Evaluating ScanSAR Interferometry Deformation Time Series Using Bursted Stripmap Data

We demonstrate scanning synthetic aperture radar (ScanSAR) advanced radar interferometry processing for surface deformation time series analysis. We apply the small baseline subsets (SBAS) technique to ScanSAR data synthesized from 40 ERS-1 and ERS-2 stripmap SAR images over known deformation in Phoenix, Arizona. The strategy is to construct a burst pattern similar to Envisat ScanSAR data for two scenarios, namely, an idealized 100% burst overlap case and a realistic variable-burst synchronization case in which any image pair has at least 50% burst overlap. We And this latter scenario to be reasonable based on an assessment of the effect of burst overlap on Phoenix interferometric phase coherence. The differences between the variable burst overlap ScanSAR and stripmap SAR SBAS-derived pixel velocities have a mean of 0.02 cm/year and a standard deviation of 0.02 cm/year. It is noted that one can expect SBAS velocity and displacement one-sigma errors of 0.1 cm/year and 0.5 cm, respectively, from multilooked stripmap data. We observe that 96% and 99% of the variable burst overlap ScanSAR pixel velocities are within ±0.1 and ±0.2 cm/year (one- and two-sigma), respectively, of our stripmap SAR pixel velocities. These results are similar to those reported for SBAS analysis applied to low-resolution multilook interferograms derived from coherence-preserving down sampling of stripmap data. We also And that the rms deviations between variable burst overlap ScanSAR and stripmap SBAS displacement estimates are 0.40 ± 0.30 cm. 68% and 94% of the variable burst overlap ScanSAR pixel displacements are within ±0.5 and ±1.0 cm, respectively, of the stripmap displacements.