State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences
As the key precursors leading to ozone pollution, atmospheric volatile organic compounds (VOCs) are indispensable parts of urban air quality modeling. Due to their complex composition and the lack of monitoring data, the understanding of their simulation accuracy is still poor. In this paper, the nested grid air quality model prediction system (NAQPMS) is used to simulate VOCs in the Pearl River Delta region from September 21 to November 20, 2017. The VOCs concentration monitoring data from 8 ground stations of photochemical monitoring network is used to evaluate the accuracy of key VOCs components. The results show that the model has high simulation accuracy for toluene, ethylene and xylene with concentration deviation ratio of 0.4-26.6%, which can well reproduce the trend of daily average concentration and the double-peak characteristics of diurnal variation. However, the model has a large simulation deviation for isoprene with strong chemical reaction activity and closed relation to plant emissions. The deviation ratio is nearly 100%, which cannot reproduce the diurnal variation characteristics of high concentration in daytime and low concentration at night. It is found that the total amount of VOCs emitted by plants in the Pearl River Delta region is relatively large. However, the ignorance of biological VOCs emissions in the current simulation system may be the key reason for this simulation deviation. Besides, the results of simulation evaluation also show that the model still exists great uncertainty in the VOCs spatial distribution. This paper shows that there is an urgent need to combine VOCs observation data in the model to reveal and reduce the uncertainty of VOCs simulation.