Fig. 4

Interferograms produced during the procedure of correction of ionospheric disturbances for the pair of images April 26 and June 21, 2016 of P131-F640. a Original differential interferogram in radar coordinate. b Interferogram for higher band. c Interferogram for lower band. d Double-differenced interferogram; i.e., difference between higher and lower band interferograms. e Estimated ionospheric components. f Non-dispersive components in original interferogram; i.e., subtracted phase of ionospheric components from original one. g Flattened and filtered non dispersive components of interferogram. h Geocoded flattened and filtered nondispersive components of interferogram