WRF-Fire: Coupled Weather–Wildland Fire Modeling with the Weather Research and Forecasting Model

Abstract

A wildland fire-behavior module, named WRF-Fire, was integrated into the Weather Research and Forecasting (WRF) public domain numerical weather prediction model. The fire module is a surface firebehavior model that is two-way coupled with the atmospheric model. Near-surface winds from the atmospheric model are interpolated to a finer fire grid and are used, with fuel properties and local terrain gradients, to determine the fire's spread rate and direction. Fuel consumption releases sensible and latent heat fluxes into the atmospheric model's lowest layers, driving boundary layer circulations. The atmospheric model, configured in turbulence-resolving large-eddy-simulation mode, was used to explore the sensitivity of simulated fire characteristics such as perimeter shape, fire intensity, and spread rate to external factors known to influence fires, such as fuel characteristics and wind speed, and to explain how these external parameters affect the overall fire properties. Through the use of theoretical environmental vertical profiles, a suite of experiments using conditions typical of the daytime convective boundary layer was conducted in which these external parameters were varied around a control experiment. Results showed that simulated fires evolved into the expected bowed shape because of fire-atmosphere feedbacks that control airflow in and near fires. The coupled model reproduced expected differences in fire shapes and heading-region fire intensity among grass, shrub, and forest-litter fuel types; reproduced the expected narrow, rapid spread in higher wind speeds; and reproduced the moderate inhibition of fire spread in higher fuel moistures. The effects of fuel load were more complex: higher fuel loads increased the heat flux and fire-plume strength and thus the inferred fire effects but had limited impact on spread rate.

Recent advances and applications of WRF–SFIRE

“…The current code and documentation are available from OpenWFM.org. A version from 2010 is distributed with the WRF release as WRF-Fire (Coen et al, 2013;OpenWFM, 2012).…”

Some Requirements for Simulating Wildland Fire Behavior Using Insight from Coupled Weather—Wildland Fire Models

“…Idealized studies have examined fine-scale fire phenomena such as fire whirls [16] and tested sensitivity to fire environment parameters [67]. Some studies attempt to reproduce real prescribed fires [68], often fires conducted during instrumented experiments [19,23,69,70], yet struggle with representing the ambient wind environment [69], which can vary over a small area, and small-scale atmospheric fluctuations [19].…”

A study of the influence of forest gaps on fire–atmosphere interactions

“…The fire is represented herein as a static line of enhanced surface vertical turbulent heat flux that is independent of both temporal and spatial variability in the atmosphere and the presence or absence of vegetation in its vicinity. Unlike coupled fire-atmosphere models such as FIRETEC and WRF-Fire (Coen et al, 2013), ARPS-CANOPY has no fire spread module; thus, the complex interactions between fire, fuels, and atmosphere simulated in models like FIRETEC are only partially accounted for in ARPS-CANOPY. The absence of a fire spread module eliminates complexity as well as uncertainty related to fire spread routines; however, it also raises concerns regarding the applicability of results to real-world fires.…”