Measurement and simulation of bi-directional reflectance on three zonal soils in the south-east of China

Abstract

Knowledge of radiative transfer over bare soils is a prerequisite to addressing vegetation canopies and predicting soil properties by remote sensing. In this study, the bi-directional spectral reflectance for three zonal soils in the south-east of China (i.e., red soil, paddy soil and coastal saline soil) was measured in the laboratory. The results showed that the soil bi-directional reflectance increases with increasing off-nadir view angle for all azimuth directions and it is azimuthally symmetric in the orthogonal plane. Additionally, the bi-directional reflectance is highest in the back-scattering direction and lowest in forward-scattering direction. The bi-directional reflectance in the near infrared wavebands and the observed spectra of soils were simulated satisfactorily utilising the Hapke model by a nonlinear least-square fitting algorithm. A single-scattering albedo was retrieved from the measured bi-directional reflectance and increased across the whole spectrum as soils dried. This study indicates clearly that the Hapke model can be used to simulate the whole spectral curve and then to retrieve the soil surface characteristics. © 2007 Taylor & Francis Group, LLC.