Evaluation of CO2 and energy balance fluxes from a maize canopy in east Tennessee using the SURFATM model

Field crops can emit or store carbon depending on the season and cropping practices. A process-based modeling approach allowed us to predict the transfer pattern of the CO₂ fluxes and energy balance between soil, vegetation, and atmosphere. In this study, the SURFATM-CO₂ model was developed to simulate distinctly the CO₂ exchanges between soil, plants, and the atmosphere. The model couples soil respiration, taking into account its temperature sensitivity, with photosynthesis and plant respiration process-based, taking into account the plant's CO₂ compensation point. The SURFATM-CO₂ process model was evaluated using field measurements obtained from a novel multiport profile system consisting of 4 vertical measurement heights to monitor the spatial and temporal variation of CO₂, water, and temperature within and above the maize canopy in east Tennessee. The 5Hz frequency raw data were averaged into 15-minute runs and used as input for the SURFATM model. The model satisfactorily simulates the energy balance, and we are currently testing the model for the CO₂ fluxes.  The main objective of this study is to understand the exchanges of CO₂ between the soil, vegetation and atmosphere compartments. The finding of the SURFATM-CO₂ model will highlight the ability of the SURFATM-model to capture the canopy-atmosphere interaction as well as provide a base for model application in the studies of carbon dynamics, and cropland ecosystem management.