Ocean current

An ocean current is a continuous, directed movement of seawater generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences.{{cite web |date=2009-03-01 |title=What is a current? |url=https://oceanservice.noaa.gov/facts/current.html |access-date=2023-03-14 |website=National Ocean Service |publisher=National Oceanic and Atmospheric Administration }} Depth contours, shoreline configurations, and interactions with other currents influence a current's direction and strength. Ocean currents move both horizontally, on scales that can span entire oceans, as well as vertically, with vertical currents (upwelling and downwelling) playing an important role in the movement of nutrients and gases, such as carbon dioxide, between the surface and the deep ocean.

Ocean currents flow for great distances and together they create the global conveyor belt, which plays a dominant role in determining the climate of many of Earth's regions. More specifically, ocean currents influence the temperature of the regions through which they travel. For example, warm currents traveling along more temperate coasts increase the temperature of the area by warming the sea breezes that blow over them. Perhaps the most striking example is the Gulf Stream, which, together with its extension the North Atlantic Drift, makes northwest Europe much more temperate for its high latitude than other areas at the same latitude. Another example is Lima, Peru, whose cooler subtropical climate contrasts with that of its surrounding tropical latitudes because of the Humboldt Current.

The largest ocean current is the Antarctic Circumpolar Current (ACC), a wind-driven current which flows clockwise uninterrupted around Antarctica. The ACC connects all the ocean basins together, and also provides a link between the atmosphere and the deep ocean due to the way water upwells and downwells on either side of it.

Ocean currents are patterns of water movement that influence climate zones and weather patterns around the world. They are primarily driven by winds and by seawater density, although many other factors influence them – including the shape and configuration of the ocean basin they flow through. The two basic types of currents – surface and deep-water currents – help define the character and flow of ocean waters across the planet.the ocean current is divided in to two warm ocean current and cold ocean current

Causes

File:CSIRO ScienceImage 11128 The bathymetry of the Kerguelen Plateau in the Southern Ocean governs the course of the new current part of the global network of ocean currents.jpg of the Kerguelen Plateau in the Southern Ocean governs the course of the Kerguelen deep western boundary current, part of the global network of ocean currents.{{cite web |title=Massive Southern Ocean current discovered |url=https://www.sciencedaily.com/releases/2010/04/100427101234.htm |website=ScienceDaily |date=Apr 27, 2010}}{{cite journal |display-authors=etal|last1=Yasushi Fukamachi, Stephen Rintoul |title=Strong export of Antarctic Bottom Water east of the Kerguelen plateau |journal=Nature Geoscience |date=Apr 2010 |volume=3 |issue=5 |pages=327–331 |doi=10.1038/NGEO842 |bibcode=2010NatGe...3..327F |hdl=2115/44116 |s2cid=67815755 |url=https://www.researchgate.net/publication/47656862|hdl-access=free }}]]

Ocean currents are driven by the wind, by the gravitational pull of the moon in the form of tides, and by the effects of variations in water density.{{Cite web |last=National Oceanic and Atmospheric Administration |date=16 June 2024 |title=What is a current? |url=https://oceanservice.noaa.gov/facts/current.html#:~:text=Ocean%20currents%20are%20driven%20by,or%201.15%20miles%20per%20hour). |access-date=2024-09-03 |website=oceanservice.noaa.gov |language=EN-US}} Ocean dynamics define and describe the motion of water within the oceans.

Ocean temperature and motion fields can be separated into three distinct layers: mixed (surface) layer, upper ocean (above the thermocline), and deep ocean. Ocean currents are measured in units of sverdrup (Sv), where 1 Sv is equivalent to a volume flow rate of {{convert|1000000|m3|ft3|abbr=on}} per second.

