Inversion of Landes Forest biomass using SIR-C/X-SAR data: experiment and theory

Polarimetric radar data acquired by the Spaceborne Imaging Radar C/XSAR in April 1994 over the Landes Forest are analyzed. Experimental backscattering coefficients σ⁰hh, σ⁰vv and σ⁰hv for both forest stands and clear-cut areas at L band and C band, as well as the depolarization ratio σ⁰ hv/σ⁰vv and the normalized complex correlation coefficient between HH and VV polarizations, are compared with a four layer radiative transfer model. This model is subsequently used to drive simulations in order to determine the major backscattering mechanisms for a given configuration (incidence, frequency, polarization). The overall objective of this study is to assess the capability of spaceborne polarimetric data at L and C band for forest biomass inversion, mapping of forest/nonforest areas and mapping of the regenerating forest. Both from supervised classification and from unsupervised classification based on theoretical model, it is found that the correlation coefficient between HH and VV polarizations and the ratio between cross- and co-polarized return are useful for biomass inversion