A Coupled Vegetation–Soil Bidirectional Reflectance Model for a Semiarid Landscape

A model for the bidirectional reflectance over soils is from grasslands to shrublands will affect the biogeochemical cycles and the interactions between the land surface coupled with a vegetation reflectance model to predict the bidirectional reflectance of semiarid landscape. The vegetaand the atmosphere over those regions. Satellite remote sensing provides the only technically consistent and temtion model is a hybrid of geometric optical and radiative transfer (GORT) model for bidirectional reflectance over porally regular means of monitoring those changes at regional scales and estimating landsurface biophysical padiscontinuous plant canopies. The coupling is done by relaxing the assumption of Lambertian background into a rameters (Sellers et al., 1994). The land surface scatters solar radiation anisotropinon-Lambertian case in the vegetation GORT model. The non-Lambertian soil background is modeled by a soil BRDF cally. Even for the same location, for different overpasses, satellites receive reflected solar radiation signals differently model. The coupled model is validated with POLDER and due to changing viewing or illumination angles. This anisoAVHRR imagery collected in a semiarid site during the tropical effect is described in Eq. (1) by the bidirectional Jornada PROVE’97 campaign with good accuracy. It is a reflectance distribution function (BRDF), which is defined very simple but analytical model for bidirectional reflecas the ratio of the radiance scattered by a surface into a tance over a semiarid landscape and has the potential for given direction to the incident irradiance (radiant power surface parameter retrieval for the study of biosphere– per unit area of surface) (Nicodemus et al., 1977): atmosphere interaction. Elsevier Science Inc., 2000