Identification of long-term evolution of ozone sensitivity to precursors based on two-dimensional mutual verification

Leifeng Yang; Zibing Yuan; Huihong Luo; Yiran Wang; Yuanqian Xu; Yusen Duan; Qingyan Fu

doi:10.1016/j.scitotenv.2020.143401

Identification of long-term evolution of ozone sensitivity to precursors based on two-dimensional mutual verification

Sci Total Environ. 2021 Mar 15:760:143401. doi: 10.1016/j.scitotenv.2020.143401. Epub 2020 Nov 5.

Authors

Leifeng Yang¹, Zibing Yuan², Huihong Luo³, Yiran Wang³, Yuanqian Xu³, Yusen Duan⁴, Qingyan Fu⁴

Affiliations

¹ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou 510655, China. Electronic address: yangleifeng@scies.org.
² School of Environment and Energy, South China University of Technology, Guangzhou 510006, China. Electronic address: zibing@scut.edu.cn.
³ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
⁴ Shanghai Environmental Monitoring Center, Shanghai 200235, China.

PMID: 33243506
DOI: 10.1016/j.scitotenv.2020.143401

Abstract

Tropospheric ozone pollution has been continuously worsening in China during the past decade. Identification of long-term evolution of ozone sensitivity to precursors is essential to evaluating the impact of emission reduction measures on ozone pollution. Traditional observation-based model and 3-d numerical model are not suitable for analyzing long-term variation of ozone sensitivity to precursors. In this study, by transforming the conventional ozone isopleth plot into a VOCR isopleth plot in the functional space of NO_x and ozone concentrations, we developed a novel approach to identify ozone sensitivity to precursors by simply using long-term monitoring data of ozone, NO_x and temperature. This approach estimated ozone formation regimes (OFR) by ozone sensitivity to NO_x and temperature separately, and the convergence of OFR serves as a way of mutual verification. We found that ozone formation was generally in the VOCR-limited or transitional regime in Shanghai, the largest metropolitan area in China. However, OFR was shifted to NO_x-limited at Pudong station during 2017-19 due much to the stringent NO_x emission control. OFR was also shifted to NO_x-limited along with the increasing temperature. When temperature was over 30 °C, Shanghai was mostly in a NO_x-limited OFR. This highlights that the NO_x emission control measures need to be strengthened to reduce peak ozone levels more efficiently. Jinshan station exhibited a different trend with OFR shifted to VOCR-limited in 2017-19, which proved the effectiveness of VOCs emission control on petrochemical sector. However, OFR was shifted to NO_x-limited when temperature was over 30 °C, suggesting more stringent VOCs emissions control should be targeted on days with higher temperature.

Keywords: Long-term evolution; Ozone formation regime; Ozone pollution; Shanghai; VOCR isopleth.