Explicit diagnosis of the local ozone production rate and the ozone-NOx-VOC sensitivities

Tan, Zhaofeng; Lu, Keding; Dong, Huabin; Hu, Min; Li, Xin; Liu, Yuhan; Lü, Sihua; Shao, Min; Su, Rong; Wang, Haichao; Wu, Yusheng; Wahner, Andreas; Zhang, Yuanhang

doi:10.1016/j.scib.2018.07.001

Cited by 140 publications

(66 citation statements)

References 44 publications

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“…However, the chemical modulation tests carried out under low NO conditions (< 1 ppbv) do not show a significant interference. This result is consistent with other tests that were performed with our LIF technique in field campaigns in China (Tan et al, 2018b(Tan et al, , 2017 and in laboratory and chamber experiments (Fuchs et al, 2016. For this reason, we consider OH interference to be an unlikely explanation here, although we cannot strictly exclude the possibility that there were OH interferences only at times when the chemical modulation system was not used.…”

Section: Oh Interferencesupporting

confidence: 90%

Experimental budgets of OH, HO2, and RO2 radicals and implications for ozone formation in the Pearl River Delta in China 2014

Tan

Hofzumahaus³

et al. 2019

Atmos. Chem. Phys.

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Abstract. Hydroxyl (OH) and peroxy radicals (HO2 and RO2) were measured in the Pearl River Delta, which is one of the most polluted areas in China, in autumn 2014. The radical observations were complemented by measurements of OH reactivity (inverse OH lifetime) and a comprehensive set of trace gases including carbon monoxide (CO), nitrogen oxides (NOx=NO, NO2) and volatile organic compounds (VOCs). OH reactivity was in the range from 15 to 80 s−1, of which about 50 % was unexplained by the measured OH reactants. In the 3 weeks of the campaign, maximum median radical concentrations were 4.5×106 cm−3 for OH at noon and 3×108 and 2.0×108 cm−3 for HO2 and RO2, respectively, in the early afternoon. The completeness of the daytime radical measurements made it possible to carry out experimental budget analyses for all radicals (OH, HO2, and RO2) and their sum (ROx). The maximum loss rates for OH, HO2, and RO2 reached values between 10 and 15 ppbv h−1 during the daytime. The largest fraction of this can be attributed to radical interconversion reactions while the real loss rate of ROx remained below 3 ppbv h−1. Within experimental uncertainties, the destruction rates of HO2 and the sum of OH, HO2, and RO2 are balanced by their respective production rates. In case of RO2, the budget could be closed by attributing the missing OH reactivity to unmeasured VOCs. Thus, the presumption of the existence of unmeasured VOCs is supported by RO2 measurements. Although the closure of the RO2 budget is greatly improved by the additional unmeasured VOCs, a significant imbalance in the afternoon remains, indicating a missing RO2 sink. In case of OH, the destruction in the morning is compensated by the quantified OH sources from photolysis (HONO and O3), ozonolysis of alkenes, and OH recycling (HO2+NO). In the afternoon, however, the OH budget indicates a missing OH source of 4 to 6 ppbv h−1. The diurnal variation of the missing OH source shows a similar pattern to that of the missing RO2 sink so that both largely compensate each other in the ROx budget. These observations suggest the existence of a chemical mechanism that converts RO2 to OH without the involvement of NO, increasing the RO2 loss rate during the daytime from 5.3 to 7.4 ppbv h−1 on average. The photochemical net ozone production rate calculated from the reaction of HO2 and RO2 with NO yields a daily integrated amount of 102 ppbv ozone, with daily integrated ROx primary sources being 22 ppbv in this campaign. The produced ozone can be attributed to the oxidation of measured (18 %) and unmeasured (60 %) hydrocarbons, formaldehyde (14 %), and CO (8 %). An even larger integrated net ozone production of 140 ppbv would be calculated from the oxidation rate of VOCs with OH if HO2 and all RO2 radicals react with NO. However, the unknown RO2 loss (evident in the RO2 budget) causes 30 ppbv less ozone production than would be expected from the VOC oxidation rate.

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Section: Oh Interferencesupporting

confidence: 90%

Experimental budgets of OH, HO2, and RO2 radicals and implications for ozone formation in the Pearl River Delta in China 2014

Tan

Hofzumahaus³

et al. 2019

Atmos. Chem. Phys.

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123

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“…The modeled HCHO concentrations range from 3 to 8 ppbv ( Fig. S7) and are consistent with previous studies in these regions (Tang et al, 2009;Zhang et al, 2012;Chen et al, 2016;Song et al, 2018). The modeled acetaldehyde concentrations range from 2 to 3 ppbv in Beijing, Shanghai, and Chongqing but are 1 ppbv larger in Guangzhou because of the larger contribution of aromatic VOCs, which produce acetaldehyde during OH degradation.…”

