Exploring the potential of Pol-InSAR techniques at X-band first results and experiments from TanDEM-X

In this paper, first Pol-InSAR TanDEM-X datasets over a number of sites distributed across worldwide are investigated with respect to interferometric volumetric effects in order to provide first insights on the potential of the TanDEM-X mission for characterisation of natural volume scatterers. The dependency of the interferometric Cpherence on spatial baseline and polarization is investigated over a variety of natural scatterers as vegetation, snow and ice layers and sand. For this purpose dual polarimetric (HH/VV and/or HH/HV) datasets from the pursuit monostatic commissioning phase (lasting until September 2010 where both TanDEM-X and TerraSAR-X operated in a monostatic mode separated approximately 20km in along-track that translates in a temporal baseline of approx 3sec.) and the bistatic phase (starting in October 2010 TanDEM and TerraSAR are flying in a close formation and are operated in a bistatic mode with zero temporal baseline) are used. TanDEM-X - successfully launched in June 2010 forms together with TerraSAR-X the first single-pass polarimetric interferometer in space. This allows for the first time the acquisition and analysis of Single-, Dual-, and Quad-Pol-InSAR data without the disturbing effect of temporal decorrelation. Even if X-band has when compared to lower frequencies a reduced penetration capability recent airborne experiments demonstrated several cases where a rather surprising penetration into natural volume scatterers as vegetation and ice could be proven. In this sense, the investigation of the Tandem-X Pol-InSAR data sets will strongly contribute to our understanding of scattering processes at X-band and potential new Pol-InSAR applications.