Impact of the time-spatial background ionosphere variation on geosynchronous SAR interferometric phase screen

Because of working in L band, geosynchronous synthetic aperture radar interferometry (GEO InSAR) and differential interferometry (GEO D-InSAR) system is sensitive to the interferometric phase screen errors introduced by ionosphere. However, conventional ionosphere time-spatial freezing model used in Low Earth Orbit (LEO) SAR is no longer valid due to the long integration time and large imaging width of GEO SAR. In this paper, especially aimed at the time-spatial background ionosphere variation, we firstly theoretically analyzed its impacts on GEO InSAR phase screen. Then, some simulations were conducted by virtue of the real Total Electron Content (TEC) data to study the impacts. The results suggest the serious errors will be brought in the GEO InSAR phase screen by the time-spatial background ionosphere variation.