TanDEM-X Performance over Sandy Areas

The interferometric SAR mission TanDEM-X started in 2010 and comprises the two twin satellites TerraSAR-X and TanDEM-X. Its primary objective is to generate a worldwide, consistent, and high-precision digital elevation model (DEM). Two global coverages have been completed until August 2013, and a very good performance has been verified for most of the land masses. However, some areas all around the world still exhibit for different reasons unsatisfactory quality of the data. The main scope of this paper is to present a detailed performance analysis over sandy desert areas, which have shown to degrade the TanDEM-X interferometric products. The influence of several acquisition parameters on SAR and InSAR performance is evaluated by means of statistical analyses as well as repeated acquisitions on defined test sites. The present investigations better characterize the effects of the scattering mechanisms occurring at X-band over sandy surfaces. This allows to opportunely plan a dedicated reacquisition of such affected areas with an optimized imaging geometry in order to improve the quality of the final TanDEM-X DEM.