Correcting Ionospheric Error for MAI Based on Along-Track Gradient and 1-D Linear Fitting

As a supplement to synthetic aperture radar interferometry (InSAR), multiple-aperture InSAR (MAI) can measure along-track surface deformation, but it is limited by ionospheric path delays, especially with the L- or P-band data. In this letter, we propose a method to correct an ionospheric error in the MAI measurement based on the along-track gradient and 1-D linear fitting. The method depends on the uniqueness of the spatial variation of the along-track gradient of ionospheric error in MAI measurements, which can be well distinguished from other components, such as deformation by using 1-D linear fitting. The method is first evaluated by employing the L-band ALOS-2 PALSAR-2 dataset of the 2019 Ridgecrest earthquake, U.S., and then applied to estimate glacial movements of Grove Mountain, Antarctica, with the ALOS-2 PALSAR-2 dataset.