ERS-ENVISAT permanent scatterers interferometry

The permanent scatterers (PS) technique (Ferretti et al, 2001, 2000, Colesanti et al., 2003), is a powerful and fully operational tool for monitoring ground deformations on a high spatial density grid of point-wise targets, exploiting long series of SAR data. The most attractive aspects of this approach is the capability of providing measurements relative to individual radar targets with unprecedented precision. Up to now, PS analyses have been carried out on ERS, RADARSAT, and JERS data sets. The purpose of this presentation is to discuss the feasibility of updating results obtained by means of a PS analysis on ERS interferometric data using ENVISAT ASAR images. In particular, the main goal is to stitch coherently the new ENVISAT ASAR measurements to the already available ERS displacement time series relative to individual PS. To this end, we will model the interferometric phase of point-wise targets taking account the different ERS and ENVISAT carrier frequencies. Then, we identify the main constraints to be met at individual permanent scatterers in order to guarantee the feasibility of coherent stitching.