Validation of a rough surface model based on fractal Brownian geometry with SIRC and ERASME data over Orgeval

During the 1994 SIRC/XSAR mission, a part of the scientific activities was devoted to hydrology applications. To complement the shuttle radar data, the helicopter scatterometer ERASME was used on the Orgeval site. As a result, incidence angles ranging from 25 to 50 degrees are available in C- and X-band. Terrain measurements of soil moisture and roughness were done. The objective of this paper is to investigate the description of soil structures in this data set with a fractional Brownian model to improve the geometrical characterisation of soil and the simulation of radar backscattering over agricultural fields. The experimental soil profiles are found fractal over spatial range of few cms (clods structure). The relation between the correlation function and the fractal dimension is proved. A new empirical correlation function is developed to adjust experimental ones. It introduces improvement in the IEM model simulations of soil backscattering. Soil profiles generated with combination of fractal Brownian local structure and global structure profile are used in moment method model which gives results in good agreement with radar data