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| Titel |
Effect of chemical degradation on fluxes of reactive compounds – a study with a stochastic Lagrangian transport model |
| VerfasserIn |
J. Rinne, T. Markkanen, T. M. Ruuskanen, T. Petäjä, P. Keronen, M. J. Tang, J. N. Crowley, Ü. Rannik, T. Vesala |
| 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 ; 12, no. 11 ; Nr. 12, no. 11 (2012-06-01), S.4843-4854 |
| Datensatznummer |
250011214
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| Publikation (Nr.) |
 copernicus.org/acp-12-4843-2012.pdf |
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| Zusammenfassung |
| In the analyses of VOC fluxes measured above plant
canopies, one usually assumes the flux above canopy to equal the exchange at
the surface. Thus one assumes the chemical degradation to be much slower
than the turbulent transport. We used a stochastic Lagrangian transport
model in which the chemical degradation was described as first order decay
in order to study the effect of the chemical degradation on above canopy
fluxes of chemically reactive species. With the model we explored the
sensitivity of the ratio of the above canopy flux to the surface emission on
several parameters such as chemical lifetime of the compound, friction
velocity, stability, and canopy density. Our results show that friction
velocity and chemical lifetime affected the loss during transport the most.
The canopy density had a significant effect if the chemically reactive
compound was emitted from the forest floor. We used the results of the
simulations together with oxidant data measured during HUMPPA-COPEC-2010
campaign at a Scots pine site to estimate the effect of the chemistry on
fluxes of three typical biogenic VOCs, isoprene, α-pinene, and
β-caryophyllene. Of these, the chemical degradation had a major
effect on the fluxes of the most reactive species β-caryophyllene,
while the fluxes of α-pinene were affected during nighttime. For
these two compounds representing the mono- and sesquiterpenes groups, the
effect of chemical degradation had also a significant diurnal cycle with the
highest chemical loss at night. The different day and night time loss terms
need to be accounted for, when measured fluxes of reactive compounds are
used to reveal relations between primary emission and environmental
parameters. |
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