There are two main types of currents, surface currents and deep water currents. Generally surface currents are driven by wind systems and deep water currents are driven by differences in water density due to variations in water temperature and salinity.{{Cite web |last=National Oceanic and Atmospheric Administration |date=1 August 2011 |title=Ocean currents |url=https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-currents#:~:text=via%20research%20ship.-,Surface%20currents,influencing%20local%20and%20global%20climate. |access-date=2024-09-14 |website=www.noaa.gov |language=en}}

= Wind-driven circulation =

Surface oceanic currents are driven by wind currents, the large scale prevailing winds drive major persistent ocean currents, and seasonal or occasional winds drive currents of similar persistence to the winds that drive them,{{cite web |url=https://www.nationalgeographic.org/encyclopedia/current/#:~:text=or%20as%20lightning.-,Air%20Currents,flow%20in%20a%20certain%20direction |title=Current |publisher=National Geographic |website=www.nationalgeographic.org |date=2 September 2011 |access-date=7 January 2021 }} and the Coriolis effect plays a major role in their development.{{cite web|url=https://dashamlav.com/ocean-currents-world-map-types-causes-characteristics/|title=Ocean Currents of the World: Causes|date=29 August 2020|access-date=2020-11-20}} The Ekman spiral velocity distribution results in the currents flowing at an angle to the driving winds, and they develop typical clockwise spirals in the northern hemisphere and counter-clockwise rotation in the southern hemisphere.

{{cite web |url= http://oceanservice.noaa.gov/education/kits/currents/05currents1.html |title = Surface Ocean Currents |last = National Ocean Service |date = March 25, 2008 |website= noaa.gov |publisher= National Oceanic and Atmospheric Administration |access-date = 2017-06-13 |url-status= live |archive-url= https://web.archive.org/web/20170706062957/https://oceanservice.noaa.gov/education/kits/currents/05currents1.html |archive-date = July 6, 2017}}

In addition, the areas of surface ocean currents move somewhat with the seasons; this is most notable in equatorial currents.

Deep ocean basins generally have a non-symmetric surface current, in that the eastern equator-ward flowing branch is broad and diffuse whereas the pole-ward flowing western boundary current is relatively narrow.

= Thermohaline circulation =

{{Further|Deep ocean water}}File:Meddes-20060320-browse.jpg

Large scale currents are driven by gradients in water density, which in turn depend on variations in temperature and salinity. This thermohaline circulation is also known as the ocean's conveyor belt. Where significant vertical movement of ocean currents is observed, this is known as upwelling and downwelling. The adjective thermohaline derives from thermo- referring to temperature and {{nowrap|-haline}} referring to salt content, factors which together determine the density of seawater.

The thermohaline circulation is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes.{{cite journal|last=Rahmstorf|first=S|title=The concept of the thermohaline circulation|journal=Nature|volume=421|page=699|year=2003|url=http://www.pik-potsdam.de/~stefan/Publications/Nature/nature_concept_03.pdf|pmid=12610602|issue=6924|doi=10.1038/421699a|bibcode = 2003Natur.421..699R |s2cid=4414604|doi-access=free}}{{cite journal|last=Lappo|first=SS|title=On reason of the northward heat advection across the Equator in the South Pacific and Atlantic ocean|journal=Study of Ocean and Atmosphere Interaction Processes|year=1984|pages=125–9|publisher=Moscow Department of Gidrometeoizdat (in Mandarin)}} Wind-driven surface currents (such as the Gulf Stream) travel polewards from the equatorial Atlantic Ocean, cooling en route, and eventually sinking at high latitudes (forming North Atlantic Deep Water). This dense water then flows into the ocean basins. While the bulk of it upwells in the Southern Ocean, the oldest waters (with a transit time of around 1000 years)The global ocean conveyor belt is a constantly moving system of deep-ocean circulation driven by temperature and salinity; [http://oceanservice.noaa.gov/facts/conveyor.html What is the global ocean conveyor belt?] upwell in the North Pacific.{{cite journal|doi=10.1175/JPO2699.1|last=Primeau|first=F|title=Characterizing transport between the surface mixed layer and the ocean interior with a forward and adjoint global ocean transport model|journal=Journal of Physical Oceanography|volume=35|issue=4|pages=545–64|year=2005|bibcode=2005JPO....35..545P|s2cid=130736022 |url=https://escholarship.org/content/qt5f76r4wn/qt5f76r4wn.pdf?t=n3tp5j}} Extensive mixing therefore takes place between the ocean basins, reducing differences between them and making the Earth's oceans a global system. On their journey, the water masses transport both energy (in the form of heat) and matter (solids, dissolved substances and gases) around the globe. As such, the state of the circulation has a large impact on the climate of the Earth. The thermohaline circulation is sometimes called the ocean conveyor belt, the great ocean conveyor, or the global conveyor belt. On occasion, it is imprecisely used to refer to the meridional overturning circulation, (MOC).