Section: Voc Compositions and Ozone Production Efficiencysupporting

confidence: 88%

“…As mentioned in Sect. 3.3, the current model could have flaws under high-NO x conditions, which might lead to the underestimation of the peroxy radical concentrations and thus the local ozone production in China (Shirley et al, 2006;Kanaya et al, 2007;Dusanter et al, 2009;Ren et al, 2013;Brune et al, 2016;Griffith et al, 2016;Tan et al, 2017Tan et al, , 2018d;Whalley et al, 2018). However, quantitative estimation is not possible due to the absence of in situ radical measurements.…”

Section: Local Ozone Productionmentioning

confidence: 98%

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Daytime atmospheric oxidation capacity in four Chinese megacities during the photochemically polluted season: a case study based on box model simulation

et al. 2019

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Abstract. Atmospheric oxidation capacity is the basis for converting freshly emitted substances into secondary products and is dominated by reactions involving hydroxyl radicals (OH) during daytime. In this study, we present in situ measurements of ROx radical (hydroxy OH, hydroperoxy HO2, and organic peroxy RO2) precursors and products; the measurements are carried out in four Chinese megacities (Beijing, Shanghai, Guangzhou, and Chongqing) during photochemically polluted seasons. The atmospheric oxidation capacity is evaluated using an observation-based model and radical chemistry precursor measurements as input. The radical budget analysis illustrates the importance of HONO and HCHO photolysis, which account for ∼50 % of the total primary radical sources. The radical propagation is efficient due to abundant NO in urban environments. Hence, the production rate of secondary pollutants, that is, ozone (and fine-particle precursors (H2SO4, HNO3, and extremely low volatility organic compounds, ELVOCs) is rapid, resulting in secondary air pollution. The ozone budget demonstrates its high production in urban areas; also, its rapid transport to downwind areas results in rapid increase in local ozone concentrations. The O3–NOx–VOC (volatile organic compound) sensitivity tests show that ozone production is VOC-limited and that alkenes and aromatics should be mitigated first for ozone pollution control in the four studied megacities. In contrast, NOx emission control (that is, a decrease in NOx) leads to more severe ozone pollution. With respect to fine-particle pollution, the role of the HNO3–NO3 partitioning system is investigated using a thermal dynamic model (ISORROPIA 2). Under high relative humidity (RH) and ammonia-rich conditions, nitric acid converts into nitrates. This study highlights the efficient radical chemistry that maintains the atmospheric oxidation capacity in Chinese megacities and results in secondary pollution characterized by ozone and fine particles.

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“…Figures S2-S3 further compare daily MDA8 values in the nine city clusters and in individual cities. We use MDA8 throughout the analysis as it is the ozone air quality standard in China and also an important metric of human health exposure (Turner et al, 2016). The model reproduces the spatial distribution of observed surface MDA8 ozone in the warm season (May-August) with a high spatial correlation coefficient (r) of 0.81-0.82 and a relatively small positive mean bias of 4.5-7.4 ppbv (7 %-13 %) in the 169 cities.…”

Section: Model Configurationsmentioning

confidence: 99%

Exploring 2016–2017 surface ozone pollution over China: source contributions and meteorological influences

et al. 2019

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Published by Copernicus Publications on behalf of the European Geosciences Union. 8340 X. Lu et al.: Exploring 2016-2017 surface ozone pollution over ChinaBVOC ozone enhancements) and ozone chemical production, increase the thermal decomposition of peroxyacetyl nitrate (PAN), and further decrease ozone dry deposition velocity. More stringent emission control measures are thus required to offset the adverse effects of unfavorable meteorology, such as high temperature, on surface ozone air quality.

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Explicit diagnosis of the local ozone production rate and the ozone-NOx-VOC sensitivities

Cited by 140 publications

References 44 publications

Experimental budgets of OH, HO<sub>2</sub>, and RO<sub>2</sub> radicals and implications for ozone formation in the Pearl River Delta in China 2014

Experimental budgets of OH, HO<sub>2</sub>, and RO<sub>2</sub> radicals and implications for ozone formation in the Pearl River Delta in China 2014

Daytime atmospheric oxidation capacity in four Chinese megacities during the photochemically polluted season: a case study based on box model simulation

Exploring 2016–2017 surface ozone pollution over China: source contributions and meteorological influences

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Explicit diagnosis of the local ozone production rate and the ozone-NOx-VOC sensitivities

Cited by 140 publications

References 44 publications

Experimental budgets of OH, HO&lt;sub&gt;2&lt;/sub&gt;, and RO&lt;sub&gt;2&lt;/sub&gt; radicals and implications for ozone formation in the Pearl River Delta in China 2014

Experimental budgets of OH, HO&lt;sub&gt;2&lt;/sub&gt;, and RO&lt;sub&gt;2&lt;/sub&gt; radicals and implications for ozone formation in the Pearl River Delta in China 2014

Daytime atmospheric oxidation capacity in four Chinese megacities during the photochemically polluted season: a case study based on box model simulation

Exploring 2016–2017 surface ozone pollution over China: source contributions and meteorological influences

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Experimental budgets of OH, HO<sub>2</sub>, and RO<sub>2</sub> radicals and implications for ozone formation in the Pearl River Delta in China 2014

Experimental budgets of OH, HO<sub>2</sub>, and RO<sub>2</sub> radicals and implications for ozone formation in the Pearl River Delta in China 2014