ERS - ASAR Integration in the Interferometric Point Target Analysis
Urs Wegmuller(1) , Charles Werner(1)
, Tazio Strozzi(1)
, and Andreas Wiesmann(1)
Gamma Remote Sensing AG,
CH - 3073 Gümligen,
The possibility to continue deformation monitoring between the rich archive of SAR data acquired by the ERS satellites and ENVISAT ASAR is essential for related applications and services. In many cases the current time monitoring is in the center of the interest, but the existence of the ERS archive is relevant as a record of the deformation history. Another important factor is that the reliability and accuracy of current time monitoring with ASAR is improved by the availability of the historic ERS observations, this particularly in cases where only few ASAR images were acquired.
In this contribution, the integration of ERS and ASAR data in the Interferometric Point Target Analysis (IPTA) is presented. An important advantage of the use of targets with point like scatter characteristics in a SAR interferometric analysis is that coherence is maintained for many scatterers across series including both ERS and ENVISAT data - this in spite of the slightly different sensor carrier frequencies. The main steps of the integration are the transformation of the ASAR scenes to the ERS reference geometry, the consideration of the different carrier frequencies in the phase interpretation, and the estimation of a point-wise ERS - ASAR phase offset. Based on examples mainly from the mining subsidence application the steps done and the results achieved are discussed