Forward and inverse modelling of multi-baseline L-band Pol-InSAR E-SAR data

The objective of this paper is the analysis of forward and inverse modelling of multi-baseline L-band polarimetric SAR interferometry (Pol-InSAR) data. The first part of this study deals with an analysis of the differential phase between interferograms in different polarisation states. It is shown that conventional polarisations in the (h, v)- or Pauli-polarisation basis, while identifying different scattering mechanisms, cannot provide unambiguous interferometric phase centres in vegetation volumes at L-band. On the other hand, the Pol-InSAR optimised singular polarisations provide the largest vertical separability of interferometric phase centres within volume scatterers. The representation of the interferometric coherence in the complex unitary circle as a function of polarisation complements these observations. The second part of the paper concentrates on the forward modelling of Pol-InSAR measurables using a well-known coherent scattering model. The behaviour of the coherence is simulated to provide a more detailed interpretation of the physical meaning of the singular polarisations than was possible in the first part of the paper. Physical parameter ambiguities are emphasised and analysed. In the third part of the paper, Pol-InSAR observables are obtained through inversion of the model mentioned above. The analyses make use of multi-baseline airborne L-band E-SAR data.