The regional budget of O3 mass and concentration variations within the atmospheric boundary layer using the CMAQ model: An example from the Pearl River Delta, China
- 1State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
- 2International Joint Laboratory for Regional Pollution Control, Ministry of Education, Beijing, 100816, China
- 3State Key Laboratory of Regional Air Quality Monitoring, Guangdong Key Laboratory of Secondary Air Pollution Research, Guangdong Environmental Monitoring Center, Guangzhou 510308, China
Tropospheric O3 pollution notably contributes to the deterioration of air quality in many metropolitan regions, resulting in detrimental effects on human health and ecosystem. Due to the moderate atmospheric lifetimes of O3, horizontal transport, exchange between atmospheric boundary layer (ABL) and free troposphere (FT), and chemical process within the ABL all potentially play important roles in regional O3 pollution. In this study, we developed a post-calculation tool to quantify the hourly contributions of these processes to the regional budget of O3 mass and concentration variations within the ABL based on the modelling results of the Community Multiscale Air Quality (CMAQ) model. The new features of this tool include: (1) the contributions of ABL-FT exchange on O3 pollution can be quantified; (2) horizontally, the targeted region can be freely defined by users and vertically, the volumes are non-fixed owing to the diurnal variations of ABL; and (3) the budgets of O3 mass and concentration variations are separately calculated and analysed. The Pearl River Delta (PRD) region, located in the South China and faced with severe O3 pollution, was selected as the target region in this study. Results show that the variations of total O3 mass within the ABL of the PRD were controlled by ABL-FT exchange, that is, the increase (decrease) of O3 mass in the morning (afternoon) was driven by O3 inflow (outflow) through ABL-FT exchange. By contrast, it was the chemical process that drove the variations of regional-mean O3 concentrations. Except that ABL-FT exchange contributed to the rise of O3 concentrations in several hours after sunrise, O3 transport did not lead to the notable variation of O3 concentration in the remaining hours of the day. Combining source apportionment methods, we found that outside O3 (including O3 produced by emissions within the East and Central China and background O3) entered the PRD mainly through ABL-FT exchange. For chemical process, local sources played a major part, but the contributions of outside emissions cannot be neglected, suggesting the contributions of precursor transport. The effects of typhoon periphery, the weather system most related to O3 pollution in the PRD, were also examined by comparing the budget results on O3 pollution days with and without the occurrence of typhoons. The usage of this tool will help to comprehensively understand the influence of transport and chemical process in O3 pollution on the regional scale, which is crucial for effective and strategic O3 control.
Acknowledgement. This work is sponsored by the National Key Research and Development Program of China (Grant No. 2018YFC0213204, 2018YFC0213506) and the National Science and Technology Pillar Program of China (Grant No. 2014BAC21B01).
How to cite: Qu, K., Wang, X., Cai, X., Yan, Y., Jin, X., Shen, J., Xiao, T., Zeng, L., and Zhang, Y.: The regional budget of O3 mass and concentration variations within the atmospheric boundary layer using the CMAQ model: An example from the Pearl River Delta, China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11180, https://doi.org/10.5194/egusphere-egu21-11180, 2021.
