History of Ocean Exploration 9 April 2018 - uaf.edu · navigator who observed the sun’s height at noon. ... Not until the invention of the chronometer in early 1700s did ... Early

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.