The interferometric decomposition identifies arbitrary scattering mechanisms in two interferometric SAR images and optimises the interferometric coherence. Polarimetric SAR inter-ferometry (Pol-InSAR) is sensitive to the distribution of oriented objects in vegetation layers. It has been demonstrated in various studies that the estimated scattering mechanisms have different vertical loci that can be related to certain vegetation structures. Additionally, theoretical scattering models allow for the reconstruction of the quasi-three-dimensional spatial distribution of such interferometric scattering mechanisms within multi-layer morphologies and the derivation of vegetation-related physical parameters. This paper deals with a sensitivity analysis of the behaviour of the amplitude of the complex interferometric coherence as a function of the aforementioned geo-and biophysical model parameters as well as various acquisition characteristics. Therein, the polarisation-dependent sensitivity of the coherence to these parameters is analysed. The role of the complex interferometric coherence statistics, which are polarisation-dependent, will be shown for the particular case of the estimation of surface topography beneath a vegetation cover by means of Pol-InSAR. These investigations are based on a coherent Pol-InSAR scattering model consisting of a random volume over a multi-polarising ground. The measurements and the theoretical simulations are based on the configuration of a real airborne experiment. This data set provides multi-baseline L-band scattering matrices acquired by the SIR-C system for the lake Baikal test site as well as by the DLR experimental SAR sensor (E-SAR) for a pre-alpine Swiss test site.
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