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CHAPTER 7CHAPTER 7Ocean CirculationOcean Circulation
Words…Words…
Ocean currentsOcean currents
Moving seawaterMoving seawaterSurface ocean currentsSurface ocean currents–– Transfer heat from warmer to cooler Transfer heat from warmer to cooler
areasareas
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
–– Similar to pattern of major wind beltsSimilar to pattern of major wind belts–– Affect coastal climatesAffect coastal climates
Deep ocean currentsDeep ocean currents–– Provide oxygen to deep seaProvide oxygen to deep sea
Affect marine lifeAffect marine life
Types of ocean currentsTypes of ocean currents
Surface currentsSurface currents–– WindWind--drivendriven–– Primarily horizontal motionPrimarily horizontal motion
Deep currentsDeep currents
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
pp–– Driven by differences in density caused by Driven by differences in density caused by
differences in temperature and salinitydifferences in temperature and salinity–– Vertical and horizontal motionsVertical and horizontal motions
Measuring surface currentsMeasuring surface currents
Direct methodsDirect methods–– Floating device Floating device
tracked through timetracked through time–– Fixed current meterFixed current meter
Oceanography Oceanography 101 101 –– Phil FarquharsonPhil Farquharson
Indirect methodsIndirect methods–– Pressure gradientsPressure gradients–– Radar altimetersRadar altimeters–– Doppler flow meterDoppler flow meter
Fixed current meterFixed current meter
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
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Measuring surface currentsMeasuring surface currents
Oceanography Oceanography 112 112 –– Phil FarquharsonPhil Farquharson
Measuring surface currents (accidentally)Measuring surface currents (accidentally)
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
Curt EbbesmeyerCurt Ebbesmeyer
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
Measuring surface currentsMeasuring surface currents
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
Measuring deep currentsMeasuring deep currents
Floating devices tracked through timeFloating devices tracked through timeChemical tracersChemical tracers–– TritiumTritium
Oceanography Oceanography –– Phil FarquharsonPhil Farquharson
–– ChlorofluorocarbonsChlorofluorocarbonsCharacteristic temperature and Characteristic temperature and salinitysalinity
Measuring Deep CurrentsMeasuring Deep CurrentsArgoArgo–– Global array of freeGlobal array of free--
drifting profiling floatsdrifting profiling floats–– Floating device Floating device
tracked through timetracked through timegg
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Measuring Deep CurrentsMeasuring Deep CurrentsArgoArgo
Surface CurrentsSurface CurrentsOccur above pycnoclineOccur above pycnocline–– Affect only 10% of ocean water on EarthAffect only 10% of ocean water on Earth
Friction between wind and ocean surfaceFriction between wind and ocean surface–– 2% of wind energy transferred to ocean 2% of wind energy transferred to ocean
surfacesurface–– Surface currents slower speed than Surface currents slower speed than
corresponding windscorresponding windsGenerally follow Earth’s wind belt patternGenerally follow Earth’s wind belt pattern
Surface currentsSurface currentsFrictional drag between wind and oceanFrictional drag between wind and oceanWind plus other factors such asWind plus other factors such as–– Distribution of continentsDistribution of continents–– GravityGravity–– FrictionFriction
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
–– FrictionFriction–– Coriolis effectCoriolis effect
GyresGyres or large circular loops of moving or large circular loops of moving waterwater
Ocean gyresOcean gyresSubtropical gyresSubtropical gyres
Centered about Centered about 3030oo
N or SN or SEquatorial currentEquatorial currentWestern Boundary Western Boundary
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
currentscurrentsNorthern or Southern Northern or Southern Boundary currentsBoundary currentsEastern Boundary Eastern Boundary currentscurrents
Other surface currentsOther surface currentsEquatorial CountercurrentsEquatorial CountercurrentsSubpolar gyresSubpolar gyres
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
Ocean CirculationOcean Circulation
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surface currentssurface currentsFrom Curt Ebbesmeyer:From Curt Ebbesmeyer:Five Subtropical GyresFive Subtropical Gyres
