Updating and evaluating the NH3 gas-phase chemical mechanism of MOZART-4 in the WRF-Chem model

Guangyao Li; Qiang Chen; Wei Sun; Jing She; Jia Liu; Yuhuan Zhu; Wenkai Guo; Ruixin Zhang; Yufan Zhu; Mingyue Liu

doi:10.1016/j.envpol.2023.122070

Updating and evaluating the NH₃ gas-phase chemical mechanism of MOZART-4 in the WRF-Chem model

Environ Pollut. 2023 Sep 15:333:122070. doi: 10.1016/j.envpol.2023.122070. Epub 2023 Jun 16.

Authors

Guangyao Li¹, Qiang Chen², Wei Sun¹, Jing She¹, Jia Liu¹, Yuhuan Zhu¹, Wenkai Guo³, Ruixin Zhang⁴, Yufan Zhu¹, Mingyue Liu⁵

Affiliations

¹ Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, 730000, China.
² Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, 730000, China; Lanzhou University Applied Technology Research Institude Co., Ltd, Lanzhou, 730000, China. Electronic address: chenqqh@lzu.edu.cn.
³ Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, 611756, China.
⁴ School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
⁵ Ordos Meteorological Bureau of Inner Mongolia, Ordos, 017000, China.

PMID: 37331578
DOI: 10.1016/j.envpol.2023.122070

Abstract

The accuracy of determining atmospheric chemical mechanisms is a key factor in air pollution prediction, pollution-cause analysis and the development of control schemes based on air quality model simulations. However, the reaction of NH₃ and OH to generate NH₂ and its subsequent reactions are often ignored in the MOZART-4 chemical mechanism. To solve this problem, the gas-phase chemical mechanism of NH₃ was updated in this study. Response surface methodology (RSM), integrated gas-phase reaction rate (IRR) diagnosis and process analysis (PA) were used to quantify the influence of the updated NH₃ chemical mechanism on the O₃ simulated concentration, the nonlinear response relationship of O₃ and its precursors, the chemical reaction rate of O₃ generation and the meteorological transport process. The results show that the updated NH₃ chemical mechanism can reduce the error between the simulated and observed O₃ concentrations and better simulate the O₃ concentration. Compared with the Base scenario (original chemical mechanism simulated), the first-order term of NH₃ in the Updated scenario (updated NH₃ chemical mechanism simulated) in RSM passed the significance test (p < 0.05), indicating that NH₃ emissions have an influence on the O₃ simulation, and the effects of the updated NH₃ chemical mechanism on NOx-VOC-O₃ in different cities are different. In addition, the analysis of chemical reaction rate changes showed that NH₃ can affect the generation of O₃ by affecting the NOx concentration and NOx circulation with radicals of OH and HO₂ in the Updated scenario, and the change of pollutant concentration in the atmosphere leads to the change of meteorological transmission, eventually leading to the reduction of O₃ concentration in Beijing. In conclusion, this study highlights the importance of atmospheric chemistry for air quality models to model atmospheric pollutants and should attract more research focus.

Keywords: Chemical mechanism; IRR; NH(3); O(3); RSM; WRF-Chem.

MeSH terms

Air Pollutants* / analysis
Air Pollutants* / toxicity
Air Pollution* / analysis
China
Computer Simulation
Environmental Monitoring / methods
Environmental Pollutants* / analysis
Environmental Pollution / analysis
Ozone* / analysis
Ozone* / toxicity

Substances

Air Pollutants
Ozone
Environmental Pollutants