An overarching intent of FLUXNET, and its regional partners, is to provide data that can be used to validate terrestrial carbon fluxes derived from sensors on NASA satellites, such as TERRA and AQUA, and from biogeochemical models. To achieve this overarching goal, the objectives and priorities of FLUXNET have evolved as the network has grown and matured. During the initial stages of FLUXNET, the priority of our research was to develop value-added products, such as gap-filled data sets of net ecosystem productivity, NEP, evaporation, energy exchange and meteorology. The rationales for this undertaking were: 1) to compute daily, monthly and annual sums of net carbon, water and energy exchange; and 2) to produce continuous datasets for the execution and testing of a variety of biogeochemical/biophysical/ecosystem dynamic models and satellite-based remote sensing algorithms.