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Identification of the location phase screen of ERS-ENVISAT Permanent Scatterers

Claudio Prati(1) and Alessandro Ferretti(2)

(1) Politecnico di Milano, Via Ponzio, 34/5, 20133 Milano, Italy
(2) Tele-Rilevamento Europa (TRE), Via V. Colonna 7, 20149 Milano, Italy


It can be shown from a theoretical point of view that the phase time series of a point-wise Permanent Scatterer would show an additional phase gap passing from ERS to ENVISAT SAR images. This phase gap depends both on the existing 30MHz frequency shift between ERS and ENVISAT and on the location of the PS within the slant range resolution cell. The additional phase gap changes passing from one PS to another, but it maintains a constant value in all the ENVISAT images. A sparse matrix containing the additional phase gap of each PS can thus be formed. We call it "location phase screen" of the ERS-ENVISAT Permanent Scatterers. In this presentation the first experimental evidence of the existence of such a "location phase screen" is shown. A data set of 60 ERS images and 4 ENVISAT images (ERS-like mode) on Milano has been used. Moreover, it will be shown how the estimated location phase screen can be exploited to stitch in a coherent way ERS/ENVISAT SAR images and to identify the precise location of the Permanent Scatterers.


Full paper

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry