Identifying the spatiotemporal variations in ozone formation regimes across China from 2005 to 2019 based on polynomial simulation and causality analysis

Abstract

Abstract. Ozone formation regimes are closely related to the ratio of volatile organic compounds (VOCs) to NOx. Different ranges of HCHO/NO2 indicate three formation regimes, including VOC-limited, transitional, and NOx-limited regimes. Due to the unstable interactions between a diversity of precursors, the range of the transitional regime, which plays a key role in identifying ozone formation regimes, remains unclear. To overcome the uncertainties from single models and the lack of reference data, we employed two models, polynomial simulation and convergent cross-mapping (CCM), to identify the ranges of HCHO/NO2 across China based on ground observations and remote sensing datasets. The ranges of the transitional regime estimated by polynomial simulation and CCM were [1.0, 1.9] and [1.0, 1.8]. Since 2013, the ozone formation regime has changed to the transitional and NOx-limited regime all over China, indicating that ozone concentrations across China were mainly controlled by NOx. However, despite the NO2 concentrations, HCHO concentrations continuously exert a positive influence on ozone concentrations under transitional and NOx-limited regimes. Under the circumstance of national NOx reduction policies, the increase in VOCs became the major driver for the soaring ozone pollution across China. For an effective management of ozone pollution across China, the emission reduction in VOCs and NOx should be equally considered.

Multiple Impacts of Aerosols on O3 Production Are Largely Compensated: A Case Study Shenzhen, China

“…We noted that the conclusion of this work was mainly derived from a case study for a specific episode in the urban area of Shenzhen, while previous studies demonstrated that the VOC- and NO x -limited regimes for O 3 production show temporal and spatial variation in the PRD and other urban agglomerations. − Therefore, more efforts are needed to design a coordinated O 3 pollution control strategy. Recently, NO x emission reduction was found to be effective over the past decade, while VOC mitigation was less successful. , The reduction of NO x helps to reduce peak ozone levels, while the negative effect mainly happens at nighttime and in regions with less ozone pollution . Moreover, the continuous effort to control NO x emission not only shifts to the NO x -limited regime but also helps to reduce particulate pollution as particulate nitrate has become the major contributor to PM 2.5 . − However, the nonlinearity between O 3 and particulate nitrate formation and primary emissions urges better understanding of their formation mechanisms.…”

“…Recently, NO x emission reduction was found to be effective over the past decade, while VOC mitigation was less successful. 87,88 The reduction of NO x helps to reduce peak ozone levels, while the negative effect mainly happens at nighttime and in regions with less ozone pollution. 89 Moreover, the continuous effort to control NO x emission not only shifts to the NO x -limited regime but also helps to reduce particulate pollution as particulate nitrate has become the major contributor to PM 2.5 .…”

The Influence of Synoptic Weather Patterns on Spatiotemporal Characteristics of Ozone Pollution Across Pearl River Delta of Southern China

“…In general, the urban areas were VOC‐limited owing to higher NO 2 emissions from traffic and industrial activities. Suburbs were NOx‐limited because of less anthropogenic activity and high BVOC emissions (X. Chen et al., 2019; R. Li et al., 2021). Under different SWPs, the O 3 ‐sensitive areas in the PRD urban area were substantially different.…”

“…Suburbs were NOx-limited because of less anthropogenic activity and high BVOC emissions (X. Chen et al, 2019;R. Li et al, 2021).…”

Spatiotemporal Variation in Ground Level Ozone and Its Driving Factors: A Comparative Study of Coastal and Inland Cities in Eastern China

“…Volatile organic compounds (VOCs) and nitrogen oxides (NO x ≡ NO + NO 2 ) are precursors of O 3 [ 27 ]. Many studies have explored the relationship, photochemical reaction mechanism, and influence factors between O 3 and its precursors [ 28 , 29 , 30 , 31 , 32 , 33 ]. Meteorological conditions are important factors of O 3 generation and transmission.…”