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| Titel |
Peroxy radical chemistry and the control of ozone photochemistry at Mace Head, Ireland during the summer of 2002 |
| VerfasserIn |
Z. L. Fleming, P. S. Monks, A. R. Rickard, D. E. Heard, W. J. Bloss, P. W. Seakins, T. J. Still, R. Sommariva, M. J. Pilling, R. Morgan, T. J. Green, N. Brough, G. P. Mills, S. A. Penkett, A. C. Lewis, J. D. Lee, A. Saiz-Lopez, J. M. C. Plane |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 6, no. 8 ; Nr. 6, no. 8 (2006-06-20), S.2193-2214 |
| Datensatznummer |
250003927
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| Publikation (Nr.) |
 copernicus.org/acp-6-2193-2006.pdf |
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| Zusammenfassung |
| Peroxy radical (HO2+ΣRO2) measurements, using the
PEroxy Radical Chemical Amplification (PERCA) technique at the North
Atlantic Marine Boundary Layer EXperiment (NAMBLEX) at Mace Head in
summer 2002, are presented and put into the context of marine,
boundary-layer chemistry. A suite of other chemical parameters (NO,
NO2, NO3, CO, CH4, O3, VOCs, peroxides),
photolysis frequencies and meteorological measurements, are used to
present a detailed analysis of the role of peroxy radicals in
tropospheric oxidation cycles and ozone formation. Under the range
of conditions encountered the peroxy radical daily maxima varied
from 10 to 40 pptv. The diurnal cycles showed an asymmetric shape
typically shifted to the afternoon. Using a box model based on the
master chemical mechanism the average model measurement agreement
was 2.5 across the campaign. The addition of halogen oxides to the
model increases the level of model/measurement agreement, apparently
by respeciation of HOx. A good correlation exists between
j(HCHO).[HCHO] and the peroxy radicals indicative of the
importance of HCHO in the remote atmosphere as a HOx source,
particularly in the afternoon. The peroxy radicals showed a strong
dependence on [NO2] with a break point at 0.1 ppbv, where the
radicals increased concomitantly with the reactive VOC loading, this
is a lower value than seen at representative urban campaigns. The
HO2/(HO2+ΣRO2) ratios are dependent on
[NOx] ranging between 0.2 and 0.6, with the ratio increasing
linearly with NOx. Significant night-time levels of peroxy
radicals were measured up to 25 pptv. The contribution of
ozone-alkenes and NO3-alkene chemistry to night-time peroxy
radical production was shown to be on average 59 and 41%. The
campaign mean net ozone production rate was 0.11±0.3 ppbv
h-1. The ozone production rate was strongly dependent on [NO]
having linear sensitivity (dln(P(O3))/dln(NO)=1.0). The
results imply that the N(O3) (the in-situ net
photochemical rate of ozone production/destruction) will be strongly
sensitive in the marine boundary layer to small changes in [NO]
which has ramifications for changing NOx loadings in the
European continental boundary layer. |
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