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Earth's Systems / Energy flow / Heat redistribution by air and ocean / Wind-driven ocean circulation, upwelling, ocean heat uptake and sea level

Wind-driven ocean circulation, upwelling, ocean heat uptake and sea level

How winds drive the surface gyres, western boundary currents and coastal upwelling, how the ocean takes up most of the planet's surplus heat, and how warming water and melting ice raise sea level.

Boundary: where this process starts

Starts with: Wind drags the surface layer and the Coriolis effect turns it, so the net Ekman transport is at right angles to the wind

Boundary: where it ends

Ends after: Sea level rises unevenly: winds and currents pile water regionally, and land sinks or rises (Hudson Bay uplifts about 10 mm/yr, land south of the Great Lakes si; Ice-mass loss from glaciers and ice sheets has raised sea level twice as much as thermal expansion since 1900

PARTICIPANTSRESOURCESOceanOcean currentsWindUpwellingCoriolis effectSeawaterHeatNutrientsMeltwaterImpact +4 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.Impact +2 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.Impact +2 of 5. Click for details and evidence.Wind drags the surface layer and the Coriolis effect turns it, so the net Ekman transport is at right angles to the wind: uses SeawaterTrade winds and westerlies make surface water converge in the subtropics, and Sverdrup flow fills five great gyres: uses SeawaterGyres are intensified on their western sides: the Gulf Stream carries 30 to 33.5 Sv through the Florida Straits: uses SeawaterGyres are intensified on their western sides: the Gulf Stream carries 30 to 33.5 Sv through the Florida Straits: uses HeatWhere winds blow along a coast, Ekman transport pushes surface water offshore and cold, nutrient-rich water wells up (eastern boundary upwelling): uses SeawaterWhere winds blow along a coast, Ekman transport pushes surface water offshore and cold, nutrient-rich water wells up (eastern boundary upwelling): makes NutrientsmakesUpwelled nutrients fertilise the surface, so the eastern boundary upwelling ecosystems are among the most productive fishing grounds: uses NutrientsWarming may strengthen alongshore winds and upwelling (Bakun hypothesis), while the poleward shift of the Hadley cell and subtropical highs moves upwelling wind: uses SeawaterHeat entering the surface is carried down by mixing, Ekman pumping and overturning: most warming is in the top 700 m, but the deep ocean below 2000 m is gaining: uses SeawaterHeat entering the surface is carried down by mixing, Ekman pumping and overturning: most warming is in the top 700 m, but the deep ocean below 2000 m is gaining: uses up Heatuses upWarming seawater expands: thermal expansion added 1.39 mm/yr of the 3.69 mm/yr sea-level rise in 2006-2018 (about 38%): uses SeawaterWarming seawater expands: thermal expansion added 1.39 mm/yr of the 3.69 mm/yr sea-level rise in 2006-2018 (about 38%): uses HeatIce-mass loss from glaciers and ice sheets has raised sea level twice as much as thermal expansion since 1900: uses SeawaterIce-mass loss from glaciers and ice sheets has raised sea level twice as much as thermal expansion since 1900: uses MeltwaterSea level rises unevenly: winds and currents pile water regionally, and land sinks or rises (Hudson Bay uplifts about 10 mm/yr, land south of the Great Lakes si: uses SeawaterusesSeawater: usesusesSeawater: usesusesSeawater: usesusesHeat: usesusesSeawater: usesmakesNutrients: makesusesNutrients: usesusesSeawater: usesusesSeawater: usesuses upHeat: uses upusesSeawater: usesusesHeat: usesusesSeawater: usesusesMeltwater: usesusesSeawater: usesStart: Wind-drivenocean circulation,upwelling, ocean he…STARTStart: Wind-driven ocean circulation, upwelling, ocean heat uptake and sea levelEnd: Wind-driven oceancirculation, upwelling,ocean