Since the 2000s an international program called Argo has been mapping the temperature and salinity structure of the ocean with a fleet of automated platforms that float with the ocean currents. The information gathered will help explain the role the oceans play in the earth's climate.{{Cite web |last=Scripps Institution of Oceanography, UC San Diego |title=Argo |url=https://argo.ucsd.edu/ |archive-url=https://web.archive.org/web/20240901191501/https://argo.ucsd.edu/ |archive-date=1 September 2024 |access-date=2024-09-05 |website=Argo |language=en-US}}

Effects on climate and ecology

Ocean currents affect temperatures throughout the world. For example, the ocean current that brings warm water up the north Atlantic to northwest Europe also cumulatively and slowly blocks ice from forming along the seashores, which would also block ships from entering and exiting inland waterways and seaports, hence ocean currents play a decisive role in influencing the climates of regions through which they flow.{{Cite web |title=What Is the Gulf Stream? {{!}} NOAA SciJinks – All About Weather |url=https://scijinks.gov/gulf-stream/ |access-date=2024-04-15 |website=scijinks.gov}} Ocean currents are important in the study of marine debris.{{Cite web |last=National Oceanic and Atmospheric Administration |date=1 April 2020 |title=Ocean pollution and marine debris |url=https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-pollution |access-date=2024-09-08 |website=www.noaa.gov |language=en}}{{Cite journal |last1=van Sebille |first1=Erik |last2=Aliani |first2=Stefano |last3=Law |first3=Kara Lavender |last4=Maximenko |first4=Nikolai |last5=Alsina |first5=José M |last6=Bagaev |first6=Andrei |last7=Bergmann |first7=Melanie |last8=Chapron |first8=Bertrand |last9=Chubarenko |first9=Irina |last10=Cózar |first10=Andrés |last11=Delandmeter |first11=Philippe |last12=Egger |first12=Matthias |last13=Fox-Kemper |first13=Baylor |last14=Garaba |first14=Shungudzemwoyo P |last15=Goddijn-Murphy |first15=Lonneke |date=2020-02-01 |title=The physical oceanography of the transport of floating marine debris |url=https://iopscience.iop.org/article/10.1088/1748-9326/ab6d7d |journal=Environmental Research Letters |volume=15 |issue=2 |pages=023003 |doi=10.1088/1748-9326/ab6d7d |bibcode=2020ERL....15b3003V |issn=1748-9326|hdl=2117/187082 |hdl-access=free }}

File:Marine microplankton.jpg

Upwellings and cold ocean water currents flowing from polar and sub-polar regions bring in nutrients that support plankton growth, which are crucial prey items for several key species in marine ecosystems.{{Cite book |url=https://linkinghub.elsevier.com/retrieve/pii/B9780126009521X50002 |title=Introduction to the Practice of Fishery Science |date=1996 |publisher=Elsevier |isbn=978-0-12-600952-1 |editor-last=Royce |editor-first=William F. |chapter=Circulation |doi=10.1016/b978-0-12-600952-1.x5000-2}}

Ocean currents are also important in the dispersal and distribution of many organisms, including those with pelagic egg or larval stages. An example is the life-cycle of the European Eel. Terrestrial species, for example tortoises and lizards, can be carried on floating debris by currents to colonise new terrestrial areas and islands.{{Cite journal |last=Hays |first=Graeme C. |date=5 June 2017 |title=Ocean currents and marine life |url=https://linkinghub.elsevier.com/retrieve/pii/S0960982217300775 |journal=Current Biology |language=en |volume=27 |issue=11 |pages=R470–R473 |doi=10.1016/j.cub.2017.01.044|pmid=28586681 |bibcode=2017CBio...27.R470H }}

