Satellite remote sensing of primary production: an improved production efficiency modeling approach

Application and validation of a modified production efficiency model (PEM) appropriate for the regional and global scales is presented. The model calculates not just the conversion efficiency of absorbed photosynthetically active radiation (APAR) but also the component carbon fluxes that ultimately determine net and gross primary production. This approach, driven with remotely sensed observations, moves beyond simple correlative or associative models to a more mechanistic basis and avoids the need for a full suite of ecophysiological process algorithms that require explicit (e.g. species-specific) parameterization. We show that surface variables recovered from the satellite observations, including net primary production, are in good agreement with field measurements and independent model simulations in a number of ecosystems. These results illustrate the utility of PEMs for terrestrial primary production modeling over large areas and suggest that some complex ecophysiological models may be functionally simpler than their structure suggests.