Globalmodelsofinternal0desandwavesforthe

SWOTmissionUSING:Realis0cHYCOMandMITgcmSimula0ons

SWOTSession,AGUmee0ng,13December2016

BrianK.Arbic,UniversityofMichiganAnnaC.Savage,UniversityofMichigan

MaPhewH.Alford,ScrippsIns0tu0onofOceanography,UCSanDiegoMaartenC.Buijsman,UniversityofSouthernMississippiJ.ThomasFarrar,WoodsHoleOceanographicIns0tu0onDimitrisMenemenlis,JetPropulsionLaboratory,NASA

JamesG.Richman,CenterforOcean-AtmosphericPredic0onStudies,FloridaStateUniversity

JayF.Shriver,NavalResearchLaboratory,StennisSpaceCenterAlanJ.WallcraX,NavalResearchLaboratory,StennisSpaceCenter

LuisZamudio,CenterforOcean-AtmosphericPredic0onStudies,FloridaStateUniversity

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Relevanceofglobalinternal0de/wavemodelsforpresent-daynadirand

futurewide-swathal0metry

–  Internal0desandIGWswillbeimportantsignalandnoisefieldsintheplannedSWOTwide-swathsatelliteal0metermission

– High-vs.low-frequencycomponentsofSSHwavenumberspectrum

•  (Richmanetal.2012,CalliesandFerrari2013,Rochaetal.2016a,2016b,Savageetal.in-prepara0on)

–  Internal0denon-sta0onarity•  (RayandZaron2011,Shriveretal.2014,ZaronandEgbert2014,Savageetal.inrevision)

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Historyofglobalhydrodynamicalinternal0de/wavemodeling

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•  Firstglobalinternal0demodels:Arbicetal.(2004),Simmonsetal.(2004)–  Tide-only–  Horizontallyuniformstra0fica0on

•  Globalmodelswithsimultaneous0dalandatmosphericforcing

–  HYCOM(BrianArbicandcollaborators;Arbicetal.2010,2012)–  GOLD(HarperSimmonsandcollaborators;Waterhouseetal.2014,Zhaoetal.

2016)–  STORMTIDE(MalteMüllerandcollaborators;Mülleretal.2012,2014)–  MITgcm(DimitrisMenemenlisandcollaborators;Rochaetal.2016a,2016b)

•  Internal0des+near-iner0alwaves+non-linearinterac0onsàanIGW

con0nuumspectrum–  Firstdemonstra0onofanIGWcon0nuumspectruminaglobalmodeldonein

HYCOM(Mülleretal.2015)–  OngoingworkonIGWspectrumbeingdoneinHYCOMsimula0onsand

MITgcmsimula0ons(someresultsshownhere)

Mechanicsofadding0destoageneralcircula0onmodel

•  Mustadd–  Astronomical0dalpoten0al(Newton1687,Laplace1775)–  Adjustmentforsolidearthbody0des(HendershoP1972)–  Self-aPrac0onandloading(SAL;MunkandMacDonald1960,HendershoP1972)

•  Recentforwardbarotropic0demodelsalsoadd–  Parameterizedtopographicinternalwavedrag(JayneandSt.Laurent2001,andmanyothers)

•  Ourmul0-layerHYCOMsimula0onsalsoadd– Wavedragac0ngon0dalflowinboPom500meters

•  Thusactsonbothbarotropicandlow-modebaroclinicflow–  Onemightask--doesaddi0onofwavedragtoaglobalinternalwavemodelrepresent“doublecoun0ng”?

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DifferencesbetweenglobalHYCOMandMITgcmsimula0ons

•  HYCOM/MITgcm

–  ~12publishedmodel-observa0onalcomparisons,mo0vatedbyNavyopera0onalneeds–  Muchnewer;nopublishedvepngofglobalbarotropicandinternal0des–  Includesatopographicwavedragparameterizingbreakingofunresolvedhighver0cal

modes–  Nowavedrag

–  Canincludedataassimila0on(Cummings2005,CummingsandSmedstad2013)ac0ngonmesoscaleeddiesandanAugmentedStateEnsembleKalmanFilter(ASEnKF)ac0ngon0des(Ngodocketal.2016)

–  Nodataassimila0ononeddiesor0des(ideahasbeenputforwardtodoanECCO-stylestatees0matewith0des)

–  41hybridver0calcoordinatelayers,horizontalresolu0onsof1/12.5°and1/25°–  90z-levels,horizontalresolu0onsof1/12°,1/24°and1/48°

ImprovingHYCOMbarotropic0deswithanAugmentedStateEnsembleKalmanFilter(ASEnKF;Ngodocketal.2016)

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Comparisonofinternal0desinearlyHYCOMsolu0onstoalong-trackal0metry(Shriveretal.2012)

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Impactofdampingonlow-modeinternal0des(Ansongetal.2015)

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ComparisonofearlyHYCOM0dalkine0cenergiestomooredcurrentmeterdata(Timkoetal.2012,2013)

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Demonstra0onofaninternalgravitywavespectruminHYCOMinNorthPacificregion(Mülleretal.2015)

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10−2 100 10210−4

10−2

100

102

104

ω (rad/day)

