Modeling evapotranspiration by combing a two-source model, a leaf stomatal model, and a light-use efficiency model

Modeling and partitioning ecosystem evapotranspiration (ET) are important in predicting the responses of ecosystem water cycles to global climate change and land use. By incorporating the Ball-Berry stomatal conductance model and a light use efficiency-based gross primary productivity (GPP) model into the Shuttleworth-Wallace model, we developed a new model, SWH, for estimating ET with meteorological data and remote sensing products. Since the new model solved the problem of estimating canopy stomatal conductance, it can be used at sites equipped with meteorological observation systems around the world. Compared with eddy covariance measurements, the SWH model demonstrated satisfactory estimates of ET at a temperate forest and an alpine grassland. Eight meteorological variables and two remote sensing products (i.e., leaf area index, LAI, and enhanced vegetation index, EVI or normalized difference vegetation index, NDVI, or fraction of photosynthetically active radiation, FPAR) are required in our model. This will facilitate estimates of ET and its components, and further elucidate the mechanisms underlying their variations at regional scale. In addition, our model estimates ET and GPP simultaneously, making it convenient to address the coupling of these two key fluxes in terrestrial ecosystems. (C) 2013 Elsevier B.V. All rights reserved.