North Atlantic North Atlantic –– Columbus GyreColumbus GyreSouth Atlantic South Atlantic –– Navigator GyreNavigator GyreNorth Pacific North Pacific –– Turtle GyreTurtle GyreSouth Pacific South Pacific –– Heyerdahl GyreHeyerdahl GyreIndian Ocean Indian Ocean –– MajidMajid GyreGyre
Subtropical Gyres and CurrentsSubtropical Gyres and Currents Gyres and Boundary CurrentsGyres and Boundary Currents
Subtropical Gyre CurrentsSubtropical Gyre CurrentsEquatorial Currents Equatorial Currents –– North or southNorth or south–– Travel westward along equatorTravel westward along equator
Western Boundary Currents Western Boundary Currents W t f t i l iW t f t i l i–– Warm waters from equatorial regionsWarm waters from equatorial regions
–– Western edge of ocean basinsWestern edge of ocean basins
Subtropical Gyre CurrentsSubtropical Gyre CurrentsNorthernNorthern or or Southern Boundary Currents Southern Boundary Currents –– Easterly water flow across ocean basinEasterly water flow across ocean basin–– Northern boundary currents in Northern Northern boundary currents in Northern
HemisphereHemisphere–– Southern boundary currents in SouthernSouthern boundary currents in Southern–– Southern boundary currents in Southern Southern boundary currents in Southern
HemisphereHemisphereEastern Boundary Currents Eastern Boundary Currents –– Cool watersCool waters–– Eastern edge of ocean basinsEastern edge of ocean basins
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Other Surface CurrentsOther Surface CurrentsEquatorial Countercurrents Equatorial Countercurrents –– Eastward flow between North and South Eastward flow between North and South
Equatorial CurrentsEquatorial Currents–– Due to minimal Coriolis effect at equatorDue to minimal Coriolis effect at equator
Subpolar GyresSubpolar GyresSubpolar Gyres Subpolar Gyres –– Rotate opposite subtropical gyresRotate opposite subtropical gyres–– Smaller and fewer than subtropical gyresSmaller and fewer than subtropical gyres
Ekman Spiral and Ekman TransportEkman Spiral and Ekman Transport
Observation that Arctic Ocean ice moved at a Observation that Arctic Ocean ice moved at a 2020-- to 40to 40--degree angle to the right of the winddegree angle to the right of the windSouthern Hemisphere movement to the left of Southern Hemisphere movement to the left of the windthe windthe windthe wind
Ekman SpiralEkman Spiral
V. Walfrid Ekman V. Walfrid Ekman –– Developed circulation model in 1905Developed circulation model in 1905
Ekman spiral Ekman spiral –– Explains balance between friction andExplains balance between friction andExplains balance between friction and Explains balance between friction and
Coriolis effectCoriolis effect–– Describes direction and flow of Describes direction and flow of
surface waters at different depthssurface waters at different depths
Ekman spiralEkman spiralSurface currents move at angle to windSurface currents move at angle to windEkman spiral describes speed and direction of Ekman spiral describes speed and direction of seawater flow at different depthsseawater flow at different depthsEach successive layer moves increasingly to right Each successive layer moves increasingly to right (N hemisphere)(N hemisphere)
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
Ekman transportEkman transportAverage movement of seawater under influence of Average movement of seawater under influence of windwind9090oo to right of wind in Northern hemisphereto right of wind in Northern hemisphere9090oo to left of wind in Southern hemisphereto left of wind in Southern hemisphere
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
Ekman SpiralEkman Spiral
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Geostrophic flowGeostrophic flowEkman transport Ekman transport piles up water piles up water within subtropical within subtropical gyresgyresSurface water Surface water flows downhill flows downhill (gravity) and(gravity) and
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
Also to the right Also to the right (Coriolis effect)(Coriolis effect)Balance of Balance of downhill and to downhill and to the right causes the right causes geostrophic flow geostrophic flow around the “hill”around the “hill”
Western IntensificationWestern IntensificationTop of hill of water displaced toward west Top of hill of water displaced toward west due to Earth’s rotation.due to Earth’s rotation.Western boundary currents intensified in Western boundary currents intensified in both hemispheres.both hemispheres.–– FasterFaster–– NarrowerNarrower–– DeeperDeeper–– WarmerWarmer
Coriolis effect contributes to western Coriolis effect contributes to western intensification.intensification.
