The comparison of the summertime (June–July–August) mean MDA8 concentrations between our model predictions and the CNEMC monitoring data over 2014–2019 for selected regions. (A) Central-East China; and (B) the Shandong Peninsula. The blue columns represent the CNEMC observations, and the orange columns represent our model predictions. The height of the columns and the error bars represent the mean MDA8 concentrations and the standard errors. Note: CNEMC, China National Environmental Monitoring Center; MDA8, daily maximum 8-h average; NCP, the North China Plain; , ozone; PRD, the Pearl River Delta, YRD: the Yangtze River Delta.