The Impact of the Ionosphere on Interferometric SAR Processing

The impact of ionospheric propagation effects on the signal properties of SAR systems is significant and increases with decreasing carrier frequency. Besides polarimetric applications, also interferometric SAR processing can be significantly affected. Relative range shifts, internal image deformations, range and azimuth blurring, and interferometric phase errors are the most significant effects to be considered. In this paper we provide the theoretical background for ionospheric effects on InSAR. We quantify expected magnitudes of the respective effects for various existing SAR sensors and discuss methods for their detection and correction. Real data examples, mainly stemming from the ALOS PALSAR mission, are presented to verify the derived theory.