Determination of standard biome directional signatures for reflectance normalization issues

摘要

Standard directional models are proposed to describe the reflectance directional signatures of the Earth's major biome types. These Bidirectional Anisotropy Standard shapEs (BASEs) depend on a single spectral parameter only, that can be adjusted from any reflectance measurement, thus offering the possibility to correct operationally radiometric data acquired by single angle instruments from the bidirectional effects. The BASEs are determined from the analysis of the rich archive of POLDER-1 reflectance measurements. They are applied to normalize the Pathfinder AVHRR Land records. The results show a significant reduction of the reflectance noise associated to variations in observation geometry. Therefore, the methodology allows to substitute to the commonly used Normalized Difference Vegetation Index (NDVI) the Difference Vegetation Index (DVI) which is found to be more robust and carry more meaningfull information.