Variograms for atmospheric phase screen estimation from TerraSAR-X high resolution spotlight data

The PSInSAR technique, invented by Ferretti et. al. [1], [2], [3] ten years ago, meanwhile has proven its capability for very precise measurement of surface deformations. To achieve this, the influence of the atmospheric phase screen (APS) has to be removed. We investigated the APS for two series of TerraSAR-X high resolution spotlight data of a scene in Bavaria. In order to account for stratified troposphere and turbulence we augmented the APS estimation of StaMPS (Stanford Method for Persistent Scatterers) [4], that is we consider the APS as composed of a phase ramp, a part stratified with height and a turbulent component. The turbulent component is estimated via kriging. The necessary variograms can be computed under the assumption of isotropy as well as allowing for anisotropy. For short distances the variograms show a regime which is not visible for lower resolutions. In this paper we discuss the choice of appropriate variogram models with respect to our data.