A review of methods for mitigating ionospheric artifacts in differential SAR interferometry

Interferometric synthetic aperture radar (InSAR) has been widely used to measure ground displacements related to geophysical and anthropic activities over the past three decades. Satellite SAR systems use microwave signals that interact with the ionosphere when they travel through it during the imaging processes. In this context, ionospheric variations can significantly contaminate SAR imagery, which in turn affects spaceborne InSAR measurements. This bias also leads to a decrease in the coherence and accuracy of InSAR measurements, especially for the low-frequency SAR systems. In this paper, we give an overview of the latest methods for mitigating the ionospheric contributions in InSAR, including Faraday rotation method, azimuth shift method, and range split-spectrum method, and only focus on the single pair of InSAR interferograms. The current challenges and future perspectives are outlined at the end of this paper.