean Sea, ...
s and
ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wor ...
s in pre-historic times. Observations on
tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...
s were recorded by
Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ...
and
Strabo Strabo''Strabo'' (meaning "squinty", as in strabismus) was a term employed by the Romans for anyone whose eyes were distorted or deformed. The father of Pompey was called " Pompeius Strabo". A native of Sicily so clear-sighted that he could s ...
in 384-322 BC. Early exploration of the oceans was primarily for
cartography Cartography (; from grc, χάρτης , "papyrus, sheet of paper, map"; and , "write") is the study and practice of making and using maps. Combining science, aesthetics and technique, cartography builds on the premise that reality (or an i ...
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.Pedro Nunes Salaciense
at the MacTutor History of Mathematics archive (retrieved 13/06/2020)
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). 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. The main problem in navigating back from the south of the
Canary Islands The Canary Islands (; es, :es:Canarias, Canarias, ), also known informally as the Canaries, are a Spanish Autonomous communities of Spain, autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to ...
(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 will push south along the northwest bulge of Africa, while the uncertain winds where the Northeast trades meet the Southeast trades (the doldrums) 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 largo' or 'volta do mar'. The 'rediscovery' of the 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 ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...
, in 1436, reveals the western extent of the return route.Carlos Calinas Correia, A Arte de Navegar na Época dos Descobrimentos, Colibri, Lisboa 2017; 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. 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 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 Sierra Leone,)]. officially the Republic of Sierra Leone, is a country on the southwest coast of West Africa. It is bordered by Liberia to the southeast and Guinea surrounds the northern half of the nation. Covering a total area of , Sierr ...
, spending 3 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 Alvares 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). Furthermore, there were systematic expeditions pushing into the western Northern Atlantic (Teive, 1454; Vogado, 1462; Teles, 1474; Ulmo, 1486). 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, 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. 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 3 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 Monte Pascoal is a mountain to the south of the city of Porto Seguro, in the state of Bahia, Brazil. According to history, it was the first part of land viewed by Portuguese explorer Pedro Álvares Cabral, allegedly the first European to arriv ...
, Brazil. The Danish expedition to Arabia 1761-67 can be said to be the world's first oceanographic expedition, as the ship Grønland had on board a group of scientists, including naturalist Peter Forsskål, who was assigned an explicit task by the king, Frederik V, to study and describe the marine life in the open sea, including finding the cause of
mareel Mareel is a multi-purpose entertainment venue located on the waterfront of Lerwick, the capital of Shetland. Opening in 2012, the facility includes a music venue, cinema, conference rooms and educational facilities. Facilities Mareel is desi ...
, 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. Although Juan Ponce de León in 1513 first identified the Gulf Stream, and the current was well known to mariners,
Benjamin Franklin Benjamin Franklin ( April 17, 1790) was an American polymath who was active as a writer, scientist, inventor, statesman, diplomat, printer, publisher, and political philosopher. Encyclopædia Britannica, Wood, 2021 Among the leading int ...
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. Information on the currents of the
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the conti ...
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 The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
and
Indian Indian or Indians may refer to: Peoples South Asia * Indian people, people of Indian nationality, or people who have an Indian ancestor ** Non-resident Indian, a citizen of India who has temporarily emigrated to another country * South Asia ...
oceans. During a voyage around the Cape of Good Hope in 1777, he mapped ''"the 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). Sir James Clark Ross took the first modern sounding in deep sea in 1840, and
Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended ...
published a paper on
reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes—deposition of sand, wave erosion planing down rock ...
s and the formation of
atoll An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can gro ...
s as a result of the 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 Edward Forbes FRS, FGS (12 February 1815 – 18 November 1854) was a Manx naturalist. In 1846, he proposed that the distributions of montane plants and animals had been compressed downslope, and some oceanic islands connected to the mainlan ...
undertook dredging in the
Aegean Sea The Aegean Sea ; tr, Ege Denizi ( Greek: Αιγαίο Πέλαγος: "Egéo Pélagos", Turkish: "Ege Denizi" or "Adalar Denizi") is an elongated embayment of the Mediterranean Sea between Europe and Asia. It is located between the Balkans ...
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 Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land 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.


