GROUND-BASED RADAR INTERFEROMETRY FOR MONITORING UNSTABLE SLOPES

Abstract: A ground-based coherent radar instrumentation acquires a time series of radar images. The complex product, pixel by pixel, of a pair of holographic radar images, taken at different moments, gives an interferogram whose phase is related to pixel distance from the sensor. When terrain displacements occur in the time elapsed between two image acquisitions, the phase of the corresponding pixel will vary accordingly. Ground-based radar interferometry is a powerful technique for monitoring terrain deformation on unstable slopes. In this paper the technique is briefly described with reference to some recent experimental cases, reviewing in its potentials and limits. In spite of its indubitable advantages, a number of potential error sources have been recognized: instrumentation instability, repeatability of the measurements after removal and further reinstallation of the instrumentation, atmospheric path delay changes, temporal decorrelation of the scenario, and phase wrapping. All these limits can be overcome by suitable solutions (atmospheric corrections, coherent points analysis, phase unwrapping techniques) that will be discussed in this paper. 1