Ocean currents and climate change

The continued rise of atmospheric temperatures is anticipated to have various effects on the strength of surface ocean currents, wind-driven circulation and dispersal patterns.{{Cite journal |last1=Wilson |first1=Laura J. |last2=Fulton |first2=Christopher J. |last3=Hogg |first3=Andrew McC |last4=Joyce |first4=Karen E. |last5=Radford |first5=Ben T. M. |last6=Fraser |first6=Ceridwen I. |date=2016-05-02 |title=Climate-driven changes to ocean circulation and their inferred impacts on marine dispersal patterns |url=https://onlinelibrary.wiley.com/doi/10.1111/geb.12456 |journal=Global Ecology and Biogeography |language= |volume=25 |issue=8 |pages=923–939 |doi=10.1111/geb.12456 |bibcode=2016GloEB..25..923W |issn=1466-822X}}{{Cite journal |last=Miller |first=Johanna L. |date=2017 |title=Ocean currents respond to climate change in unexpected ways |url=https://pubs.aip.org/physicstoday/article/70/1/17/1040900 |journal=Physics Today |volume=70 |issue=1 |pages=17–18}}{{Cite journal |last1=Peng |first1=Qihua |last2=Xie |first2=Shang-Ping |last3=Wang |first3=Dongxiao |last4=Huang |first4=Rui Xin |last5=Chen |first5=Gengxin |last6=Shu |first6=Yeqiang |last7=Shi |first7=Jia-Rui |last8=Liu |first8=Wei |date=2022-04-22 |title=Surface warming–induced global acceleration of upper ocean currents |journal=Science Advances |volume=8 |issue=16 |pages=eabj8394 |doi=10.1126/sciadv.abj8394 |issn=2375-2548 |pmc=9020668 |pmid=35442733|bibcode=2022SciA....8J8394P }} Ocean currents play a significant role in influencing climate, and shifts in climate in turn impact ocean currents.

File:Fig 1.4.1 Atmospheric circulation cells, dominant wind directions.png

Over the last century, reconstructed sea surface temperature data reveal that western boundary currents are heating at double the rate of the global average.{{Cite journal |last1=Wu |first1=Lixin |last2=Cai |first2=Wenju |last3=Zhang |first3=Liping |last4=Nakamura |first4=Hisashi |last5=Timmermann |first5=Axel |last6=Joyce |first6=Terry |last7=McPhaden |first7=Michael J. |last8=Alexander |first8=Michael |last9=Qiu |first9=Bo |last10=Visbeck |first10=Martin |last11=Chang |first11=Ping |last12=Giese |first12=Benjamin |date=2012-01-29 |title=Enhanced warming over the global subtropical western boundary currents |url=https://www.nature.com/articles/nclimate1353 |journal=Nature Climate Change |volume=2 |issue=3 |pages=161–166 |doi=10.1038/nclimate1353 |bibcode=2012NatCC...2..161W |issn=1758-6798|hdl=1912/5125 |hdl-access=free }} These observations indicate that the western boundary currents are likely intensifying due to this change in temperature, and may continue to grow stronger in the near future. There is evidence that surface warming due to anthropogenic climate change has accelerated upper ocean currents in 77% of the global ocean. Specifically, increased vertical stratification due to surface warming intensifies upper ocean currents, while changes in horizontal density gradients caused by differential warming across different ocean regions results in the acceleration of surface zonal currents.

