Experimental determination of energy and matter exchange processes and their modelling on stand scale

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Within this sub-project the physical and partly also chemical processes on the stand scale will be investigated by experimental and modelling activities. Different experiments for summer, autumn, winter, and spring and a long term observing programme in the forest are planned to observe the following processes: advection, turbulence structure, flux gradients of meteorological and chemical quantities, boundary layer. Eddy-covariance and different REA techniques for energy and matter fluxes (including trace gases and isotopes) will be used. All data and especially the flux data are quality controlled with recently developed tools (similar as developed for CarboEuroflux). Pdfs (probability density functions) will be created for state variables and higher moments on the basis of the footprint, QA/QC and the meso- and microscale meteorological conditions. The current use of wavelet analysis to investigate coherent structures will be continued with conditional sample tools to be employed for more quantitative investigations and for determining the influence on forcing parameters to develop a more extended parameterization of the transilient matrix of the FLAME model (Forest-Land-Atmosphere Model). FLAME is actually applied to model exchange processes on the stand scale. In the first phase of the project, the 1D/2D-version, coupled to a detailed soil-plant model, is applied to predict the influences of detailed stand hydrology, physiology and advection on the cycles of water, energy, and trace substances. The sensitivity towards external and internal forcings will be studied. Pdfs for state variables and turbulent moments will be compared to those from experiments and extended for the application on landscape scale. The development of a 3D-version – first on stand scale – also requires the development and evaluation of the 3D transilient theory to describe the turbulent and convective mixing from the forest floor to the top of the atmospheric boundary layer. Based on the BayCEER monitoring programme with meteorological data und carbon dioxide and water vapour fluxes (http://www.bayceer.uni-bayreuth.de/), the relevant data will be made available for all sub-projects, with a focus on mainly on the modelling and remote sensing parts.