Application of a coherent modeling on Sahelian grassland

The validity of a coherent Sahelian-grassland scattering model is determined by comparing the model predictions with satellite measurements of a representative site. This model considers the realistic botanical structure of grassland. The site Agoufou, located in the Northern Mali, was selected as the test target. This site is governed by a semi-arid tropical climate. Its vegetation is mainly composed of shrubs and annual grass. HH polarization backscattering data was collected over an entire growing season at different incidence angles by means of the ENVISAT ASAR. Simulations provided by the coherent model show a good agreement with measured data having a correlation coefficient equal to 0.92. Model predictions show that the HH polarization component is higher than the W polarization component during all growing season. Significant parameters are shown to be the grass density, the soil moisture content and the grass moisture content. The most sensitive parameter is the ground soil moisture content. Moreover, it is observed that the variation of the backscattering coefficient for all parameters can be represented by a linear regression function.