Integrated Modeling of Photosynthesis and Transfer of Energy, Mass and Momentum in the Soil-Plant-Atmosphere Continuum System

Abstract. Root water uptake is an important component of the terrestrial water balance and a critical factor that influences energy, water vapor, and carbon exchange among soil, vegetation and atmosphere interfaces. However, most of the current vegetation photosynthesis models do not account for root water uptake, which compromises their applications under water stressed conditions. To address this limitation, this study integrates photosynthesis and transfer of energy, mass and momentum in the soil-plant-atmosphere continuum system, via a simplified 1D root growth model and a resistance scheme (from soil, through root zones and plants, to atmosphere). The coupled model was evaluated with field measurement of a maize canopy. The results indicated that the simulation of land surface fluxes was significantly improved due to considering the root water uptake, especially when vegetation is experiencing sever water stress. This finding highlights the importance of enhanced soil heat and moisture transfer, as well as dynamic root distribution, on simulating ecosystem functioning.