Detection of persistent scatterer pairs on satellite radar images with use of surface relief data

An effective control of geodynamic processes using multiple radar satellite survey and differential interferometric processing of received data requires the identification of terrain areas that preserve an acceptable level of coherence on radar images over a long period. Analysis of the phase component of the images for such areas, called persistent scatterers, makes it possible to estimate the values of small displacements of the observed surface with velocities less than several centimeters per year. In this paper, two radar differential interferometry methods based on the identification of persistent scatterers are considered: the standard method of persistent scatterers and the proposed modification of the method based on the use of persistent scatterer pairs. For both methods it is suggested not to perform a direct phase unwrapping, which is most difficult when most known methods are used. For the method of persistent scatterer pairs it is suggested to apply the quadratic penalty not for the phase unwrapping, but at the final processing stage to recover the absolute values of displacements and corrections of an a priori elevation model from the obtained relative values. The application of the algorithms considered is illustrated by the processing of an interferometric series of 35 radar images obtained by the COSMO-SkyMed system.