Thomas, C*; Foken, T: Dynamical characteristics of coherent structures over spruce forest using wavelet analysis
Vortrag, European Geosciences Union, 1st General Assembly, Nice: 25.04.2004 - 30.04.2004

Coherent structures are an inherent part of turbulent vector and scalar time series obtained over tall vegetated surfaces. They manifest themselves as a low-frequent ramp pattern superimposing the signals of high-frequent turbulence and have been found to contribute to the budgets of energy and matter significantly. Nonetheless their origin and their development in space and time are still poorly understood. This study presents results of the dynamics of coherent structures over and in a spruce forest. Detection and analysis bases on the wavelet transform providing an objective and powerful tool. Data were obtained using a vertical profile of six sonic anemometers operated at high sampling rates covering the sub-canopy, canopy and partly the roughness sublayer during the WALDATEM 2003 summer field campaign at the Waldstein site/ Fichtelgebirge mountains, Germany. The name of this campaign was chosen from the analysing system used, whereas WALD stands for WaveLet Detection and ATEM for Atmospheric TurbulencE Measurements and was carried out in the framework of the BITOEK- research program. Special interest is paid to the link between typical event duration, spatial and temporal separation of the coherent structures between different height levels and inherent properties of the layer in and above the canopy.

Letzte Änderung 23.10.2004