地球同步轨道圆迹SAR重轨干涉技术监测地表三维形变

Spaceborne repeat pass interferometric SAR(InSAR)has been widely applied in the surface deformation measurement of some earth physical phenomena such as volcanoes, coseismic motions and subsidence. However, the conventional spaceborne InSAR has the problems long revisit period and only containing the surface deformation information in the radar's line of sight. Geosynchronous circular SAR (GEOCSAR) is an innovative SAR imaging mode, which has advantages of large coverage, short revisit period and high resolution measurement. In this program, we mainly study the theory and techniques of mapping three-dimensional surface deformation using GEOCSAR repeat pass interferometry. Firstly, the interferometric phase of GEOCSAR is modeled based on the model of the geosynchronous SAR orbit and the theory of interferometric SAR. Then, according to the 3D imaging characteristic of GEOCSAR, the registration method of 3D interferometric images is studied and the 3D interferogram is generated. Furthermore, the retrieval technique of 3D surface deformation is proposed based on the interferometric phase model of GEOCSAR.The simulation results validate the theory and technique of mapping 3D deformation with GEOCSAR repeat pass interferometry,and the parameters are optimized for reducing the retrieval error. The research results are expected to provide the theoretical and technical basis for the development of GEOCSAR and its applications on the interferometric measurement.

星载重轨干涉SAR(InSAR)已被广泛应用于地震、火山、沉降等方面的地表形变测量中,但常规星载InSAR系统存在重访周期长、仅能获取视线向一维地表形变等问题。地球同步轨道圆迹SAR是一种较新的SAR成像模式，它具有覆盖区域大、重访周期短、空间分辨率高等优势。本项目重点研究利用地球同步轨道圆迹SAR（GEOCSAR）进行重轨干涉测量反演地表三维形变的机理和方法：基于GEOCSAR信号模型和InSAR理论，建立GEOCSAR重轨干涉相位模型；针对GEOCSAR三维成像特点，研究三维图像精确配准和三维干涉条纹图生成方法；基于GEOCSAR重轨干涉相位模型，提出三维形变解算方法；对本研究建立的GEOCSAR重轨干涉相位模型以及提出的三维形变反演方法进行仿真验证和效果评估，并提出参数优化方案以提高反演性能。研究成果可望为GEOCSAR技术的发展及其在干涉测量上的应用提供理论依据和技术基础。

地球同步轨道圆迹SAR(GEOCSAR)将圆迹SAR模式应用到地球同步轨道上，具有覆盖区域大、重访周期短、空间分辨率高等优势。本项目重点研究了基于地球同步轨道圆迹SAR进行重轨干涉测量反演地表三维形变的机理和方法。首先，基于GEOCSAR信号模型和干涉SAR原理，建立了GEOCSAR干涉相位模型，并分析了影响干涉性能的各个影响因素，对相干系数进行了量化分析和说明。其次，针对GEOCSAR轨道高度高、合成孔径时间长、旁瓣高的特点，重点分析了对流层和电离层时空变化、水平二维高旁瓣对GEOCSAR性能的影响。最后，提出GEOCSAR反演地表三维形变的方法，通过仿真进行效果验证和评估，并基于反演结果误差分析提出参数优化方案。研究结果表明：对于地球同步轨道圆迹SAR干涉，大气效应是影响干涉相干性和干涉性能的重要因素，其中电离层周日随机变化可能导致GEOCSAR干涉完全去相干；GEOCSAR旁瓣对相干性的影响以基线去相干和配准去相干的形式呈现，且随着空间基线和失配量的增大，相关性呈近似贝赛尔函数的形式下降；利用GEOCSAR三个子孔径的重轨干涉测量，可进行地表的三维形变反演，在不考虑大气噪声等引入的相位噪声情况下，由最优孔径参数反演得到的水平向形变量在厘米级，高度向形变量可达到毫米级。