Study on Ozone and Its Critical Influencing Factors in Key Regions of China

Solar radiation is the fundamental energy source of climate change, which has a significant impact on the generations of secondary fine particulate matter (PM2.5) and ozone (O3) in the atmosphere. Additionally, surface solar radiation is also affected by the concentration of PM2.5, which in turn affects the generation of O3. To clarify the relationships among the O3, PM2.5 and the total radiation intensity, this study analyzes their temporal and spatial variation trends from 2017 to 2019. Meanwhile, as a common precursor of O3 and PM2.5, concentration variations in nitrogen dioxide (NO2) are discussed as well in this study. The results showed the following: (1) There are significant positive correlations between the O3-8 h concentrations and the total radiation intensities in critical regions, especially in the “2 + 26” cities, Fen-Wei Plain and Yangtze River Delta. (2) The decrease in PM2.5 concentrations is in good agreement with the trend of NO2 concentrations, while the response of O3 concentration to the NO2 concentration variation differs in different regions, except in the Pearl River Delta. (3) In addition to the meteorological factors, changes in the concentrations and ratios of precursors such as NO2 and volatile organic compounds (VOCs) likely contribute to the observed fluctuations in O3 concentrations in recent years.