Foken, T; Thomas, C; Ruppert, J; Lüers, J; Göckede, M: Turbulent exchange processes in and above tall vegetation
Vortrag, 16th Symposium on Boundary Layers and Turbulence, Portland, ME: 09.08.2004 - 13.08.2004

This study presents first results of the complex turbulence structures observed during the experiment WALDATEM-2003 at the 'Weidenbrunnen' FLUXNET measur-ing site of the University of Bayreuth, Germany. This forest site is situated in the Fich-telgebirge 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 vicin-ity 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 at-mospheric 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 iso-tope 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 simi-larity of different scalars and the decoupling and coupling between the canopy and the atmosphere.

Letzte Änderung 29.09.2004