Assessing Ionospheric Influence on L-Band SAR Data: Implications on Coseismic Displacement Measurements of the 2008 Sichuan Earthquake

Ionospheric contributions to the phase of L-band synthetic aperture radar (SAR) signals put severe limitations on ground displacement measurements retrieved by either differential SAR interferometry or radar amplitude-image offsets. Such contributions result in an ionospheric phase screen on the differential interferogram and in directional fluctuations in the relative position of azimuth pixels on offsets maps. In this letter, we propose a procedure for estimating and removing ionospheric contributions to surface displacement measurements derived from L-band SAR data. We test the procedure on SAR data from the May 28, 2008 Sichuan Earthquake. The applied corrections allow both a clearer interpretation of the surface rupture and a more accurate measurement of the surface displacement, which has important implications in earthquake modeling based on L-band SAR data.