NTSG NASA

Algorithm Description: MOD17A2 :   1KM 8-Day PSN Algorithm Description: MOD17A2 is a Gross Primary Production algorithm. This vegetation production product is designed to provide an accurate regular measure of the growth of the terrestrial vegetation. Production is determined by first computing a daily net photosynthesis value which is then summed over a 8 day interval. For more information please visit the NTSG MODIS website or download the Official MOD17 User's Guide. For current data product issues go to the MODLAND MOD17 Known Issues Page. Variables: GPP: The rate at which light energy is converted to plant biomass is termed primary productivity. The sum total of the converted energy is called gross primary productivity (GPP). PSNnet: Net photosynthesis (PSNnet) is equal to GPP less the maintenance respiration.