An approach for mapping light-use efficiency on regional scales using satellite observations

Light-use-efficiency (LUE), which is the ratio of carbon dioxide uptake to intercepted photosynthetically active radiation (IPAR) for a plant canopy, is a simple way to characterize plant productivity. By combining the concept of LUE with a stomatal-response model for leaves that is adapted to canopies, the authors have derived a simple analytical biophysical (SAB) model of canopy assimilation and conductance that agrees with a detailed soil-plant-atmosphere model named Cupid under a range of conditions. Assimilation predictions from this SAB model include effects of IPAR, carbon dioxide concentration, atmospheric humidity, temperature and available soil water. This SAB model has been integrated into a two-source model for estimating surface energy balance components from satellite observations (vegetation index, albedo, surface radiometric temperature) along with plant type and ground measurements of wind speed and atmospheric lapse rates. By obtaining an estimate of vapor pressure near the surface, which is possible from a combination of surface synoptic network measurements and sunrise surface temperature measurements from a satellite like GOES, the LUE can be estimated. Predictions from the SAB model compare reasonably with measurements from FIFE