There are suggestions that the Atlantic meridional overturning circulation (AMOC) is in danger of collapsing due to climate change, which would have extreme impacts on the climate of northern Europe and more widely,{{Cite journal |last1=Ditlevsen |first1=Peter |last2=Ditlevsen |first2=Susanne |date=2023-07-25 |title=Warning of a forthcoming collapse of the Atlantic meridional overturning circulation |journal=Nature Communications |volume=14 |issue=1 |pages=4254 |doi=10.1038/s41467-023-39810-w |issn=2041-1723 |pmid=37491344|pmc=10368695 |arxiv=2304.09160 |bibcode=2023NatCo..14.4254D }}{{Cite journal |last1=Zhu |first1=Chenyu |last2=Liu |first2=Zhengyu |last3=Zhang |first3=Shaoqing |last4=Wu |first4=Lixin |date=2023-03-04 |title=Likely accelerated weakening of Atlantic overturning circulation emerges in optimal salinity fingerprint |journal=Nature Communications |language=en |volume=14 |issue=1 |pages=1245 |doi=10.1038/s41467-023-36288-4 |pmid=36871075 |issn=2041-1723|pmc=9985640 |bibcode=2023NatCo..14.1245Z }}{{Cite journal |last1=Boulton |first1=Chris A. |last2=Allison |first2=Lesley C. |last3=Lenton |first3=Timothy M. |date=2014-12-08 |title=Early warning signals of Atlantic Meridional Overturning Circulation collapse in a fully coupled climate model |journal=Nature Communications |language=en |volume=5 |issue=1 |pages=5752 |doi=10.1038/ncomms6752 |pmid=25482065 |issn=2041-1723|pmc=4268699 |bibcode=2014NatCo...5.5752B }} although this topic is controversial and remains an active area of research.{{Cite web |last=Science Media Centre |date=25 July 2023 |title=Expert reaction to paper warning of a collapse of the Atlantic meridional overturning circulation |url=https://www.sciencemediacentre.org/expert-reaction-to-paper-warning-of-a-collapse-of-the-atlantic-meridional-overturning-circulation/ |access-date=2024-09-12 |website=Science Media Centre |language=en-GB}}{{Cite journal |last=Rahmstorf |first=Stefan |date=10 April 2024 |title=Is the Atlantic Overturning Circulation Approaching a Tipping Point? |url=https://tos.org/oceanography/article/is-the-atlantic-overturning-circulation-approaching-a-tipping-point |journal=Oceanography |volume=37 |issue=3 |pages=1–0 |doi=10.5670/oceanog.2024.501|doi-access=free }}{{Cite web |last=Met Office Press |date=2 May 2024 |title=The Atlantic Meridional Overturning Circulation in a changing climate |url=https://blog.metoffice.gov.uk/2024/05/02/the-atlantic-meridional-overturning-circulation-in-a-changing-climate/ |access-date=2024-09-12 |website=Official blog of the Met Office news team |language=en}} The "State of the cryosphere" report, dedicates significant space to AMOC, saying it may be en route to collapse because of ice melt and water warming. In the same time, the Antarctic Circumpolar Current (ACC) is also slowing down and is expected to lose 20% of it power by the year 2050, "with widespread impacts on ocean circulation and climate".{{cite book |title=State of the Cryosphere 2024 Lost Ice, Global Damage |date=November 2024 |publisher=International Cryosphere Climate Initiative |pages=x (in the beginning), 8, 48, 52 |url=https://articles.unesco.org/sites/default/files/medias/fichiers/2024/11/State%20of%20the%20Cryosphere%20Report%202024.pdf |access-date=20 November 2024}} UNESCO mentions that the report in the first time "notes a growing scientific consensus that melting Greenland and Antarctic ice sheets, among other factors, may be slowing important ocean currents at both poles, with potentially dire consequences for a much colder northern Europe and greater sea-level rise along the U.S. East Coast."{{cite web |title=State of the Cryosphere Report 2024 Lost Ice, Global Damage |url=https://www.unesco.org/en/articles/state-cryosphere-report-2024 |website=UNESCO |access-date=20 November 2024}}

