GP17 in the context of the global survey€¦ · Cruise (s) Nov 2021 – Feb 2022 Fill-gap...
Transcript of GP17 in the context of the global survey€¦ · Cruise (s) Nov 2021 – Feb 2022 Fill-gap...
GP17inthecontextoftheglobalsurvey
GP17
SeaWiFS-AnnualMeanChlorophyll
https://earthobservatory.nasa.gov/IOTD/view.php?id=4097
GP17-LowestmodeldustfluxintheSouthernOcean
AresurfaceFeconcentrationscorrelatedwithmodern(model)dustflux?TestbycomparingGP17withothersections(pink).DustmodelofAlbani,Mahowaldetal.,2014
MotivationfortheGP17Section1) Ultra-oligotrophic South Pacific Gyre
Low dust, productivity, particles – impact on scavenging? Record deep DCM – impact on colloid cycling?
2) Southern Ocean regulation of global biological pump efficiency Upwelling hot spots – source of Fe? Dust vs. upwelling sources of micronutrients SE Pacific low biomass – control by Fe, MLD, other?
3) Dispersal of continental sources of micronutrients Basal melt Subglacial meltwater runoff Extent of signal
4) Outflow of Fe carried by Pacific Deep Water Large Fe sources from margins and ridges How much reaches Southern Ocean? Stabilization of Fe (and other TEIs) by ligands
P16FeandNitrate
Fe and N have similar distributions in the north, dissimilar in the south. Causes & consequences for ecosystems? Complements of Chris Measures & Mariko Hatta
P16FeandAl
SPSG: High Al coincides with low Fe – ultra-low scavenging intensity? Complements of Chris Measures & Mariko Hatta
P16FeandAl
Low Al in the Southern Ocean – diatom scavenging? Complements of Chris Measures & Mariko Hatta
GP17TentativeCruiseTrack
NBP1702 with Orsi climatological fronts
TempandSalinity
UCDW
SAF?
AlittletrickytosaywhatthenorthwardextentofthesubsurfaceTminimumis–seemstogomuchfurthernorththanwhatyou’dusuallycalltheAPF
DatafromRebeccaRobinson&MarkBrzezinski
UCDWLCDW?
ObviousO2minimumassociatedwithUCDW
Oxygen
DatafromRebeccaRobinson&MarkBrzezinski
dSiandbSi
ConsistencybetweenSiOH4drawdownat61-63ºSwithhighestbSivaluesthere–regionofmostintensediatomproductivity.HighSiOH4southof63S(incompleteutilizationofnutrientssuppliedbydeepwintermixing?),lowSiOH4inwaterscarriednorthof~61SbyEkmantransport
DatafromRebeccaRobinson&MarkBrzezinski
PicturefromSi*isthesame–surfaceSi*valuesarelowestat62S,higherbutstillnegativeat63S,andpositiveat64S.
Note500mdepthscale
DatafromRebeccaRobinson&MarkBrzezinski
Si*=[Si]–[NO3]
PicturefromSi*isthesame–surfaceSi*valuesarelowestat62S,higherbutstillnegativeat63S,andpositiveat64S.
Note500mdepthscale
DatafromRebeccaRobinson&MarkBrzezinski
Si*=[Si]–[NO3]
Entire SH nutrient source has negative Si* because of processes occurring here
WhatisthesourceofdFetosupportthisdiatomgrowth?
DatafromRebeccaRobinson&MarkBrzezinski
Si*=[Si]–[NO3]
Entire SH nutrient source has negative Si* because of processes occurring here
NutrientdataisconsistentwithlocationsofmostintenseParemovalanddecouplingalongneutraldensitysurfaces.
LowestsurfacePafrom63S-61S
Strongestisopycnal231Pagradientsat/belowyn=27.6openupbetweenstation7(62S)andstation5(63S)
NutrientdataisconsistentwithlocationsofmostintenseParemovalanddecouplingalongneutraldensitysurfaces.
LowestsurfacePafrom63S-61S
Strongestisopycnal231Pagradientsat/belowyn=27.6openupbetweenstation7(62S)andstation5(63S)
WhatotherTEIsarescavengedbyopalaswell?Al?
