Measurement and modelling of air pollution and atmospheric chemistry in the U.K. West Midlands conurbation: Overview of the PUMA Consortium project

Harrison, Roy M.; Yin, Jianxin; Tilling, Rob M.; Cai, Xiaoming; Seakins, Paul W.; Hopkins, James R.; Lansley, D.L.; Lewis, Alastair C.; Hunter, Maxwell C.; Heard, Dwayne E.; Carpenter, Lucy J.; Creasey, D. J.; Lee, James; Pilling, Michael J.; Carslaw, Nicola; Emmerson, Kathryn M.; Redington, Alison L.; Derwent, R.G.; Ryall, DB; Mills, G.; Penkett, S. A.

doi:10.1016/j.scitotenv.2005.08.053

Cited by 115 publications

(81 citation statements)

References 30 publications

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“…3), showed that winter concentrations of hydroxyl were about 50% of summer concentrations whereas scaling based upon ozone photolysis predicts concentrations only around 5% of summer concentrations. 8,9 This led to a realisation that other sources of hydroxyl are more important in the urban polluted atmosphere and these include photolysis of nitrous acid and formaldehyde as well as the decomposition of the Criegee biradical intermediate formed from ozone-alkene reactions 10 (see Box 1). Such processes are typically included in Chemistry-Transport Models (e.g., the RADM2 scheme 11 used in the WRF-Chem model), but depend critically upon reliable predictions of HONO and HCHO concentrations.…”

Section: Chemical Reaction Processes In the Urban Atmospherementioning

confidence: 99%

Urban atmospheric chemistry: a very special case for study

Harrison

2018

npj Clim Atmos Sci

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Studies of the chemistry of the urban atmosphere provide special challenges which arise from the high density of emissions, strong concentration gradients and relatively high pollutant concentrations. In contrast to the regional and global atmosphere, local dispersion processes play a much larger role in determining atmospheric concentrations and also have a substantial effect on chemical transformations. On the other hand, residence times in the urban atmosphere are relatively short, hence limiting the range of chemical reaction processes which are significant. Some key species such as the hydroxyl radical have different predominant source processes in the urban and the regional atmosphere. A case is made that the differences are so large that urban atmospheric chemistry needs to be given special treatment and cannot simply be considered as subtlely different from regional and global atmosphere studies.

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Section: Chemical Reaction Processes In the Urban Atmospherementioning

confidence: 99%

Urban atmospheric chemistry: a very special case for study

Harrison

2018

npj Clim Atmos Sci

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“…As the closest example for comparison, the Pollution of the Urban Midlands Atmosphere (PUMA) summer campaign (Emmerson et al, 2005a,b;Harrison et al, 2006;Heard et al, 2004) D)) was 3.6 × 10 −6 s −1 for PUMA and 4.7×10 −6 s −1 for TORCH; and average H 2 O concentrations were 3.6×10 17 molecule cm −3 for PUMA and 3.7×10 17 molecule cm −3 for TORCH. In other campaigns, the reaction of O 1 D+H 2 O was a major source of OH during the Nashville Southern Oxidants Study (SOS) in the USA , with photolysis of HONO and formaldehyde becoming more important as the UV light diminished at the ends of the day.…”

Section: Radical Propagationmentioning

confidence: 99%

“…The Pollution of the Urban Midlands Atmosphere (PUMA) campaign (Emmerson et al, 2005a,b;Harrison et al, 2006;Heard et al, 2004) took place in Birmingham city centre during summer 1999 and winter 2000. Whilst there was generally good agreement between the modelled and measured OH concentrations, the model tended to underpredict during daylight hours (between 11:00 and 15:00 h), with modelled to measured ratios of 0.6 and 0.5 for OH during summer and winter respectively.…”