In addition to water surface temperatures, the wind systems are a crucial determinant of ocean currents.{{Cite journal |last=Constantin |first=Adrian |date=2021-01-02 |title=Frictional effects in wind-driven ocean currents |journal=Geophysical & Astrophysical Fluid Dynamics |volume=115 |issue=1 |pages=1–14 |doi=10.1080/03091929.2020.1748614 |issn=0309-1929|doi-access=free |bibcode=2021GApFD.115....1C }} Wind wave systems influence oceanic heat exchange, the condition of the sea surface, and can alter ocean currents.{{Cite journal |last1=Dobrynin |first1=Mikhail |last2=Murawski |first2=Jens |last3=Baehr |first3=Johanna |last4=Ilyina |first4=Tatiana |date=2015-02-15 |title=Detection and Attribution of Climate Change Signal in Ocean Wind Waves |url=https://journals.ametsoc.org/view/journals/clim/28/4/jcli-d-13-00664.1.xml |journal=Journal of Climate |volume=28 |issue=4 |pages=1578–1591 |doi=10.1175/JCLI-D-13-00664.1 |bibcode=2015JCli...28.1578D |issn=0894-8755}} In the North Atlantic, equatorial Pacific, and Southern Ocean, increased wind speeds as well as significant wave heights have been attributed to climate change and natural processes combined. In the East Australian Current, global warming has also been accredited to increased wind stress curl, which intensifies these currents, and may even indirectly increase sea levels, due to the additional warming created by stronger currents.{{Cite journal |last1=Cai |first1=W. |last2=Shi |first2=G. |last3=Cowan |first3=T. |last4=Bi |first4=D. |last5=Ribbe |first5=J. |date=2005-12-10 |title=The response of the Southern Annular Mode, the East Australian Current, and the southern mid-latitude ocean circulation to global warming |url=https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2005GL024701 |journal=Geophysical Research Letters |volume=32 |issue=23 |doi=10.1029/2005GL024701 |bibcode=2005GeoRL..3223706C |issn=0094-8276}}

As ocean circulation changes due to climate, typical distribution patterns are also changing. The dispersal patterns of marine organisms depend on oceanographic conditions, which as a result, influence the biological composition of oceans. Due to the patchiness of the natural ecological world, dispersal is a species survival mechanism for various organisms.{{Cite journal |last=Kininmonth |first=Stuart |date=2011-04-11 |title=Dispersal connectivity and reserve selection for marine conservation |url=https://www.sciencedirect.com/science/article/abs/pii/S0304380011000445 |journal=Ecological Modelling |volume=222 |issue=7 |pages=1272–1282|doi=10.1016/j.ecolmodel.2011.01.012 |bibcode=2011EcMod.222.1272K |url-access=subscription }} With strengthened boundary currents moving toward the poles, it is expected that some marine species will be redirected to the poles and greater depths.{{Cite journal |last1=Vergés |first1=Adriana |last2=Steinberg |first2=Peter D. |last3=Hay |first3=Mark E. |last4=Poore |first4=Alistair G. B. |last5=Campbell |first5=Alexandra H. |last6=Ballesteros |first6=Enric |last7=Heck |first7=Kenneth L. |last8=Booth |first8=David J. |last9=Coleman |first9=Melinda A. |last10=Feary |first10=David A. |last11=Figueira |first11=Will |last12=Langlois |first12=Tim |last13=Marzinelli |first13=Ezequiel M. |last14=Mizerek |first14=Toni |last15=Mumby |first15=Peter J. |date=2014-08-22 |title=The tropicalization of temperate marine ecosystems: climate-mediated changes in herbivory and community phase shifts |journal=Proceedings of the Royal Society B: Biological Sciences |volume=281 |issue=1789 |pages=20140846 |doi=10.1098/rspb.2014.0846 |issn=0962-8452 |pmc=4100510 |pmid=25009065}} The strengthening or weakening of typical dispersal pathways by increased temperatures are expected to not only impact the survival of native marine species due to inability to replenish their meta populations but also may increase the prevalence of invasive species. In Japanese corals and macroalgae, the unusual dispersal pattern of organisms toward the poles may destabilize native species.{{Cite journal |last1=Kumagai |first1=Naoki H. |last2=García Molinos |first2=Jorge |last3=Yamano |first3=Hiroya |last4=Takao |first4=Shintaro |last5=Fujii |first5=Masahiko |last6=Yamanaka |first6=Yasuhiro |date=2018-09-04 |title=Ocean currents and herbivory drive macroalgae-to-coral community shift under climate warming |journal=Proceedings of the National Academy of Sciences |volume=115 |issue=36 |pages=8990–8995 |doi=10.1073/pnas.1716826115 |doi-access=free |issn=0027-8424 |pmc=6130349 |pmid=30126981|bibcode=2018PNAS..115.8990K }}

