Atmospheric OH reactivity in central London: observations, model predictions  and estimates of in situ ozone production

Whalley, Lisa K.; Stone, Daniel; Bandy, Brian; Dunmore, Rachel E.; Hamilton, Jacqueline F.; Hopkins, James R.; Lee, James; Lewis, Alastair C.; Heard, Dwayne E.

doi:10.5194/acp-16-2109-2016

Cited by 87 publications

(117 citation statements)

References 27 publications

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“…Yoshino et al (2006) found a good correlation between missing reactivity and measured oxygenated VOCs (OVOCs) in three seasons, except for winter, assuming that the unmeasured OVOCs could be major contributors of missing reactivity; in one case, the OVOCs could increase reactivity by over 50 % (Lou et al, 2010). The observation-based model (OBM) was widely used to evaluate the measured reactivity (Lee et al, 2010;Lou et al, 2010;Whalley et al, 2016), confirming the important contribution from OVOCs and undetected intermediate compounds.…”

Section: Introductionmentioning

confidence: 99%

How the OH reactivity affects the ozone production efficiency: case studies in Beijing and Heshan, China

et al. 2017

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Abstract. Total OH reactivity measurements were conducted on the Peking University campus (Beijing) in August 2013 and in Heshan (Guangdong province) from October to November 2014. The daily median OH reactivity was 20 ± 11 s −1 in Beijing and 31 ± 20 s −1 in Heshan, respectively. The data in Beijing showed a distinct diurnal pattern with the maxima over 27 s −1 in the early morning and minima below 16 s −1 in the afternoon. The diurnal pattern in Heshan was not as evident as in Beijing. Missing reactivity, defined as the difference between measured and calculated OH reactivity, was observed at both sites, with 21 % missing reactivity in Beijing and 32 % missing reactivity in Heshan. Unmeasured primary species, such as branched alkenes, could contribute to missing reactivity in Beijing, especially during morning rush hours. An observation-based model with the RACM2 (Regional Atmospheric Chemical Mechanism version 2) was used to understand the daytime missing reactivity in Beijing by adding unmeasured oxygenated volatile organic compounds and simulated intermediates of the degradation from primary volatile organic compounds (VOCs). However, the model could not find a convincing explanation for the missing reactivity in Heshan, where the ambient air was found to be more aged, and the missing reactivity was presumably attributed to oxidized species, such as unmeasured aldehydes, acids and dicarbonyls. The ozone production efficiency was 21 % higher in Beijing and 30 % higher in Heshan when the model was constrained by the measured reactivity, compared to the calculations with measured and modeled species included, indicating the importance of quantifying the OH reactivity for better understanding ozone chemistry.

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Section: Introductionmentioning

confidence: 99%

How the OH reactivity affects the ozone production efficiency: case studies in Beijing and Heshan, China

et al. 2017

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“…Nashville, USA (SOS) 11.0 3.8 (Kovacs et al, 2003) New York, USA (PMTACS-NY2001) 18.8 0.7 (Ren et al, 2003a(Ren et al, , 2003b New York, USA (PMTACS-NY2004) 25.1 4.0 (Ren et al, 2006a) Mexico City, Mexico (MCMA-2003) 47.5 14.3 (Shirley et al, 2006) Houston, USA (TexAQS) 9.4 0.4 (Mao et al, 2010) Houston, USA (TRAMP2006) 12.24 0.03 (Mao et al, 2010) Paris, France (MEGAPOLI) 40.3 22.8 (Dolgorouky et al, 2012) Lille, France 7.4 0 (Hansen et al, 2015) London, UK (ClearfLo) 18.1 5.9 2.7 † (Whalley et al, 2016) Remote Michigan, USA (Prophet2000) 7.8 2.6 (Di Carlo et al, 2004) Hyytiälä, Finland (BFORM) 8.6 3.9 (Sinha et al, 2010) Hyytiälä, Finland (HUMPPA-COPEC2010) 11.5 8.9 (Nölscher et al, 2012) Rocky Mountains, USA (BEACHON-SRM08) 6.7 2.1 (Nakashima et al, 2014) Michigan, USA (CABINEX) 11.6 6.3 (Hansen et al, 2014) Amazon, Brazil (ATTO) dry season 49.6 35.8 …”

Section: Urbanmentioning

confidence: 99%

“…15 In an attempt to account for the additional OH reactivity potentially arising from unmeasured oxidation intermediates, a number of studies invoked box modelling to determine the abundance of these species and their contribution to kOH. These efforts have been met with mixed results: while some managed to reconcile the total kOH with the sum of reactivities once the oxidation intermediates were taken into account (Whalley et al, 2016), others obtained different degrees of improvement on the agreement between the two, leaving different fractions of kOH still unaccounted for (Edwards et al, 2013;Elshorbany et al, 20 2012;Kaiser et al, 2016;Kovacs et al, 2003;Lee et al, 2009;Lou et al, 2010;Mao et al, 2012;Mogensen et al, 2011;Yang et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Global modelling of the total OH reactivity: investigations on the missing OH sink and its atmospheric implications