Eastern Boundary CurrentsEastern Boundary CurrentsEastern side of ocean basinsEastern side of ocean basinsTend to have the opposite properties of Tend to have the opposite properties of Western Boundary CurrentsWestern Boundary Currents–– ColdCold–– SlowSlow–– ShallowShallow–– WideWide
Eastern and Western Boundary CurrentsEastern and Western Boundary Currents
Ocean currents and climateOcean currents and climate
Warm ocean currents warm air at Warm ocean currents warm air at coastcoast–– Warm, humid airWarm, humid air
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
–– Humid climate on adjoining landmassHumid climate on adjoining landmassCool ocean currents cool air at coastCool ocean currents cool air at coast–– Cool, dry airCool, dry air–– Dry climate on adjoining landmassDry climate on adjoining landmass
Ocean currents and climateOcean currents and climate
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil FarquharsonAverage AugustTemperatures
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Ocean currents and climateOcean currents and climateAverage February
Temperatures
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
Upwelling and DownwellingUpwelling and Downwelling
UpwellingUpwelling –– Vertical movement of cold, Vertical movement of cold, nutrientnutrient--rich water to surfacerich water to surface–– High biological High biological productivity productivity –– an abundance of an abundance of
l t th b f th f d bl t th b f th f d balgae at the base of the food webalgae at the base of the food webDownwellingDownwelling –– Vertical movement of Vertical movement of surface water downward in water columnsurface water downward in water column
Diverging surface seawaterDiverging surface seawaterSurface Surface seawater seawater moves away moves away Deeper Deeper seawater seawater (cooler, (cooler, nutrientnutrient--rich) rich) replacesreplacesreplaces replaces surface watersurface waterUpwellingUpwellingHigh High biological biological productivityproductivity Fig. 7.9
Converging surface seawaterConverging surface seawaterSurface seawater Surface seawater moves towards moves towards an areaan areaSurface seawater Surface seawater piles uppiles up
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
Seawater moves Seawater moves downwarddownwardDownwellingDownwellingLow biological Low biological productivityproductivity
Coastal upwelling and downwellingCoastal upwelling and downwelling
Ekman transport Ekman transport moves surface moves surface seawater seawater onshore onshore (downwelling) or(downwelling) or
Oceanography Oceanography 112 112 –– Phil FarquharsonPhil Farquharson
Offshore Offshore (upwelling)(upwelling)
Coastal upwelling and downwellingCoastal upwelling and downwelling
Ekman transport Ekman transport moves surface moves surface seawater seawater onshore onshore (downwelling) or(downwelling) or
Oceanography Oceanography 112 112 –– Phil FarquharsonPhil Farquharson
Offshore Offshore (upwelling)(upwelling)
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Other Causes of UpwellingOther Causes of Upwelling
Offshore windsOffshore windsSeafloor Seafloor obstruction obstruction Coastal Coastal
t ht hgeometry changegeometry changeLack of Lack of pycnoclinepycnocline–– High latitude High latitude
oceansoceans
Antarctic CirculationAntarctic Circulation
Antarctic Circumpolar Antarctic Circumpolar CurrentCurrent–– Also called Also called West Wind West Wind
DriftDrift and and Penguin GyrePenguin Gyre–– Only current toOnly current toOnly current to Only current to
completely encircle completely encircle EarthEarth
–– Moves more water Moves more water than any other currentthan any other current
Antarctic CirculationAntarctic CirculationAntarctic ConvergenceAntarctic Convergence–– Cold, dense Antarctic waters converge with Cold, dense Antarctic waters converge with
warmer, less dense subwarmer, less dense sub--Antarctic waters.Antarctic waters.–– Northernmost boundary of Antarctic OceanNorthernmost boundary of Antarctic Ocean
East Wind Drift East Wind Drift –– Polar EasterliesPolar Easterlies–– Creates surface divergence with opposite Creates surface divergence with opposite
