Study On Scanning Synthetic Aperture Radar Interferometry Theory And Application For Deformation Mornitoring

Wide swath synthetic aperture radar interferometry is a technique which can monitor the earth's surface and process corresponding radar data to get deformation information based on ScanSAR mode of SAR satellites, therefore it is also named as scanning synthetic aperture radar interferometry.Wide swath SAR intensity data has been used and acquired important effect for many aspects such as resource perambulation,monitoring environment,ocean exploration, preventing and dcreasing disasters,land use and forest investiagation,crop assess and nation security.With melioration and enhance of facility and orbit tecqnique of SAR satellite, scanning pattern synchronization and the critical baseline of precondition condition for scanning synthetic aperture radar interferometry have been pledged,at the same time,many SAR satellites have been launched or will be eradiated soon so that they can provide more abundant data for WSInSAR.Therefore,scanning synthetic aperture radar interferometry can offer chance for studing plank movement and geodynamics.As far as scanning synthetic aperture radar interferometry is concerned,although its resolution is very low, it has two merits:i.e,wider swath and short period revisiting target.The merit of short period denotes it can measure easily slow deformation of the earth's surface.The other merit denotes not only baseline error can be removed,but its wider deformation field can be also applied to analyze mechanism of earthquake.At the same time, ScanSAR mode data can be combined with stripmap mode data to form a series of interferograms at a denser temporal spacing than is possible with normal InSAR,therefore scanning synthetic aperture radar interferometry has become a hot topic and new direction of application.Although wide swath mode is one of modes of spaceborne SAR satellites, their modes are different, and imaging principle and process of interferometry also have a lot of dissimilitudes such as coherence,coregistering,correction of atmosphere effects and geoid undulation.In order to make use of ScanSAR data to get wider deformation field, theory and its application of scanning synthetic aperture radar interferometry are studied, including the following contents: 1) Principles of image and interferometry of wide swath SAR: Based on theory of synthetic aperture radar and ScanSAR,their imaging parameters and capability are analyzed. Compared to IM interferometry, mathematic model and flow of ScanSAR interferometry are studied in TCN corordinate system.2)Mosaicing of wide swath SAR data:According to different frequcency peculiarity of stripmap mode and burst mode data, mosaic algorithm of ScanSAR level 0 data is studied.After getting single burst interferogram, methods of mosaicing single burst interferogram are introduced. As method of mosaicing sub-swath interferogram by using geometry relation of image has shortage, a method based on coregistering and weight is put forward,and is validated by experiment.3) Research of removing coherence of wide swath SAR interferometry:After comparing with stripmap interferometry,removing coherence of geometry and azimuth scanning pattern synchronization is investigated, especially relation between geometry coherence and critical baseline of ScanSAR interferometry.For probability which relative high difference within one resolution of wide swath SAR exceeds coherence high difference is n times than image mode.critical baseline of ScanSAR interferometry is (?) of IM interferometry.4) Ingredient research influenced quality of WSInSAR:ScanSAR interferometry is suffered from many sources of errors such as baseline error and DEM error, so,mathematical model of these errors is duduced and validated by an example of bam earthquake. Although there is a little difference of precision between GDEM and SRTM, ScanSAR interferometry need not be taken into account influence because of shorter baseline.Baseline error takes on cumulation domino offect in the ScanSAR interferogram so that WSInSAR need more precise orbit data.Geoid undulation can also influence ScanSAR interferometry,when Geoid undulation is 20m and perpendicular baseline is 100m, the influence value is 6.4mm.Therefore, geoid undulation is computed by using EGM96 model and it improve greatly results of ScanSAR interferometry.5) Correction of atmospheric effects on ScanSAR interferogram:In order to remove or reduce atmospheric effects, algorithms of correction of atmospheric effects on IM interferogram are concluded and introduced for ScanSAR interferogram,at the same time,correction methods based on exterior and non-ecterior data are studied for ScanSAR mode,especially MERIS and DEM; permanent scatters ScanSAR Interferometry is invertigated simply.6) Capture of earthquake deformation field based on spacebome wide swath interferometry: After analysis of non coherent region for different mode and different wavelength, deformation fusion method based on mulit-mode and multi-wavelength is put forward and applied to get fused deformation field.Defomation field after fusion not only can reflect earthquake deformation,but also non coherent region diminish. Deformation field of 8.0 Wenchuan earthquake and 7.3 Yutian earthquake are gained by making use of ScanSAR interferometry;at the same time, atmospheric effects of these deformation field have been corrected based on MERIS and DEM data respectively.