Identification of close relationship between atmospheric oxidation and ozone formation regimes in a photochemically active region

• 作者: Kaihui Zhao Huihong Luo Zibing Yuan Danni Xu Yi Du Shu Zhang Yuqi Hao Yonghua Wu Jianping Huang Ying Wang Rongsheng Jiang
• 来源期刊: 环境科学学报（英文版）
• 年，卷（期）: 2021,（4）
• 页码范围: 373-383
• 页数: 11页
• 语种: 英文

摘要

Understanding ozone(O3)formation regime is a prerequisite in formulating an effective O3 pollution control strategy.Photochemical indicator is a simple and direct method in iden-tifying O3 formation regimes.Most used indicators are derived from observations,whereas the role of atmospheric oxidation is not in consideration,which is the core driver of O3 for-mation.Thus,it may impact accuracy in signaling O3 formation regimes.In this study,an advanced three-dimensional numerical modeling system was used to investigate the rela-tionship between atmospheric oxidation and O3 formation regimes during a long-lasting O3 exceedance event in September 2017 over the Pearl River Delta(PRD)of China.We discov-ered a clear relationship between atmospheric oxidative capacity and O3 formation regime.Over eastern PRD,O3 formation was mainly in a NOx-limited regime when HO2/OH ratio was higher than 11,while in a VOC-limited regime when the ratio was lower than 9.5.Over central and western PRD,an HO2/OH ratio higher than 5 and lower than 2 was indicative of NOx-limited and VOC-limited regime,respectively.Physical contribution,including hori-zontal transport and vertical transport,may pose uncertainties on the indication of O3 for-mation regime by HO2/OH ratio.In comparison with other commonly used photochemical indicators,HO2/OH ratio had the best performance in differentiating O3 formation regimes.This study highlighted the necessities in using an atmospheric oxidative capacity-based indicator to infer O3 formation regime,and underscored the importance of characterizing behaviors of radicals to gain insight in atmospheric processes leading to O3 pollution over a photochemically active region.