基于低频的L和P波段SAR数据的InSAR技术具有较强的抵抗时空失相关的能力，因此被广泛用于大地测量领域。然而低频SAR数据对大气中的电离层延迟非常敏感，使得InSAR技术的形变测量能力和精度受到极大限制。现有方法大多只能针对InSAR电离层影响（包括法拉第效应、相位变化和方位向偏移）的其中一部分影响进行改正，其可行性和精度也缺乏足够的验证。因此，随着越来越多的低频SAR卫星计划的实施，亟需展开对InSAR电离层延迟改正的系统性研究。本项目以多时相InSAR技术为核心，联合极化SAR和GPS技术，旨在（1）充分利用现有资料，建立一套完整的InSAR电离层探测和延迟改正的理论与模型，突破InSAR的技术瓶颈；（2）提高InSAR监测形变的能力和精度，为地质灾害监测提供技术支撑；（3）反演电离层TEC在精细尺度下的扰动情况，为电离层变化规律研究开辟一条新的途径。

InSAR based on low frequency SAR data, such as the L and P frequency band SAR data, is advantageous in resisting the effect of spatial and temporal decorrelation. It is therefore used widely in geodesy. However, low frequency SAR data are sensitive to ionospheric effects. Its accuracy is often limited by the effects. The current methods for mitigating the effects only focus on some of the effects, e.g., Faraday effect, phase change and azimuth shift. Their usefulness and accuracy are also lack of sufficient validation. Therefore, it is important to carry out more research on ionospheric effects on InSAR in view of the increasing number of low frequency SAR missions planned. This project will use multi-temporal InSAR technique and results from polarimetric SAR and GPS measurements to (1) establish a set of theories and models for detecting and correcting ionospheric effects by fully using all the available information to resolve the bottle-neck problem in SAR application, (2) enhance the capability of InSAR in monitoring deformations to provide technique support for geohazards studies, and (3) cotribute ionospheric studies by investigating the fine scale spatial and temporal TEC variations.