Spatiotemporal variability and driving factors of ground-level summertime ozone pollution over eastern China

Ground-level ozone is detrimental to human and vegetation health. The ground-level ozone concentration in China has been increasing in recent years. It is necessary to take actions to mitigate ozone pollution. Identifying the variability of ozone concentration is significant for developing an optimal mitigation strategy. In this study, complex empirical orthogonal functions (CEOFs) are used to analyze the spatial-temporal variability in the summertime surface ozone distribution over eastern China during 2015-2017. The first CEOF explains 50% of the ozone variance and represents anthropogenic sources over the North China, with an O-3 exceedance period of 7-9 days (maximum daily 8-h average (MDA8) O-3 more than 160 mu g m(-3)). The second CEOF indicates a north-south dipole pattern of ozone fluctuation over eastern China. This pattern is mainly subject to the north-south movement of the subtropical high over eastern China and is ultimately modulated by the Philippine Sea Anticyclone Anomaly (PSAA). Our results suggest that policymakers should take weather patterns and interactions between different regions into consideration when designing a strategy to meet O-3 air quality objectives.