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

During the 1994 SIRC/XSAR mission, part of the scientific activities were d evoted 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 degrees to 57 degrees are available in th e C band. Terrain measurements of soil moisture and roughness were also tak en. The objective of this study was to take advantage of this data set to i mprove the geometrical characterization of local soil structure using a fra ctional Brownian model in order to simulate radar backscattering over agric ultural fields. The experimental soil profiles are proved to be locally fra ctal over a spatial range of a few centimeters (clod structure). The relati on between the shape of the correlation function and the fractal dimension is brought to light. A new empirical correlation function is used to adjust the experimental one. It leads to an improvement in the analytic backscatt ering model Integral Equation Model. Soil profiles, generated with combinat ion between fractional Brownian local structure and global structure with r espect to the surface root mean square (rms height) and the correlation len gth, are used in Moment Method backscattering simulations, which provide re sults in excellent agreement with radar data. (C) Elsevier Science Inc., 20 00.