A high accuracy coregistration method for TOPSAR interferometry

This paper introduces a high accuracy coregistration method for synthetic aperture radar (SAR) interferometry acquired in Terrain Observation by Progressive Scans (TOPS) mode. Due to the large variation of Doppler centroid frequency in azimuth, even a coregistration error of 0.01 pixels will result in a phase ramp of approximately 37° within one burst. Our method begins with a geometric coregistration, using the precise orbit information and an external digital elevation model (DEM) to achieve good relative accuracy. Then, the remained coregistration error is estimated using the interferometric phase difference between the burst overlaps. The method is applied on Sentinel-1 TOPS interferometric data over the 2015 Mw 7.8 Nepal earthquake fault. The results prove the very high accuracy of our method.