Cunren Liang, Piyush Agram, Mark Simons, Eric Jameson Fielding 

The Copernicus Sentinel-1A/B satellites operating at C-band in TOPS mode bring unprecedented opportunities for measuring large-scale tectonic motions using interferometric synthetic aperture radar. However, while the ionospheric effects are only about one sixteenth of those at L-band, the measurement accuracy might still be degraded by long-wavelength signals due to the ionosphere. We implement the range split-spectrum method for correcting ionospheric effects in InSAR with C-band Sentinel-1 TOPS data. We perform InSAR time series analysis and evaluate these ionospheric effects using data acquired on both ascending (dusk-side of the Sentinel-1 dawn-dusk orbit) and descending (dawn-side) tracks over representative mid-latitude and low-latitude (geomagnetic latitude) areas. We find that the ionospheric effects are very strong for data acquired at low-latitudes on ascending tracks. For other cases, ionospheric effects are not strong or even negligible. Application of the range split-spectrum method, despite some implementation challenges, largely removes ionospheric effects and thus improves the InSAR time series analysis results.