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| Titel |
Seasonal dependence of peroxy radical concentrations at a Northern hemisphere marine boundary layer site during summer and winter: evidence for radical activity in winter |
| VerfasserIn |
Z. L. Fleming, P. S. Monks, A. R. Rickard, B. J. Bandy, N. Brough, T. J. Green, C. E. Reeves, S. A. Penkett |
| 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. 12 ; Nr. 6, no. 12 (2006-12-05), S.5415-5433 |
| Datensatznummer |
250004195
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| Publikation (Nr.) |
 copernicus.org/acp-6-5415-2006.pdf |
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| Zusammenfassung |
| Peroxy radicals (HO2+Σ RO2) were measured at the
Weybourne Atmospheric Observatory (52° N, 1° E), Norfolk
using a PEroxy Radical Chemical Amplifier (PERCA) during the winter
and summer of 2002. The peroxy radical diurnal cycles showed a
marked difference between the winter and summer campaigns with
maximum concentrations of 12 pptv at midday in the summer and
maximum concentrations as high as 30 pptv (10 min averages) in
winter at night. The corresponding nighttime peroxy radical
concentrations were not as high in summer (3 pptv). The peroxy
radical concentration shows a distinct anti-correlation with
increasing NOx during the daylight hours. At night, peroxy
radicals increase with increasing NOx indicative of the role of
NO3 chemistry. The average diurnal cycles for net ozone
production, N(O3) show a large variability in ozone production,
P(O3), and a large ozone loss, L(O3) in summer relative to
winter. For a daylight average, net ozone production in summer was
higher than winter (1.51±0.5 ppbv h−1 and 1.11±0.47 ppbv h−1, respectively). The variability in NO concentration
has a much larger effect on N(O3) than the peroxy radical
concentrations. Photostationary state (PSS) calculations show an
NO2 lifetime of 5 min in summer and 21 minutes in the
winter, implying that steady-state NO-NO2 ratios are not always
attained during the winter months. The results show an active peroxy
radical chemistry at night and that significant oxidant levels are
sustained in winter. The net effect of this with respect to
production of ozone in winter is unclear owing to the breakdown in
the photostationary state. |
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