Extended Abstract (348K)P1.2
Turbulent exchange processes in and above tall vegetation
Thomas Foken, University of Bayreuth, Bayreuth, Germany; and C. Thomas, J. Ruppert, J. Lueers, and M. Goeckede
This study presents first results of the complex turbulence structures observed during the experiment WALDATEM-2003 at the 'Weidenbrunnen' FLUXNET measuring site of the University of Bayreuth, Germany. This forest site is situated in the Fichtelgebirge mountains (50° 09' N, 11° 52' E, 765 m a.s.l.), with spruce (picea abies) as the dominant tree species and a maximum tree height of 19 m in the immediate vicinity of the tower. The turbulence structure of the wind vector, the temperature, water vapour and carbon dioxide concentration were studied using a wavelet tool. It was possible to separate high frequent turbulence from coherent structures and, during the night, also gravity waves. Additionally, the turbulence structure in the lower atmospheric boundary layer was observed with a Sodar-RASS system. The nearly real-time analysis of the turbulence structure allowed an optimal handling of a whole air hyperbolic relaxed accumulation system to measure carbon dioxide and 13C isotope fluxes. Profile systems for wind, temperature, humidity and carbon dioxide and a horizontal gradient system for the measurement of advection and drainage flow were installed. In addition, a quality assessment tool using footprint analyses was applied to identify the source areas and thus to determine the representativeness of the measurement positions.
The experiment allowed a complete overview of fluxes and turbulent exchange processes in a forest – boundary layer system. First results are available for the similarity of different scalars and the decoupling and coupling between the canopy and the atmosphere.
Poster Session 1, Posters for the 26th Conference on Agricultural and Forest Meteorology
Wednesday, 25 August 2004, 5:30 PM-8:30 PM
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