An Onboard Calibration Technique for Synthetic Aperture Radar Interferometry Using Multisource Data

The synthetic aperture radar interferometry (InSAR) is a powerful tool for retrieving the Earth’s geophysical parameters, such as terrain height, displacement and soil moisture. The standard processing chain typically involves wrapped phase extraction, phase unwrapping (PU) and calibration, where the accuracy of PU and calibration can directly determines the reliability of final InSAR-derived parameters. Traditionally, PU and calibration are performed as two separate steps–first, unwrapping and then, calibrating–which are prone to error propagation and error accumulation, especially in low-quality regions. To overcome this limitation, we develop a multisource data-based calibration technique (MDCT) in this article, which integrates PU and calibration into a unified framework with the assistance of auxiliary data. Unlike conventional calibration approaches, MDCT does not rely on in-situ measurements and can theoretically achieve calibration performance approaching unit coherence. Experiments verify the effectiveness of MDCT by achieving a calibration accuracy of 15.70 m in glacier elevation retrieval in Greenland and 0.58 m in water-level change retrieval in the Congo River. Furthermore, MDCT can be extended from the single-baseline (SB) InSAR domain to the multibaseline (MB) InSAR domain when multiple ( ≥2 ) interferograms with baseline diversity are available.