VIIRS Green Vegetation Fraction (GVF) Product

The S-NPP VIIRS GVF system has been running operationally at NDE since February 2015, and now continue generated in NDE Vegetation Products Processing System (NVPS). The NVPS will produce daily rolling weekly Green Vegetation Fraction from S-NPP VIIRS granule data and J01 VIIRS granule data. The GVF output files include a 0.009 ○ (1-km) GVF regional file, and a 0.036 ○ (4-km) GVF global file, both in NetCDF4 format. The NetCDF4 output will be converted to GRIB2 at NDE using a standalone conversion tool. The daily rolling weekly production scheme means that the GVF products are derived from VIIRS input data from the past 7 days, but the output is generated every day.

Seven major steps are required to generate the GVF products (global and regional):

identification of VIIRS granules to be gridded for each tile
gridding at 0.003 ○ spatial resolution of daily VIIRS observations for I1, I2, and M3 bands
compositing of the gridded daily observations of the past 7 days into a weekly composite
EVI calculation from weekly composite
EVI gap filling and smoothing based on an EVI time series
GVF computation at 0.003 ○
GVF aggregation to 0.009 ○ for the regional product and to 0.036 ○ for the global product.

The GVF product is smooth and therefore no quality flags provided in the output file. For detailed information about the GVF algorithm, see the GVF Algorithm Theoretical Basis Document.