Invertibility of a 1-D discrete ordinates canopy reflectance model

The invertibility of an accurate discrete ordinates canopy reflectance model is investigated through a series of experiments. Effects of different canopy types, noise levels, spectral ranges, and sampling geometries [including the NOAA Advanced Very High Resolution Radiometer (AVHRR) and the proposed Multi-angle Imaging SpectroRadiometer (MISR) satellite sampling schemes] are considered. Both error-free synthetic bidirectional reflectance data and empirical field reflectance data are utilized. Results suggest that the model can retrieve soil and canopy parameters with reasonable accuracy in most cases, and surface state parameters (absorbed radiation, spectral albedo and photosynthetic efficiency) with high accuracy in all cases. The efficiency of several commonly used optimization algorithms is also assessed, and a model sensitivity study is conducted.