Assessment of the impact of small-scale ionospheric tec variations on insar

The effect of small- scale ionospheric TEC variations (SSTV) on InSAR is assessed using ground GNSS data. The spectrum of standard deviation of differential TEC (SDT) is derived using GNSS data to characterize SSTV at spatial scales between 1 km and 50 km. Validation of this technique is conducted by comparing the GNSS SDT measurements with ALOS PalSAR data over Chili. The comparison shows consistent magnitude and variation trend between the GNSS and SAR data. The effects of SSTV on NISAR and the future Surface Deformation Change (SDC) mission are assessed using global SDT measurements during seven years from 2013 to 2019. The period covers high, medium, and low solar EUV radiation activities that affect TEC values and variations. Our analysis indicates that the effect of SSTV is substantial and can be on the order of 2 cm at high latitudes and 0.4 cm at middle and low latitudes.