Anthropogenic and natural causes for the interannual variation of PM 2.5 in East Asia during summer monsoon periods from 2008 to 2018

Abstract. There was a significant difference in near-surface PM2.5 across China after the implementation of the Clean Air Action Plan in 2013. This study used the regional climate-chemistry-ecosystem coupled model RegCM-Chem-YIBs to investigate interannual variations in PM2.5 across East Asia from 2008 to 2018. The drivers of PM2.5 variability were examined from anthropogenic and natural perspectives. Compared to 2008, PM2.5 showed little variation during the pre-governance (PreG) period (2009–2013). However, during the post-governance (PostG) period (2014–2018), a substantial decline in PM2.5 was simulated, particularly in the North China Plain (−36.76 µg m−3) and the Sichuan Basin (−33.96 µg m−3). Anthropogenic pollutant emissions were the primary drivers of PM2.5 reductions, contributing −10.39 to −3.82 µg m−3 in the PreG period and −33.86 to −8.45 µg m−3 in the PostG period. The influence of meteorological conditions on PM2.5 during the PreG period (−6.31 to 2.32 µg m−3) was comparable to that of anthropogenic pollutant emissions. Additionally, in the vegetation-rich region, the impact of CO2 emission changes on PM2.5 was comparable to that of anthropogenic pollutant emissions. Our study comprehensively examined the drivers of PM2.5 concentration changes from 2008 to 2018. We highlight a significant intensification in the contribution of anthropogenic pollutant emissions and reveal that, in regions characterized by dense vegetation, changes in CO2 concentrations exert a pronounced impact on PM2.5 variations.