Meteorological conditions contributed to changes in dominant patterns of summer ozone pollution in Eastern China

Ground-level O3 pollution has become one of the most consequential air quality problems in China. Many previous studies have addressed the increasing trend of surface O3 concentrations in Eastern China. In this study, a new feature, i.e. the change in the dominant patterns of surface O3, was revealed, and the associated physical mechanisms were analyzed. The impacts of meteorological conditions and anthropogenic emissions were separated, and the change in the O3 dominant pattern was found to be mainly due to the variability in the meteorological conditions. From 2017 to 2019, the stable confrontation of the western Pacific subtropical high (WPSH) and East Asian deep trough (EADT) was closely related to the south-north covariant pattern of O3, because the variability in the meteorological conditions centered on the North China and Huanghuai regions. In the period of 2015-2016, the joint movements of the WPSH and EADT modulated the meteorological anomalies, creating a dipole mode in Eastern China that contributed to out-of-phase variations in O3 in North China and the Yangtze River Delta.