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1、JOURNALOFGEOPHYSICALRESEARCH,VOL.111,D02109,doi:10.1029/2005JD005932,2006Radiationfluxesandcanopytransmittance:ModelsandmeasurementsinsideawillowcanopyMattiMottusandMadisSulevTartuObservatory,Toravere,EstoniaReceived2March2005;revised25July2005;accepted7November2005
2、;published25January2006.[1]Upwardanddownwardfluxesofphotosyntheticallyactiveandbroadbandsolarradiation,andthetransmittanceofdirectsolarradiationmeasuredatdifferentheightsinsideawillow(Salixviminalis)canopyarecomparedwithmodelingresults.Twoapproachesareusedformodelin
3、gtheradiationfieldinsidethecanopy:solvingtheradiativetransferequationusingtheexactkerneldiscreteordinatesmethodandaMonteCarlomodel.Themeasuredandmodeledcanopiesincludea1-year-oldwillowcoppicewithleafareaindex(LAI)=5anda4-year-oldcoppicewithLAI=8.Biometricaldatausedi
4、nthemodelsaretakenfromdetailedmeasurementsofcanopystructure;measuredfluxesareusedasboundaryconditions.Anattemptismadetoincludetheeffectofclumpingonthepenetrationofdirectsolarradiationintotheradiativetransfermodel.Allmodelsagreedwellwithmeasurementresults;enhancement
5、ofmodeledfluxesduetoinclusionofclumpingdependedontheheightinsidethecanopywhilethedistributionofleafinclinationanglehadaminimaleffectontheradiationregimeofthestand.Citation:Mo˜ttus,M.,andM.Sulev(2006),Radiationfluxesandcanopytransmittance:Modelsandmeasurementsinsidea
6、willowcanopy,J.Geophys.Res.,111,D02109,doi:10.1029/2005JD005932.1.Introduction1960].However,astheconditionsinsideaplantcanopyviolatemostofthesesimpleapproximations,amorecom-[2]Theradiationfieldbothaboveandunderneathaplantplexmodelisneeded,oftenincludingverymanyinput
7、canopyisfrequentlymeasuredusingseveralwavelengthsofparameters[e.g.,KuuskandNilson,2000].electromagneticradiation.Abovevegetation,variousspace-[4]Whenamodelofpenetrationofsolarradiationinsideborneandairborneinstrumentslookdownatthesurfaceofaplantcanopyisconstructed,i
8、tismostlogicaltoverifyitourplanet,forbothscientificandcommercialpurposes.bymeasuringtransmittedradiationbelowthecanopy,Muchlessinformation
