Persistent scatterer interferometery (PSI)

DInSAR methods exploit the temporal baselines among one or more interferograms to extract the phase components correlated with scatterer motion. The performance of these methods is limited by the presence of unwanted phase components, such as the atmospheric phase screen (APS), and phase degradation caused by temporal and geometric decorrelations. Persistent scatterer interferometry (PSI) is an advanced DInSAR concept that circumvents these limitations by observing the phase histories of the so-called persistent scatterers (PSs) in a relatively large stack of interferograms. These are single dominant point-like scatterers marked by high temporal coherence across the entire stack. Since they are less susceptible to the decorrelation phenomena, their unknown motion parameters can be more reliably estimated. A large quantity of PSs is generally desired to effectively retrieve information about the observed geophysical process. PSI techniques are used to analyse deformation signals in urban and alpine regions.