Evolution of Ozone Formation Sensitivity during a Persistent Regional Ozone Episode in Northeastern China and Its Implication for a Control Strategy
Yujie Zhang, Jian Gao, Yujiao Zhu, Yi Liu, Li Hong, Li Hong, Xin Yang, Xuelian Zhong, Min Zhao, Wan Wang, Fei Che, Derong Zhou, Shuai Wang, Guorui Zhi, Likun Xue, Haisheng Li, Haisheng Li
Abstract
In recent years, the magnitude and frequency of regional ozone (O 3 ) episodes have increased in China. We combined ground-based measurements, observation-based model (OBM), and the Weather Research and Forecasting and Community Multiscale Air Quality (WRF–CMAQ) model to analyze a typical persistent O 3 episode that occurred across 88 cities in northeastern China during June 19–30, 2021. The meteorological conditions, particularly the wind convergence centers, played crucial roles in the evolution of O 3 pollution. Daily analysis of the O 3 formation sensitivity showed that O 3 formation was in the volatile organic compound (VOC)-limited or transitional regime at the onset of the pollution episode in 92% of the cities. Conversely, it tended to be or eventually became a NO x -limited regime as the episode progressed in the most polluted cities. Based on the emission-reduction scenario simulations, mitigation of the regional O 3 pollution was found to be most effective through a phased control strategy, namely, reduction of a high ratio of VOCs to NOx at the onset of the pollution and lower ratio during evolution of the O 3 episode. This study presents a new possibility for regional O 3 pollution abatement in China based on a reasonable combination of OBM and the WRF–CMAQ model.