Causes of variation of air pollutant concentration in Shenyang during the COVID-19 epidemic based on WRF-Chem and EMI-index

ABSTRACT

Using air quality monitoring data, surface meteorological observational data, meteorological environment assessment index (EMI-index) products, National Centers for Environmental Prediction (NCEP) reanalysis data and output of the Weather Research and Forecasting model coupled to Chemistry (WRF-Chem) from 2015 to 2020 in Shenyang, we analyzed the variation of criteria air pollutants and meteorological elements in Shenyang during the epidemic of COVID-19 and evaluated the response of air quality to emission reduction and meteorological conditions. The results showed that mass concentrations of PM2.5, PM10, and NO2 in Shenyang during the epidemic of COVID-19 decreased, while O3 concentration slightly increased. PM2.5 and NO2 were more sensitive to anthropogenic emission reduction. PM2.5 concentration decreased by 16.37% due to meteorological conditions and by 22.96% due to the prevention and control measures. Under the background of prevention and control measures, adverse meteorological conditions and sudden enhancement in pollutant emissions caused heavy pollution periods, among which adverse meteorological conditions played a more important role. Meanwhile, the emission reduction measures significantly weakened the peak of pollutant concentration in heavy pollution events. © 2021, Science Press. All right reserved.