Source attribution of near-surface ozone pollution in Jiangsu Province of China over 2013–2019

Near-surface ozone (O₃) is one of the most severe air pollutants in China, particularly over densely populated Jiangsu Province in the Yangtze River Delta. In this study, an O₃ source tagging technique is utilized in a chemistry-climate model to quantify the source contributions of various emission sectors and regions for nitrogen oxides (NO_x) and volatile organic compounds (VOCs) to O₃ concentrations in Jiangsu Province during 2013–2019. The results show that the near-surface O₃ in Jiangsu Province is mainly contributed by surrounding and remote anthropogenic NO_x emissions through long-range transport. Local anthropogenic NO_x emissions account for only 13 % and 18 % of the annual and summertime mean near-surface O₃ in Jiangsu Province, respectively. Anthropogenic NO_x emissions from the surface transportation, industry, and energy sectors account for 21 %, 22 % and 20 % of the annual mean near-surface O₃ concentration in Jiangsu Province, respectively. Biogenic and anthropogenic VOCs emissions each explains one-third of the annual mean near-surface O₃ concentration in Jiangsu, while methane and stratospheric chemical production contribute 21 % and 6 %, respectively. The sources from stratospheric production, aircraft, lightning, and foreign emissions are the primary contributors to O₃ in the mid- and high troposphere. During high pollution days in Jiangsu Province, the near-surface O₃ concentrations increase with the maximum exceeding 20 ppb, which is attributed to both the enhanced photochemical production and regional transport in favorable meteorological conditions.