Extending algorithm of JPSS VIIRS Vegetation Index Product to GOES-R ABI Data

Vegetation indices (VI) are band reflectance ratios that use the contrast between red and near-infrared reflectances from photosynthesizing vegetation as indicators of green vegetation presence. There is a long heritage of vegetation index products from polar-orbiting satellites, recently including SNPP and NOAA-20 of the JPSS program. The GOES-R Advanced Baseline Imager (ABI) instrument has red, near-infrared, and blue bands that are similar to those used to calculate vegetation indices from VIIRS on SNPP and NOAA-20, though the ABI spatial resolution is 2km while it is 750m for VIIRS. Therefore, we extended the VIIRS VI algorithm for the ABI VI computation. Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI), two VI products, have been calculated from the GOES-R ABI reflectances. When composited over 7- and 16-day periods, the GOES-R VI demonstrates greater clear sky condition coverage than NDVI from SNPP/NOAA-20 VIIRS data composited over the same period, since ABI observations are mostly hourly while the VIIRS observations are mostly daily. Distributions of NDVI and EVI values show some similarity between the two instruments, but there are also differences most likely due to BRDF effects. Geostationary vegetation indices could be produced operationally and would have utility for monitoring and as model input.