HYCOM KE frequency spectra at 38.95° N, 185.08° E

MooringHYCOM 1/12.5°

HYCOM 1/25°

Kine0cenergyfrequencyspectrum

Kine0cenergyfrequency-horizontalwavenumberspectrum

Revisi0ngconclusionsofRichmanetal.(2012)

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InRichmanetal.(2012)wesaidthatinternal0desflaPenwavenumberspectraButthelow-andhigh-passingusedinthatpaperdidnotallowustodis0nguishtheeffectsofinternal0desandtheIGWcon0nuumWenowrealizethatthemodelhasanIGWcon0nuumandthatthecon0nuumimpactsthewavenumberspectraSeealsoRochaetal.(2016a,2016b)

Boxesforhorizontalwavenumber/frequencyanalysesofHYCOM/

MITgcm

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• Preliminary MITgcm results

1/12th

1/24th 1/48th

1/12th

Kuroshio horizontal wavenumber-frequency spectrum of surface kinetic energy in 1/12°, 1/24°,

and 1/48° MITgcm, 1/12° and 1/25° HYCOM (Ansong et al. in preparation)

•  Spectralunitsarelog10[cm2/(cpd)(cpkm)].

Frequency (cpd) Frequency (cpd)

Frequency (cpd)

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enum

ber (

cpkm

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cpkm

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NorthPacifichorizontalwavenumber-frequencyspectrumofSSHin1/12°,1/24°,and1/48°MITgcm,1/12°and1/25°HYCOM(Savageetal.inprepara0on)

PreliminarySSHwavenumber

spectrainNorthPacific(Savageetal.,inprepara0on))

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StericSSHvariance(cm2)fromoneyearof1/25°HYCOM(Savageetal.,inrevision)

Area-weightedvaluesindeepoceanTotalsemidiurnal0des1.05cm2

Non-sta0onarysemidiurnal0des0.43cm2

Super0dalinternalgravitywavecon0nuum0.15cm2

Sta0onaryinternal0des,non-sta0onaryinternal0des,andtheinternalgravitywavecon0nuumallhavesubstan0alSSHsignatures

StericSSHfrequencyspectrainHYCOMvs.in-situver0cal

profiledata(Savageetal.,in

revision)

X - 38 SAVAGE ET AL.: FREQUENCY CONTENT OF SEA SURFACE HEIGHT

Figure 8. Example steric SSH spectral densities from (a) McLane profiler located at

120.61�E, 12.84�N (b) surface mooring located at 38�W, 24.58�N and corresponding HYCOM25

gridpoints. The dashed vertical lines denote K1 diurnal and M2 semidiurnal tidal frequencies.

The 95% confidence intervals shown account only for random error in spectral density calcula-

tions.D R A F T December 5, 2016, 4:38pm D R A F T

•  FrequencyspectraoftemperaturevarianceandKEinmodelsand1000sofhistoricalmooredobserva0ons

• HYCOMMITGCM

• 1/12°1/12°

• 1/25°1/24°• 1/48°

On-going research: Conrad Luecke, University of Michigan

Impactofmodelresolu0ononver0calwavenumber

10−4 10−3 10−2 10−1 10010−10

10−9

10−8

10−7

10−6

10−5

10−4

10−3

10−2

10−1

100

Vertical wavenumber m (cpm)

E(m

) (kg

/m3 )2 /(c

pm)

McLane ProfilerMIT 1/12°

MIT 1/24°

MIT 1/48°

Ver0calwavenumberspectrumofhigh-passed(2-daycutoff)poten0aldensityvarianceover90-1388dbfromMITgcmandfromMaPhewAlford’sMcLaneprofilerdataataNorthPacificloca0onnearHawai’i.ExtradashedlinedenotesGarreP-Munkm-2predic0on..Havebegunacollabora.onwithDimitrisMenemenlistoperformMITgcmsimula.onswithevenhigherresolu.oninalimitedregionwhereMcLaneprofilerdataexists.

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Summary•  BothHYCOMandMITgcmarenowbeingrungloballyatveryhigh

resolu0on(from1/12°to1/48°),with0desincluded•  TheMITgcmsolu0onshavehigherhorizontalandver0calresolu0on•  TheHYCOMsolu0onnowincludesdata-assimila0onac0ngonthe

barotropic0des,andhasbeencomparedwithobserva0onsmuchmorethoroughly

•  Bothmodelsareresolvingsomeoftheinternalgravitywave(IGW)con0nuumspectrum

•  Bothmodelscanbeusedtoexaminetheimpactsofsta0onaryinternal0des,non-sta0onaryinternal0des,andtheIGWcon0nuumonSWOTmeasurements

•  Inanewcollabora0onwithDimitrisMenemenlis,wearerunning/examiningaregionalMITgcmsimula0onwithevenhigherver0calandhorizontalresolu0ons.Thissimula0oncanbeusedto:–  Examinever0calwavenumberspectraandmixing–  Examinecontribu0onsfromlow-andhigh-frequencymo0onstoSSH

wavenumberspectra–  Doahigher-resolu0onOSSEfortheSWOTCal/Val

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