The application of a dedicated device to acquire bidirectional reflectance factors over natural surfaces

A portable goniometric device was used in the field to observe four natural surfaces: one composed of a mixed herbaceous species, one of an Alpine pratum, one of a Colza crop and one snow covered. Under stable environmental conditions 66 bidirectional reflectance factors were collected for each target. These data allowed the anisotropic behaviour of each surface to be studied and the actual albedo to be predicted. The differences between the values of albedo and the Lambertian-assumed values were all positive, ranging from 7.1% for the white snow target to 3.3% for the grassy surfaces.