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1、APleaforRadarBrightnessR.K.RaneyT.FreemanR.W.HawkinsR.BamlerCCRSJPLCCRSDLR588BoothStreet4800OakGrove588BoothStreetOberpfaffenhofen,Ottawa,CanadaPasadena,CA,USAOttawa,CanadaGermanyK1AOY791109K1AOY782234TheStandardApproachesAbstractTheradarreflectivitycoeff
2、icientofadistributedscotterer,Theareaincrementisdeterminedbytheproductofitsapressedeitheras00ory,dependsonlocalincidenceangle.PriorsizeinazimuthA.,andinrangeA,;AA=AA,AR.Theazimuthtoincidenceangleprojection,thereflectivitycoefficientmaybesizeisassumedtobec
3、onstantforthisdiscussion.Therangecalled"radarbrightness';denotedby"betanought"/F'.Inmostdirectionofferschoices,assuggestedinFigure1.Assumeforthepracticalsituations,thelocalincidenceangleisnotknown,sothemomentthatthelocalslopea,=0'.Forilluminationatanimage
4、radiometricscannotbecorrectedforit.Itfollowsthatp"isincidenceangleOi,anincrementA,intheslantrangedirectionalmostalwaysthemoreappropriateradiometricattributeofradarisscaledbyl/sinO,whenprojectedontothelocalgeoid.Thisimagey,whethercalibratedoruncalibratedIt
5、isrecommendedthatleadstothedefinitionofU',whichdescribesthe(mean)d(ory)beresentedforsituationsinwhichboththelocalterrainreflectivityofapatchofdistributedscatterersperunitareaofaslopeandtheilluminationincidenceanglesareknown,andthehorizontalsurface(Ulabyet
6、al.,1982).Likewise,theslantrangeimagefirehasbeenadjustedtotakebothanglesintoaccount.incrementA,isscaledbyl/tanOiwhenprojectedontotheOtherwise,radarbrightnessiscorrect,whichshouldbeadoptedassurfaceorthogonaltotheradarline-of-sight.Useofthisscalingthestanda
7、d,bothasconceptandasworkingterminology.Thkhasleadstothedefinitionofy,whichdescribesthe(mean)beenendorsedbytheCEOSSARCalibrationWorkingGroup.reflectivityofdistributedscatterersperunitareaoftheincidentwavefront(Cosgriffetal,1960).yhasthevirtuethatitINTRODUC
8、TIONmaintainsrelativelyconstantreflectivityoverawiderangeofincidenceanglesforroughsurfaces.oohasthevirtuesthatitsTheSAR(syntheticapertureradar)CalibrationWorkingnormalizationareaiseasilyvisualized,andthatitisthemost