(PLUMBER) Summary and ongoing work · The PALS Land sUrface Model Benchmarking Evaluaon pRoject...

ThePALSLandsUrfaceModelBenchmarkingEvalua<onpRoject

(PLUMBER)

Summaryandongoingwork

GabAbramowitzUNSWSydney&ARCCSS

Mar<nBest,NedHaughton,MartynClark,AnnaUkkola,AndyPitman,DaniOr+otherPLUMBERcoauthors:H.Johnson,G.Balsamo,E.Blyth,ABoone,P.

Dirmeyer,J.Dong,M.Ek,Z.Guo,V.Haverd,B.vandenHurk,H.Kim,R.Koster,S.Kumar,G.Nearing,T.Oki,B.Pak,C.Peters-Liddard,A.Pitman,J.Polcher,J.

Santanello,L.Stevens,P.Viterbo,N.Vuichard,…

Expandedexample:ThePALSLandsUrfaceModelBenchmarkingEvalua<onpRoject(PLUMBER)

•  20Fluxtowersites;latentandsensibleheat,•  4metrics:bias,correla<on,SD,normalisedmeanerror•  9LSMs,15LSMversions•  Benchmarks:two‘physical’–PMandManabebucket;3empirical

Best et al, 2015

ThethreeempiricalbenchmarksinPLUMBER

•  All3empiricalmodelsrelatemetforcingandaflux

•  Trainedwithdatafromsitesotherthanthetes<ngsite(i.e.outofsample)

•  TheyareeachcreatedforLE,H:o  “1lin”:linearregressionoffluxagainstdownwardshortwave(SW)

o  “2lin”:asabovebutagainstSWandsurfaceairtemperature(T)

o  “3km27”:non-linearregression–27-nodek-meansclustering+linearregressionagainstSW,Tandrela<vehumidityateachnode

•  Allareinstantaneousresponsestometvariableswithnoknowledgeofvegeta<ontype,soiltype,soilmoistureortemperature,Cpools.

PLUMBERresults

Ver<calaxisistherankofeachLSM(black)againstthe5benchmarks,averagedover:•  20Fluxtowersites–9IGBPvegeta<ontypes;•  4metrics:bias,correla<on,SD,normalisedmeanerror

•  Onaverage,LSMsoutperformPenman-MonteithandManabebucketimplementa<ons•  Onaverage,LSMssensibleheatpredic<onisworsethananout-of-samplelinear

regressionagainstdownwardSWradia<on•  Forallfluxes,modelsarecomfortablybeatenbyout-of-sampleregressionagainst

Swdown,TairandRelHum

Best et al, 2015, J Hydromet.

•  Lackoffluxtowerenergyconserva<onadvantagingempiricalmodels?

•  Timescale–daily,monthly,seasonalratherthanper<mestepperformance?

•  Timeofday–diurnalbiasesinfluxtowerfavouringempiricalmodels?

•  PoorLSMini<alisa<on?

•  Areranksnotrepresenta<veofmetricvalues?

•  Biasedbymetricchoice?

•  Biasedbysitechoice?

PLUMBERresults–methodology?

PLUMBERresults–why?Notenergyconserva<on.

•  Constraineachempiricalmodeltohavethesamesumof(latent+sensible)heatfluxastheLSMatevery<mestep

–  Eachempiricalmodeltheneffec<velyhasthesameRnetandgroundheatfluxastheLSMit’sbeingcomparedto–andconservesenergy.

•  ResultsaremixedbuttheregressionagainstSWdown,TairandRelHums<llcomesoutontop,especiallyforsensibleheatflux.

Haughton et al, 2016

PLUMBERresults–sharedmodelissues?



Qh error, binned by (RelHum, SWdown,)

LSMs


Qh error, binned by (Swdown, Tair)

LSMs

Canwebuildabemerempiricalmodel?

MartynClark:PLUMBERmodelswithinaBudykoframework

•  TheBudykoframeworkexamineshowthedrynessindex(PET/P)affectstheevapora<vefrac<on(ET/P).

•  Thesta<s<calmodelstendtobelowerthantheBudykocurveforthewemersitesandhigherthantheBuykocurvesforthedriersites.

•  Atdriersitesthesta<s<calmodelscanhaveETgreaterthanP(i.e.,anevapora<vefrac<ongreaterthan1).

•  Approach–  RMSEacrossthe20fluxnetsites

–  Impactofthesmallsamplesizeischaracterizedbyresamplingthesites(withreplacement)1000<mes

•  Results–  Mostofthelandmodels

actuallyoutperformthesta<s<calmodels.

–  TheBudykocurveprovidesbemerpredic<onsthanmostofthelandmodels,sugges<ngthatthelandmodelsareincapableofpredic<ngdeparturesfromtheBudykocurve.

•  TheconclusionsofPLUMBERs<llhold,withasimplemodel(Budyko)outperformingmostlandmodels.

MartynClark:PLUMBERmodelswithinaBudykoframework

Dry-downeventsatPLUMBERsites(AnnaUkkola)

Ukkola et al, in press, ERL

Evapora<vedroughtatPLUMBERsites

Ukkola et al, in press, ERL

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OngoingworkaroundPLUMBER

•  NedHaughton(UNSWSydney,+Gab)–howgoodcanempiricalmodelsbe?–  Con<nuingtolookforanuber-modelusingallmetvariables,fluxhistory,markovchain

approachetc–  Buildinconserva<on?

•  MartynClark(UCAR)–inves<ga<ngPLUMBERwithSUMMAmodellingarchitecture

•  Mar<nBesthasmen<onedwan<ngtousePLUMBERdataforsomekindoffrequencydomainanalysis

PLUMBERresults–<mescale?


PLUMBERresults–<meofday?


PLUMBERresults–ini<alisa<on?"


PLUMBERresults–ranksvsmetricvalues?"

Haughton et al, J Hydromet, in review

PLUMBERresults–metric?


PLUMBERresults–sites?

Haughton et al, J Hydromet, in review

(PLUMBER) Summary and ongoing work · The PALS Land sUrface Model Benchmarking Evaluaon pRoject...

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