Samplingresolution
Standard GEOTRACES sampling at 5° resolution could miss the zone of maximum diatom productivity Higher resolution sampling is essential
IronsourceandimplicationsSouthoftheAPF
JGOFS Hypothesis: FescarcitylimitsdSiutilizationsouthoftheSBACCImplications:
dFeinupwelledUCDWissufficientforcompletedSiconsumptiondFeismuchlowerinLCDWupwelledfurthersouthQuestion:Ifso,ishigherdFeinUCDWhydrothermal?
IronsourceandimplicationsNorthoftheAPF
Fe Recycling Hypothesis:
Landing:AerosolsourceofFeissufficientforPPintheNPacificAerosolFeisinsufficientforPPintheSPacific (P6TEIdata+Satellite-basedmodels)H1:LateralsourceofbioavailabledFeH2:PlanktonrecycleFemoreefficientlyintheSPacific(Rafter
hypothesis) InvokedbySchlosseretal.forSAtlantic Testableusingsiderophoremeasurements(ReneBoiteau/
DanRepeta) ParticlesintheSPSGwithultralowdustfluxesshouldhave
highFe/TiratiosifthereisasourceofdFefromupwellingorfromlateraltransportbycurrents.
Nfixation:ControlsandConsequencesGP15 + GP17 will sample:
3regimesw/oNfixation(SNP,EqPac,SoOcean)2regimeswithNfixation(NPSG,SPSG)
Wangetal.,Nature,2019(w/News&ViewsbyGruber) offerpredictions(hypotheses)aboutglobalNfixation testablewithGEOTRACESdataonGP15+GP17
DodissolvedandparticulateTEIdata(includingNisotopes) supporttheseparadigms? WhatroledoesFeplay?
ComparewithNAtlantic(GA03)totesthypothesisthat lowPlimitsNfixationintheNAtlantic (needsGEOTRACESnanonutrients)
SoOceanprocessessetend-memberwatermassmicronutrientcomposition
Biological uptake:
ForCd,Zn,others(?)ismuchgreaterintheSouthernOcean thanatlowerlatitudes.Why?
H1:ResponsetoFelimitationH2:dMeinupwelledwaterexceedsligandconcentration Highconcentrationsoffreeinorganicions “Luxury”uptakeoffreemetal
SoOceanprocessessetend-memberwatermassmicronutrientcomposition
Regeneration:
ForCd,Zn,others(?)ismuchgreaterintheSouthernOcean thanatlowerlatitudes(becauseofhighuptake).
Highlatitudedataneededtosetend-memberMe/Pratios
EssentialforOMPAanalysistoderiveregeneratedTEIs atlowerlatitudes
Notonlymicronutrients e.g.,OMPAevidenceforsubstantialbenthicREEsource
SoOceanprocessessetend-memberwatermassmicronutrientcomposition
Regeneration:
ForCd,Zn,others(?)ismuchFASTERintheSouthernOcean thanatlowerlatitudes(becauseofhighuptake).
But-Martinpowerlawabsolute“b”values(0.2–0.5)seemto
betoosmall(bothinSoOcandatlowlatitudes) BasedoninversemodelofRoshanetal.(2018)
TestableusingGEOTRACESdata Calculate“b”valuesforTEIsacrossgradientsin nutrients,productivityandecosystems
SamplingoffChile
PDWfluxtoSoOcean
concentratedalongeasternboundary
3Hedistributionandflowinthelayer27.98kgm−3<γn<28kgm−3
a) Observationsb) Posteriormean
Faure&Speer,2012SeealsoTamsittetal.2017,2018
PDWfluxtoSoOcean
concentratedalongeasternboundary
HighresolutionsamplingneededapproachingChilemargin.
Faure&Speer,2012SeealsoTamsittetal.2017,2018
GP17cruiseandproposaltimeline
Tentative timeline for discussion (working backwards) Cruise (s) Nov 2021 – Feb 2022 Fill-gap proposals Feb 2021 PI proposals Aug 2020 Management proposal Feb 2020 Iftwoshipsthenbacktobackorinsequentialyears?
