the oceans, their basins and circulation drivers · ocean basins over time – plate tectonics *...

TheOceans,TheirBasinsandCirculationDrivers

MorethanyoueverwanttoknowabouttheOceansandtheirbasins

OceansOverview

* TheOceanBasinsandHowTheyareConnected* AtmosphericOceanCirculationDrivers* DensityCurrentCirculationDrivers* Tides* HowtheOceanBasinsHaveChangedOverTime* ViolentStormGenerationandMovement

TopicsofDiscussion

OceanBasins

EasternPacific Atlantic

Indian

WesternPacific

Arctic

Antarctic

DifferenceBetweenanOceanandaSea

SeasarefoundonthemarginsoftheoceanandarepartiallyenclosedbyLand.AboveyoucanSeethattheBeringSeaispartofthePacificOcean

BeringSea

PacificOcean

OceanBasinFeatures

HowweMaptheBottom

WhatitMightbeLiketoTravelThrough

*  Theatmosphereaffectstheoceansandisinturninfluencedbythem–ASymbioticRelationship

*  Windcreateswavesandinfluencestheoceancurrents*  Strongwindsproducedropletsthatareabsorbedbythe

atmospherecreatingnucleifortheformationoffogandotherphenomena

*  Whenwaterevaporates,heatisremovedfromtheoceansandstoredintheatmosphere

*  Whencondensationoccurs,thisstoredheatisreleasedtotheatmospheretodevelopthemechanicalenergyofitsmotion

*  Theatmosphereobtainsnearlyhalfofitsenergyforcirculationfromthecondensationofevaporatedoceanwater

*  Thepatternofatmosphericcirculationlargelydeterminesthepatternofoceanicsurfacecirculation

*  Thepatternofatmosphericcirculationlargelydeterminesthepatternofoceanicsurfacecirculationaswellasthelocationofcloudswhichinfluencethetemperatureoftheoceans*  InorganicSymbiosisatitsbest

RelationshipBetweenTheOceansandtheAtmosphere

*  Twoforcesproducethenon-tidaloceancurrents*  Thewindexertingastressontheseasurface*  Fluxesbetweentheoceanandatmospherethatalterthe

densityofthesurfacewater*  Theformerinducesthewinddrivenoceancirculation,the

latterthethermo-halinecirculation(DensityDriven)

*  SurfacewaterismadedenserthroughtheremovalofheatandfreshwatergivingDensitydrivencurrents*  Surfacelayerdescendstodeeperdepths*  Canreachthedeepseafloor*  Thiscirculationiscalledthermo-halinecirculationand

engagesthefullvolumeoftheoceanintotheclimatesystem*  Thusoceanwater'meets'andinteractsdirectlywiththe

atmosphereaboutevery100-1000years

CirculationDriversOfTheOceansOr

MoreThanYouWouldEverWantToKnow

*  RedistributionofthebuoyantsurfacelayerinducesWindDriven*  Sealevel"valleys"indivergentregions*  Andsealevel"hills"inconvergenceregions*  Hillsandvalleysamounttoonlya1.5meterinamplitude*  Induceshorizontalpressuregradientswhichinitiatewinddrivencirculation

*  Winddrivencirculationislargeclock-wiseandcounterclock-wiseflowinggyres(circularpattern)Thenormalcurrents

*  TheEkmanLayertransport(windstress)isat90°tothedirectionofthewind,*  Rightofthewindinthenorthernhemisphere*  Leftofthewindinthesouthernhemisphere.*  Canproducedivergence(upwelling)orconvergence(sinking)ofsurfacewater

*  Thesurfacelayerislessdense(morebuoyant)thandeeperlayers*  TheEkmantransportfieldactstoredistributethebuoyantsurfacewater*  Thinsthebuoyancysurfacelayerindivergenceregions*  Thickensthebuoyantsurfacelayerinconvergenceregions

*  Thuswehaveaverticalandhorizontalcirculationsystemthatisinfluencedbythepositionofthecontinents

CirculationDriversOfTheOceans(Cont.)

Oceancurrents“conveyorbelt”

TidalGeneration

WhatWeAreAlreadySeeingintheUS

*  PlateTectonicsisthenowacceptedtermfortheprocessesofseafloorspreadingandcontinentaldrift*  AlfredWegneratthebeginningofthe20thCentury

discoveredaremarkablesimilarityofgeologicfeatures,fossils,andcontinentalcoastalfits*  Suggestedthecontinentsmusthavebeenconnectedata

pasttime*  Suggestedthattheydriftedapart.*  Problem–nomechanism

*  PlateTectonicstotherescuebyidentifyingthemechanismsthatdrivesthemovementofthecontinents*  Astorythatmustbetoldinanotherdiscussionbuthereis

theshortversion

OceanBasinsOverTime–PlateTectonics

*  Tropicalstormsoccurinseveraloftheworld'soceans,andtheyareessentiallythesametypeofstorm.IntheAtlanticOcean,GulfofMexico,andtheEasternPacificOcean,theyarecalledhurricanes.IntheWesternPacificOcean,theyarecalledtyphoons

*  Watervaporisthe"fuel"forthehurricanesbecauseitreleasesthe"latentheatofcondensation"whenitcondensestoformcloudsandrain,warmingthesurroundingair*  Inthisway,Hurricanesaswellasviolentstormsarethewaythattheatmosphere

releasessomeofitsstoredenergy*  Hurricanesareviolentstormswhichcanbringintensewinds,heavyrain,astorm

surge,floods,coastalerosion,landslides,andalsospawntornadoes*  TropicalCyclonesasthesestormsaregenerallynamedoriginateover

tropicalorsubtropicalwatersandrotateclockwiseinthesouthernhemisphereandcounter-clockwiseinthenorthernhemisphere.*  RotationisduetotheCariolesEffect–relatedtothefactthattheEarthisa

sphereandthespeedofrotationisfasterattheequatorthanatthepoles*  Thinkofamerry-go-round

Hurricanes

Questions?

Tides

IllustrationofThermo-halineCirculation

ElNino–LaNina

NormalCurrents

PlateTectonics

DifferenceFromTornadoes