RemoteSensingofEnvironment114(2010)2393–2402

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RemoteSensingofEnvironment

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DevelopmentofahybridmethodforestimatinglandsurfaceshortwavenetradiationfromMODISdata

Hye-YunKima,b, ,ShunlinLianga

ab

DepartmentofGeography,UniversityofMaryland,CollegePark,MD20742,USAI.M.SystemGroup,Inc.atNOAA/NESDIS,CampSprings,MD20746,USA

articleinfoabstract

Accurateestimationofshortwavenetradiation(Sn)atahighspatialresolutioniscriticalforregionalandgloballandsurfacemodels.Currentsurfaceradiationbudgetproductshave netemporalresolutions,butonlycoarsespatialresolutionsthatarenotsuitableforlandapplications.AhybridalgorithmwasdevelopedinthisstudytoestimateSnfromMODISdataunderbothclearandcloudyskyconditionswithoutrequiringcoarserresolutionancillarydata.ThisalgorithmwasvalidatedusinggroundmeasurementsatsevensitesoftheSURFaceRADiationbudgetobservingnetwork(SURFRAD)intheUnitedStates.InstantaneousSnestimatedbythismethodwasalsocomparedwithGEWEX/SRBandISCCPdata,andothermethods.TheresultsindicatethatouralgorithmcanproduceSnat1-kmresolutionwithimprovedaccuracyandiseasilyimplementedtogenerateoperationalglobalproducts.DailyintegratedSnisestimatedat1-kmresolutionusinginstantaneousSn.These nerspatialresolutiondatasetscapturethespeci csequenceoftheredistributionoftheavailableenergyattheEarth'ssurface.Therefore,theysupportrecenthighresolutionlandsurfacemodels.

©2010ElsevierInc.Allrightsreserved.

Articlehistory:

Received26November2008

Receivedinrevisedform7May2010Accepted9May2010

Keywords:Landsurface

ShortwavenetradiationMODIS

Multispectral

Dailyintegratedshortwavenetradation

1.Introduction

Surfaceshortwavenetradiation(Sn)isrequiredtoestimatetheenergyexchangebetweentheatmosphereandtheland/oceansurfaces.ItisthefundamentalquantityofenergyavailableattheEarth'ssurface,whichdrivestheprocessesofevaporation,airandsoilheating,aswellasother,smallerenergy-consumingprocessessuchasphotosynthesis.Snisalsofrequentlyusedtoestimateall-wavenetradiation(Rn)(Jacobsetal.,2004,2002;Samanietal.,2007).Snin uencesatmosphericcirculations,aswellassurfaceclimate(Whitlocketal.,1995),andisusedinnumericalweathersimulationsandlandsurfacemodeling.

Thecurrentsurfaceradiationbudgetproductsthatincludeshort-wavenetradiationhave netemporalandcoarsespatialresolutionsthatarenotsuitableforlandapplications(Table1).InternationalSatelliteCloudClimatologyProject(ISCCP)FDdatahavebeenusedtoestimateglobalmonthlymeanSRB(Zhangetal.,2004)andtheyhavea2.5°-spatialand3-hourtemporalresolution.GlobalEnergyandWatercycleEXperiment(GEWEX)/SRBdatacontain3-hourlyglobal eldsofshortwaveradiationderivedwiththeshortwavealgorithmoftheNASAWorldClimateResearchProgramme(WCRP)/GEWEXsurfaceradiationbudgetat1°-spatialresolutioninthetropics(Stackhouse,2004).TheEuropeanEnergyandWaterBalance

Correspondingauthor.DepartmentofGeography,UniversityofMaryland,CollegePark,MD20742,USA.

E-mailaddress:Hye-Yun.Kim@noaa.gov(H.-Y.

Kim).0034-4257/$–seefrontmatter©2010ElsevierInc.Allrightsreserved.doi:

10.1016/j.rse.2010.05.012

MonitoringSystem(EWBMS)providesaseriesof10-dailyproductsbasedonthemeteorologicalsatelliteMETEOSAThourlydataat5kmresolution(Suarez-Seoaneetal.,2004).CloudsandtheEarth'sRadiantEnergySystem(CERES)CloudsandRadiationSwath(CRS)productsincludesurfaceshortwavedownwardandnet uxbyusingSSFasinputdatathathave～30kmspatialresolutionatnadirforEarthObservingSystem(EOS)TerraandAquaplatform(Geieretal.,2003).Theseproductsdonothaveglobalcoverageorhaveaspatialresolutionthatistoocoarseforlandapplications.Recentlandsurfaceandclimatemodelsrequirea10-kmor nerspatialresolution(Bromwichetal.,2005;Kustasetal.,2004;Lietal.,2008;Societal.,2006;Treitz&Howarth,2000).Therefore,ahybridalgorithmtoestimateshortwavenetradiationat1-kmresolutionhasbeende-velopedinthisstudyusingModerateResolutionImagingSpectro-radiometer(MODIS)data.MODISisoneofthesensorsontheNationalAeronauticsandSpaceAdministration(NASA)EarthObservingSystem(EOS)Terraplatformlaunchedin1999,andAquaplatformlaunchedin2002.MODISprovidesfrequent,comprehensiveglobalEarthimagingin36spectralbands,andatvariablespatialresolutions,withnadirfootprintsnogreaterthan1km.

Althoughsomestatisticalmethodsestimatesurfaceshortwavenetradiation(Sn)byestablishingtheregressionrelationbetweensatellite-measuredradiationandSnmeasurement(Canoetal.,1986;Hay&Hanson,1978;Tarpley,1979),manystudiesestimateshortwavenetradiation(Sn)usingTOAradiance,atmosphericandsurfacevariables(Cessetal.,1991;Cess&Vulis,1989;Lietal.,1993;Pinkeretal.,1985;Pinker&Laszlo,1992;Rossow&Zhang,1995;Tang