Modeling Spectral and Bidirectional Soil Reflectance

SOILSPECT is a radiative transfer model, derived from Hapke's model, that represents the optical properties of soil from 450 nm to 2450 nm. The spectral and bidirectional reflectance of 26 soils was measured in the laboratory both with a field spectroradiometer (1000 narrow wavebands from 450 nm to 2450 nm) and a radiometer simulating TM channels (the five TM2, TM3, TM4, TM5, and TM7 broad bands). The input parameters of the model [single scattering albedo w, phase function P(g,g'), and variable characteristic of the soil roughness h] were fitted to these observations. We show that the single scattering albedo is only dependent on wavelength and on soil humidity; the other parameters depend mainly on surface conditions.