Worsening urban ozone pollution in China from 2013 to 2017 – Part 1: The complex and varying roles of meteorology

Liu, Yiming; Wang, Tao

doi:10.5194/acp-2019-1120

Cited by 5 publications

(6 citation statements)

References 23 publications

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“…The heterogeneous reactions in the original CMAQ model (version 5.2.1) includes only uptakes of NO2, NO3, and N2O5 on aerosol surfaces. To faithfully reproduce the effect of aerosols on O3 via scavenging gaseous pollutants, we updated the 105 heterogeneous reaction rate of NO2 and NO3 on the aerosol surface and incorporated additional heterogeneous reactions of gases into the CMAQ model, namely the uptakes of HO2, O3, OH, and H2O2 (refer to Table S2 in the companion paper (Liu and Wang, 2020) for the detailed heterogeneous reactions in the original and updated CMAQ models). The uptake coefficients (γ) of gases are the key parameters of heterogeneous reactions, but they vary according to factors such as aerosol water content and aerosol composition.…”

Section: Updating Heterogeneous Reactionsmentioning

confidence: 99%

“…The shipping emissions were kept unchanged in the 5-year simulation, due to a lack of data for recent years. In Part 1 of our work (Liu and Wang, 2020), we showed the effect of changes in total anthropogenic 150 emission on O3 changes by comparing the O3 concentrations in 2013 simulated using anthropogenic emissions from different years. In this study, three additional sets of modeling experiments were established.…”

Section: Experiments Settingmentioning

confidence: 99%

“…We have been further investigating the meteorological and chemical driver(s) of the increasing summer surface O3 in urban areas of China during 2013-2017 using an improved regional chemical transport model (WRF-CMAQ) driven by interannual meteorological data and anthropogenic emission inventories. The role of meteorological variation and total emission changes, 80 and the effect of individual meteorological factors, are discussed in a companion paper, Part 1 (Liu and Wang, 2020). The goal of the present work is to quantify (1) the effect of the changes in anthropogenic emissions of individual pollutants (NOx, VOCs, CO, PM, SO2, and NH3) on urban O3, which has not been addressed in the aforementioned studies but is important for further development of mitigation policy and (2) the effects of changes in aerosol concentrations on O3 using a regional model with up-to-date radical sources and heterogeneous reactions.…”

mentioning

confidence: 99%

“…simulations in this study. The model settings and emission inputs are described in the companion paper (Liu and Wang, 2020).…”

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confidence: 99%

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Worsening urban ozone pollution in China from 2013 to 2017 – Part 2: The effects of emission changes and implications for multi-pollutant control

Liu¹,

Wang²

2020

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Abstract. The Chinese government launched the Air Pollution Prevention and Control Action Plan in 2013, and various stringent measures have since been implemented, which have resulted in significant decreases in emissions and ambient concentrations of primary pollutants such as SO2, NOx, and particulate matter (PM). However, surface ozone (O3) concentrations have still been increasing in urban areas across the country. In a previous analysis, we examined in detail the roles of meteorological variation during 2013–2017 in the summertime surface O3 trend in various regions of China. In this study, we evaluated the effect of changes in multi-pollutant emissions from anthropogenic activities on O3 concentrations during the same period, by using an up-to-date regional chemical transport model (WRF-CMAQ) driven by an interannual anthropogenic emission inventory. The CMAQ model was improved with regard to heterogeneous reactions of reactive gases on aerosol surfaces, which led to better model performance in reproducing the ambient concentrations of those gases. The model simulations showed that the maximum daily 8-hour average (MDA8) O3 concentration in urban areas increased by 0.46 ppbv per year (ppbv a-1) (p = 0.001) from 2013 to 2017. In contrast, a slight decrease in MDA8 O3 concentrations by 0.17 ppbv a-1 (p = 0.005) in rural areas was predicted, mainly attributable to the NOx emission reduction. The effects of changes in individual pollutant emissions on O3 were also simulated. The reduction of NOx emission increased the O3 concentration in urban areas due to the non-linear NOx-volatile organic compound (VOC) chemistry and decreasing aerosol effects; the slight increase in VOCs emissions enhanced the O3 concentrations; the reduction of PM emissions increased the O3 concentrations by enhancing the photolysis rates and reducing the loss of reactive gases on aerosol surfaces; and the reduction of SO2 emissions resulted in a drastic decrease in sulfate concentrations, which increased the O3 concentrations through aerosol effects. In contrast to the unfavorable effect of the above changes in pollutant emissions on efforts to reduce surface concentrations of O3, the reduction of CO emissions did help to decrease the O3 concentrations in recent years. The dominant cause of increasing O3 concentrations due to changes in anthropogenic emission varied geographically. In Beijing, NOx and PM emission reductions were the two largest causes of the O3 increase; in Shanghai, the reduction of NOx and increase in VOC emissions were the two major causes; in Guangzhou, NOx reduction was the primary cause; and in Chengdu, the PM and SO2 emission decreases contributed most to the O3 concentration increase. Regarding the effects of decreasing concentrations of aerosols, the drop in heterogeneous uptake of reactive gases – mainly HO2 and O3 – was found to be more important than the increase in photolysis rates. The adverse effect of the reductions of NOx, SO2, and PM emissions on O3 abatement in Beijing, Shanghai, Guangzhou, and Chengdu would have been avoided if the anthropogenic VOCs emission had been reduced by 24 %, 23 %, 20 %, and 16 %, respectively, from 2013 to 2017. Our analysis revealed that the NOx reduction in recent years has helped to contain the total O3 production in China. However, to reduce O3 concentrations in major urban and industrial areas, VOCs emissions control should be added to the current NOx-SO2-PM policy.

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Section: Updating Heterogeneous Reactionsmentioning

confidence: 99%

Section: Experiments Settingmentioning

confidence: 99%

mentioning

confidence: 99%

“…simulations in this study. The model settings and emission inputs are described in the companion paper (Liu and Wang, 2020).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Worsening urban ozone pollution in China from 2013 to 2017 – Part 2: The effects of emission changes and implications for multi-pollutant control

Liu¹,

Wang²

2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Some studies showed an O 3 increase in cities, e.g. maximum daily 8-hour average O 3 concentrations increased by on average 0.46 ppb per year in 74 cities across China from 2013 to 2017 (Liu et al, 2018;Liu and Wang, 2020). The ground-level O 3 is considered one of the most harmful air pollutants in terms of effects on human health (e.g.…”

Section: Introductionmentioning

confidence: 99%