Monday, 17 November 2003: 11:45 AM
Simulations of wildfire incidents using coupled atmosphere-fire modeling
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