Capturing Plume Rise and Dispersion with a Coupled Large-Eddy Simulation: Case Study of a Prescribed Burn

Abstract

Current understanding of the buoyant rise and subsequent dispersion of smoke due to wildfires has been limited by the complexity of interactions between fire behavior and atmospheric conditions, as well as the uncertainty in model evaluation data. To assess the feasibility of using numerical models to address this knowledge gap, we designed a large-eddy simulation of a real-life prescribed burn using a coupled semi-emperical fire–atmosphere model. We used observational data to evaluate the simulated smoke plume, as well as to identify sources of model biases. The results suggest that the rise and dispersion of fire emissions are reasonably captured by the model, subject to accurate surface thermal forcing and relatively steady atmospheric conditions. Overall, encouraging model performance and the high level of detail offered by simulated data may help inform future smoke plume modeling work, plume-rise parameterizations and field experiment designs.

An emergency response model for evaluating the formation and dispersion of plumes originating from major fires (BUOYANT v4.20)

“…The RxCADRE experiments were conducted in Florida, USA during 2008-2012. These datasets have previously been used, for instance, in the evaluation of the empirical-stochastic plume model Daysmoke (Achtemeier et al, 2012), the Stochastic Time-Inverted Lagrangian Transport (STILT) model (Mallia et 370 al., 2018), and the Weather Research and Forecasting Model combined with a semi-empirical fire-spread algorithm (WRF-SFIRE) (Mallia et al, 2020;Moisseeva and Stull, 2019).…”

WRF-LES Simulation of the Boundary Layer Turbulent Processes during the BLLAST Campaign

“…During the last decades, researchers have used LES approximation to study specific problems such as air pollution dispersion in urban street canyons [8][9][10], flow distortion caused by wind turbines [11][12][13], large fires [14,15] or cloud and precipitation processes development [16][17][18][19]. Many other studies have used real case LES to simulate atmospheric flows in complex terrain areas [20][21][22] where grid sizes of few hundreds of metres are needed to resolve the terrain elevation and LES approximation is required.…”

Study of atmosphere-wildland fires interactions, using numerical models, in Greece

“…3.10 and 3.11), assuming a "scale height" of 25 m, as their extinction depth parameter. However, in their results, Moisseeva and Stull (2019) discussed potential limitations arising from the choice of heat extinction depth parameter mostly based on the preliminary results of the current analysis that were presented in Kartsios et al (2017).…”

“…In this chapter, the sensitivity of WRF-SFIRE model to the choice of different heat extinction depths (zext) is evaluated, in order to investigate its role to the overall fire behavior. Although it was not accounted in their simulations, Moisseeva and Stull (2019) pointed out potential implications in the choice of the different e-folding depths. Since there is no widely accepted value for zext, its value remains an active field of research, due to strongly dependency on fuel properties, flame length, fire intensity and the environment of the fire (Sun et al, 2006).…”

“…Several studies (Jenkins et al, 2011;Kartsios et al, 2014aKartsios et al, , 2014bKochanski et al, 2013aKochanski et al, , 2013cMoisseeva and Stull, 2019;Simpson et al, 2016Simpson et al, , 2014Simpson et al, , 2013aThomas et al, 2017) focusing on atmosphere-fire interactions have demonstrated that WRF in LES mode can reproduce several aspects of the coupling between fire evolution and atmospheric dynamics. Here, a single 3-D domain was configured, with a west-east and south-north extent of 7.5 km and a uniform and flat terrain.…”