InSAR Phase Bias Correction Processor: Recent Developments

The Sentinel-1 satellite's short revisit time is advantageous for maintaining better coherence in interferograms over short intervals, resulting in more accurate assessments of rapid deformation. However, the use of shorter-interval, multilooked interferograms may introduce a bias, known as a "fading signal," in the interferometric phase, leading to unreliable velocity estimates. In the first part of our research, funded by the European Space Agency (ESA), we explore characterizing phase bias, focusing on one of its primary indicators—the closure phase. We explore loop closure time-series across various datasets, considering different look directions (ascending and descending), evaluating the impact of filtering and multilooking on closure phases, investigating loop closures across diverse landcovers, and examining the polarization dependency of closure phases. Additionally, we establish correlations between the time series of phase closures and various environmental proxies. In the second stage, we present our progress on developing a universally applicable phase bias correction. We previously developed an empirical mitigation strategy that corrects the phase bias based on the assumption that the change in strength of the bias in interferograms of different length has a constant ratio (Maghsoudi et al. 2022). In this presentation, we investigate the applicability of the proposed method across various scenarios and compare it with alternative approaches. Correcting for the phase bias is particularly important for InSAR processing systems, such as the COMET LiCSAR system (Lazecký et al. 2020), which aims to study geohazards over large areas.   References Maghsoudi, Y., Hooper, A.J., Wright, T.J., Lazecky, M., & Ansari, H. (2022). Characterizing and correcting phase biases in short-term, multilooked interferograms. Remote Sensing of Environment, 275, 113022 Lazecký, M., Spaans, K., González, P.J., Maghsoudi, Y., Morishita, Y., Albino, F., Elliott, J., Greenall, N., Hatton, E., Hooper, A., Juncu, D., McDougall, A., Walters, R.J., Watson, C.S., Weiss, J.R., & Wright, T.J. (2020). LiCSAR: An Automatic InSAR Tool for Measuring and Monitoring Tectonic and Volcanic Activity. Remote Sensing, 12