Isoprene oxidation mechanisms: measurements and modelling of OH and HO2 over a South-East Asian tropical rainforest during the OP3 field campaign

Stone, D, Evans, MJ, Edwards, PM, Commane, R, Ingham, T, Rickard, AR, Brookes, DM, Hopkins, J, Leigh, RJ, Lewis, AC, Monks, PS, Oram, D, Reeves, CE, Stewart, D and Heard, DE (2011) Isoprene oxidation mechanisms: measurements and modelling of OH and HO2 over a South-East Asian tropical rainforest during the OP3 field campaign. Atmospheric Chemistry and Physics, 11 (13). pp. 6749-6771. ISSN 1680-7324

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Abstract

Forests are the dominant source of volatile organic compounds into the atmosphere, with isoprene being the most significant species. The oxidation chemistry of these compounds is a significant driver of local, regional and global atmospheric composition. Observations made over Borneo during the OP3 project in 2008, together with an observationally constrained box model are used to assess our understanding of this oxidation chemistry. In line with previous work in tropical forests, we find that the standard model based on MCM chemistry significantly underestimates the observed OH concentrations. Geometric mean observed to modelled ratios of OH and HO2 in airmasses impacted with isoprene are 5.32-4.43+3.68 and 1.18-0.30+0.30 respectively, with 68 % of the observations being within the specified variation. We implement a variety of mechanistic changes into the model, including epoxide formation and unimolecular decomposition of isoprene peroxy radicals, and assess their impact on the model success. We conclude that none of the current suggestions can simultaneously remove the bias from both OH and HO2 simulations and believe that detailed laboratory studies are now needed to resolve this issue.

Item Type: Article
Faculty \ School: Faculty of Science > School of Environmental Sciences
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Depositing User: Users 2731 not found.
Date Deposited: 07 Sep 2011 11:47
Last Modified: 21 Apr 2020 16:54
URI: https://ueaeprints.uea.ac.uk/id/eprint/34689
DOI: 10.5194/acp-11-6749-2011

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