Modeling atmospheric transport and dispersion of smoke from wildland fires

Prediction of smoke transport and dispersion from prescribed and wildland fires is a particularly challenging subject especially in areas of complex terrain. In this study, we evaluate the ability of the Weather Research and Forecast (WRF) model coupled to a Lagrangian particle dispersion model in simulating smoke dispersion over regions of highly complex terrain. The October 2007 episode of Southern California wildfire outbreak is examined. The WRF simulated meteorological fields are compared with data from a network of surface and upper air stations in the region and the simulated spatial distribution of the smoke concentrations are compared to observations from the PM network and satellite imagery. The major pathways of the smoke under different synoptic conditions are analyzed. A series of sensitivity experiments are conducted to examine the effects of the complex topography on local and regional circulations and the subsequent influence of these multi-scale circulations on smoke transport and dispersion in the region. These sensitivity experiments highlight the potential for large-scale impact of smoke from wildland fires. The experiments also reveal the importance of obtaining accurate information on plume rise and equilibrium height in numerical simulations of smoke dispersion.