Estimation of ionospheric height variations during an aurora event using multiple semi-focusing levels

Many methods, to estimate the ionospheric effects on SAR images and interferograms, have been proposed and studied in the past years. However, depending on the conditions of the ionosphere, different methods can or should be applied. The effects that an aurora event has on SAR images and interferograms possibly have some differences with respect to the effects generated by a more normal ionospheric state. This work shows one of these differences, which is supposed to be a change in the ionosphere vertical profile, and propose and demonstrates a method to deal with it. This method improves the integrated-azimuth-shifts method, and permits to obtain a better estimate of the ionospheric phase screen.