2011_InSAR_practical_considerations

InSARpracticalconsiderationsMatthewPritchardCornellUniversityHowtogetdataUnderstandingtheLineofSightSourcesoferrorResampling/downsamplingdataMulti-interferogrammethods:timeseriesPSInSARHowtoaccessdata:Overviewofavailabledatasources&mostup-to-dateinfoisatroipac.org/AccessToDataAtooltosearchforavailableERSandEnvisatdataisfreelyavailablefordownloadfromESA:calledEOLISAIfyouwouldlikeinformationonbaselinesbetweenpotentialdatatakes,visitroipac.org•NoCostdata--butneedtoapplyforaccess•ESAdataavailablefornocost:writeaCategory-1proposal•“Supersites”availableforsmallareasofinterest(Mt.Etna,LosAngeles,etc.)seeroipac.orgforlink•GeoEarthscope:•Ifataresearchinstitution,writea“Mini-Cat”proposal•(ERS,Envisat,RadarsatoverNorthAmerica)•AlaskaSatelliteFacility•ALOSdatapool--ifaWInSARmember,signaformandgetaccess•ERS/JERSwithinASFsatellitediskmask,Radarsatalmostanywhereintheworld--writea2-pageproposal•WesternNorthAmericaInSARConsortium•(ERS,EnvisatoverNorthAmerica)•Yourinstitutionmustbeamember(nocosttojoin!),needpassword•Forpurchase•Commercialcompanies(usually$100’sto$1000’sperscene)•Accesstosoftware:•InSAR:OverviewofavailablepackagesfocusingontheopensourceROI_PAC•GMTSARfromDavidSandwelletal.(seewebsitatUCSD)•NotesfromUNAVCOshortcourseonInSAR&ROI_PAC::unw2png.plwillconvertgeocodedinterferogramtoGoogleEarthkmlfileandpng(needfreeimagemagicksoftware)VariousGMTscriptsExampleMatlabandIDLscriptsforloadingdataForGISsoftware,use.rscfiletocreatemetadatafileandperhapsrmg2mag_phstomakeasinglebinaryfileMakelosscript:createsfilewiththesatelliteheadingandincidenceangleateachpixelAccesstotopographicdataSourceIusemostoften:SRTM1degreetileseitherat3arcsec(90m)or1arcsecforU.S.(30m)Roipac.org/ContribSoftwareget_SRTM.plandmakedem.plAlsoavailablefromseamlessUSGSserver.CanaccessavailableLidarandNEDdataforU.S.ASTERGDEM--postedat1arcsecond,butvariousanalysisindicatesitiscloserto3arcsec(GDEM2availablethisfall)FormatneedstobeI*2(16bit)binaryfilewithnoheaderNeedtocreate.rscfilewithupperleftcoordinates,#ofrowsandcolumns,andpixelspacing•Previouslyunmappedfault(right-lateralstrike-slip)WhereintheworldamI?•Magnitude6.6earthquake:26December2003inBam,Iran•Aridandmountainousregionwithfrequentearthquakes(collisionbetweenArabianandEurasianplates)NorthBamBaravat10km20kmInterferogramcourtesyofYuriFialkoLandsatsatelliteimagefrom1999,fromFunningetal.,2005From:Farsinet.comWhatamIlookingat?North20km•Eachfringe:contourofgrounddeformationindirectionofsatelliteradarbeam•Eachscene:•20metersperpixel•100’sofkmperimage•Resolvedeformation~mm/year•Thisexample:•FromEuropeanspaceAgencyEnvisatsatellite(5.6cmradarwavelength)•Eachfringeis2.8cmofdeformationVisualizing3Ddeformationina1Dinterferogram•Step1:Faultmotionproduces3Ddeformationfield•Step2:Project3Ddeformationontosatelliteradarline-of-sightTrade-offbetweenhorizontalandverticaldeformationcreatesasymmetricpattern•Step3:Createafringeevery/2centimeters(“wrappedimage”)Bothimages:Funningetal.,2005Reconstructingthefull3Ddeformationfield•UseinterferogramsfromdifferentsatellitelookdirectionsFialkoetal.,2005InferredverticaldisplacementInferredhorizontaldisplacementObservedinterferogramsObservedpixeltrackingBeforeAfter•PLUS:usetheamplitudeimagestotrackpixelsthatmovedSARTrack/FrameGeometryIranModifiedfromRowenaLohmanDescendingAscendingHectorMineEQModifiedfromRowenaLohmanWhatarethesourcesoferror?Howdoweevaluatethem?•Unwrappingerrors:assessbylookingaimagewithdifferentwraprates•Atmospheric/ionosphericerrors:usemultipleimagesandpairwiselogic(e.g.,Feigl&Massonnet,1995)•Orbitalerrors:understandtheirbasiccharacteristics,trydifferentorbitalestimates,processtracksofdifferentlengths,tandempairscanbeuseful•DEMerrors:inspecttherawDEM,processinterferogramswithdifferentbaselinesandtimespans,tandempairscanbeusefulWrappedvs.UnwrappedColorCycle=300cmColorCycle~3cmModifiedfromRowenaLohmanHectorMineEQModifiedfromRowenaLohmanModifiedfromRowenaLohmanModifiedfromRowenaLohmanUnwrappedaftermaskingUnwrappedbeforemaskingModifiedfromRowenaLohmanOrbitalErrors(“Ramps”)•~0.1-1muncertaintyinsatellitepositions•Orbitalfringesnotalways100%removed•Inparticular,notsensitivetolongwavelengthdeformationHowtoovercome?•SimultaneouslysolveforpositionandgeophysicsReportedvs.ActualModifiedfromRowenaLohmanAtmosphericcontamination:TwotypesTurbulenceVerticalstratificationBothFrom:Pritchard&Simons,2004Canweremovetheatmosphericsignalfrominterferograms?0)Useinterferogramsthemselvestoestimatelinearorexponentialphasewithelevation:constantforimageorspatiallyvariable1)Directwatervaporand“drydelay”observations:Fromsatellite(e.g.,Lietal.,2005)FromGPS&othergroundsensors(e.g.,Webleyetal.,2002)2)DatastacksorAPS:Assumeatmosphererandomintimeorlow-passtimedomainfiltering(e.g.,Ferrettietal.,2001;SimonsandRosen,2007)3)GlobalandRegionalModelscomputedbydatacenter(~100kmhorizontalresolutionbyECM