transport modeling issues lori bruhwiler
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TransportModelingIssuesLoriBruhwiler
Con$nentalObserva$onsInfluenceFluxEs$matesLessthanMarineBoundaryObserva$ons
Babenhauserheide,A.,Basu,S.,Houweling,S.,Peters,W.,andButz,A.:ComparingtheCarbonTrackerandTM5-4DVardataassimilaGonsystemsforCO2surfacefluxinversions,Atmos.Chem.Phys.Discuss.,15,8883-8932,doi:10.5194/acpd-15-8883-2015,2015.
CH4intheCanadianArc$c:Con$nentalDataCouldConstrainTerrestrialEmissions
2007 2008 2009 2010 2011 2012 2013
Year
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StationChurchillBehchokoAlertInuvikCambridge Bay
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Alertisa“backgroundsite”,theothersareconGnentalandlikelynearstronglocalsources.
(DatacourtesyofD.Worthy,EnvironmentCanada)
WhatCanBeLearnedFromHigh-FrequencyData?
TownofBarrow
Wetlands
HeterogenousEmissions
“UsingFig.1,fortransportprocessesacorrespondingGmeresoluGon(effT)maybeontheorderofO(U/L)-1.UsinganadvecGvespeedofabout10ms-1wemaygeteffT~(effr/4)/10~30min.Acouplingintervalof60minwouldinthiscasecorrespondtoaneffecGvehorizontalresoluGonof14dx.”GrellandBaklanov,2010
Ls=(z-Hs)TR-1(z-Hs)+(s-sp)TQ-1(s-sp)z=observaGonsHs=simulatedobservaGonssp,s=priorandposteriorsources/sinksQ=priorsource/sinkuncertaintyR=“measurement”uncertainty
TheFluxInversionCostFunc$on
Robs=theactualmeasurementuncertainty(usuallyreallysmall)Rrep=therepresentaGonerrorresulGngfromsub-gridscalevariabilityRtrns=transportmodelerrorsR=(Robs
2+Rrep2+Rtrns
2)1/2
WhatDoestheMeasurementUncertaintyRepresent?
Robs=theactualmeasurementuncertainty(usuallyreallysmall)Rrep=therepresentaGonerrorresulGngfromsub-gridscalevariabilityRtrns=transportmodelerrorsR=(Robs
2+Rrep2+Rtrns
2)1/2
But…1)Errorsareprobablycorrelated.2)Therearealsobiases.3)It’sdifficulttoquanGfytransportR’s
So…1)Understandmodelperformance.
2)Usethebestmodel.
WhatDoestheMeasurementUncertaintyRepresent?
MeridionalTracerGradients
TheTM5gradientistoosteep!(Petersetal.,2004)
TheMeridionalGradienthelpsustoevaluateamodelchange.(hip://www.esrl.noaa.gov/gmd/ccgg/carbontracker/CT2013B_doc)
TheInter-HemisphericGradient
909294969800020406
Patraetal.,2011
Modelsusedthesameemissionssodifferencesareduetotransport
Representa$onError(7kmNASANatureSimula$on)
ModelGridBox
Linetal.,GRL2004;Anempiricalanalysisofthespa$alvariabilityofatmosphericCO2:Implica$onsforinverseanalysesandspace-bornesensors
The variance of differences (variogram) in column-averaged CO2 as a funcGon ofseparaGondistanceh.PointsingreyarevariogramesGmateswithoneobservaGondeleted (Jackknife method). VerGcal bars represent 1-σ errors derived fromJackknife staGsGcs. The solid line represents a power variogrammodel, and thedashedlinescorrespondtothe95%confidenceintervalforthevariogramfit.
Representa$onError
Representa$onError
Linetal.,GRL2004;Anempiricalanalysisofthespa$alvariabilityofatmosphericCO2:Implica$onsforinverseanalysesandspace-bornesensors
DiazIsaacetal.,JournalofGeophysicalResearch:AtmospheresVolume119,Issue17,pages10536-10551,2SEP2014DOI:10.1002/2014JD021593hip://onlinelibrary.wiley.com/doi/10.1002/2014JD021593/full#jgrd51666-fig-0003
TM5(100km)vs.WRF(10km)drivenwithsameCO2fluxes
WRFmayhavebeierverGcalmixingnearsurface.(LEF-WI)
Largedifferencesinmodel-dataresidualsinsummerdrivenenGrelybytransportdifferences.
DiazIsaacetal.,JournalofGeophysicalResearch:AtmospheresVolume119,Issue17,pages10536-10551,2SEP2014DOI:10.1002/2014JD021593hip://onlinelibrary.wiley.com/doi/10.1002/2014JD021593/full#jgrd51666-fig-0003
TM5(100km)vs.WRF(10km)drivenwithsameCO2fluxes
TaylordiagramsummarizesstaGsGcalinfo.onmodel-obsagreement.It’snotobviousthatWRFisbeier!
AssessingTransportErrorusinganEnsembleApproach
Angevineetal.,20146memberWRFEnsembleEnsemblespread(0-100ma.g.l.)suggeststhattransporterrorsforCOmaybesignificant.NormalizedtomeanCO(1meansthatthespreadequalsthemeanarea).
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