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Einflüsse kohärenter Strukturen auf den Energie- und Stoffaustausch in hohen Beständen


From 01/2002 to 12/2004

Principal Investigator: Thomas Foken
Staff: Christoph Thomas, Jens-Christopher Mayer
Grant: 0339476 D Grundlagen zur nachhaltigen Entwicklung von Ökosystemen bei veränderter Umwelt

The main objective is to enhance the understanding of the exchange of energy and matter occurring through coherent structures. Coherent structures are turbulent gusts and bursts, distinctly located in space and time showing a distinct phase relationship between flow variables and its constituents, which cannot be detected by classical eddy analysis. For this purpose, wavelet analysis methods will be applied, proofed for its applicability on transport processes above and in tall vegetation and recently advanced for an energy conserving processing at the department of micrometeorology of the University of Bayreuth. A deepened understanding of initialising processes and dynamics of the coherent exchange of energy and matter is needed to estimate its order of magnitude. The coherent exchange is supposed to play an important role in the current discussion, whether forests serve as a carbon sink or source, for estimating the evapotranspiration of forested areas and to enhance determination methods used nowadays. The influence on relaxed-eddy-accumulation-methods (REA) and transilient modelling of the exchange of energy and matter will be investigated primarily. Among other things, this study aims to improve the underlying transilient-matrix and to assess possible paths for soil released gaseous matter, like water vapour and carbon dioxide, into the atmosphere. The project uses the experimental base of the long term measuring program of the exchange of energy and matter using eddy-covariance-methods (EC) of the water vapour and carbon dioxide fluxes at the site “Weidenbrunnen”, continuing the long term observations and including additional measurements. For data processing, special wavelet-analysis programs will be used, aiming on the detection of characteristics of coherent structures, their patterns and frequencies. Wavelet analysis provides the general possibility of quantitative analysis, as it resolves the energy distribution in temporally located spectra.

List of publications of this Project

Zhang, G; Thomas, C; Leclerc, MY; Karipot, A; Gholz, HL; Binford, M; Foken, T: On the effect of clearcuts on turbulence structure above a forest canopy, Theoretical and Applied Climatology, 88, 133-137 (2007), doi:10.1007/s00704-006-0250-8 -- Details
Thomas, C; Foken, T: Organised motion in a tall spruce canopy: temporal scales, structure spacing and terrain effects, Boundary-Layer Meteorology, 122, 123-147 (2007), doi:10.1007/s10546-006-9087-z -- Details
Thomas, C; Foken, T: Flux contribution of coherent structures and its implications for the exchange of energy and matter in a tall spruce canopy, Boundary-Layer Meteorology, 123, 317-337 (2007), doi:10.1007/s10546-006-9144-7 -- Details
Göckede, M; Thomas, C; Markkanen, T; Ruppert, J; Mauder, M; Foken, T: On the sensitivity of Lagrangian stochastic footprint modeling to within canopy flow statistics derived from wavelet analysis, Report Series in Aerosol Science, 79, 247-249 (2006)
Ruppert, J; Mauder, M; Thomas, C; Lüers, J: Innovative gap-filling strategy for annual sums of CO2 net ecosystem exchange, Agricultural and Forest Meteorology, 138, 5-18 (2006), doi:10.1016/j.agrformet.2006.03.003 -- Details
Thomas, C; Mayer, JC; Meixner, FX; Foken, T: Analysis of the low-frequency turbulence above tall vegetation using a Doppler sodar, Boundary-Layer Meteorology, 119, 563-587 (2006), doi:10.1007/s10546-005-9038-0 -- Details
Ruppert, J; Thomas, C; Foken, T: Scalar similarity for relaxed Eddy accumulation methods , Boundary-Layer Meteorology, 120, 39-63 (2006) -- Details
Thomas, C; Foken, T: Detection of long-term coherent exchange over spruce forest, Theoretical and Applied Climatology, 80, 91-104 (2005) [Link] -- Details
Thomas, C; Foken, T: Re-evaluation of integral turbulence characteristics and their parameterisations. 15th Conference on Turbulence and Boundary Layers, Wageningen, NL, 15-19 July 2002, Am. Meteorol. Soc., 129-132 (2002)
Thomas, C; Wichura, B; Foken, T: Integrale Turbulenzcharakteristiken - ein Überblick, Österr. Beitr. Meteorol. & Geophys.(Extended Abstract and pdf-file on CD), 27, 223 (2001)

Related links:
  • Diploma Thesis: Characterisation of the Atmospheric Boundary-Layer in a Complex Terrain using SODAR-RASS
  • Experiment: WALDATEM-2003: Waldstein, 12.05. - 18.07.2003
  • Field of research: CO2: Carbon dioxide fluxes
  • Field of research: QA/QC: Quality Assurance and Quality Control of Micrometeorological Measurements
  • PhD Thesis: Detection and analysis of coherent structures within and above tall-vegetated canopies
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