Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 15, 8179-8200, 2015
https://doi.org/10.5194/acp-15-8179-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
23 Jul 2015
Night-time measurements of HOx during the RONOCO project and analysis of the sources of HO2
H. M. Walker1, D. Stone1, T. Ingham1,2, S. Vaughan1, M. Cain3,4, R. L. Jones3, O. J. Kennedy3, M. McLeod3, B. Ouyang3, J. Pyle3,4, S. Bauguitte5,6, B. Bandy7,8, G. Forster7,8, M. J. Evans9,10, J. F. Hamilton9, J. R. Hopkins9,10, J. D. Lee9,10, A. C. Lewis9,10, R. T. Lidster9, S. Punjabi9,10, W. T. Morgan11,12, and D. E. Heard1,2 1School of Chemistry, University of Leeds, Leeds, UK
2National Centre for Atmospheric Science, University of Leeds, Leeds, UK
3Department of Chemistry, University of Cambridge, Cambridge, UK
4National Centre for Atmospheric Science, University of Cambridge, Cambridge, UK
5Facility for Airborne Atmospheric Measurements (FAAM), Cranfield University, Cranfield, UK
6National Centre for Atmospheric Science, FAAM, Cranfield University, Cranfield, UK
7Centre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich, UK
8National Centre for Atmospheric Science, University of East Anglia, Norwich, UK
9Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, York, UK
10National Centre for Atmospheric Science, University of York, York, UK
11School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, UK
12National Centre for Atmospheric Science, University of Manchester, Manchester, UK
Abstract. Measurements of the radical species OH and HO2 were made using the fluorescence assay by gas expansion (FAGE) technique during a series of night-time 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 night-time flights or during the winter daytime flights, placing upper limits on [OH] of 1.8 × 106 molecule cm−3 and 6.4 × 105 molecule cm−3 for the summer and winter flights, respectively. HO2 reached a maximum concentration of 3.2 × 108 molecule cm−3 (13.6 pptv) during a night-time flight on 20 July 2010, when the highest concentrations of NO3 and O3 were also recorded. An analysis of the rates of reaction of OH, O3, and the NO3 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 HO2 from the reactions of O3 and NO3 with alkenes has shown that, on average, reactions of NO3 dominated the night-time production of HO2 during summer and reactions of O3 dominated the night-time HO2 production during winter.

Citation: Walker, H. M., Stone, D., Ingham, T., Vaughan, S., Cain, M., Jones, R. L., Kennedy, O. J., McLeod, M., Ouyang, B., Pyle, J., Bauguitte, S., Bandy, B., Forster, G., Evans, M. J., Hamilton, J. F., Hopkins, J. R., Lee, J. D., Lewis, A. C., Lidster, R. T., Punjabi, S., Morgan, W. T., and Heard, D. E.: Night-time measurements of HOx during the RONOCO project and analysis of the sources of HO2, Atmos. Chem. Phys., 15, 8179-8200, https://doi.org/10.5194/acp-15-8179-2015, 2015.
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