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Assessment of the correlation between reflectance anisotropy and NDVI using MODIS BRDF product

Many previous studies attempted to extract prior reflectance anisotropy knowledge from historical Bidirectional reflectance distribution function (BRDF) product based on normalized difference vegetation index (NDVI) data. However, the correlation between reflectance anisotropy and NDVI is still controversial. This study used BRDF archetypes to represent different reflectance anisotropy, and analyzed the correlation between reflectance anisotropy and NDVI based on five-year time series MODIS BRDF data. Nadir reflectance and NDVI retrieved from different BRDF archetypes and same multi-angular observations were also compared with each other to further study this correlation. Results show that the six BRDF archetype classes are all contained in any range of NDVI with one BRDF archetype class accounting for a maximum of 40%. Nadir reflectance and NDVI retrieved from different BRDF archetypes have little difference with each other at different solar zenith angles. NDVI is not a reliable clue to distinguish surface reflectance anisotropy.