Night-time measurements of HO<sub><i>x</i></sub> during the RONOCO project and analysis of the sources of HO<sub>2</sub>
Measurements of the radical species OH and HO<sub>2</sub> 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 li...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/15/8179/2015/acp-15-8179-2015.pdf |
| Summary: | Measurements of the radical species OH and HO<sub>2</sub> 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 × 10<sup>6</sup> molecule cm<sup>−3</sup> and
6.4 × 10<sup>5</sup> molecule cm<sup>−3</sup> for the summer and winter
flights, respectively. HO<sub>2</sub> reached a maximum concentration of
3.2 × 10<sup>8</sup> molecule cm<sup>−3</sup> (13.6 pptv) during a night-time
flight on 20 July 2010, when the highest concentrations of NO<sub>3</sub> and
O<sub>3</sub> were also recorded. An analysis of the rates of reaction of OH,
O<sub>3</sub>, and the NO<sub>3</sub> 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<sub>2</sub> from the
reactions of O<sub>3</sub> and NO<sub>3</sub> with alkenes has shown that, on average,
reactions of NO<sub>3</sub> dominated the night-time production of HO<sub>2</sub> during
summer and reactions of O<sub>3</sub> dominated the night-time HO<sub>2</sub> production
during winter. |
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| ISSN: | 1680-7316 1680-7324 |