Estimation of Surface Height Changes and Deformation Time Series with Improved SBAS-InSAR Technique

Surface heights often change over tens meters in certain scenarios, such as, mountain excavation and city construction (MECC). It is critical to estimate the time and magnitude of surface height changes and the deformation time series with interferometric synthetic aperture radar (InSAR) technique. For the height change regions, ground points become temporarily coherent scatterers, i.e., they are coherent before and after the height changes, but they become incoherent across the height change event. In this case, the traditional Small Baseline Subset (SBAS) InSAR method cannot estimate the DEM errors and deformation with high accuracy, as height changes will introduce time-variable signals, which can be misinterpreted as ground deformation. Therefore, this paper proposes an improved SBAS method to estimate the time and magnitude of surface height changes and deformation time series. As the DEM errors have different linear relationships with the perpendicular baseline before and after the surface height changes, the time point of the height changes can be detected by minimizing the sum of the squares of the residuals. The simulated and real experimental results show that the improved method can accurately acquire the time and magnitude of surface height changes, which can accurately remove the DEM error from different temporal subsets, and contribute to the high accurate estimation of deformation time series in the height change regions.