Flow modeling within a Central European forest using large-eddy simulation

With the aim to simulate the exchange of energy and matter between air and vegetation, we applied the LES PALM to a typical Central European forest. The presentation shows how the level of detail within vegetation model and the orography alters the simulated flow.

The site of investigation is a managed mixed forest stand (mainly Picea abies, height 30 m; a long-term CarboEurope monitoring site) within the Tharandter Wald near Dresden, Germany. Terrestrial laser scans (TLS) provided the data basis for the high-resolution vegetation model of this forest stand and a nearby clearing (50x90 m) building the inner range of the model domain. To investigate orographic effects on the flow, we extended the domain for about 1.5 km to the west. This includes the S-Berg, which is about 40 m height and therefore the highest elevation on the windward side. We used information from airborne laser scanning (ALS) along with forest inventory data to build a vegetation model as well as a digital elevation model for the extended area (2 km in streamwise and 1.5 km in lateral direction) with a resolution of (2m)³. 

In a first step, we restricted all simulations to a neutral atmosphere to exclude effect of buoyancy.

Wind data from four measurement towers (from DFG SPP 1276 MetStröm) provided data for a validation of the simulations. They were located within the inner domain along a west-east transect over the clearing.