MotivationfortheGP17Section1) Ultra-oligotrophic South Pacific Gyre
Low dust, productivity, particles – impact on scavenging? Record deep DCM – impact on colloid cycling?
2) Southern Ocean regulation of global biological pump efficiency Upwelling hot spots – source of Fe? Dust vs. upwelling sources of micronutrients SE Pacific low biomass – control by Fe, MLD, other?
3) Dispersal of continental sources of micronutrients Basal melt Subglacial meltwater runoff Extent of signal
4) Outflow of Fe carried by Pacific Deep Water Large Fe sources from margins and ridges How much reaches Southern Ocean? Stabilization of Fe (and other TEIs) by ligands
BIOSOPE–DeepChlorophyllMaximum
FromClaustreetal.,2008
Are colloidal TEIS removed from the DCM under extreme: 1) low dust input 2) Deep DCM?
SPGLocalhydrothermalsignalunlikely
FromFrankiePavia,LDEO
German UltraPac section – 2015/2016 Geostrophic transport is eastward
SPGLocalhydrothermalsignalunlikely
FromFrankiePavia,LDEO
Updated map δ3He at 2500 m
GP17
MotivationfortheGP17Section1) Ultra-oligotrophic South Pacific Gyre
Low dust, productivity, particles – impact on scavenging? Record deep DCM – impact on colloid cycling?
2) Southern Ocean regulation of global biological pump efficiency Upwelling hot spots – source of Fe? Dust vs. upwelling sources of micronutrients SE Pacific low biomass – control by Fe, MLD, other?
3) Dispersal of continental sources of micronutrients Basal melt Subglacial meltwater runoff Extent of signal
4) Outflow of Fe carried by Pacific Deep Water Large Fe sources from margins and ridges How much reaches Southern Ocean? Stabilization of Fe (and other TEIs) by ligands
SEPacificLowChlorophyll–Why?
https://earthobservatory.nasa.gov/IOTD/view.php?id=4097
SEPacificLowChlorophyllrepresentedindifferent
NPPmodels
Winter(left)andsummer(right)NPPFromArteagaetal.,JGR-O,2018
SEPacificLowChlorophyllrepresentedindifferent
NPPmodels
Winter(left)andsummer(right)NPPFromArteagaetal.,JGR-O,2018
Why?LowFesupply?Deepmixedlayers?
SEPacific–DeepWinterMixedLayers
ButMLDinsummerseemsnottobeexceptional.Snapshotfrommonthlyanimationat:https://www.pmel.noaa.gov/mimoc/mimoc_gallery.html
Eddy-drivenupwellinghot-spotsassociatedwithtopography
Locationswhereparticlesreleasedindeepwaterat30°Supwellacross200m.Upwellingisconcentratedin5regionsoftopographyGP17willsampleat2locationsdownstreamofPARhotspot–Fegradient?Tamsittetal.,2017
MotivationfortheGP17Section1) Ultra-oligotrophic South Pacific Gyre
Low dust, productivity, particles – impact on scavenging? Record deep DCM – impact on colloid cycling?
2) Southern Ocean regulation of global biological pump efficiency Upwelling hot spots – source of Fe? Dust vs. upwelling sources of micronutrients SE Pacific low biomass – control by Fe, MLD, other?
3) Dispersal of continental sources of micronutrients Basal melt Subglacial meltwater runoff Extent of signal
4) Outflow of Fe carried by Pacific Deep Water Large Fe sources from margins and ridges How much reaches Southern Ocean? Stabilization of Fe (and other TEIs) by ligands
40
Highbiomassinsomeareassuggestbenthicsourceofironstimulatingphytoplanktongrowth
SeaWiFSImagespreparedforCROZEXProgramCourtesyofRaymondPollardSOC
South-to-NorthsectionofdissolvedFenear90°W(inredonmap)fromdeBaaretal.(1999)
AmundsenseasummaryfromPeteSedwick
South North
DissolvedFedatafromPineIslandPolynya(Gerringaetal.,2012)andGPpr03cruisereport
North-to-SouthDFesectionalongboxinmap
North-to-SouthDFesectionalongboxinmap DFeprofilesfromStn3(seemap)andStn160(inACCnear66°30’S,128°W)
AmundsenseasummaryfromPeteSedwick
SouthNorth
DissolvedtracemetaldatafromAmundsenSeaPolynya(Sherrelletal.,2015)–Shelfsedimentandiceshelfmetalsources.
