Estimation of Ocean Tidal Loading Deformation From Time-Series InSAR Based on Blind Source Signal Separation and Physical Modeling

Abstract

Estimating coastal ground deformation caused by ocean tidal loading (OTL) through time-series interferometric synthetic aperture radar (InSAR) techniques is challenging but achievable. Based on the two-dimensional wavelet decomposition method to extract spatial long-wavelength interferometric phases, the OTL deformation, residual orbital error, and atmospheric delay error hidden in long-wavelength phases can be isolated by independent component analysis. The ground OTL deformation in time-series InSAR phases is then accurately estimated using tidal harmonic functions. Experiments conducted with Sentinel-1 measurements in coastal areas reveal the following findings. Leveraging the blind source separation method allows for the effective extraction of high spatial resolution and large-scale ground OTL deformation correlation signals from the time-series InSAR phase. The differences between parameter values of main constituents estimated by the modeled InSAR ground OTL deformation and the FES2014b global tidal model range from 1.1% to 5.8%. Additionally, the difference in their predicted OTL deformation values is within the range of 0.9–4.9 mm. Compared to the FES2014b model correction method, the proposed approach removes OTL deformation from the time-series InSAR and results in a 26.1% reduction in the residual standard deviation value of ground deformation, which leads to a significant enhancement in the accuracy of ground deformation acquired for coastal areas. This work provides a novel approach to the theoretical research on OTL deformations, contributing to the refinement of InSAR ground deformation monitoring accuracy in coastal areas.

Keywords

• Independent component analysis (ICA)
• interferometric synthetic aperture radar (InSAR)
• ocean tidal loading (OTL) deformation
• physical modeling
• two-dimensional wavelet