Ferracci¹,

Heimann²,

Abraham³

et al. 2018

Preprint

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Abstract. The hydroxyl radical (OH) plays a crucial role in the chemistry of the atmosphere as it initiates the removal of most trace gases. A number of field campaigns have observed the presence of a "missing" OH sink in a variety of regions across the planet. Comparison of direct measurements of the OH loss frequency, also known as total OH reactivity (kOH), with the 10 sum of individual known OH sinks (obtained via the simultaneous detection of species such as volatile organic compounds and nitrogen oxides) indicates that, in some cases, up to 80 % of kOH is unaccounted for. In this work, the UM-UKCA chemistry-climate model was used to investigate the wider implications of the missing reactivity on the oxidising capacity of the atmosphere. Simulations of the present-day atmosphere were performed and the model was evaluated against an array of field measurements to verify that the known OH sinks were reproduced well, with a resulting good agreement found for most 15 species. Following this, an additional sink was introduced to simulate the missing OH reactivity as an emission of a hypothetical molecule, X, which undergoes rapid reaction with OH. The magnitude and spatial distribution of this sink were underpinned by observations of the missing reactivity. Model runs showed that the missing reactivity accounted for on average 6 % of the total OH loss flux at the surface, and up to 50 % in regions where emissions of the additional sink were high. The lifetime of the hydroxyl radical was reduced by 3 % in the boundary layer, while tropospheric methane lifetime increased by 20 2 % when the additional OH sink was included. The UM-UKCA simulations also allowed us to establish the atmospheric implications of the newly characterised reactions of peroxy radicals (RO2) with OH. While the effects of this chemistry on kOH were minor, the reaction of the simplest peroxy radical, CH3O2, with OH was found to be a major sink for CH3O2 and source of HO2 over remote regions at the surface and in the free troposphere. Inclusion of this reaction in the model increased tropospheric methane lifetime by up to 3 %, depending on its product branching. Simulations based on the latest kinetic and 25 product information showed that this reaction cannot reconcile models with observations of atmospheric methanol, in contrast to recent suggestions.Atmos. Chem. Phys. Discuss., https://doi

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“…The total OH reactivity values of measured VOCs in Berlin (2.6 s −1 ) are similar to the average total OH reactivity from VOCs observed in other European cities, such as Paris (approximately 4.0 s −1 ) and London (1.8 s −1 ) (Dolgorouky et al, 2012;Whalley et al, 2016), and, not surprisingly, lower than those observed at cities in the Pearl River Delta region of China (8-14 s −1 ). Specifically, Liu et al (2008) reported OH reactivity from a measurement campaign in Ghangzhou and Xinken during 1 month in the autumn of 2004.…”

Section: Oh Reactivitymentioning

confidence: 57%

“…The GRIMM 5.416, a condensation particle counter with n-butanol, provided total PN count over a size range from 4 to 3000 nm at a flow rate of 1.5 L min −1 , and the uncertainty for 1 min sampling was ± 0.1 % or ± 15 cm −3 (Helsper et al, 2008;Wiedensohler et al, 2017). The GRIMM 5.403, a scanning mobility particle sizer equipped with a long DMA combined with a CPC with n-butanol, measured PN concentrations with size distribution information for particles between 10 and 1100 nm at a sample flow rate of 0.3 L min −1 and a sheath flow rate of 3 L min −1 .…”

Section: Particle Number Concentration and Surface Area Measurementsmentioning

confidence: 99%

BAERLIN2014 – stationary measurements and source apportionment at an urban background station in Berlin, Germany

et al. 2018

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Abstract. The "Berlin Air quality and Ecosystem Research: Local and long-range Impact of anthropogenic and Natural hydrocarbons" (BAERLIN2014) campaign was conducted during the 3 summer months (June-August) of 2014. During this measurement campaign, both stationary and mobile measurements were undertaken to address complementary aims. This paper provides an overview of the stationary measurements and results that were focused on characterization of gaseous and particulate pollution, including source attribution, in the Berlin-Potsdam area, and quantification of the role of natural sources in determining levels of ozone and related gaseous pollutants. Results show that biogenic contributions to ozone and particulate matter are substantial. One indicator for ozone formation, the OH reactivity, showed a 31 % (0.82 ± 0.44 s −1 ) and 75 % (3.7 ± 0.90 s −1 ) contribution from biogenic non-methane volatile organic compounds (NMVOCs) for urban background (2.6 ± 0.68 s −1 ) and urban park (4.9 ± 1.0 s −1 ) location, respectively, emphasizing the importance of such locations as sources of biogenic NMVOCs in urban areas. A comparison to NMVOC measurements made in Berlin approximately 20 years earlier generally show lower levels today for anthropogenic NMVOCs. A substantial contribution of secondary organic and inorganic aerosol to PM 10 concentrations was quantified. In addition to secondary aerosols, source apportionment analysis of the organic carbon fraction identified the contribution of biogenic (plant-based) particulate matter, as well as primary contributions from vehicles, with a larger contribution from diesel compared to gasoline vehicles, as well as a relatively small contribution from wood burning, linked to measured levoglucosan.

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Atmospheric OH reactivity in central London: observations, model predictions and estimates of in situ ozone production

Cited by 87 publications

References 27 publications

How the OH reactivity affects the ozone production efficiency: case studies in Beijing and Heshan, China

How the OH reactivity affects the ozone production efficiency: case studies in Beijing and Heshan, China

Global modelling of the total OH reactivity: investigations on the missing OH sink and its atmospheric implications

BAERLIN2014 – stationary measurements and source apportionment at an urban background station in Berlin, Germany

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