Section: Introductionmentioning

confidence: 99%

Free radical modelling studies during the UK TORCH Campaign in Summer 2003

et al. 2007

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Abstract. The Tropospheric ORganic CHemistry experiment (TORCH) took place during the heatwave of summer 2003 at Writtle College, a site 2 miles west of Chelmsford in Essex and 25 miles north east of London. The experiment was one of the most highly instrumented to date. A combination of a large number of days of simultaneous, collocated measurements, a consequent wealth of model constraints and a highly detailed chemical mechanism, allowed the atmospheric chemistry of this site to be studied in detail. Between 25 July and 31 August, the concentrations of the hydroxyl radical and the hydroperoxy radical were measured using laser-induced fluorescence at low pressure and the sum of peroxy radicals was measured using the peroxy radical chemical amplifier technique. The concentrations of the radical species were predicted using a zero-dimensional box model based on the Master Chemical Mechanism version 3.1, which was constrained with the observed concentrations of relatively long-lived species. The model included a detailed parameterisation to account for heterogeneous loss of hydroperoxy radicals onto aerosol particles. Quantilequantile plots were used to assess the model performance in respect of the measured radical concentrations. On average, measured hydroxyl radical concentrations were overpredicted by 24%. Modelled and measured hydroperoxy radical concentrations agreed very well, with the model overpredicting on average by only 7%. The sum of peroxy radicals was under-predicted when compared with the respective measurements by 22%. Initiation via OH was dominatedCorrespondence to: N. Carslaw (nc12@york.ac.uk) by the reactions of excited oxygen atoms with water, nitrous acid photolysis and the ozone reaction with alkene species. Photolysis of aldehyde species was the main route for initiation via HO 2 and RO 2 . Termination, under all conditions, primarily involved reactions with NO x for OH and heterogeneous chemistry on aerosol surfaces for HO 2 . The OH chain length varied between 2 and 8 cycles, the longer chain lengths occurring before and after the most polluted part of the campaign. Peak local ozone production of 17 ppb hr −1 occurred on 3 and 5 August, signifying the importance of local chemical processes to ozone production on these days. On the whole, agreement between model and measured radicals is good, giving confidence that our understanding of atmospheres influenced by nearby urban sources is adequate.

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“…The OH produced through these ozonolysis mechanisms will proceed to oxidise other VOC species. Criegee intermediates formed in the ozonolysis of alkenes are known to be an important source of HO x during the day and at night (Paulson and Orlando, 1996;Donahue et al, 1998;Kanaya et al, 1999;Salisbury et al, 2001;Geyer et al, 2003;Ren et al, 2003aRen et al, , 2006Heard et al, 2004;Harrison et al, 2006;Sommariva et al, 2007). The gas-phase ozonolysis of unsaturated VOCs, and in particular the role and subsequent chemistry of the Criegee intermediate, have been reviewed in detail by Johnson and Marston (2008), Donahue et al (2011), Vereecken and Francisco (2012), and Taatjes et al (2014).…”

Section: H M Walker Et Al: Night-time Measurements Of Ho Xmentioning

confidence: 99%

“…Reactions of O 3 with alkenes were found to be responsible for the majority of the formation of OH during the winter PUMA (Pollution of the Urban Midlands Atmosphere) campaign (a low-photolysis urban environment) (Heard et al, 2004;Emmerson et al, 2005;Harrison et al, 2006). Measurements of OH, HO 2 , and RO 2 were unavailable at night, but model-predicted values of these radicals were used to calculate that 90 % of night-time initiation via HO 2 was from O 3 reactions.…”

Section: H M Walker Et Al: Night-time Measurements Of Ho Xmentioning

confidence: 99%

Night-time measurements of HOx during the RONOCO project and analysis of the sources of HO2

et al. 2015

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Abstract. Measurements of the radical species OH and HO 2 were made using the fluorescence assay by gas expansion (FAGE) technique during a series of nighttime and daytime flights over the UK in summer 2010 and winter 2011. OH was not detected above the instrument's 1σ limit of detection during any of the nighttime flights or during the winter daytime flights, placing upper limits on [OH] of 1.8 × 10 6 molecule cm −3 and 6.4 × 10 5 molecule cm −3 for the summer and winter flights, respectively. HO 2 reached a maximum concentration of 3.2 × 10 8 molecule cm −3 (13.6 pptv) during a night-time flight on 20 July 2010, when the highest concentrations of NO 3 and O 3 were also recorded. An analysis of the rates of reaction of OH, O 3 , and the NO 3 radical with measured alkenes indicates that the summer night-time troposphere can be as important for the processing of volatile organic compounds (VOCs) as the winter daytime troposphere. An analysis of the instantaneous rate of production of HO 2 from the reactions of O 3 and NO 3 with alkenes has shown that, on average, reactions of NO 3 dominated the night-time production of HO 2 during summer and reactions of O 3 dominated the night-time HO 2 production during winter.

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Measurement and modelling of air pollution and atmospheric chemistry in the U.K. West Midlands conurbation: Overview of the PUMA Consortium project

Cited by 115 publications

References 30 publications

Urban atmospheric chemistry: a very special case for study

Urban atmospheric chemistry: a very special case for study

Free radical modelling studies during the UK TORCH Campaign in Summer 2003

Night-time measurements of HO<sub><i>x</i></sub> during the RONOCO project and analysis of the sources of HO<sub>2</sub>

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Measurement and modelling of air pollution and atmospheric chemistry in the U.K. West Midlands conurbation: Overview of the PUMA Consortium project

Cited by 115 publications

References 30 publications

Urban atmospheric chemistry: a very special case for study

Urban atmospheric chemistry: a very special case for study

Free radical modelling studies during the UK TORCH Campaign in Summer 2003

Night-time measurements of HO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; during the RONOCO project and analysis of the sources of HO&lt;sub&gt;2&lt;/sub&gt;

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Night-time measurements of HO<sub><i>x</i></sub> during the RONOCO project and analysis of the sources of HO<sub>2</sub>