Modeling Meteorological Conditions above a Grassfire on a Steep Slope

Meteorological conditions above and in the vicinity of a prescribed grassfire on a steep slope (~30%) at an EPA Superfund site near Palmerton, PA are simulated using the Advanced Regional Prediction System (ARPS) model. The ARPS model is run with fine grid spacing [O(10 m) horizontal; O(2 m) vertical] to resolve small-scale perturbations induced by the fire, as well as resolve the ambient atmospheric conditions. Specific meteorological variables examined include mean wind speed, wind direction, temperature, and turbulent kinetic energy (TKE). For all variables, comparison is made to measurements taken during the prescribed fire, and strengths and weaknesses of the model simulation are noted. The effect of the fire on the degree of anisotropy in the turbulent flow is examined, and the relative contributions of TKE generation mechanisms before and after the fire develops are discussed. The ARPS output are used to drive the FLEXPART Largrangian particle dispersion model and the results are analyzed to understand the transport and dispersion pattern of smoke from the fire.