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1、APleaforRadarBrightnessR.K.RaneyT.FreemanR.W.HawkinsR.BamlerCCRSJPLCCRSDLR588BoothStreet4800OakGrove588BoothStreetOberpfaffenhofen,Ottawa,CanadaPasadena,CA,USAOttawa,CanadaGermanyK1AOY791109K1AOY782234TheStandardApproachesAbstractTheradarreflectivitycoeffic
2、ientofadistributedscotterer,Theareaincrementisdeterminedbytheproductofitsapressedeitheras00ory,dependsonlocalincidenceangle.PriorsizeinazimuthA.,andinrangeA,;AA=AA,AR.Theazimuthtoincidenceangleprojection,thereflectivitycoefficientmaybesizeisassumedtobeconst
3、antforthisdiscussion.Therangecalled"radarbrightness';denotedby"betanought"/F'.Inmostdirectionofferschoices,assuggestedinFigure1.Assumeforthepracticalsituations,thelocalincidenceangleisnotknown,sothemomentthatthelocalslopea,=0'.Forilluminationatanimageradiom
4、etricscannotbecorrectedforit.Itfollowsthatp"isincidenceangleOi,anincrementA,intheslantrangedirectionalmostalwaysthemoreappropriateradiometricattributeofradarisscaledbyl/sinO,whenprojectedontothelocalgeoid.Thisimagey,whethercalibratedoruncalibratedItisrecomm
5、endedthatleadstothedefinitionofU',whichdescribesthe(mean)d(ory)beresentedforsituationsinwhichboththelocalterrainreflectivityofapatchofdistributedscatterersperunitareaofaslopeandtheilluminationincidenceanglesareknown,andthehorizontalsurface(Ulabyetal.,1982).
6、Likewise,theslantrangeimagefirehasbeenadjustedtotakebothanglesintoaccount.incrementA,isscaledbyl/tanOiwhenprojectedontotheOtherwise,radarbrightnessiscorrect,whichshouldbeadoptedassurfaceorthogonaltotheradarline-of-sight.Useofthisscalingthestandad,bothasconc
7、eptandasworkingterminology.Thkhasleadstothedefinitionofy,whichdescribesthe(mean)beenendorsedbytheCEOSSARCalibrationWorkingGroup.reflectivityofdistributedscatterersperunitareaoftheincidentwavefront(Cosgriffetal,1960).yhasthevirtuethatitINTRODUCTIONmaintainsr
8、elativelyconstantreflectivityoverawiderangeofincidenceanglesforroughsurfaces.oohasthevirtuesthatitsTheSAR(syntheticapertureradar)CalibrationWorkingnormalizationareaiseasilyvisualized,andthatitisthemost