flowing Antarctic Circumpolar Currentflowing Antarctic Circumpolar CurrentAntarctic DivergenceAntarctic Divergence–– Abundant marine lifeAbundant marine life
Atlantic Ocean CirculationAtlantic Ocean Circulation
North Atlantic Subtropical North Atlantic Subtropical GyreGyre
–– North Equatorial CurrentNorth Equatorial Current–– Gulf StreamGulf Stream
North Atlantic CurrentNorth Atlantic Current–– North Atlantic CurrentNorth Atlantic Current–– Canary CurrentCanary Current–– South Equatorial CurrentSouth Equatorial Current–– Atlantic Equatorial Counter Atlantic Equatorial Counter CurrentCurrent
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
Atlantic Ocean Atlantic Ocean circulationcirculation
South Atlantic South Atlantic Subtropical GyreSubtropical GyreBrazil CurrentBrazil Current
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
Antarctic Circumpolar Antarctic Circumpolar CurrentCurrentBenguela CurrentBenguela CurrentSouth Equatorial South Equatorial CurrentCurrent
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Gulf StreamGulf StreamBest studied of all ocean currentsBest studied of all ocean currentsMeanders and loopsMeanders and loopsMerges with Merges with Sargasso SeaSargasso Sea–– Circulates around center of North Atlantic GyreCirculates around center of North Atlantic Gyre–– Unique biology Unique biology –– Sargassum Sargassum
Gulf StreamGulf Stream
Meanders or loops may cause loss of water Meanders or loops may cause loss of water volume and generate:volume and generate:
–– WarmWarm--core ringscore rings –– warmer Sargasso Sea water warmer Sargasso Sea water trapped in loop surrounded by cool watertrapped in loop surrounded by cool waterColdCold core ringscore rings cold water trapped in loopcold water trapped in loop–– ColdCold--core rings core rings –– cold water trapped in loop cold water trapped in loop surrounded by warmer watersurrounded by warmer water
Unique biological Unique biological populationspopulations
Gulf StreamGulf Stream
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
Other North Atlantic currentsOther North Atlantic currents
Labrador CurrentLabrador CurrentIrminger CurrentIrminger CurrentNorwegian CurrentNorwegian CurrentNorth Atlantic CurrentNorth Atlantic Current
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
North Atlantic CurrentNorth Atlantic Current
Climate effects of North Atlantic currentsClimate effects of North Atlantic currents
Gulf Stream warms East coast of U.S. and Gulf Stream warms East coast of U.S. and Northern EuropeNorthern EuropeNorth Atlantic and Norwegian Currents North Atlantic and Norwegian Currents warm northwestern Europewarm northwestern Europe
Oceanography Oceanography 101 101 –– Phil FarquharsonPhil Farquharson
ppLabrador Current cools eastern CanadaLabrador Current cools eastern CanadaCanary Current cools North Africa coastCanary Current cools North Africa coast
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Indian Ocean CirculationIndian Ocean Circulation
MonsoonsMonsoons –– seasonal reversal of winds seasonal reversal of winds over northern Indian Oceanover northern Indian OceanHeat Capacity DifferentialHeat Capacity DifferentialNortheast monsoon Northeast monsoon –– winterwinterSouthwest monsoon Southwest monsoon –– summer summer
Indian Ocean CirculationIndian Ocean Circulation
Indian Ocean MonsoonIndian Ocean MonsoonAffects seasonal Affects seasonal land land weather weather Affects seasonal Affects seasonal Indian Indian Ocean current Ocean current circulationcirculationAffects phytoplankton productivityAffects phytoplankton productivity
Indian Ocean CirculationIndian Ocean Circulation
Indian Ocean Subtropical GyreIndian Ocean Subtropical Gyre–– Agulhas CurrentAgulhas Current
Australian CurrentAustralian Current–– Australian CurrentAustralian Current–– LeeuwinLeeuwin CurrentCurrent
Pacific Ocean CirculationPacific Ocean Circulation
North Pacific Subtropical GyreNorth Pacific Subtropical Gyre–– Kuroshio CurrentKuroshio Current–– North Pacific CurrentNorth Pacific Current–– California CurrentCalifornia Current–– North Equatorial CurrentNorth Equatorial Current–– Alaskan Alaskan CurrentCurrent
Pacific Ocean CirculationPacific Ocean Circulation
