A Comparative Study of Ionospheric Correction on SAR Interferometry—A Case Study of L’Aquila Earthquake

Abstract

Synthetic Aperture Radar Interferometry (InSAR) has shown its potential on seismic deformation monitoring since it can achieve the accuracy of centimeter level or even the millimeter level. However, the irregular varieties of ionosphere can induce the additional phase delay on SAR interferometry, restricting its further application in high-precision deformation monitoring. Although several methods have been proposed to correct the ionospheric phase delay on SAR interferometry, the performances of them haven’t been evaluated and compared. In this study, three commonly used methods, including polynomial fitting, azimuth offset and split-spectrum are applied to L’Aquila Earthquake to correct the ionospheric phase delay on two Phased Array type L-band Synthetic Aperture Radar (PALSAR) onboard the Advanced Land Observing Satellite-1 (ALOS-1) images. The result indicates that these three methods can effectively correct the ionospheric phase delay error for SAR interferometry, where the standard deviations of the ionosphere-corrected results have decreased by almost a factor of 1.8 times for polynomial fitting method, 4.2 times for azimuth offset method and 2.5 times for split-spectrum method, compared to those of the original phase. Furthermore, the result of the sliding distribution inversion of the seismic fault shows the best performance for split-spectrum method.

Keywords

• |sar interferometry|ionospheric effects|split-spectrum method|azimuth offset method|performance evaluation