Landsat Data productsWord文档格式.docx

Landsat Data productsWord文档格式.docx

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11.1Level0RProduct

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UnlikeearlierLandsatprograms,theLandsat7systemwasnotoriginallydesignedtoproducehighlevel（i.e.Level1）productsforusers.Thebaselinedprogramphilosophywastoproviderawdataonlywhichwouldleavethevalueaddeddomainforcommercialcompanies.Aprevailing"

waitandsee"

positionbycommercialvendorspromptedNASAtoaddasystematiccorrectioncapabilitytoensureproductavailability.Theprimaryproductforusersandvendorsseekinghigherlevelprocessing,however,is0Rdata-anessentiallyrawdataformthatismarginallyusefulpriortoradiometricandgeometriccorrection.Thisisreadilyapparentwhenviewingasimulated0Rimage.ALandsat70Rproduct,however,doescontainalltheancillarydatarequiredtoperformthesecorrectionsincludingacalibrationparameterfile（CPF）generatedbytheLandsat7IAS.

LPSspatiallyreformatsearthimageryandcalibrationdataintoLevel0Rdata.Thisinvolvesshiftingpixelsbyintegeramountstoaccountforthealternatingforward-reversescanningpatternoftheETM+sensor,theodd-evendetectorarrangementwithineachband,andthedetectoroffsetsinherenttothefocalplanearrayengineeringdesign.AllLPs0Rcorrectionsarereversible;

thepixelshiftparametersusedaredocumentedintheIASCPF.

TheLPs0RoutputisHDF-EOSformattedandarchived.DetailsofthearchivalformatcanbefoundintheLandsat7SystemWidebandDFCB,Vol.4.

11.1.1ProductSize

Threeoptions,depictedinFigure11.2,existwhendefiningthesizeorspatialextentofaLandsatlevel0RproductorderedfromtheLP-DAAC.

∙StandardWorldwideReferenceSystem（WRS）Scene.ThestandardWRSsceneasdefinedforLandsats4and5waspreservedasaproductforLandsat7.TheWRSindexesorbits（paths）andscenecenters（rows）intoaglobalgridsystemcomprising233pathsby248rows.Thepath/rownotationwasoriginallyemployedtoprovideastandarddesignatorforeverynominalscenecenterandallowstraightforwardreferencingwithoutusinglongitudeandlatitudecoordinates.

ThedistancebetweenWRScenterpointsalongapathis161.1kilometers.Apathdistanceof90kilometersbeforeandafteraWRScenterpointdefinesthestandardscenelengthof180km.Thislengthincludes20scansofoverlapwithneighboringscenes.ThestandardWRSsceneoverlapsneighboringscenesalongapathby5%attheequatorandhasawidthorcrosstrackdistanceof185kilometers.

Landsat7browseisframedaccordingtoWRSscenes.Anorderedscenewillcoverthesamegeographicextentobservedinthebrowsewiththefollowingcaveat.StandardWRSsceneshave375scans.Partialscenes（lessthan375scans）mayexistatthebeginningorendofasubintervalduetothefactthatimagingeventsdonotalwaysstartandendonsceneboundaries.Browseandscenemetadatafortheseoccurrencesaccuratelyreflecttheirpartialscenenatureandgeographicextentalthoughpartialsarecurrentlynotofferedduetocomplexitiesassociatedwithlevel1processing.

∙Subinterval.AnintervalisascheduledETM+imageperiodalongaWRSpath,andmaybefromoneto90scenesinlength.AsubintervalisacontiguoussegmentofrawwidebanddatareceivedduringaLandsat7contactperiod.Subintervalsarecausedbybreaksinthewidebanddatastreamduetocommunicationdropoutsand/ortheinabilityofthespacecrafttotransmitacompleteobservation（interval）withinasingleLandsat7contactperiod.Thelargestpossiblesubintervalis35sceneslong.ThesmallestpossiblesubintervalisasingleETM+scene.

∙PartialSubintervalApartialLandsat7subintervalcanalsobeordered.ThepartialsubintervalisdimensionedaccordingtostandardWRSscenewidth,isatleastoneWRSsceneinlength,andcanbeupto10scenesinlengthiforderedin0Rformor3scenesinlengthin1Gform.Apartialsubintervalcanfloatorbepositionedatanyscanlinestartingpointwithinasubinterval.PartialsubintervalsaredefinedbyeithercontiguousWRSlocationsoraboundinglongitude/latituderectangle.Inthelattercase,allscanlinestouchedbytheboundingrectangleareincludedintheirentirety.

11.1.2ProductComponents

Acompletescene-sized0Rproductconsistsof19datasetsderivedfromthewidebandtelemetry,anIAS-generatedcalibrationparameterfile,aproductspecificmetadatafile,ageolocationindexgeneratedbyEOSDISCoreSystem（ECS）,andanHDFdirectory.Therefore,ifyouorderacomplete（i.e.allbands）scene-based0Rproductitwillhave23distinctfiles.Abriefdescriptionofeachfollows.