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 The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against Fr ...
's efforts to chart all of the world's
coast The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. The Earth has around of coastline. Coasts are important zones in n ...
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 Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
, so too did the mysteries of the unexplored oceans. The seminal event in the founding of the modern science of oceanography was the 1872–1876 '' Challenger'' expedition. As the first true oceanographic cruise, this expedition laid the groundwork for an entire academic and research discipline.Then and Now: The HMS Challenger Expedition and the 'Mountains in the Sea' Expedition
Ocean Explorer website (NOAA), accessed 2 January 2012
In response to a recommendation from the
Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...
, the British Government announced in 1871 an expedition to explore world's oceans and conduct appropriate scientific investigation.
Charles Wyville Thomson Sir Charles Wyville Thomson (5 March 1830 – 10 March 1882) was a Scottish natural historian and marine zoologist. He served as the chief scientist on the Challenger expedition; his work there revolutionized oceanography and led to his knigh ...
and Sir John Murray launched the ''Challenger'' expedition. , leased from the Royal Navy, was modified for scientific work and equipped with separate laboratories for natural history and
chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...
. Under the scientific supervision of Thomson, ''Challenger'' travelled nearly surveying and exploring. On her journey circumnavigating the globe, 492 deep sea soundings, 133 bottom dredges, 151 open water trawls and 263 serial water temperature observations were taken. Around 4,700 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 The University of Edinburgh ( sco, University o Edinburgh, gd, Oilthigh Dhùn Èideann; abbreviated as ''Edin.'' in post-nominals) is a public research university based in Edinburgh, Scotland. Granted a royal charter by King James VI in 1 ...
, which remained the centre for oceanographic research well into the 20th century. Murray was the first to study marine trenches and in particular the
Mid-Atlantic Ridge The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North A ...
, 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 A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of Colony (biology), colonies of coral polyp (zoology), polyps held together by calcium carbonate. Most coral reefs are built from stony corals, wh ...
development. In the late 19th century, other 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. In 1881 the geographer
John Francon Williams John Francon Williams (1854 – 4 September 1911) was a Welsh writer, geographer, historian, journalist, cartographer, and inventor, born in Llanllechid, Caernarvonshire. His seminal work was ''The Geography of the Oceans''. Family John Fran ...
published a seminal book, ''Geography of the Oceans''. Between 1907 and 1911 Otto Krümmel published the ''Handbuch der Ozeanographie'', which became influential in awakening public interest in oceanography. The four-month 1910
North Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe a ...
expedition headed by 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 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 Roger Randall Dougan Revelle (March 7, 1909 – July 15, 1991) was a scientist and scholar who was instrumental in the formative years of the University of California, San Diego and was among the early scientists to study anthropogenic global ...
. 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'' in 1942, 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 Robert Duane Ballard (born June 30, 1942) is an American retired Navy officer and a professor of oceanography at the University of Rhode Island who is most noted for his work in underwater archaeology: maritime archaeology and archaeolo ...
in the submersible . In the 1950s,
Auguste Piccard Auguste Antoine Piccard (28 January 1884 – 24 March 1962) was a Swiss physicist, inventor and explorer known for his record-breaking hydrogen balloon flights, with which he studied the Earth's upper atmosphere. Piccard was also known for h ...
invented the bathyscaphe and used the bathyscaphe to investigate the ocean's depths. The United States nuclear submarine made the first journey under the ice to the North Pole in 1958. In 1962 the FLIP (Floating Instrument Platform), a 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 The Ishiguro Storm Surge Machine is an analogue computer built by Japanese oceanographer Shizuo Ishiguro. Between 1960 and 1983, it was used to model storm surges in the North Sea by the UK National Institute of Oceanography. It is now on display i ...
) generally now replaced by numerical methods (e.g. 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 The World Ocean Circulation Experiment (WOCE) was a component of the international World Climate Research Program, and aimed to establish the role of the World Ocean in the Earth's climate system. WOCE's field phase ran between 1990 and 1998, and ...
(WOCE) which continued until 2002.
Geosat The GEOSAT (GEOdetic SATellite) was a U.S. Navy Earth observation satellite, launched on March 12, 1985 into an 800 km, 108° inclination orbit, with a nodal period of about 6040 seconds. The satellite carried a radar altimeter capable of m ...
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 Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...
, the biosphere and
biogeochemistry Biogeochemistry is the scientific discipline that involves the study of the chemical, physical, geological, and biological processes and reactions that govern the composition of the natural environment (including the biosphere, the cryosphere ...
. The atmosphere and ocean are linked because of
evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when h ...
and
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
as well as
thermal flux Heat flux or thermal flux, sometimes also referred to as ''heat flux density'', heat-flow density or ''heat flow rate intensity'' is a flow of energy per unit area per unit time. In SI its units are watts per square metre (W/m2). It has both a ...
(and solar insolation). Recent studies have advanced knowledge on
ocean acidification Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...
, ocean heat content,
ocean currents An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contou ...
,
sea level rise Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cr ...
, the oceanic carbon cycle, the
water cycle The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle that describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly co ...
, Arctic sea ice decline,
coral bleaching Coral bleaching is the process when corals become white due to various stressors, such as changes in temperature, light, or nutrients. Bleaching occurs when coral polyps expel the zooxanthellae ( dinoflagellates that are commonly referred to as ...
, marine heatwaves,
extreme weather Extreme weather or extreme climate events includes unexpected, unusual, severe, or unseasonal weather; weather at the extremes of the historical distribution—the range that has been seen in the past. Often, extreme events are based on a locat ...
,
coastal erosion Coastal erosion is the loss or displacement of land, or the long-term removal of sediment and rocks along the coastline due to the action of waves, currents, tides, wind-driven water, waterborne ice, or other impacts of storms. The landwar ...
and many other phenomena in regards to ongoing
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
and
climate feedback Climate Feedback (CF) is a web-based content annotation tool that allows qualified scientists to comment on stories online, adding context and noting inaccuracies. It is one of three websites under the Science Feedback parent organization that ...
s. In general, understanding the world ocean through further scientific study enables better
stewardship Stewardship is an ethical value that embodies the responsible planning and management of resources. The concepts of stewardship can be applied to the environment and nature, economics, health, property, information, theology, cultural resources e ...
and sustainable utilization of Earth's resources. The Intergovernmental Oceanographic Commission reports that 1.7% of the total national research expenditure of its members is focused on ocean science.


