HistoryofOceanExploration
9April2018• MarkJohnson,PhysicalOceanography(oceanphysics)
• Seehttp://www.uaf.edu/cfos/people/faculty/detail/index.xml?id=146
THEN:DarwinleftLondonforPlymouthon16October1831toprepareforthestartofthevoyage.Afewofthescientificitemshebroughtwithhimincluded:1microscope(asinglelensmodelbyBancks&Son,London)1geologicalcompass,1plaincompass2pistols(withspareparts),1rifle(withspareparts)1telescope1geologicalhammer5simisometers[probablysympiesometer,alightweight
barometer]3mountainbarometers1clinometer1cameraobscura1hygrometer(belongedtoFitzRoy)NOW:
Darwinwasgivenquartersinthechartroom,onedeckaboveCapt.FitzRoy'squarters,atthesternoftheship.Itwas9feetby11with5feetofheadroomwithbookshelves,cabinets,anoven,andawashstand,plusa4x6charttableinthemiddle.Therewasabout6feetby8feetofroomtoworkin.Darwinlivedinthisroom,onandoff,fornearlyfiveyearssettingthestageforhisthetheoryofevolution.
Beaglereplica(90ft)RVSikuliaq(262ft)
Astudyofhistoryusesthepasttobetterunderstandthepresent.
Wherearewe?TheearlyPolynesiansknewabuttheocean,withoutlatitudeandlongitude,clocks,orsatnavigation.
Estimatingone’slatitudewasdonebythenavigatorwhoobservedthesun’sheightatnoon.Atnight,thepositionoftheNorthStarandtheorientationofmajorconstellationshelpeddetermineaship’slocation.SolutionstofindingthecorrectlatitudebeginwiththeArabnavigatorswhousedthe“Kamal,”alengthofcordattachedatthecentertoarectangleofwood.Thecordhadknotsinitthatcorrespondedtothelatitudeofknownports.Thenavigatorheldtheknottohiseye,lineduptheloweredgeoftheboardwiththehorizonandtheupperedgecorrespondedtothecorrectlatitudewhenitalignedwiththenoonsun.
TheCross-staff,inventedaround400B.C.,wasproposedfornavigationbyJohannWernerin1514.Thecross-staff’ssinglevanewasmovedtotoalignthehorizonandthesunorothercelestialbody.Ithadtwocriticalproblems.First,theuserwaslookingdirectlyattheblindingsun,andsecond,tryingtosightitandthehorizonatthesametimemeanthavingtofocusontwoobjectssimultaneously,animpossibletaskforthehumaneye.
TheQuadrant,adeviceformeasuringthealtitudeofacelestialbody,wasfirstrecordedinusein1461.TheQuadrantdidnotrequiresightofthehorizon.ItdidrequirestaringintotheSuninordertofinditsaltitude.
TheAstrolabewasadaptedformarinenavigationaround1480.Itwasheldbythethumbringatthetop,aboveeyelevelandthealidade,thepointerinthecenter,wasalignedtopointtothesun.Thealtitudewasthenreadoffthewheelandthatcorrespondstothelongitude..
Longitudeisadifferentproblem,anddependsonknowingthetime,whichwasmeasuredbyasandglass.Notuntiltheinventionofthechronometerinearly1700sdidestimatinglongitudebegintobereliable.Measuringtimeatsea,hencemeasuringlongitude,wassolvedwiththeinventionofthechronometerinearly1700sbyJohnHarrison.OncelocaltimewasknownasanoffsetfromLisbon(orone’shomeport),thenestimatinglongitudewaspossible.JamesCookhadtwoHarrisonchronometersonboardtheEndeavorduringhisfirstPacificnavigationin1768.
NOW:GPSprovidespositioningtowithinameterorless.
Earlyoceanexplorationfocusedonmappingtheworldandexpandingtheknownboundaries.
AtleftisCook’sdrawingsofTahitimadewhileobservingtheTransitofVenusin1769.AtrightisasatelliteviewofTahitifromGoogleEarth.GoogleEarthusesLandsatimagerynearly250yearslatertoshowanimprovedpictureofMoorea.Bothimagesshowtheshallowbeachessurroundingtheislands.GoogleEarthimagehasbetterinlanddetails.
1665:RobertHooke’sinstrumentformeasuringpressure(depth)
RobertHooke’sinstrumentforcollectingwatersamples
AFundamentallyImportantOceanographicExpeditionfrom1872-1876TheHMSChallenger,asailingshipof2,300tonswithauxiliarysteampower,conductedoneofthemajorexpeditionseverwithfundingfromtheTheBritishRoyalSociety.Challengerwastaskedtosystematicallycollectobservationsoftheoceansevery200milesandmeasurethedepthtotheseafloorandmeasuretemperatureatvariousdepths.Usingasoundingrope,theycollectedwatersamplesanddredgedthebottomforrocksanddeep-seamarinelife.TheChallengerexpeditionestablishedthegeneralprotocolforallexpeditionstofollowinthenext50years.Theresultsfromtheexpeditionfillastaggering50volumes.
ModernOceanography
• Fourmaindisciplines– Biological– Chemical– Geological– Physical
AdvancesinGeologicalOceanographyThedevelopmentofthetheoryofPlateTectonicswasascientificrevolutiondatingtoWegner'stheoryofcontinentaldriftfromthe1920s.
AmajoradvanceingeologicalOceanographyisthereconstructionoftheearthspaleo-climatesfromdeepseacores.
Deep-seadrillshipJoidesResolution
Coresbeingsampled.
PriortoWorldWarII,biologicaloceanographyhadtwocentralthemes.Fisheriessciencewasthefirsttheme,focusingonfindingwherethegreatfisherieswerelocated,whytheyvariedinspaceandtime,andattemptedtofindwheremoreresourcesbefound.Todaythisfieldisreally“fisheriesoceanography.”