∙1-9.EarthImageData-TheuniquebandsofETM+imagedatacomprisenineofthedatasets.Thedataislaidoutinascanlinesequentialformatindescendingdetectororder（i.e.detector16followedbydetector15andsoonforthe30meterbands）.Band6iscapturedtwice-onceinlowandtheotherinhighgainmode.Undernominalsatelliteconfigurationthelowgainformofband6willbepresentinformat1.Allimagesamplesorpixelsare8bitsinsize.

∙10.Internalcalibrator（IC）data-format1-ICdataforformat1consistsofscanlineorderedinternallampandshutterdataforbands1-5andblackbodyradianceandshutterdataforlowgainband6.Thedataiscollectedonceperscanandstructuredinabandsequentialformatindescendingdetectororder（e.g.detector16followedbydetector15andsoonforthe30meterbands）.

∙11.Internalcalibrator（IC）data-format2-ICdataforformat2consistsofscanorderedinternallampandshutterdataforbands7and8andblackbodyradianceandshutterdataforhighgainband6.Thedataiscollectedonceperscanandstructuredinabandsequentialformatindescendingdetectororder（e.g.detector16followedbydetector15andsoonforthe30meterbands）.

∙12.MSCD-format1.AlogicalrecordofMSCDexistsforeachdatascanpresentinthe0Rproductordered.Eachlogicalrecordconsistsof3MSCDdatavalues-thefirsthalfscanerror,thesecondhalfscanerror,andthescanlinedirection.Thisinformation,whichactuallyappliestothepreviousscan,isusedtocomputedeviationsfromnominalscanmirrorprofilesasmeasuredonthegroundandreportedinthecalibrationparameterfile.AlsoincludedintheMSCDfilearescanbasedvaluessuchastimecode,gainstatusandprocessingerrorsencounteredbyLPsTheMSCDistrimmedtofittheproductorderedalthoughoneadditionalrecordisaddedtothefileduringthesubsettingprocessduetothefactthatscanerroranddirectioninformationcorrespondstothepriorscan.

∙13.MSCD-format2.AduplicatesetofMSCDisgeneratedwhenformat2isprocessedandiskeptwiththeproductintheeventformat1MSCDislostorcorrupted.

∙14.PCD-format1ThePCDforformat1consistsofattitudeandephemerisprofilesaswellhighfrequencyjittermeasurements.PCDfortheentiresubintervalisincludedwiththe0Rproductregardlessofthesizeofthedatasetordered.

∙15.PCD-format2AduplicatesetofPCDisgeneratedwhenformat2isprocessedandiskeptwiththeproductintheeventformat1islostorcorrupted.

∙16.Scanlineoffsets-format1.DuringLPsprocessingimagedataisshiftedinanextendedbuffertoaccountforpredetermineddetectorandbandshifts,scanlinelength,andpossiblebumperwear.Thescanlineoffsetsrepresenttheactualstartingandendingpixelpositionsforvalid（non-zerofill）earthimagedataonadatalinebydatalinebasisforbands1through6lowgain.TheleftstartingpixeloffsetsalsoapplytotheICdata.

∙17.Scanlineoffsets-format2.DuringLPsprocessingimagedataisshiftedinanextendedbuffertoaccountforpredetermineddetectorandbandshifts,scanlinelength,andpossiblebumperwear.Thescanlineoffsetsrepresenttheactualstartingandendingpixelpositionsforvalid（non-zerofill）earthimagedataonadatalinebydatalinebasisforbands6highgainthrough8.TheleftstartingpixeloffsetsalsoapplytotheICdata.

∙18.Metadata-format1.DuringLPsformat1processingmetadataisgeneratedthatcharacterizesthesubinterval'

sspatialextent,content,anddataqualityforbands1through6lowgain.Thisfile,initsentiretyandoriginalform,accompaniesthe0Rproduct.

∙19.Metadata-format2.Format2metadataissimilarbutnotidenticaltoformat1metadata.Thesubinterval-relatedmetadatacontentsareidentical;

thescene-relatedmetadataisspecifictobands6-highgain,7,and8.Also,theformat2metadatadoesnotincludecloudcoverassessmentdataorreferencestobrowsedataproducts.Thisfile,initsentiretyandoriginalform,accompaniesthe0Rproduct.

∙20.Metadata-ECS.AthirdmetadatafilegeneratedbyECSduringorderprocessing.Thisfilecontainsproductspecificinformationsuchascornercoordinatesandnumberofscans.

∙21.GeolocationIndex.ThegeolocationindexisalsoproducedbyECS.Thistablecontainsscenecornercoordinatesandtheirproduct-specificscanlinenumbersforbandsatallthreeresolutions.Itspurposeisprovideforefficientsubsettingofa0Rproduct.

∙22.Calibrationparameters.TheIASregularlyupdatestheCPFtoreflectchangingradiometricandgeometricparametersrequiredforlevel1processing.ThesearestampedwithapplicabilitydatesandsenttotheLP-DAACforstorageandbundlingwithoutbound0Rproducts.

∙23.HDFDirectory.Afilecontainingallthepointers,filesizeinformation,anddataobjectsrequiredtoopenandprocessthe0RproductusingtheHDFlibraryandinterfaceroutines.

Ausermayorderasubsetoftheavailablebandswhichwillaffectt