A New Index Developed for Fast Diagnosis of Meteorological Roles in Ground-Level Ozone Variations

China experienced worsening ground-level ozone (O₃) pollution from 2013 to 2019. In this study, meteorological parameters, including surface temperature (T₂), solar radiation (SW), and wind speed (WS), were classified into two aspects, (1) Photochemical Reaction Condition (PRC = T₂ × SW) and (2) Physical Dispersion Capacity (PDC = WS). In this way, a Meteorology Synthetic Index (MSI = PRC/PDC) was developed for the quantification of meteorology-induced ground-level O₃ pollution. The positive linear relationship between the 90th percentile of MDA8 (maximum daily 8-h average) O₃ concentration and MSI determined that the contribution of meteorological changes to ground-level O_-3 varied on a latitudinal gradient, decreasing from ~40% in southern China to 10%–20% in northern China. Favorable photochemical reaction conditions were more important for ground-level O₃ pollution. This study proposes a universally applicable index for fast diagnosis of meteorological roles in ground-level O₃ variability, which enables the assessment of the observed effects of precursor emissions reductions that can be used for designing future control policies.