GaoFen-3 Mission for InSAR Time Series Analysis: A Quantitative Evaluation

GaoFen-3 (GF-3) is China's first civilian high-resolution synthetic aperture radar (SAR) satellite mission. Since its launch in 2016, GF-3 has achieved remarkable success in various SAR application fields. However, till this date, research and applications focusing on SAR interferometry (InSAR) time series analysis have not received enough attention. InSAR time series analysis stands out for its ability to accurately measure surface displacements over a wide range with millimeter-level precision. Currently, there is a notable lack of comprehensive understanding of GF-3’s InSAR time series capabilities, untapped potential, and possible areas for improvement. In this study, we conducted a thorough evaluation of GF-3’s InSAR time series analysis performance using the persistent scatterer interferometry (PS-InSAR) method. For the first time, we processed 25 GF-3 images taken between 2020 and 2023 using the PS-InSAR method. Our results demonstrated that GF-3 is capable of producing high-quality PS-InSAR outcomes. When compared to Sentinel-1 (S1), the root mean square error of the estimated velocity between GF-3 and S1 was 2 mm/yr. The measured point density delivered by GF-3 amounted to 7610/km<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula>, substantially the same as TerraSAR-X and 50% higher than the highest standard set by the European ground motion service. At last, despite GF-3’s spatial baseline variation exceeding 660m (1<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sigma$</tex-math></inline-formula>), since the persistent scatterers hardly decorrelate, the PS-InSAR performance quality is virtually unaffected. This pioneering study conclusively demonstrated that GF-3 is capable of delivering high-quality PS-InSAR results. With the three satellites GF-3 constellation now in orbit, our work will provide vital support and lay a solid foundation for operational PS-InSAR applications using domestic satellites. Furthermore, we anticipate that the promising results obtained from this work will facilitate substantial progress in China's InSAR related research and operational applications.