North-to-SouthDFesectionalongboxinmapDoesnotextendbeyondshelfbreak.
NS
AmundsenseasummaryfromPeteSedwick
AmundsenSeaOden-2007
AmundsenSea–Oden,2007HighTMconcentrations(exceptMn)extendbeyondtheshelfbreak-Sherrellunpublished
CLIVARSP4-2011
ChrisMeasures–unpublisheddata,figuresfromPosterat2012OSM
Circumpolar Section
150˚W Section 170˚W Section
Ross Sea
Antarctic Peninsula
150˚W Section
Coastal inputs from the Antarctic continent
67˚S 76˚S
CLIVARSP4–2011150°WSection
ChrisMeasures–unpublished,Posterat2012OSM
N S
CLIVARSP4–2011CircumpolarSection
ChrisMeasures–unpublished,Posterat2012OSM
Circumpolar Section
177˚E 73˚W
CoastalinputsofFeandMnfromAntarcticPeninsula
East–WestgradientsinmacronutrientsMayalsoinfluencediatomproductivity
Nowotarski,Morton,Neeley,Hatta,Landing,Measures,Grand-PosterComplementsofPeteMorton
HighNO3andlowSiintheeast;UniformlylowFeexceptnearmargins
MotivationfortheGP17Section1) Ultra-oligotrophic South Pacific Gyre
Low dust, productivity, particles – impact on scavenging? Record deep DCM – impact on colloid cycling?
2) Southern Ocean regulation of global biological pump efficiency Upwelling hot spots – source of Fe? Dust vs. upwelling sources of micronutrients SE Pacific low biomass – control by Fe, MLD, other?
3) Dispersal of continental sources of micronutrients Basal melt Subglacial meltwater runoff Extent of signal
• TM from coastal sources extend off the shelf. • How far, and to what extent do they contribute micronutrients
to the broader Southern Ocean? • Provenance and rate tracers are needed.
Challenges-UncertaintyaboutSeaIce
MotivationfortheGP17Section1) Ultra-oligotrophic South Pacific Gyre
Low dust, productivity, particles – impact on scavenging? Record deep DCM – impact on colloid cycling?
2) Southern Ocean regulation of global biological pump efficiency Upwelling hot spots – source of Fe? Dust vs. upwelling sources of micronutrients SE Pacific low biomass – control by Fe, MLD, other?
3) Dispersal of continental sources of micronutrients Basal melt Subglacial meltwater runoff Extent of signal
4) Outflow of Fe carried by Pacific Deep Water Large Fe sources from margins and ridges How much reaches Southern Ocean? Stabilization of Fe (and other TEIs) by ligands
Can’trelyonmodelsforFesupplyfromdeepwatertoSoOceaneuphoticzone
Upwellingtrajectorydependsonmodelresolution
Magenta=1°resolution;Yellow=0.1°ResolutionDrakeetal.,GRL,2018
Upwellingtransittimeto300-misobathdependsonmodelresolution
LagrangiantimescalesofCDWupwellingdecreasefrom87yearsto31yearsto17yearsastheoceanresolutionisrefinedfrom1°to0.25∘to0.1°.Drakeetal.,GRL,2018;SimilarresultsinTamsittetal.,.2017:“Thetimescaleforhalfofthedeepwatertoupwellfrom30°Stothemixedlayeris~60–90years.”
Upwellingtransittimeto300-misobathdependsonmodelresolution
LagrangiantimescalesofCDWupwellingdecreasefrom87yearsto31yearsto17yearsastheoceanresolutionisrefinedfrom1°to0.25∘to0.1°.ThetimescaleupwellingiscomparabletotheresidencetimeofdFeinthedeepocean.WithlargeuncertaintiesinbothtransittimesandresidencetimesoneneedsempiricalconstraintsonthesupplyofdFetotheSouthernOceaneuphoticzonebyupwelling.
GP17PlausibleLogistics–requiresPalmer