Branches

The study of oceanography is divided into these five branches:


Biological oceanography

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

Chemical oceanography is the study of the
chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...
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 In Earth science, a geochemical cycle is the pathway that chemical elements take in the surface and crust of the Earth. The term "geochemical" tells us that geological and chemical factors are all included. The migration of heated and compressed ch ...
s. The following is a central topic investigated by chemical oceanography.


Ocean acidification

Ocean acidification describes the decrease in ocean pH that is caused by anthropogenic
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...
() emissions into the atmosphere. Seawater is slightly alkaline and had a preindustrial pH of about 8.2. More recently, anthropogenic activities have steadily increased the
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...
content of the atmosphere; about 30–40% of the added CO2 is absorbed by the oceans, forming carbonic acid and lowering the pH (now below 8.1) through ocean acidification. The pH is expected to reach 7.7 by the year 2100. An important element for the skeletons of marine animals is
calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...
, but calcium carbonate becomes more soluble with pressure, so carbonate shells and skeletons dissolve below the
carbonate compensation depth Carbonate compensation depth (CCD) is the depth in the oceans below which the rate of supply of calcite ( calcium carbonate) lags behind the rate of solvation, such that no calcite is preserved. Shells of animals therefore dissolve and carbonate ...
. 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, and the carbonate compensation depth will rise closer to the sea surface. Affected
plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...
ic organisms will include pteropods,
coccolithophorid Coccolithophores, or coccolithophorids, are single celled organisms which are part of the phytoplankton, the autotrophic (self-feeding) component of the plankton community. They form a group of about 200 species, and belong either to the kingd ...
s and
foraminifera Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly ...
, all important in the food chain. In tropical regions,
coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and se ...
s are likely to be severely affected as they become less able to build their calcium carbonate skeletons, in turn adversely impacting other
reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes—deposition of sand, wave erosion planing down rock ...
dwellers. 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. Of particular concern is the manner in which the combination of acidification with the expected additional stressors of higher ocean temperatures and lower oxygen levels will impact the seas.


Geological oceanography

Geological oceanography is the study of the
geology Geology () is a branch of natural science concerned with Earth and other Astronomical object, astronomical objects, the features or rock (geology), rocks of which it is composed, and the processes by which they change over time. Modern geology ...
of the ocean floor including
plate tectonics Plate tectonics (from the la, label= Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of larg ...
and paleoceanography.


Physical oceanography

Physical oceanography studies the ocean's physical attributes including temperature-salinity structure, mixing, surface waves, internal waves, surface
tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...
s,
internal tides Internal tides are generated as the surface tides move stratified water up and down sloping topography, which produces a wave in the ocean interior. So internal tides are internal waves at a tidal frequency. The other major source of internal wa ...
, and currents. The following are central topics investigated by physical oceanography.


Seismic Oceanography


Ocean currents

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 Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ...
, salinity, and temperature are the main factors determining ocean currents. The thermohaline circulation (THC) (''thermo-'' referring to
temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...
and ''-haline'' referring to salt content) connects the ocean basins and is primarily dependent on the 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 Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ...
-driven western boundary currents.


