The CAWFE(TM) Modeling System for Wildland Fires

(Coupled Atmosphere-Wildland Fire Environment)

Simulation and visualization of the 2012 High Park
                wildfireCAWFE sim of King fire
 CAWFE model simulations of the 2012 High Park fire (left) and the King Fire (right).

The CAWFE modeling system combines a numerical weather prediction (NWP) model that predicts how weather varies in time and space even in complex terrain with wildland fire behavior modules. These components are connected in two directions such that the evolving wind, along with fuel properties and terrain slope, directs where the fire grows and how fast, while heat released by the fire modifies its atmospheric environment thereby creating its own weather (e.g., fire-induced winds). The model is described in Clark et al. (2004) and Coen 2005a.  Coen (2013) documents the model equations.

<big><big>Microsoft Word - FMT2_fordist.docx</big></big>

CAWFE was developed recognizing that fires interact with the atmosphere surrounding them and that this produces many fundamental fire behaviors. Research applying CAWFE showed that fire-atmosphere interactions produce numerous wildland fire phenomena, including the commonly-observed bowed shape (below); the heading, flanks, and backing regions; fire whirls; horizontal roll vortices.

Universal fire shape simulation

(left) Heat produced by the fire (more intense colors are hotter), smoke (misty purple field), and surface winds (longer arrows indicate stronger winds, the arrow indicates direction).  In this simulation, a fire began as a line in winds that were all coming at 3 m/s from the left, but which created a fire with a head, flanks, and backing region, and shaped the winds in the fire vicinity to be moving rapidly forward at the fire head, parallel to the flanks, and weak in the backing region. (right) The Onion fire, Owens Valley, CA (courtesy of Charles George, USDA Forest Service).

Microsoft Word - FMT2_fordist.docx

CAWFE has been applied to over a dozen landscape-scale wildland fire events in varying fuel, terrain, and weather conditions. CAWFE could simulate overall rate and direction of spread, distinguishing characteristics of fire events, and transitions in fire behavior. CAWFE reproduced other fire phenomena and illuminated the conditions in which they form, such as distinctive shapes of the fire perimeter, flank runs, rotating plumes, and the splitting (example below) or merging of fire lines.