Wind dynamics over an heterogeneous forest edge: large-eddy simulation and in-situ experiment

Forest edges are commonly encountered in heterogeneous landscapes and they significantly influence the near-surface wind field. Understanding the flow dynamics near forest edges is important in the design phase of wind energy and forest management projects. In 2008, a field experiment was conducted near a dense beech forest edge on the island Falster in Denmark, where two meteorological masts equipped with several sonic anemometers were installed upwind and downwind the edge. Initial flow modeling efforts pointed to the importance of an accurate representation of the forest density right at the edge in order to minimise uncertainties. High resolution scans (>10 reflections m^-2) of the forest edge were therefore obtained using an airborne lidar to create an accurate description of the canopy structure. The lidar data were organized into a dense grid of fine resolution. We use this forest description as input in a large-eddy simulation (LES) airflow model. The aim of the study is, (i) to verify whether the simulations can reproduce the statistical wind profiles retrieved from the measurements, (ii) to analyse the effect of the edge on the first and higher order wind statistics extracted from the simulations and, (iii) to verify the effect of an heterogeneous canopy structure on the LES wind statistics.