Ocean heat content

Oceanic heat content In oceanography and climatology, ocean heat content (OHC) is a term for the energy absorbed by the ocean, where it is stored for indefinite time periods as internal energy or enthalpy. The rise in OHC accounts for over 90% of Earth’s excess ...
(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 Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cr ...
, because of
thermal expansion Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions. Temperature is a monotonic function of the average molecular kin ...
.
Ocean warming In oceanography and climatology, ocean heat content (OHC) is a term for the energy absorbed by the ocean, where it is stored for indefinite time periods as internal energy or enthalpy. The rise in OHC accounts for over 90% of Earth’s excess the ...
accounts for 90% of the energy accumulation associated with
global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
since 1971.


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

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 The International Council for the Exploration of the Sea (ICES; french: Conseil International de l'Exploration de la Mer, ''CIEM'') is a regional fishery advisory body and the world's oldest intergovernmental science organization. ICES is headqua ...
created in 1902, followed in 1919 by the
Mediterranean Science Commission The Mediterranean Science Commission, or CIESM, ( French: ''Commission Internationale pour l'Exploration Scientifique de la Méditerranée'') unites 24 Member States, hundreds of marine Institutes, and thousands of marine researchers from all sh ...
. 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 The Woods Hole Oceanographic Institution (WHOI, acronym pronounced ) is a private, nonprofit research and higher education facility dedicated to the study of marine science and engineering. Established in 1930 in Woods Hole, Massachusetts, i ...
in 1930, the Virginia Institute of Marine Science in 1938, the
Lamont–Doherty Earth Observatory The Lamont–Doherty Earth Observatory (LDEO) is the scientific research center of the Columbia Climate School, and a unit of The Earth Institute at Columbia University. It focuses on climate and earth sciences and is located on a 189-acre ( ...
at
Columbia University Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhatt ...
in 1949, and later the School of Oceanography at
University of Washington The University of Washington (UW, simply Washington, or informally U-Dub) is a public research university in Seattle, Washington. Founded in 1861, Washington is one of the oldest universities on the West Coast; it was established in Seatt ...
. In
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
, 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 The International Hydrographic Organization (IHO) is an intergovernmental organisation representing hydrography. , the IHO comprised 98 Member States. A principal aim of the IHO is to ensure that the world's seas, oceans and navigable waters ...
, was established to develop hydrographic and nautical charting standards


Related disciplines

* * * * * * * * * * * *


See also

* * * * * * * * List of seas * * * * * * * * Ocean optics * Ocean color * * * * Ocean chemistry


References


Sources and further reading

* Boling Guo, Daiwen Huang
''Infinite-Dimensional Dynamical Systems in Atmospheric and Oceanic Science''
2014, World Scientific Publishing,
Sample Chapter
* Hamblin, Jacob Darwin (2005
''Oceanographers and the Cold War: Disciples of Marine Science''
University of Washington Press. * Lang, Michael A., Ian G. Macintyre, and Klaus Rützler, eds
''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
online review[ * Steele, J., K. Turekian and S. Thorpe. (2001). ''Encyclopedia of Ocean Sciences.'' San Diego: Academic Press. (6 vols.) * Sverdrup, Keith A., Duxbury, Alyn C., Duxbury, Alison B. (2006). ''Fundamentals of Oceanography'', McGraw-Hill, * Russell, Joellen Louise
2000, Regents of the University of California.


External links


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.
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.
Woods Hole Oceanographic Institution (WHOI)
One of the world's largest private, non-profit ocean research, engineering and education organizations.
British Oceanographic Data Centre
A source of oceanographic data and information.
NOAA Ocean and Weather Data Navigator
Plot and download ocean data.
Freeview Video 'Voyage to the Bottom of the Deep Deep Sea' Oceanography Programme
by the Vega Science Trust
and the BBC/Open University.
Atlas of Spanish Oceanography
b
InvestigAdHoc

Glossary of Physical Oceanography and Related Disciplines
by Steven K. Baum, Department of Oceanography, Texas A&M University
Barcelona-Ocean.com
Inspiring Education in Marine Sciences
CFOO: Sea Atlas
A source of oceanographic live data (buoy monitoring) and education for South African coasts. *
Memorial website for USNS Bowditch, USNS Dutton, USNS Michelson and USNS H. H. Hess
{{Authority control Applied and interdisciplinary physics Earth sciences Hydrology Physical geography Articles containing video clips