Effects of Particle Size on Soil Reflectance.

Toward developing future algorithms for estimation of soil texture based on remote sensing observations, effects of soil particle size on surface reflectance in the optical domain (i.e., 400-2500 nm) have been studied experimentally and theoretically. Reflectance spectrum of glass beads and baked clays of various particle sizes was measured in laboratory using a spectroradiometer. Data indicated that smaller particles generally lead to higher reflectance. To understand how particle size affects soil reflectance, a simple analytical model for idealized porous media was developed based on radiative transfer theory. The theoretical model could successfully generate the observed functional relationship between particle size and reflectance.