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| Titel |
Analysis of coherent structures and atmosphere-canopy coupling strength during the CABINEX field campaign |
| VerfasserIn |
A. L. Steiner, S. N. Pressley, A. Botros, E. Jones, S. H. Chung, S. L. Edburg |
| 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. 23 ; Nr. 11, no. 23 (2011-12-01), S.11921-11936 |
| Datensatznummer |
250010229
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| Publikation (Nr.) |
 copernicus.org/acp-11-11921-2011.pdf |
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| Zusammenfassung |
| Intermittent coherent structures can be responsible for a large fraction of
the exchange between a forest canopy and the atmosphere. Quantifying their
contribution to momentum and heat fluxes is necessary to interpret
measurements of trace gases and aerosols within and above forest canopies.
The primary objective of the Community Atmosphere-Biosphere Interactions
Experiment (CABINEX) field campaign (10 July 2009 to 9 August 2009) was to
study the chemistry of volatile organic compounds (VOC) within and above a
forest canopy. In this manuscript we provide an analysis of coherent
structures and canopy-atmosphere exchange during CABINEX to support in-canopy
gradient measurements of VOC. We quantify the number and duration of coherent
structure events and their percent contribution to momentum and heat fluxes
with two methods: (1) quadrant-hole analysis, and (2) wavelet analysis.
Despite differences in the duration and number of events, both methods
predict that coherent structures contribute 40–50% to momentum fluxes
and 44–65% to heat fluxes during the CABINEX campaign. Contributions
associated with coherent structures are slightly greater under stable
atmospheric conditions. By comparing heat fluxes within and above the canopy,
we determine the degree of coupling between upper canopy and atmosphere, and
find that they are coupled the majority of the time. Uncoupled
canopy-atmosphere events occur in the early morning (4–8 a.m. local time)
approximately 30% of the time. This study confirms that coherent
structures contribute significantly to the exchange of heat and momentum
between the canopy and atmosphere at the CABINEX site, and indicates the need
to include these transport processes when studying the mixing and chemical
reactions of trace gases and aerosols between a forest canopy and the
atmosphere. |
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