Correction of ionospheric distortions in low frequency interferometric SAR data

In this paper we propose some ionospheric correction schemes for space-borne synthetic aperture radar (SAR) and polarimetric interferometric SAR (PolInSAR). The spatial and temporal variation of the free electron density in the uppermost atmosphere affects the propagation of the radar pulse resulting in image distortions. We estimate the total electron content (TEC) by applying the Appleton-Hartree equation to the distortions in the focusing, polarimetry, and interferometry. Then we propose a combined estimator that yields comprehensive differential TEC estimations. The effect of vertical structures of the ionosphere on interferometric phase is further discussed.