heat uptake a…ENDEnd: Wind-driven ocean circulation, upwelling, ocean heat uptake and sea levelWind drags the surfacelayer and the Corioliseffect turns it, so t…📄2Wind drags the surface layer and the Coriolis effect turns it, so the net Ekman transport is at right angles to the windTrade winds andwesterlies make surfacewater converge in t…📄2Trade winds and westerlies make surface water converge in the subtropics, and Sverdrup flow fills five great gyresGyres are intensifiedon their western sides:the Gulf Stream carri…📄3Gyres are intensified on their western sides: the Gulf Stream carries 30 to 33.5 Sv through the Florida StraitsWhere winds blow alonga coast, Ekmantransport push…📄2Where winds blow along a coast, Ekman transport pushes surface water offshore and cold, nutrient-rich water wells up (eastern boundary upwelling)Upwelled nutrientsfertilise the surface,so the eastern bounda…📄3 ↗2Upwelled nutrients fertilise the surface, so the eastern boundary upwelling ecosystems are among the most productive fishing groundsWarming may strengthenalongshore winds andupwelling (Bak…📄2Warming may strengthen alongshore winds and upwelling (Bakun hypothesis), while the poleward shift of the Hadley cell and subtropical highs moves upwelling windHeat entering thesurface is carried downby mixing, Ekm…📄2Heat entering the surface is carried down by mixing, Ekman pumping and overturning: most warming is in the top 700 m, but the deep ocean below 2000 m is gainingWarming seawaterexpands: thermalexpansion added 1.…📄2 ↗1Warming seawater expands: thermal expansion added 1.39 mm/yr of the 3.69 mm/yr sea-level rise in 2006-2018 (about 38%)Ice-mass loss fromglaciers and ice sheetshas raised sea lev…📄2 ↗1Ice-mass loss from glaciers and ice sheets has raised sea level twice as much as thermal expansion since 1900Sea level risesunevenly: winds andcurrents pile wat…📄2Sea level rises unevenly: winds and currents pile water regionally, and land sinks or rises (Hudson Bay uplifts about 10 mm/yr, land south of the Great Lakes si
Line thickness = size of impact (1 to 5)% on a line = chance a fork takes that branch📄 = pieces of evidence on a stepNegative effectLoops backHypothesisResource used up (arrow into the step)Resource used, not used upResource made or released (arrow out of the step)
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Participant
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Resource
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Step
One thing that happens in a process. Every step has at least one participant and carries evidence.
Decision fork
A step where the process can go several ways. Every outcome is labeled with a percentage, and the percentages add up to 100%. It is not limited to yes or no.
Loop
A line that carries the process back to an earlier step. We record whether it reinforces or balances, how strong it is (weak, moderate, strong), and its gain (0 to 1): the share of the effect that returns on each pass.
Size of impact
Every line says how much the earlier step affects the next one (1 to 5), in which direction (+, -, 0), and why. Thicker lines mean bigger impact.
Evidence
The support for a claim: a source and what it shows. Every step, line, change and vote needs it. Click any step or line to read its evidence.
Boundary
Where a process starts and where it ends. Every process, and every subprocess, has a start and an end.
Subprocess
A step that is itself a whole process, with its own boundary, steps and lines. Click a step marked ↘ to open it. Subprocesses nest as deep as the evidence goes.
Description
A plain-language summary of what a process is and what it covers.
Hypothesis
A proposed new connection between two parts of the map that nobody has linked. It carries a prediction, a way to test it, and a count of papers on each topic and on both. It is an unverified idea until someone tests it.

