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| Titel |
Eddy covariance flux measurements of biogenic VOCs during ECHO 2003 using proton transfer reaction mass spectrometry |
| VerfasserIn |
C. Spirig, A. Neftel, C. Ammann, J. Dommen, W. Grabmer, A. Thielmann, A. Schaub, J. Beauchamp, A. Wisthaler, A. Hansel |
| 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 ; 5, no. 2 ; Nr. 5, no. 2 (2005-02-15), S.465-481 |
| Datensatznummer |
250002357
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| Publikation (Nr.) |
 copernicus.org/acp-5-465-2005.pdf |
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| Zusammenfassung |
| Within the framework of the AFO 2000 project ECHO, two PTR-MS instruments
were operated in combination with sonic anemometers to determine biogenic
VOC fluxes from a mixed deciduous forest site in North-Western Germany. The
measurement site was characterised by a forest of inhomogeneous composition,
complex canopy structure, limited extension in certain wind directions and
frequent calm wind conditions during night time. The eddy covariance (EC)
technique was applied since it represents the most direct flux measurement
approach on the canopy scale and is, therefore, least susceptible to these
non-ideal conditions. A specific flux calculation method was used to account
for the sequential multi-component PTR-MS measurements and allowing an
individual delay time adjustment as well as a rigorous quality control based
on cospectral analysis. The validated flux results are consistent with light
and temperature dependent emissions of isoprene and monoterpenes from this
forest, with average daytime emissions of 0.94 and 0.3µg m-2s-1, respectively. Emissions of methanol reached on
average 0.087µg m-2s-1 during daytime, but fluxes
were too small to be detected during night time. Upward fluxes of the
isoprene oxidation products methyl vinyl ketone (MVK) and methacrolein
(MACR) were also found, being two orders of magnitude lower than those of
isoprene. Calculations with an analytical footprint model indicate that the
observed isoprene fluxes correlate with the fraction of oaks within the
footprints of the flux measurement. |
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