In this paper radar scattering models based on coherent and incoherent formulations for an African grassland (Sahelian) are examined. The coherent model is used to account for the structure of the grass plants and the results are compared with the same model assuming random placement and orientation of scatters, and the Radiative Transfer model. The validity of the three models applied to grass vegetation is determined by comparing the model predictions with ENVISAT ASAR data gathered in 2005 over Sahelian grassland. The Agoufou site, as defined in AMMA project, is selected as the test target and a set of ground data were collected during 2004 and 2005. Through a comprehensive data comparison, it is shown that the coherent scattering model with a generator considering botanical information is the best model to predict the backscattering data that matches ENVISAT measurements well (correlation = 0.92). At low incidence angles (<30°), the radar backscatter shows a strong dependence to soil moisture variations. The analysis of the different contributions leads to study the main scattering mechanisms. For high incidence angles, backscattering coefficient at HH polarization shows a marked seasonal variation associated to grass presence.
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