一种联合估计形变和大气误差的改进LiCSBAS方法

An Improved LiCSBAS Method for Joint Estimation of Deformation and Atmospheric Errors

  • 摘要: 多时相InSAR(interferometric synthetic aperture radar)技术以其大范围、高时空分辨率、可以获取毫米级甚至亚毫米级形变信号等特点,被广泛应用于大范围地表沉降监测。针对目前时序分析在获取研究区影像和数据预处理上耗时量大的问题,利用LiCSAR(looking inside the continents from space with synthetic aperture radar)产品,采用时序分析新方法LiCSBAS提高了解算效率。该方法采用整体干涉对质量检验和相位环闭合差,探测二维相位解缠存在的解缠误差,剔除相干性较低的干涉对和大误差像元。为了减弱大气误差的影响,利用通用型大气改正在线服务产品进行大气误差改正,并在此基础上提出了一种形变参数和大气相位联合估计方法。以成都平原地区和西部山区为例,获取2016—2020年共90景影像进行时序分析新方法实验研究。结果表明:(1)提出的联合估计算法在地形起伏明显地区可以有效地抑制大气误差的影响,同时在大气效应不明显的地区也不会错估而引入相位误差;(2)监测的大部分区域表现较为稳定,年际沉降形变速率为-11~8 mm/a;(3)LiCSAR产品适合做大区域形变调查,难以满足小范围精细监测的需求。

     

    Abstract:
      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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