Speckle statistics and long-term coherent SAR interferograms

One of the main limitations that affects DInSAR measures is the degradation of the phase quality due the changes occurring in the radar resolution cell. Nevertheless it has been observed that in some areas the phase decorrelation process saturates to an amount of coherence normally quite small but not negligible. This behavior can not always be explained with a point target model as far as the interested areas sometimes are not characterized by man-made features and the characteristics change radically with the wavelength. In this paper a method to identify this areas from a relative small amount of SAR acquisitions is proposed. The the results are compared with the residual coherence measured in a test sites acquired in X, C and L band.