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| Titel |
First direct measurements of formaldehyde flux via eddy covariance: implications for missing in-canopy formaldehyde sources |
| VerfasserIn |
J. P. DiGangi, E. S. Boyle, T. Karl, P. Harley, A. Turnipseed, S. Kim, C. Cantrell, R. L. Maudlin III, W. Zheng, F. Flocke, S. R. Hall, K. Ullmann, Y. Nakashima, J. B. Paul, G. M. Wolfe, A. R. Desai, Y. Kajii, A. Guenther, F. N. Keutsch |
| 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 ; 11, no. 20 ; Nr. 11, no. 20 (2011-10-26), S.10565-10578 |
| Datensatznummer |
250010144
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| Publikation (Nr.) |
 copernicus.org/acp-11-10565-2011.pdf |
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| Zusammenfassung |
| We report the first observations of formaldehyde (HCHO) flux measured via
eddy covariance, as well as HCHO concentrations and gradients, as observed by
the Madison Fiber Laser-Induced Fluorescence Instrument during the
BEACHON-ROCS 2010 campaign in a rural, Ponderosa Pine forest northwest of
Colorado Springs, CO. A median noon upward flux of ~80 μg
m−2 h−1 (~24 pptv m s−1) was observed with a
noon range of 37 to 131 μg m−2 h−1. Enclosure experiments
were performed to determine the HCHO branch (3.5 μg m-2
h−1) and soil (7.3 μg
m−2 h−1) direct emission rates
in the canopy. A zero-dimensional canopy box model, used to determine the
apportionment of HCHO source and sink contributions to the flux,
underpredicted the observed HCHO flux by a factor of 6. Simulated increases
in concentrations of species similar to monoterpenes resulted in poor
agreement with measurements, while simulated increases in direct HCHO
emissions and/or concentrations of species similar to 2-methyl-3-buten-2-ol
best improved model/measurement agreement. Given the typical diurnal
variability of these BVOC emissions and direct HCHO emissions, this suggests
that the source of the missing flux is a process with both a strong
temperature and radiation dependence. |
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