On validation of the MODIS gross primary production product

Validation can be defined as "the process of assessing by independent means the quality of the data products derived from the system outputs." Thus, it is necessary to derive alternative sources of data that correspond to the variable in question, in this case the gross primary production as generated from the Moderate Resolution Imaging Spectrometer (MODIS). The communication makes a swift analysis of the concept behind the MODIS MOD17 GPP product, the issues behind validation of the MOD17 GPP algorithm and reviews the observations made in studies on the performance of MOD17 in comparison against in situ observations. Some conclusions are made on the issues associated with the MOD17 product, its validation, and the validation of EO products in general