Every step, with its evidence

The same information as the map, as a list you can search and share. Click a participant or resource to see everywhere it appears.

Wind drags the surface layer and the Coriolis effect turns it, so the net Ekman transport is at right angles to the wind
WindOceanCoriolis effectSeawater
Evidence (2) · added by Briangold-Claude
  • NOAA National Ocean Service, Currents tutorial: The Ekman spiral, https://oceanservice.noaa.gov/education/tutorial_currents/04currents4.html: The Ekman spiral, theorised by Ekman in 1902, is a consequence of the Coriolis effect acting on wind-driven surface currents, each layer deflected from the one above. (confidence 0.85)
  • Sverdrup 1947, Wind-driven currents in a baroclinic ocean; with application to the equatorial currents of the eastern Pacific, PNAS 33:318-326, https://doi.org/10.1073/pnas.33.11.318: Wind-driven transport in a rotating ocean is set by the curl of the wind stress. (confidence 0.8)
Trade winds and westerlies make surface water converge in the subtropics, and Sverdrup flow fills five great gyres
Ocean currentsTrade windsWesterly windsSeawater
Evidence (2) · added by Briangold-Claude
  • NOAA National Ocean Service, What is a gyre?, https://oceanservice.noaa.gov/facts/gyre.html: A gyre is a large system of rotating ocean currents; there are five major gyres: North and South Atlantic, North and South Pacific, and Indian Ocean. (confidence 0.9)
  • Sverdrup 1947, Wind-driven currents in a baroclinic ocean; with application to the equatorial currents of the eastern Pacific, PNAS 33:318-326, https://doi.org/10.1073/pnas.33.11.318: The meridional transport integrated over depth equals the wind-stress curl divided by beta (Sverdrup relation). (confidence 0.85)
Gyres are intensified on their western sides: the Gulf Stream carries 30 to 33.5 Sv through the Florida Straits
Ocean currentsGulf StreamSeawaterHeat
Evidence (3) · added by Briangold-Claude
  • Stommel 1948, The westward intensification of wind-driven ocean currents, Eos Trans. AGU 29:202-206, https://doi.org/10.1029/TR029i002p00202: The variation of the Coriolis parameter with latitude makes wind-driven gyre currents strongest on the western side of ocean basins. (confidence 0.9)
  • Baringer & Larsen 2001, Sixteen years of Florida Current transport at 27N, Geophys. Res. Lett. 28:3179-3182, https://doi.org/10.1029/2001GL013246: Sixteen years of cable measurements give a Florida Current annual cycle from 30 Sv in January to 33.5 Sv in July. (confidence 0.9)
  • NOAA National Ocean Service, Currents tutorial: Boundary currents, https://oceanservice.noaa.gov/education/tutorial_currents/04currents3.html: Each gyre is flanked by a strong narrow western boundary current such as the Gulf Stream and a weak broad eastern boundary current. (confidence 0.85)
Where winds blow along a coast, Ekman transport pushes surface water offshore and cold, nutrient-rich water wells up (eastern boundary upwelling)
UpwellingWindOceanSeawaterNutrients
Evidence (2) · added by Briangold-Claude
  • NOAA National Ocean Service, What is upwelling?, https://oceanservice.noaa.gov/facts/upwelling.html: Winds blowing along the shore push surface water away and water rises from beneath to replace it; upwelled water is colder and rich in nutrients. (confidence 0.9)
  • Bonino et al. 2019, Interannual to decadal variability within and across the major Eastern Boundary Upwelling Systems, Scientific Reports 9:19949, https://doi.org/10.1038/s41598-019-56514-8: Wind forcing and thermocline depth control the variability of the four Eastern Boundary Upwelling Systems. (confidence 0.8)
Upwelled nutrients fertilise the surface, so the eastern boundary upwelling ecosystems are among the most productive fishing grounds
UpwellingPhytoplanktonFishNutrients
Evidence (3) · added by Briangold-Claude
  • NOAA National Ocean Service, What is upwelling?, https://oceanservice.noaa.gov/facts/upwelling.html: Upwelled nutrients fertilise surface waters, giving high biological productivity; good fishing grounds are typically found where upwelling is common. (confidence 0.85)
  • Chavez & Messie 2009, A comparison of Eastern Boundary Upwelling Ecosystems, Prog. Oceanogr. 83:80-96, https://doi.org/10.1016/j.pocean.2009.07.032: The four eastern boundary upwelling ecosystems (California, Humboldt, Canary, Benguela) are compared as highly productive systems. (confidence 0.7)
  • Pauly & Christensen 1995, Primary production required to sustain global fisheries, Nature 374:255-257, https://doi.org/10.1038/374255a0: Fisheries catch is sustained by primary production, with upwelling systems needing a large share of their production to support their catch. (confidence 0.6)
Warming may strengthen alongshore winds and upwelling (Bakun hypothesis), while the poleward shift of the Hadley cell and subtropical highs moves upwelling wind
UpwellingWindHadley cellSeawater
Evidence (2) · added by Briangold-Claude
  • Bakun 1990, Global climate change and intensification of coastal ocean upwelling, Science 247:198-201, https://doi.org/10.1126/science.247.4939.198: Bakun proposed that greenhouse warming intensifies the land-sea pressure gradient and hence alongshore winds and coastal upwelling. (confidence 0.7)
  • IPCC AR6 WG1 2021, Chapter 9: Ocean, Cryosphere and Sea Level Change, https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-9/: Poleward expansion of the Hadley cell and migration of subtropical highs produce robust patterns of changed upwelling in eastern boundary systems. (confidence 0.8)
Heat entering the surface is carried down by mixing, Ekman pumping and overturning: most warming is in the top 700 m, but the deep ocean below 2000 m is gaining
OceanOcean currentsHeatSeawater
Evidence (2) · added by Briangold-Claude
Warming seawater expands: thermal expansion added 1.39 mm/yr of the 3.69 mm/yr sea-level rise in 2006-2018 (about 38%)
OceanSeawaterHeatSeawater
Evidence (2) · added by Briangold-Claude
Ice-mass loss from glaciers and ice sheets has raised sea level twice as much as thermal expansion since 1900
GlaciersIce sheetsOceanSeawaterMeltwater
Evidence (2) · added by Briangold-Claude
Sea level rises unevenly: winds and currents pile water regionally, and land sinks or rises (Hudson Bay uplifts about 10 mm/yr, land south of the Great Lakes si
OceanLand surfaceOcean currentsSeawater
Evidence (2) · added by Briangold-Claude