Objectives Multi-temporal interferometric synthetic aperture radar (InSAR) technology is widely used in deformation monitoring over wide areas due to its characteristics of large-scale, high spatial-temporal resolution and the capability to monitor deformation signal with millimeter precision even submillimeter. For the time-consuming problem in acquiring image and data preprocessing over research area, this paper uses looking inside the continents from space with synthetic aperture radar (LiCSAR) products and takes a new time series analysis LiCSBAS method, which greatly improve the computational efficiency.
Methods The quality check and the closure error of the phase loop are used to detect the unwrapping error in the two-dimensional phase unwrapping, and the interferogram with low coherence and the large error pixels are excluded.To minimize atmospheric artifacts, utilizing the generic atmospheric correction online service for InSAR (GACOS) products and based on this, a method for joint estimation of deformation and atmospheric phase is proposed. Taking the Chengdu Plain and western mountainous area as the study area, totally 90 images from 2016 to 2020 are obtained for experimental study on this new time series analysis method.
Results The results show that: (1) The proposed algorithm can effectively weaken the atmospheric artifacts in the area with obvious terrain undulation, within the 34 interferograms, 68% gained positive correction performance, and the standard deviation of the interferogram decreased by 95%. Comparatively, in the area where the atmospheric effect was inapparent, without introducing phase error, and the worst performance increased by 2.06%; (2) most areas are relatively stable with little change and the deformation velocity is -11‒8 mm/a.
Conclusions The proposed method is efficient and phase deviation will not be introduced even if the atmospheric delay error is not significant. In addition, this study also find that the LiCSAR products are suitable for large area deformation investigation and not optimized for more localized deformation studies.
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