The effect of anthropogenic emission, meteorological factors, and carbondioxide on the surface ozone increase in China from 2008 to 2018 during theEast Asia summer monsoon season

Despite the implementation of the Clean Air Action Plan by the Chinese government in 2013, the issue of increasing surface ozone (O-3) concentrations remains a significant environmental concern in China. In this study, we used an improved regional climate-chemistry-ecology model (RegCM-Chem-YIBs) to investigate the impact of anthropogenic emissions, meteorological factors, and CO2 changes on summer surface O-3 levels in China from 2008 to 2018. Compared to its predecessor, the model has been enhanced concerning the photolysis of O-3 and the radiative impacts of CO2 and O-3. The investigations showed anthropogenic emissions were the primary contributor to the O-3 increase in China, responsible for 4.08-18.51 ppb in the North China Plain. However, changed meteorological conditions played a crucial role in decreasing O-3 in China and may have a more significant impact than anthropogenic emissions in some regions. Changed CO2 played a critical role in the variability of O-3 through radiative forcing and isoprene emissions, particularly in southern China, inducing an increase in O-3 on the southeast coast of China (0.28-0.46 ppb) and a decrease in southwest and central China ( 0.51 to 0.11 ppb). Our study comprehensively analyzed O-3 variation across China from various perspectives and highlighted the importance of considering CO2 variations when designing long-term O-3 control policies, especially in high-vegetation-coverage areas.

Automated summary

Despite the implementation of the Clean Air Action Plan, increasing surface ozone (O-3) concentrations remain a significant environmental concern in China. This study used an improved regional climate-chemistry-ecology model to investigate the impact of anthropogenic emissions, meteorological factors, and CO2 changes on O-3 levels in China from 2008 to 2018. The results showed that anthropogenic emissions were the primary contributor to O-3 increase, but meteorological conditions and CO2 changes also played important roles.