Synoptic and meteorological drivers of regional ozone pollution events in China

Abstract

Surface ozone (O3) pollution events are becoming more frequent and have recently emerged as a severe air pollution problem in China. However, the spatial–temporal distribution of surface O3, as well as its primary synoptic and meteorological drivers, remains poorly understood. The purpose of this study was to identify the key synoptic and meteorological drivers of O3 pollution in different regions of China. To achieve this goal, this study established meteorology overlaps of regional O3 pollution events in space and time and applied a comprehensive statistical model selection method for optimal synoptic and meteorological models, based on a newly released O3 dataset for 2015–2018. It was observed that extreme regional O3 pollution events (duration >7 d) occurred more frequently and exhibited a high co-occurrence frequency (>50%) with air stagnation (AS). Moreover, the beginning and end of 69% of the regional O3 pollution events coincided with regional daily maximum temperature changes. The intensity of AS is the dominant driver of O3 pollution event intensity across most of the six selected megacity regions. Although other meteorological drivers, such as the intensity of hot days (HD) and meridional wind of 10 m were also important, their impacts varied according to the region. Overall, increase in extreme AS and HD led to the worsening of regional O3 pollution events. These findings imply that mitigating regional O3 pollution should consider changing synoptic and meteorological conditions.