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Stone, D., Evans, M. J., Commane, R., Ingham, T., Floquet, C. F. A., McQuaid, J. B., Brookes, D. M., Monks, P. S., Purvis, R., Hamilton, J. F., Hopkins, J., Lee, J., Lewis, A. C., Stewart, D., Murphy, J. G., Mills, G., Oram, D., Reeves, C. E. 
ORCID: https://orcid.org/0000-0003-4071-1926 and Heard, D. E.
(2010)
HOx observations over West Africa during AMMA: Impact of isoprene and NOx.
Atmospheric Chemistry and Physics, 10 (19).
pp. 9415-9429.
ISSN 1680-7324
Abstract
Aircraft OH and HO2 measurements made over West Africa during the AMMA field campaign in summer 2006 have been investigated using a box model constrained to observations of long-lived species and physical parameters. "Good" agreement was found for HO2 (modelled to observed gradient of 1.23 ± 0.11). However, the model significantly overpredicts OH concentrations. The reasons for this are not clear, but may reflect instrumental instabilities affecting the OH measurements. Within the model, HOx concentrations in West Africa are controlled by relatively simple photochemistry, with production dominated by ozone photolysis and reaction of O(1D) with water vapour, and loss processes dominated by HO2 + HO2 and HO2 + RO2. Isoprene chemistry was found to influence forested regions. In contrast to several recent field studies in very low NOx and high isoprene environments, we do not observe any dependence of model success for HO2 on isoprene and attribute this to efficient recycling of HOx through RO2 + NO reactions under the moderate NOx concentrations (5–300 ppt NO in the boundary layer, median 76 ppt) encountered during AMMA. This suggests that some of the problems with understanding the impact of isoprene on atmospheric composition may be limited to the extreme low range of NOx concentrations.
| Item Type: | Article |
|---|---|
| Faculty \ School: | Faculty of Science > School of Environmental Sciences University of East Anglia Research Groups/Centres > Theme - ClimateUEA |
| UEA Research Groups: | Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences Faculty of Science > Research Groups > Marine and Atmospheric Sciences (former - to 2017) Faculty of Science > Research Groups > Atmospheric Chemistry (former - to 2018) Faculty of Science > Research Groups > Climate, Ocean and Atmospheric Sciences (former - to 2017) |
| Related URLs: | |
| Depositing User: | Rosie Cullington |
| Date Deposited: | 01 Jun 2011 10:03 |
| Last Modified: | 20 Mar 2023 09:32 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/31670 |
| DOI: | 10.5194/acp-10-9415-2010 |
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