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| Titel |
Fluxes of reactive and non-reactive trace gases close to the forest floor |
| VerfasserIn |
M. Riederer, K. Hens, F. X. Meixner, T. Foken |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250021800
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| Zusammenfassung |
| During the experiment EGER, which took place at Weidenbrunnen site (50Ë 08’31" N, 11Ë
52’01" E, 775 m a.s.l.) in the Fichtelgebirge, a Bavarian spruce forest, in July-October 2007
and May-July 2008 respectively, the University of Bayreuth and the Max Planck Institute for
Chemistry investigated i.a. vertical concentration and flux profiles of both reactive (NO,
NO2, O3) and non-reactive (CO2, H2O) trace gases at the forest floor – trunk space
interface.
The two radon isotopes 220Rn and 222Rn also were essential to measure due to its
property of being chemical inert and unaffected by the biosphere. That allows argumentation
about interactions with the biosphere and chemical reactions of the other trace gases. The
vertical distribution of the short-lived isotope 220Rn (T1 -2 = 55.6s) affords in combination
with the decay constant (0.0125 s-1) the determination of vertical bulk turbulent transfer
velocities (vtr). These, in turn, can be compared with characteristic times of atmospheric
reactions of NO, NO2 and O3 and make validation of derived Damköhler numbers come
true.
Surface flux measurement by a static chamber of the longer-lived isotope 222Rn (T1 -2 =
3.8 d) in combination with the vertical radon profile, provides a real measured profile of
turbulent diffusion coefficients.
Along with common meteorological parameters a basis for further investigation with two
different implemented model types - hydrodynamical multilayer models and the Louis
parameterisation is formed. These models actually represent fluxes of momentum,
sensible and latent heat but scalar similarity theory makes the transfer to trace gas flux
parameterisation possible. |
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