OH and HO2 radical chemistry in a forested region of north-western Greece

Citation
N. Carslaw et al., OH and HO2 radical chemistry in a forested region of north-western Greece, ATMOS ENVIR, 35(27), 2001, pp. 4725-4737
Citations number
38
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology,"Earth Sciences
Journal title
ATMOSPHERIC ENVIRONMENT
ISSN journal
1352-2310 → ACNP
Volume
35
Issue
27
Year of publication
2001
Pages
4725 - 4737
Database
ISI
SICI code
1352-2310(200109)35:27<4725:OAHRCI>2.0.ZU;2-9
Abstract
This paper explores several aspects of the chemistry of a forested region i n north-western Greece, from data collected during the AEROBIC97 campaign. An observationally constrained box model has been constructed to enable com parisons between modelled concentrations of OH and HO2 and those determined by the fluorescence assay by gas expansion (FAGE) technique. These results represent the first comparison of measured and modelled OH concentrations in such an environment. The modelled OH concentrations are, on average, sim ilar to 50% of those measured (range of 16-61 %) over 4 days of model and m easurement comparison. Possible reasons for the model-measurement discrepan cy are discussed. A rate of production analysis illustrates the dominance o f isoprene and the monoterpenes on OH loss, as well as the significance of the ozonolysis of biogenic species as an OH source. The measured and modell ed [HO2]/[OH] ratio averaged between 11:00 and 15:00 h is much higher than has been found previously for similar NO, concentrations, similar to 75 and 340, respectively, cf. 10-20. The high ratio reflects the rapid recycling through the OH-HO2 oxidation chain, involving biogenic species. The high bi ogenic concentrations result in a midday OH lifetime of similar to 0.15 s. Finally, for the conditions encountered during the campaign, there is high net photochemical ozone production, peaking at similar to 20 ppbv h(-1) aro und 09:00h. (C) 2001 Elsevier Science Ltd. All rights reserved.