The Split-Spectrum Method for Differential InSAR Ionospheric Phase Screen Correction

Abstract:

The differential ionospheric path delay is a major error source in L-band interferograms. It is superimposed to topography and ground deformation signals hindering the measurement of geophysical processes like earthquakes. Exploiting the ionosphere dispersive nature of the ionosphere, the method separates the ionospheric component of the interferometric phase from the non-dispersive component, related to topography, ground motion and tropospheric path delay. An implementation of the split-spectrum method is in this work exposed in detail and its performance is analyzed. We test the method using various ALOS PALSAR interferometric pairs with different characteristics: high to low coherence, moving and non-moving terrain, with and without topography and different ionosphere states. Ionospheric errors of almost one meter have been corrected to a centimeter or millimeter level. The results show how the method is able to systematically compensate the ionospheric phase in interferograms. In this work we also present ALOS PALSAR ionospheric-free interferograms and the related ionospheric phase screens for the 2015 Nepal earthquake, the 2008 Wenchuan earthquake, the 2008 Kyrgyzstan earthquake, and the 2011 Myanmar earthquke.