Simulations of Summertime Ozone and PM2.5 Pollution in Fenwei Plain (FWP) Using the WRF-Chem Model

In recent years, ozone and PM2.5 pollution has often occured in the Fenwei Plain due to heavy emission and favorable geographical conditions. In this study, we used the weather research and forecasting/chemistry (WRF-Chem) model to reproduce the complex air pollution of the ozone and PM2.5 in the Fenwei Plain (FWP) from 20 May to 29 May 2015. By comparing the simulation results with the observed data, we found that although in some cities there was a bias between the simulated values and observed data, the model captured the trend of pollutants generally. Moreover, according to the assessment parameters, we validated that the deviations are acceptable. However, according to these parameters, we found that the WRF-Chem performed better on ozone simulation rather than PM2.5. Based on the validation, we further analyzed the pollutant distribution during the contaminated period. Generally speaking, the polluted area is mainly located in the cities of the Shanxi province and Henan province. Moreover, in this time period, pollution mainly occurred on 27 May and 28 May. In addition, due to different formation conditions of ozone and PM2.5 pollution, the distribution characteristics of these two pollutants were also found to be different. Ozone pollution mainly occurred north of FWP due to the prevailing wind and the chemistry of ozone production. As for PM2.5, the pollution occurred at night and the polluted area was located in the FWP. Furthermore, high PM2.5 areas were closed to emission sources in the FWP, showing a high correlation with primary emissions.

Automated summary

The study used the WRF-Chem model to reproduce the ozone and PM2.5 pollution in Fenwei Plain from May 20th to May 29th, 2015. Although there were deviations between the simulation results and observed data, the model generally captured the trend of pollutants and the deviations were acceptable. The WRF-Chem model performed better in simulating ozone than PM2.5. Ozone pollution mainly occurred north of Fenwei Plain due to wind patterns and ozone production chemistry, while PM2.5 pollution occurred at night and was concentrated in the Fenwei Plain.