Evaluation of WRF-LES for Dispersion and Transport Modeling Over Complex Terrain

The vast range of space-time scales associated with turbulent flow over rugged terrain presents one of the greatest challenges to complex terrain dispersion modeling. Subtle variations in flow properties, linked to interactions with the topography, can be responsible for radically different scalar behavior eventually leading to large model errors. The popular WRF model contains a large-eddy simulation (LES) framework capable of capturing transient turbulence features associated with rugged terrain, such as boundary layer separation and recirculation zones. In this talk, passive scalars were introduced into the WRF-LES model in order to simulate scalar transport and dispersion over complex terrain. Using measurements from the Cinder Cone Butte (CCB) field campaign, we evaluate the ability of WRF-LES to realistically simulate the transport of Sulfur Hexafluoride (SF6) tracers over and around CCB under both neutral and stably stratified environments. We observe realistic scalar behaviors, such as plume sensitivity to thermal stability and wind direction and accuracy comparable to, or slightly better, than recent modeling results found by other computational fluid dynamics models.