Vegetation index compositing with AVHRR, MODIS and FY3 VIRR

Normalized difference vegetation index is a key parameter to describe physical and biological processes of plants. Vegetation compositing technology offers a new method to obtain NDVI products with special consistency and continuity. MODIS BRDF compositing scheme reduces angular, sun-target-sensor variations with use of a BRDF model, but the Walthall BRDF model inversion required at least five good quality observations. This limits the temporal resolution of NDVI product and increases the change uncertainty in the composite period, especially when the vegetation grow fast. Therefore, the multi-sensor composite strategy was developed to improve the temporal resolution to 4 days. We use a similar MODIS NDVI compositing as the initial algorithm to analyze the multi-sensor datasets, and A Multi-sensor NDVI composing algorithm was developed. Cross validation with MODIS NDVI products also show a satisfactory agreement.