Achievementsinbiologicaloceanography
Thesecondmajorthemewassimplynewdiscoverieswherethegoalwasincreasingknowledgeforthesakeofknowledge.AfterWWII,theproblemsofpollutionanditstransportrequiredthatweknowhowtheoceanfunctionedsoitcouldbemanagedandtheconceptofsustainabilitybecamemorewidespread.
AfterWWII,oneofthemostimportantbiologicaloceanographicdiscoverieswastheunexpectedfindingofchemosynthetichydrothermalventcommunities.Insteadofsunlight,thesecommunitiesreliedonbacteria.Theywerefirstdiscoveredin1977neartheGalapagosislands.
Thishydrothermalventcommunity,locatedontheGalapagosRift,includesgianttubeworms(Riftiapachyptila),mussels(Bathymodiolusthermophilus),andcrabs(Bythograeathermydron)atadepthof2,500mdepth.(PhotobyFredGrasslel,WHOI)
Chemosyntheticecosystemshaveturnedupeverywhereintheocean:onthecontinentalshelvesandslopes,inthedeepsea,atplatemargins,andridgecrests
Autotrophicbacteria(abletoformnutritionalorganicsubstancesfromsimpleinorganicsubstancessuchascarbondioxide)oxidizehydrogensulfideinventwatertoobtainenergy,whichisthenusedtoproduceorganicmaterialforgrowth.Theprimaryproducers(plantsinourphotosyntheticworld)intheventsarechemosyntheticbacteriathatformthebaseofventfoodwebs.Allventanimalsultimatelydependonthesebacteriaforfood.
In1978,theCoastalZoneColorScanner(CZCS)waslaunchedandshowed,forthefirsttime,thecoherenceofoceanbiology,revealingitspatterns,variability,andcomplexity,totheoceanographiccommunity.
CZCSwasfollowedin1997byanimprovedU.S.oceancolorsatelliteSea-ViewingWideFieldofViewSensor(SeaWiFS).
Oceancolorshowedthat(1)theoceanisveryundersampled,(2)mesoscale(basin)physicalprocessesdeterminethespatialdistributionofphytoplankton,(3)bottomtopographyorbathymetryinfluencesplantbiomass,(4)thereiscomplexityintheseasonalphytoplanktonsignal,and(5)themagnitudeofinterannualvariabilityisbetterknown.
Specificadvancesinbiologicaloceanography1. Understandingofdeep-seadiversityinthelate1960sfueleddebatesonhowdiversityis
maintainedinalarge,monotonousenvironment.
2. ThelandmarkachievementbyDugdaleandJohnGoering(1967)showingthatprimaryproductivityintheoceancanbedividedintolocallyrecyclednutrients,regeneratedproduction,andnewnutrientstransportedintotheeuphoticzoneasnewproduction.Thisisdrivenbythephysicalprocessesofmixingandupwelling.
3. Determiningthatzooplanktonswim,feed,breed,andliveinaviscous,highlystructuredmedium.
In1998,amajoroceanographicdiscoveryoceanographycamefromestimatesofsubseafloorsedimentarymicrobialabundancewhichsuggestedmicrobesmayaccountfor27–33%ofEarth’slivingbiomass.Thisisanastonishingandpreviouslyunheardamountofbiomass,althoughmorerecentestimatesreducethisestimatesomewhat.
AdvancesinChemicalOceanographyAristotleconsideredtheoriginsofsaltinthesea,and,sinceAristotle'stime,manyscientistshavemadesignificantcontributionstounderstandingthechemistryoftheoceans.In1647,RobertBoylewrote"ObservationsandExperimentAbouttheSaltnessoftheSea”,whichestablishedhimasthefounderchemicaloceanography.
ItwasWilliamDittmarwhoundertooktheanalysesofseawatertoestablishtheconstancyofratiosofthemajorionsinseawater.Dittmar'sreportonseawaterchemistrybasedonthe77watersamplesofthe'Challenger'expeditionwasthemostextensiveseawateranalysisperformedatthattime.
Thefocustodayisonuseofgeochemicaltracersandquantifyingratesandfluxes,particularlyofcarbonasCO2andradionuclides.
AchievementsinPhysicalOceanography
Inthe1940sand1950sageneralunderstandingoftheabyssalcirculationwaslaid-out.Inthe1950s,thebasiccurrentsweresowellknownthatthesurfacecurrentswereonhandkerchiefsgiventopilotsshouldtheyneedit.Seehttp://www.escape-maps.com/escape_maps/map_list_wwii_us_liferaft.htm
AchievementsinPhysicalOceanography
TheEkmanSpiralAllstudentsofoceanographylearnabouttheEkmanspiral,anelegantearly-centurymathematicalsolutiontothewind-drivencurrentprofile.
AchievementsinPhysicalOceanography
Duringthe1950sand1960s,thedevelopmentofthe“Hydrographicmethod”allowedoceanographerstodeterminecurrentsbasedonmeasurementsofTemperature,Salinity,andPressure.
AchievementsinPhysicalOceanography
Advancesinourthinking:Pre-1970theoceanwasviewedas“steadystate”.After1970thefocuswasonmesoscale(basinscale)variabilitywhere99%ofthekineticenergyisfound.Thisincludesinternalwaves,edgewaves,mixingevents,andothertime-dependentprocesses.TheoceanisMUCHmoreenergeticthanwerealized.Today,weaskwhereistheoceanenergysuppliedbythewinddissipated?Howanoceanproductivitybesustained?Whatroledooceancurrentsplayintransportingheataroundtheplanet?
AcousticThermometry
Today,manyofthescientificeffortsarefocusedonrestoringormaintainenvironmentalhealth.