Extended Abstract (1.1M)J2.4
Simulations of wildfire incidents using coupled atmosphere-fire modeling
Janice L. Coen, NCAR, Boulder, CO
This presentation describes the further development and application of a coupled atmosphere-fire model that uses a sophisticated high-resolution meteorological numerical model to predict the local winds which are then used as input to the prediction of fire spread. The heat and moisture fluxes from the fire are then fed back to the atmospheric dynamics, allowing the fire to influence winds that in turn affect the fire behavior. Simulations in specified atmospheric and terrain have demonstrated that this coupling is the basis for a number of features common to real fires, such as the well-recognized elliptical fire shape with heading, flanking, and backing regions, and how perturbations from this self-perpetuating shape may amplify to become fire whirls along the fire line. Recent simulations apply the model in the more realistic setting of recent wildfires, using MM5 simulations as a large-scale initialization and widely-available vegetation databases for fuel category to simulate fire progression and behavior. These simulations, performed at various atmospheric resolutions, allow us to make some tentative conclusions that have implications for predictive fire modeling: 1) The feedbacks between the fire and the atmosphere are a crucial component to simulating fire progression, determining whether winds direct the fire line into unignited fuel or inhibit spread by directing the winds inside the perimeter. 2) While very fine resolution coupled simulations with atmospheric grid spacings of 10s of meters produce detailed features of fire behavior, even simulations with atmospheric horizontal grid spacings of 1 km capture basic fire progression, spread rates, and behavior. Simulations at this resolution can be run much faster than real time on one processor of affordable PCs.
Supplementary URL: http://www.mmm.ucar.edu/fire/model/model_home.html
Joint Session 2, Fire and Atmosphere Interactions
Monday, 17 November 2003, 11:00 AM-3:30 PM
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