宽幅干涉数据电离层效应改正及对地震构造参数反演影响的研究

本项目主要进行电离层信号改正与高精度PALSAR2宽幅干涉（InSAR）形变场的获取，及其地球物理定量反演研究。PALSAR2宽幅干涉幅宽数据达到350-490公里，尤其适合对空间尺度较大的地壳形变（如地震和构造形变）进行监测，由于电离层对SAR信号的影响，降低了宽幅干涉形变场的精度。本研究以子带干涉与电离层相位图空间重建有关的电离层改正方法为主，针对L波段PALSAR2宽幅模式干涉图，总结发展适用于宽幅干涉数据的电离层改正的方法。在方法研究的基础上，针对2015年Mw7.8尼泊尔地震PALSAR2宽幅数据, 通过电离层相位改正，重建该地区同震形变的高精度宽域形变场，并进行地球物理定量反演研究，为地震研究和断层动力学演化过程提供依据。同时，也检验了所发展的电离层相位改正方法的有效性和可行性，并进一步的总结和分析电离层相位改正对基于InSAR形变场的地震和构造物理反演结果的影响。

This study proposes a research on the ionospheric signal correction in wide-swath Synthetic Aperture Radar Interferometry (InSAR) and its applications in the geophysical inversion. The spatial coverage of PALSAR ScanSAR interferogram can reach the size of 350km-490 km, which is especially useful for studying large scale crustal deformations. However, the L band PALSAR2 imagery is strongly interfered by the presents of ionosphere TEC distortion. Thus, based on the properties of PALSAR2 ScanSAR signals and ionosphere patterns in ScanSAR interferograms, we are focusing on the study of ionosphere correction methods for L band SAR images, especially split-spectrum method and spatial pattern reconstruction method. We are proposing to develop a general and robust ionosphere correction scheme for L band ScanSAR interferograms. The developed ionospheric correction strategy will be applied to PALSAR2 ScanSAR data to study the co-seismic deformation of 2015 Mw 7.8 Nepal earthquake, and derived deformation maps will be used in geophysical inversions to analysis the driven geodynamics. The deformation maps with and without ionospheric signals will be inverted separately for the fault geometry and coseismic slip distribution, in order to quantitatively evaluate the impact from ionosphere residuals to the inverted fault parameters and their error bounds.