Driving Mechanisms of Summer Mid‐Latitude Circulation Anomalies on Differential Ozone Pollution Between Beijing and Shanghai

ABSTRACT Summer surface ozone (O 3 ) pollution in Eastern China has intensified due to complex chemical–meteorological interactions, with a pronounced spatial variability in meteorological drivers across urban centres. Beijing and Shanghai, as cores of China's most severely O 3 ‐polluted metropolitan regions, exhibit comparable emission characteristics but distinct meteorological influences, highlighting the dominant role of meteorological factors in O 3 variations. This study systematically investigated the spatiotemporal evolution of O 3 pollution and the meteorological factors in Beijing and Shanghai, using gridded O 3 data from Tsinghua University's Tracking Air Pollution (TAP) in China dataset. A clustering analysis was employed to identify four distinct pollution‐month categories of O 3 concentration anomalies: Beijing Low‐Shanghai High (BLSH), Beijing High‐Shanghai Low (BHSL), Concurrent High (BHSH), and Concurrent Low (BLSL). The results verified that both Beijing and Shanghai exhibited significant upward trends in O 3 concentrations from 2013 to 2023. Temporally, negative O 3 anomalies dominated during 2013–2015, and they transitioned to sustained positive anomalies in 2016–2020. Spatial analysis revealed peak concentrations in May–July but with divergent monthly maxima: Beijing peaks in June (144.6 μg/m 3 ) versus Shanghai in May (124.7 μg/m 3 ). Key findings from composite analysis of the meteorological fields demonstrated an inverse relationship between the BHSL and BLSH patterns. The BHSL type corresponded to the anomalously warm‐humid conditions at 850 hPa, coupled with surface high‐temperature and low‐pressure systems and suppressed solar radiation. Conversely, BLSH events featured cold‐dry 850 hPa anomalies alongside surface low‐temperature and high‐pressure systems and enhanced solar radiation. Interannual O 3 variability showed an association with midlatitude circulation regimes at 500 hPa: Beijing's high O 3 episodes coincided with anomalous easterlies, and those of Shanghai corresponded to strengthened westerlies. The synergistic effects of multiscale meteorological variables, including temperature gradients, solar radiation flux, and midlatitude circulation dynamics, emerged as critical regulators of O 3 spatiotemporal evolution. These findings advance the understanding of regional O 3 pollution drivers and provide a framework for dynamic prediction models and geographically differentiated control strategies.