作为一项极具潜力的空间对地观测技术，InSAR将不可避免地受到大气中电离层延迟的影响，降低了其观测精度。特别地，随着将来低频SAR卫星(如L和P波段)的发射，这种影响将进一步加剧，严重制约了InSAR技术的进一步发展。因此，必须研究有效的方法对其进行改正。然而目前的改正方法在实际应用中存在一定的局限性，基于此本项目将展开InSAR电离层延迟改正的关键技术研究，从而建立一套完善的MT-InSAR电离层改正理论体系和技术流程。项目将发展三种方法实现对MT-InSAR电离层的改正:①根据电离层的色散特性发展距离向光谱分频法;②根据方位向偏移量与电离层相位延迟之间的关系研究方位向偏移量法；③根据法拉第旋转角与电离层之间的关系研究法拉第旋转角法。为了验证三种方案的合理性，将利用覆盖香港、汾渭盆地、鄂尔多斯盆地、美国阿拉斯加等地的多平台SAR数据进行试验。

As a potential technology of the space-to-ground observation, InSAR inevitably suffers from the ionospheric effect, degrading the precision of InSAR observations. More seriously, this effect has become and is becoming more significant with the increasing interest in the low frequency SAR systems (e.g., L- and P-bands), and limits the further development of InSAR technology. Therefore, it is necessary to develop efficient method to correct the ionospheric contributions to interferograms. To address the shortages of present research on correcting ionospheric delay on InSAR, this project attempts to develop improved methods to correct it through studying the key technologies. Three approaches are designed for this project: ① split-spectrum along range direction method according to ionospheric dispersion characteristics; ②azimuth offset method based on the relationship between azimuth offset and ionospheric phase delay; ③Faraday Rotation (FR) angle method based on the relationship between FR angle and ionospheric phase delay. For the performance test of the developed methods, multi-platform SAR images over Hong Kong, Fenwei basin, Ordos Basin, Alaska are used.