Economic importance

Knowledge of surface ocean currents is essential in reducing costs of shipping, since traveling with them reduces fuel costs. In the wind powered sailing-ship era, knowledge of wind patterns and ocean currents was even more essential. Using ocean currents to help their ships into harbor and using currents such as the gulf stream to get back home.{{Cite web |title=Atlantic Ocean - Exploration, Currents, Marine Life {{!}} Britannica |url=https://www.britannica.com/place/Atlantic-Ocean/Study-and-exploration |access-date=2024-04-20 |website=www.britannica.com }} The lack of understanding of ocean currents during that time period is hypothesized to be one of the contributing factors to exploration failure. The Gulf Stream and the Canary current keep western European countries warmer and less variable, while at the same latitude North America's weather was colder.{{Cite web |last=US Department of Commerce |first=National Oceanic and Atmospheric Administration |title=Boundary Currents - Currents: NOAA's National Ocean Service Education |url=https://oceanservice.noaa.gov/education/tutorial_currents/04currents3.html#:~:text=The%20Gulf%20Stream%20is%20a,current%20is%20the%20Gulf%20Stream |access-date=2024-04-20 |website=oceanservice.noaa.gov }} A good example of this is the Agulhas Current (down along eastern Africa), which long prevented sailors from reaching India.

In recent times, around-the-world sailing competitors make good use of surface currents to build and maintain speed.

Ocean currents can also be used for marine power generation, with areas of Japan, Florida and Hawaii being considered for test projects. The utilization of currents today can still impact global trade, it can reduce the cost and emissions of shipping vessels.{{Cite journal |last1=Chang |first1=Yu-Chia |last2=Tseng |first2=Ruo-Shan |last3=Chen |first3=Guan-Yu |last4=Chu |first4=Peter C. |last5=Shen |first5=Yung-Ting |date=November 2013 |title=Ship Routing Utilizing Strong Ocean Currents |url=https://www.cambridge.org/core/journals/journal-of-navigation/article/abs/ship-routing-utilizing-strong-ocean-currents/02039ECA1A45DCDD0B7935C94F79CBB9 |journal=The Journal of Navigation |volume=66 |issue=6 |pages=825–835 |doi=10.1017/S0373463313000441 |bibcode=2013JNav...66..825C |issn=0373-4633|hdl=10945/36070 |hdl-access=free }}

File:Skipjack tuna transporting at Pondokdadap Fishingport.jpg

Ocean currents can also impact the fishing industry, examples of this include the Tsugaru, Oyashio and Kuroshio currents all of which influence the western North Pacific temperature, which has been shown to be a habitat predictor for the Skipjack tuna.{{Cite journal |last1=Ramesh |first1=Nandini |last2=Rising |first2=James A. |last3=Oremus |first3=Kimberly L. |date=2019-06-21 |title=The small world of global marine fisheries: The cross-boundary consequences of larval dispersal |url=https://www.science.org/doi/10.1126/science.aav3409 |journal=Science |volume=364 |issue=6446 |pages=1192–1196 |doi=10.1126/science.aav3409 |pmid=31221860 |bibcode=2019Sci...364.1192R |issn=0036-8075}} It has also been shown that it is not just local currents that can affect a country's economy, but neighboring currents can influence the viability of local fishing industries.{{Cite journal |last=Talley |first=Lynne D. |date=April 1, 1995 |title=North Pacific Intermediate Water in the Kuroshio/Oyashio Mixed Water Region |url=https://journals-ametsoc-org.ezp1.lib.umn.edu/view/journals/phoc/25/4/1520-0485_1995_025_0475_npiwit_2_0_co_2.xml |journal=American Meteorological Society |volume=25 |issue=4 |pages=475–501 |doi=10.1175/1520-0485(1995)025<0475:NPIWIT>2.0.CO;2 |bibcode=1995JPO....25..475T |via=AMS Publications|doi-access=free }}

Distribution

Image:Ocean currents 1943 (borderless)3.png

Currents of the Arctic Ocean

{{annotated link|Baffin Island Current}}
{{annotated link|Beaufort Gyre}}
{{annotated link|East Greenland Current}}
{{annotated link|East Iceland Current}}
{{annotated link|Labrador Current}}
{{annotated link|North Icelandic Jet}}
{{annotated link|Norwegian Current}}
{{annotated link|Transpolar Drift Stream}}
{{annotated link|West Greenland Current}}
{{annotated link|West Spitsbergen Current}}