South Pacific Subtropical GyreSouth Pacific Subtropical Gyre–– East Australian CurrentEast Australian Current–– Antarctic Circumpolar CurrentAntarctic Circumpolar Current–– Peru CurrentPeru CurrentPeru CurrentPeru Current–– South Equatorial CurrentSouth Equatorial Current–– Equatorial Counter Equatorial Counter CurrentCurrent
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Pacific Ocean Pacific Ocean circulationcirculation
Oceanography Oceanography 112 112 –– Phil FarquharsonPhil Farquharson
Atmospheric and oceanic disturbances Atmospheric and oceanic disturbances in Pacific Oceanin Pacific Ocean
Normal conditionsNormal conditions–– Air pressure across equatorial Pacific is higher Air pressure across equatorial Pacific is higher
in eastern Pacificin eastern PacificStrong southeast trade windsStrong southeast trade winds
Oceanography Oceanography 101 101 –– Phil FarquharsonPhil Farquharson
–– Strong southeast trade windsStrong southeast trade winds–– Pacific warm pool on western sidePacific warm pool on western side–– Thermocline deeper on western sideThermocline deeper on western side–– Upwelling off the coast of PeruUpwelling off the coast of Peru
Normal conditionsNormal conditions
Oceanography Oceanography 112 112 –– Phil FarquharsonPhil Farquharson
Atmospheric and oceanic disturbances Atmospheric and oceanic disturbances in Pacific Oceanin Pacific Ocean
El NiñoEl Niño--Southern Oscillation (ENSO)Southern Oscillation (ENSO)–– Warm (El Niño)Warm (El Niño) and and cold phases (La Niña)cold phases (La Niña)–– High pressure in eastern Pacific weakensHigh pressure in eastern Pacific weakens–– Weaker trade windsWeaker trade winds–– Warm pool migrates eastwardWarm pool migrates eastward–– Thermocline deeper in eastern PacificThermocline deeper in eastern Pacific–– DownwellingDownwelling–– Lower biological productivityLower biological productivity
Corals particularly sensitive to warmer seawaterCorals particularly sensitive to warmer seawater
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
El NiñoEl Niño--Southern Oscillation (ENSO):Southern Oscillation (ENSO):Warm phase (El Niño)Warm phase (El Niño)
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
ENSO Conditions in the Pacific OceanENSO Conditions in the Pacific Ocean
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El NiñoEl Niño--Southern Oscillation (ENSO): Southern Oscillation (ENSO): cool phase (La Niña)cool phase (La Niña)
Increased pressure difference across Increased pressure difference across equatorial Pacificequatorial PacificStronger trade windsStronger trade winds
Oceanography Oceanography 101 101 –– Phil FarquharsonPhil Farquharson
Stronger upwelling in eastern PacificStronger upwelling in eastern PacificShallower thermoclineShallower thermoclineCooler than normal seawaterCooler than normal seawaterHigher biological productivityHigher biological productivity
El NiñoEl Niño--Southern Oscillation (ENSO)Southern Oscillation (ENSO)Cool phase (La Niña)Cool phase (La Niña)
Oceanography Oceanography 101 101 –– Phil FarquharsonPhil Farquharson
La La NiñNiña Conditions a Conditions
El NiEl Niñño and La Nio and La Niññaa
ENSO eventsENSO events
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
ENSO Has Global ImpactsENSO Has Global Impacts
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Notable ENSO Notable ENSO EventsEvents
19821982––1983198319971997––1998 1998 Flooding droughtFlooding droughtFlooding, drought, Flooding, drought, erosion, fires, tropical erosion, fires, tropical storms, harmful storms, harmful effects on marine lifeeffects on marine lifeUnpredictableUnpredictable
Notable ENSO Notable ENSO EventsEvents
19821982––1983198319971997––1998 1998 Flooding droughtFlooding droughtFlooding, drought, Flooding, drought, erosion, fires, tropical erosion, fires, tropical storms, harmful storms, harmful effects on marine lifeeffects on marine lifeUnpredictableUnpredictable
Occurrence of ENSO EventsOccurrence of ENSO EventsEl Niño warm phase about every El Niño warm phase about every 22––10 years10 yearsHighly irregularHighly irregularPhases usually last 12Phases usually last 12––18 months18 months10,00010,000--year sediment record of eventsyear sediment record of events10,00010,000 year sediment record of eventsyear sediment record of eventsENSO may be part of ENSO may be part of Pacific Decadal Pacific Decadal Oscillation (PDO) Oscillation (PDO) –– LongLong--term natural climate cycleterm natural climate cycle–– Lasts 20Lasts 20––30 years30 years
Predicting El Predicting El NiñNiño Events o Events
Tropical OceanTropical Ocean−−Global Atmosphere Global Atmosphere (TOGA) (TOGA) programprogram–– 19851985–– Monitors equatorial South PacificMonitors equatorial South Pacific–– System of buoysSystem of buoysy yy y
Tropical Atmosphere and Ocean (TOA) Tropical Atmosphere and Ocean (TOA) projectproject–– Continues monitoringContinues monitoring
ENSO still not fully ENSO still not fully understoodunderstood
DeepDeep--Ocean CurrentsOcean Currents
Thermohaline Circulation Thermohaline Circulation –– deep ocean deep ocean circulation driven by temperature and circulation driven by temperature and density differences in waterdensity differences in waterBelow the pycnoclineBelow the pycnocline9090% of all ocean water% of all ocean water9090% of all ocean water% of all ocean waterSlow velocitySlow velocity
Thermohaline circulationThermohaline circulation
Movement Movement caused by differences in caused by differences in density (temperature and salinity)density (temperature and salinity)–– Cooler seawater denserCooler seawater denser
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
–– Saltier seawater denserSaltier seawater denser
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Thermohaline CirculationThermohaline Circulation
Originates in high latitude surface oceanOriginates in high latitude surface oceanCooled, now dense surface water sinks Cooled, now dense surface water sinks and changes little.and changes little.DeepDeep water masses identified onwater masses identified onDeepDeep--water masses identified on water masses identified on temperaturetemperature––salinity (Tsalinity (T––S) diagram S) diagram –– Identifies deep water masses based on Identifies deep water masses based on
temperature, salinity, and resulting temperature, salinity, and resulting densitydensity
TT––S S DiagramDiagram
Thermohaline circulationThermohaline circulation
Selected deepSelected deep--water masseswater masses–– Antarctic Bottom WaterAntarctic Bottom Water–– North Atlantic Deep WaterNorth Atlantic Deep Water
Antarctic Intermediate WaterAntarctic Intermediate Water
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
–– Antarctic Intermediate WaterAntarctic Intermediate Water–– Oceanic Common WaterOceanic Common Water
Cold surface seawater sinks at polar regions Cold surface seawater sinks at polar regions and moves toward equatorand moves toward equator
Thermohaline circulationThermohaline circulation
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
Thermohaline circulationThermohaline circulation
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
ConveyorConveyor--belt circulationbelt circulationCombination deep ocean currents and surface currentsCombination deep ocean currents and surface currents
Oceanography 112 Oceanography 112 –– Phil FarquharsonPhil Farquharson
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Deep ocean currentsDeep ocean currents
Cold, oxygenCold, oxygen--rich surface water to deep rich surface water to deep oceanoceanDissolved ODissolved O22 important for life and mineral important for life and mineral processesprocesses
Oceanography 101 Oceanography 101 –– Phil FarquharsonPhil Farquharson
processesprocessesChanges in thermohaline circulation can Changes in thermohaline circulation can cause global climate changecause global climate change–– Example, warmer surface waters less dense, Example, warmer surface waters less dense,
not sink, less oxygen deep oceannot sink, less oxygen deep ocean
Power from CurrentsPower from Currents
Currents carry more Currents carry more energy than winds.energy than winds.FloridaFlorida––Gulf Stream Gulf Stream Current SystemCurrent SystemyyUnderwater turbinesUnderwater turbines–– ExpensiveExpensive–– Difficult to maintainDifficult to maintain–– Hazard to boating Hazard to boating
End of CHAPTER 7End of CHAPTER 7Ocean CirculationOcean Circulation
Oceanography Oceanography 112 112 –– Phil FarquharsonPhil Farquharson