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Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
Ocean Circulation
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Ocean Circulation

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  • 1. Chapter 8: Ocean CirculationFig. 8-26
  • 2. Ocean currents move largeamounts of water and heat Wind-drivensurface oceancirculation Density-drivendeep-oceancirculation Both redistributeheat from warmerregions to coolerFig. 8-16
  • 3. Measuring ocean currents Direct measurement Floating objects/instruments Fixed instruments Indirect measurement Distribution of density Satellite data Doppler flow meter Chemical tracers Distinctive water masses
  • 4. Surface currents Frictional drag due to winds Surface currents similar to global winds Continents affect surface currentpatterns Other factors:GravityFrictionCoriolis Effect
  • 5. Subtropical gyres Large circular flow Clockwise in northern oceans,e.g., North Atlantic Counterclockwise in southernoceans, e.g., South Atlantic 4 main currents in each gyre
  • 6. Ekman spiral and Ekmantransport  Ekman transportmoves surfaceseawater about90oto the right ofthe wind in theNorthernHemisphere 90oleft inSouthernHemisphereFig. 8-6a
  • 7. Western intensification “Hill” of seawater is steeper on western side Western currents are fast, narrow, deep
  • 8. Subtropical gyres Ekman transportpiles up “hill” ofseawater at about30oN and S Water flows downhillunder gravity andveers right (Northernhemisphere) due toCoriolis Effect Circular flow Fig. 8-7
  • 9. Upwelling Ekman transportmoves seawateroffshore Ekman transportmoves seawateraway fromanother watermassFig. 8-11a
  • 10.  Cooler, nutrient-rich water risesvertically towardsea surface High biologicproductivity DownwellingoppositeFig. 8-11b
  • 11. Surface currents Pattern similar in major oceanbasins Northern ocean gyre movesclockwise Southern ocean gyre movescounter-clockwise
  • 12. Antarctic circulation Antarctic Circumpolar Current (orWest Wind Drift) Greatest volume Connects main oceans East Wind Drift Antarctic Divergence (upwelling)
  • 13. North Atlantic Circulation North Equatorial Current Gulf Stream North Atlantic Current Gulf Stream and North AtlanticCurrents warm Europe Canary Current
  • 14. North Equatorial Current
  • 15. Gulf Stream
  • 16. North Atlantic Current
  • 17. Canary Current
  • 18. South Atlantic Ocean South Equatorial Current Brazil Current Antarctic Circumpolar Current Greatest volume Connects three main oceans Benguela Current
  • 19. South Equatorial current
  • 20. Brazil Current
  • 21. Benguela Current
  • 22. North Pacific Ocean North Equatorial Current Kuroshio Current North Pacific Current California Current Strong Equatorial Counter Current
  • 23. South Pacific Ocean South Equatorial Current East Australian Current Antarctic Circumpolar Current Peru Current Strong Equatorial Counter Current
  • 24. ENSO El Niño-SouthernOscillation Irregular shift in ocean andatmosphere characteristics every 2-10 years Affects global climate Harmful and beneficialconsequences
  • 25. El Niño ENSO Warm Phase Most obvious in Equatorial Pacific Pacific Warm Pool moves eastward acrossEquatorial Pacific Changes in pattern of upwelling/downwellingin eastern Pacific OceanFig. 8-2
  • 26. ENSO warm phase effects Warmer seawater higher sea level Warmer seawater less upwelling ineastern Pacific Lower biologic productivity Warmer seawater kills some marine life Shift in atmosphere pressure Shift in areas of precipitation
  • 27. La Niña ENSO Cool Phase Stronger tradewinds Warm pool stays in western Pacific Increased upwelling in eastern Pacific Shift in precipitation patterns Shift in atmospheric pressure
  • 28. ENSO data collection TOGA Tropical Ocean GlobalAtmosphere TAO Tropical Atmosphere Ocean Monitor ocean and atmosphere Data indicate what phase ENSO Pacific Decadal Oscillation Decades-long cycles of warmingand cooling in Pacific Ocean
  • 29. Indian Ocean Circulation North and South Equatorial Currents Equatorial Counter Current Agulhas Current Antarctic Circumpolar Current West Australian Seasonal shifts (monsoons) of windsand currents
  • 30. Thermohaline circulation 90% of world ocean Below pycnocline Large volumes ofseawater Extremely slowspeed Each ocean basin issimilar in deep-ocean circulation
  • 31. Sources of deep water Densest seawater is cold Most deep water masses frompolar oceans Sink to density level and movehorizontally
  • 32. Antarctic Bottom Water Densest deep water(coldest) Sinks aroundAntarctica Most widespreaddeep-water mass Found as far as40oN Carries O2 into deepocean Fig. 8-25
  • 33. North Atlantic Deep Water Complex mixtureof cold seawaterfrom Norwegiansea mixing with Gulf Stream MediterraneanIntermediateWater Other NA watermasses Extends fromNorth Atlantic toabout 40osouth
  • 34. Intermediate Water Masses Antarctic Intermediate Water Sinks at Antarctic Convergence Cold Salinity less than average Mediterranean Intermediate Water Warm Very salty
  • 35. Conveyor Belt Circulation Mixture of surfaceocean circulationand deep-oceancirculation Mixes surfaceand deep Mixes waters indifferent oceans Fig. 8-26
  • 36. Langmuir Circulation Alternately converging and divergingconvection cells Wind blowing over calm ocean Alternate rows of upwelling and downwelling
  • 37. End of Chapter 8: OceanCirculation

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