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| Titel |
Assessment of the applicability of NO-NO2-O3 photostationary state to long-term measurements at the Hohenpeissenberg GAW Station, Germany |
| VerfasserIn |
K. Mannschreck, S. Gilge, C. Plass-Duelmer, W. Fricke, H. Berresheim |
| 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 ; 4, no. 5 ; Nr. 4, no. 5 (2004-08-17), S.1265-1277 |
| Datensatznummer |
250001938
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| Publikation (Nr.) |
 copernicus.org/acp-4-1265-2004.pdf |
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| Zusammenfassung |
| Continuous measurements of concentrations of reactive gases, radiation, and
meteorological parameters are carried out at the Meteorological Observatory
Hohenpeissenberg (MOHp) as part of the Global Atmosphere Watch (GAW)
Program. NO, NO2, O3 and JNO2 data from a four-year period
(March 1999-December 2002) are evaluated for consistency with
photochemical steady state (PSS, Φ=1) conditions. The extent
of deviation from PSS reveals a strong dependence on wind direction at the
station. Median values of Φ in the south sector are in the range of
2.5-5.7 and show a high variability. In contrast, values for the other
directions show a relatively low variability around a median level of 2.
When taking into account peroxy radical concentrations (Φext=1)
PSS was reached in 13-32% of all cases for the years 1999-2002.
The differences in wind sectors can be explained by local effects. It is
shown that the height of the sample inlet line, its distance to the forest
and the surrounding topography has a strong impact on both the absolute and
relative deviations from PSS. Global irradiance and thus, photolysis of
NO2 is reduced within the dense forest. Since the reaction of NO with
O3 is still proceeding under these conditions, increased NO2/NO
ratios are produced locally in air which is transported through the forest
and advected to the MOHp site.
Estimates of the peroxy radical concentration (RO2) inferred from PSS
are compared with peroxy radical measurements made at the site in June 2000
during a three-week campaign. The PSS derived RO2 levels were higher
than corresponding measured levels by at least a factor of 2-3. This
analysis was made for a wind sector with minimal local effects on PSS. Thus
the corresponding Φ median of 2 can be regarded as an upper limit for
a deviation from PSS due to chemical reactions, i.e. by peroxy radicals and
possible other oxidants converting additional NO to NO2. |
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