DEM generation using ERS–ENVISAT interferometry

Space-borne SAR interferometry is one possible method for the generation of digital elevation models (DEMs). The sensitivity of this technique depends strongly on system parameters as the time interval between the observations used and the spatial baseline. Longer time intervals are less suited because of temporal decorrelation of the signal. Longer spatial baselines result in an increased height sensitivity. ERS-2 and ENVISAT ASAR operate in identical orbits at slightly different sensor frequencies with ASAR preceding ERS-2 by 28 min. This configuration offers a unique opportunity to study and apply ERS–ENVISAT interferometry. ERS-2–ENVISAT ASAR IS2 VV-polarization interferograms are characterized by a short 28 min repeat-pass interval and a long 1.5–2.5 km baseline. Given the long baseline and short time interval ERS–ENVISAT interferometry has a good potential for the generation of precise DEMs in relatively flat areas. The idea to use ERS–ENVISAT interferometry for DEM generation is not new, nevertheless, very few adequate data sets were identified and analyzed in the past. Now, thanks to a recent dedicated ERS-2–ENVISAT Tandem mission of ESA many well suited data sets became available. In this paper the ERS–ENVISAT interferometry methodology is described, its feasibility is demonstrated by presenting ERS–ENVISAT interferometry DEMs over several sites, and its potential is assessed.