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Physical Products

The GVPS operationally outputs the following physical parameters in various categories at weekly interval:
  •  Smoothed NDVI (SMN) and Smoothed T (SMT)

         SMN:  smoothed NDVI with ACDF adjustment
         SMT:  smoothed AVHRR channel 4 temperature
         SMN, SMT: are essentially the NDVI and T but smoothed by a 15-week temporal filter, no atmospheric correction was applied to NDVI and T.
  • Green Vegetation Fraction (GVF)

         GVF : green vegetation fraction, valued from 0 to 100 percent.  For each week, GVF is derived directly from smoothed NDVI by linear scaling:
                        GVF= (SMN-0.05)/0.44 *100

  • Vegetation Health Indices (VCI, TCI and VTI)

         VCI=(SMN-NDVImin)/(NDVImax-NDVImin) *100
         where, NDVImax, and NDVImin are the multi-year maximum and minimum NDVI for a pixel;
         VCI is vegetation condition index, valued from 0 to 100, shows moisture conditions. Lower VCI values indicate less vegetation cover.

         TCI=(Tmax-SMT)/(Tmax-Tmin) *100
         where, Tmax, Tmin are the multi-year maximum and minimum temperature for a pixel.
         TCI is temperature condition index, valued from 0 to 100, shows thermal conditions. Higher values of TCI indicate wetter conditions at surface.

         VTI=(VCI+TCI)/2.
         VTI is vegetation-temperature index or the so-called "Vegetation Health Index", valued from 0 to 100.VTI is a draught indicator - the lower the value, the drier the surface.