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