温度反演经典文章(21)

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Z.-L.Lietal./RemoteSensingofEnvironment131(2013)14–37

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atmosphericcorrectionsoftheTIRdata,whiletheTIRradiancecanbeusedtoimprovere ectanceretrievalsintheVSWIRespeciallywhensigni cantTIRaerosolabsorptionispresentunderhighaerosolload-ings.Moreover,thisHyspIRI-likeairbornesystemwasalsousedtodetect reregionsandretrievetheircorrespondingtemperature(Dennison&Matheson,2011;Matheson&Dennison,2012).Addi-tionally,HyspIRIisalsoprospectedtobeappliedinthe reseverityassessments,themonitoringofthevolcaniceruption,theinterpreta-tionofsnowpropertiesandtheretrievalofforestbiophysicalparam-eters,respectively(Dozieretal.,2009;Veraverbekeetal.,2012a,2012b;Zhangetal.,2012).AsfortheretrievalofLSTandLSE,HyspIRI'ssoundingchannelsinVSWIRcanprovideatmosphericdatafortheatmosphericcorrectionsoftheMIRandTIRdata,andits8spectralchannels(7between7.5and12μmand1at4μm)aresuit-ableforseveralcurrentalgorithmsintheory,suchastheTES,TISIandSWalgorithms,evenavailablefordevelopingnewretrievalLST/LSEalgorithms.Furthermore,becauseofits nerspatialresolution(60m)andrapidrevisittime(5days),theLST/LSEretrievedfromHyspIRIprovideanopportunitytovalidatetheLST/LSEproductsatcoarserresolutions,suchasMODISand(A)ATSR.Therefore,thestudyonHyspIRIwillattractmuchattentioninthefuture.5.9.Physicalmeaningofsatellite-derivedLSTanditsapplicationsTheLSTmustbephysicallyde nedwithabsolutecertainty.However,noagreementhasbeenreachedonthede nitionoftheLSTbecauseoftheunclearphysicalmeaningofthesatellite-derivedtemperature,espe-ciallyoverheterogeneousandnon-isothermalsurfaces.Thede nitionoftheLSTalsodependsonthatoftheLSEbecausetheLSTandLSEarecoupledinthetotalradiance.Therearecurrentlyseveralde nitionsoftheLSE,suchasther-emissivity(Becker&Li,1995),thee-emissivity(Norman&Becker,1995)andtheapparentemissivity(Lietal.,1999).Thesede nitionsarethesameforhomogeneoussurfacesatthermalequilibrium,butbecausenaturalsurfacesobservedfromspaceareusual-lyheterogeneous,theassumptionsofhomogeneityandthermalequilib-riumareoftenviolatedinreality,especiallyinmeasurementswithlowspatialresolution.Therefore,thedifferencesbetweenthesede nitionsareevidentinmanycases.Ther-emissivityde nitionisrecommendedforLSTandLSEretrievalfromspace-basedmeasurementsbecausether-emissivityismeasurablefromspace.

Whateverde nitionoftheLSTisused,thesatellite-derivedLST,alsoknownastheradiometrictemperatureortheskintemperature,canonlycapturethethermalradiationinformationfromaverythindepthunderneaththesurface,andthereforecannotbedirectlysubstitutedforthethermodynamicoraerodynamictemperaturesinestimatingsurface uxesorotherrelevantapplications.Instead,aconversionmustbemadebetweenthesedifferenttemperatures.However,currentstudiesseldomconsiderthesedifferencesandtreattheskintemperatureasthethermodynamicoraerodynamictemperaturewithoutanyconversion.Thissimpli cationcausesunex-pecteduncertaintiesintheirresults.Therefore,furtherattentionshouldbepaidtothisprobleminthefuturebyconsideringthephys-icalde nitionofdifferenttemperaturesandtheaccuracyrequire-mentsofrelevantapplications.5.10.Validationofsatellite-derivedLST

ThemostimportantprobleminLSTvalidationmightbetheaccu-racyandrepresentativenessoftheground-truthLSTatthesatellitepixelscale.Althoughground-basedvalidationisconsideredtobethemostreliablevalidationtechnique,measurementsoftheground-truthLSTarelimitedbythedif cultyof ndingahomoge-neousregionaslargeasthesatellitepixelsizeandbythedif cultyandassociatedcostsofsamplingoverheterogeneouslandscapes.The rstdif cultymightbesolvedbyimprovingthespatialresolutionofTIRdata,whilethesecondwillrequirethedevelopmentofanew

samplingschemeforground-levelLSTmeasurements,suchasawireless-netobservationsystemormultiple-scaleobservationmethodswithcorrespondingnewinstruments.AttemptstousetheLSTspredictedfromlanddataassimilationsystemsorclimatemodelstoindirectlyvalidatetheLSTsretrievedfromspacemustdevotemoreattentiontoimprovingtheaccuracyoftheoutputofthesemodelsanddealingwiththescalemismatchissueinbothspaceandtime.Turningtocross-validationtechniques,anappropriatescalingproceduretoremovetheeffectsofspatial,temporal,andangulareffectsontheLSTmustbedeveloped.Therefore,LSTvalidationisstillanongoingsubjectofresearch.Acknowledgments

TheauthorswouldliketothankProfessorA.R.Gillespieandotherreviewersfortheirvaluableandstimulatingcommentsthathavegreatlyimprovedthepaper.TheauthorsaregreatlyindebtedtoDr.S.J.Hookforreadingcarefullythedraftofthispaperandforgivingmanyusefulsuggestionsforimprovingitspresentation.ThisworkwassupportedbytheHi-TechResearchandDevelopmentProgramofChina(863PlanProgram)undergrantno.2012AA12A304,bytheNa-tionalNaturalScienceFoundationofChinaundergrantno.41231170and41171287,andbytheStateKeyLaboratoryofResourcesandEnvi-ronmentalInformationSystemundergrant088RA800KA.References

Adams,J.B.,Smith,M.O.,&Gillespie,A.R.(1989).Simplemodelsforcomplexnatural

surfaces:Astrategyforthehyperspectraleraofremotesensing.Proc.IEEEInternationalGeosciencesRemoteSensingSymposium(pp.16–21).

Aires,F.,Chédin,A.,Scott,N.A.,&Rossow,W.B.(2002).Aregularizedneuralnetap-proachforretrievalofatmosphericandsurfacetemperatureswiththeIASIinstru-ment.JournalofAppliedMeteorology,41,144–159.

Aires,F.,Prigent,C.,&Rossow,W.B.(2004).Temporalinterpolationofglobalsurfaceskin

temperaturediurnalcycleoverlandunderclearandcloudyconditions.JournalofGeophysicalResearch,109,D04313.

Aires,F.,Prigent,C.,Rossow,W.B.,&Rothstein,M.(2001).Anewneuralnetworkap-proachincluding rstguessforretrievalofatmosphericwatervapor,cloudliquidwaterpath,surfacetemperature,andemissivitiesoverlandfromsatellitemicro-waveobservations.JournalofGeophysicalResearch,106,14,887–814,907.

Aires,F.,Rossow,W.B.,Scott,N.A.,&Chédin,A.(2002).Remotesensingfromthein-fraredatmosphericsoundinginterferometerinstrument,2,Simultaneousretrievaloftemperature,watervapor,andozoneatmosphericpro les.JournalofGeophysicalResearch,107,4620.

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