Extract

Much effort of carbon dioxide (CO2) mitigation as the countermeasure to global changes has focused on the urban areas – the hotspots of fossil fuel and concentrated emission and pollutants. Despite their critical role in CO2 exchange in urban ecosystem, emission sources from vegetation and soil surfaces are largely overlooked in existing urban land surface models. In this study, we parameterized the biogenic CO2 exchange in cities using an advanced single-layer urban canopy model, by incorporating a plant physiological model in the built environment. In addition, the proposed model also includes the anthropogenic CO2 fluxes especially that from traffic emissions, based on gridded dataset. We evaluate the proposed model using CO2 measurements from an eddy covariance flux tower located at west Phoenix, Arizona, USA. The model results are in good agreement with the observed carbon flux over the built terrain, with a RMSE of 0.21 mg m-2s-1. Furthermore, our simulations show that the abiotic traffic-emitted CO2 amounts the largest source in cities, as expected. Nevertheless, the biogenic carbon exchange can be significantly enhanced in the built environment, which makes an equally important contributor to the total carbon emission especially in sub-urban areas.

Keywords: Anthropogenic sources; Plant physiology; Urban canopy model; CO2 exchange.

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