Correction of ionospheric and tropospheric path delay for L-band interferograms

Abstract

The differential atmospheric path delay is a major error source in L-band interferograms. Refractivity index variations with respect to the nominal value, in the troposphere and in the ionosphere, delay the propagation of radio waves changing the slant range distance. This additional delay is superimposed to topography and ground deformation signals, hindering the measure of geophysical processes. Therefore, it needs to be corrected. In this work we present the correction results for two test cases. We mitigate the impact of height-dependent tropospheric effects (stratified delay) with a method based on the direct integration using numerical weather prediction data. We compensate the ionospheric delay using the split-spectrum method, which is based on the dispersive nature of the ionosphere and estimates the delay from the SAR data itself. Errors are reduced from almost one meter to a centimeter level.