MSG/SEVIRI -- Introduction The major product of the Experimental Global Vegetation Processing System (GVPS) is the global vegetation fraction (GVF). It is derived from the NOAA/NESDIS second generation global vegetation index (GVI2) dataset. First, NDVI is calculated from weekly composite reflectance of AVHRR visibale channel 1 and 2. Then, a temporal filter is applied on NDVI to reduce the effect of cloud contamination. Smoothed NDVI is futher adjusted by ACDF technique to minimize the discrepencies due to orbiting drifting, sensor degradation, atmospheric contamination, AVHRR sensor response function differences among generations, etc. GVF is linear scaled from smoothed NDVI. (see GVF algorithm detail)