Currents of the Atlantic Ocean

File:Recording Current Meter.jpg. It records information about currents (speed, direction, depth, temperature).|alt=Device to record ocean currents]]

{{annotated link|Angola Current}}
{{annotated link|Antilles Current}}
{{annotated link|Atlantic meridional overturning circulation}}
{{annotated link|Azores Current}}
{{annotated link|Benguela Current}}
{{annotated link|Brazil Current}}
{{annotated link|Canary Current}}
{{annotated link|Cape Horn Current}}
{{annotated link|Caribbean Current}}
{{annotated link|East Greenland Current}}
{{annotated link|East Iceland Current}}
{{annotated link|Equatorial Counter Current}}
{{annotated link|Falkland Current}}
{{annotated link|Florida Current}}
{{annotated link|Guinea Current}}
{{annotated link|Gulf Stream}}
{{annotated link|Irminger Current}}
{{annotated link|Labrador Current}}
{{annotated link|Lomonosov Current}}
{{annotated link|Loop Current}}
{{annotated link|North Atlantic Current}}
{{annotated link|North Brazil Current}}
{{annotated link|North Equatorial Current}}
{{annotated link|Norwegian Current}}
{{annotated link|Portugal Current}}
{{annotated link|South Atlantic Current}}
{{annotated link|South Equatorial Current}}
{{annotated link|West Greenland Current}}
{{annotated link|West Spitsbergen Current}}

Currents of the Indian Ocean

{{annotated link|Agulhas Current}}
{{annotated link|Agulhas Return Current}}
{{annotated link|East Madagascar Current}}
{{annotated link|Equatorial Counter Current}}
{{annotated link|Indian Monsoon Current}}
{{annotated link|Indonesian Throughflow}}
{{annotated link|Leeuwin Current}}
{{annotated link|Madagascar Current}}
{{annotated link|Mozambique Current}}
{{annotated link|North Madagascar Current}}
{{annotated link|Somali Current}}
{{annotated link|South Equatorial Current}}
{{annotated link|Southwest Madagascar Coastal Current}}
{{annotated link|West Australian Current}}

Currents of the Pacific Ocean

{{annotated link|Alaska Current}}
{{annotated link|Aleutian Current}}
{{annotated link|California Current}}
{{annotated link|Cape Horn Current}}
{{annotated link|Cromwell Current}}
{{annotated link|Davidson Current}}
{{annotated link|East Australian Current}}
{{annotated link|East Korea Warm Current}}
{{annotated link|Equatorial Counter Current}}
{{annotated link|Humboldt Current}}
{{annotated link|Indonesian Throughflow}}
{{annotated link|Kamchatka Current}}
{{annotated link|Kuroshio Current}}
{{annotated link|Mindanao Current}}
{{annotated link|Mindanao Eddy}}
{{annotated link|North Equatorial Current}}
{{annotated link|North Korea Cold Current}}
{{annotated link|North Pacific Current}}
{{annotated link|Oyashio Current}}
{{annotated link|South Equatorial Current}}
{{annotated link|Subtropical Countercurrent}}
{{annotated link|Tasman Front}}
{{annotated link|Tasman Outflow}}

Currents of the Southern Ocean

{{annotated link|Antarctic Circumpolar Current}}
{{annotated link|Tasman Outflow}}
{{annotated link|Kerguelen deep western boundary current}}

Oceanic gyres

{{annotated link|Beaufort Gyre}}
{{annotated link|Indian Ocean Gyre}}
{{annotated link|North Atlantic Gyre}}
{{annotated link|North Pacific Gyre}}
{{annotated link|Ross Gyre}}
{{annotated link|South Atlantic Gyre}}
{{annotated link|South Pacific Gyre}}
{{annotated link|Weddell Gyre}}

References

External links

[https://earth.nullschool.net/#current/ocean/surface/currents/winkel3/ Current global map of sea surface currents]

Category:Oceanographical terminology

Category:Physical oceanography

Category:Articles containing video clips