<s>
In	O
computational	O
science	O
,	O
wildfire	B-Application
modeling	I-Application
is	O
concerned	O
with	O
numerical	B-General_Concept
simulation	I-General_Concept
of	O
wildland	O
fires	O
in	O
order	O
to	O
understand	O
and	O
predict	O
fire	O
behavior	O
.	O
</s>
<s>
Wildfire	B-Application
modeling	I-Application
can	O
ultimately	O
aid	O
wildland	O
fire	O
suppression	O
,	O
namely	O
increase	O
safety	O
of	O
firefighters	O
and	O
the	O
public	O
,	O
reduce	O
risk	O
,	O
and	O
minimize	O
damage	O
.	O
</s>
<s>
Wildfire	B-Application
modeling	I-Application
can	O
also	O
aid	O
in	O
protecting	O
ecosystems	O
,	O
watersheds	O
,	O
and	O
air	O
quality	O
.	O
</s>
<s>
Wildfire	B-Application
modeling	I-Application
attempts	O
to	O
reproduce	O
fire	O
behavior	O
,	O
such	O
as	O
how	O
quickly	O
the	O
fire	O
spreads	O
,	O
in	O
which	O
direction	O
,	O
how	O
much	O
heat	O
it	O
generates	O
.	O
</s>
<s>
Although	O
more	O
sophisticated	O
applications	O
use	O
a	O
three-dimensional	O
numerical	B-General_Concept
weather	I-General_Concept
prediction	I-General_Concept
system	O
to	O
provide	O
inputs	O
such	O
as	O
wind	O
velocity	O
to	O
one	O
of	O
the	O
fire	O
growth	O
models	O
listed	O
above	O
,	O
the	O
input	O
was	O
passive	O
and	O
the	O
feedback	O
of	O
the	O
fire	O
upon	O
the	O
atmospheric	O
wind	O
and	O
humidity	O
are	O
not	O
accounted	O
for	O
.	O
</s>
<s>
These	O
models	O
include	O
NCAR	O
's	O
Coupled	O
Atmosphere-Wildland	O
Fire-Environment	O
(	O
CAWFE	O
)	O
model	O
developed	O
in	O
2005	O
,	O
WRF-Fire	B-Application
at	O
NCAR	O
and	O
University	O
of	O
Colorado	O
Denver	O
which	O
combines	O
the	O
Weather	B-Application
Research	I-Application
and	I-Application
Forecasting	I-Application
Model	I-Application
with	O
a	O
spread	O
model	O
by	O
the	O
level-set	B-Algorithm
method	I-Algorithm
,	O
University	O
of	O
Utah	O
's	O
Coupled	O
Atmosphere-Wildland	O
Fire	O
Large	O
Eddy	O
Simulation	O
developed	O
in	O
2009	O
,	O
Los	O
Alamos	O
National	O
Laboratory	O
's	O
FIRETEC	O
developed	O
in	O
,	O
the	O
WUI	O
(	O
wildland	O
–	O
urban	O
interface	O
)	O
Fire	O
Dynamics	O
Simulator	O
(	O
WFDS	O
)	O
developed	O
in	O
2007	O
,	O
and	O
,	O
to	O
some	O
degree	O
,	O
the	O
two-dimensional	O
model	O
FIRESTAR	O
.	O
</s>
<s>
The	O
cost	O
of	O
added	O
physical	O
complexity	O
is	O
a	O
corresponding	O
increase	O
in	O
computational	O
cost	O
,	O
so	O
much	O
so	O
that	O
a	O
full	O
three-dimensional	O
explicit	O
treatment	O
of	O
combustion	B-Application
in	O
wildland	O
fuels	O
by	O
direct	O
numerical	B-General_Concept
simulation	I-General_Concept
(	O
DNS	O
)	O
at	O
scales	O
relevant	O
for	O
atmospheric	O
modeling	O
does	O
not	O
exist	O
,	O
is	O
beyond	O
current	O
supercomputers	O
,	O
and	O
does	O
not	O
currently	O
make	O
sense	O
to	O
do	O
because	O
of	O
the	O
limited	O
skill	O
of	O
weather	B-General_Concept
models	I-General_Concept
at	O
spatial	O
resolution	O
under	O
1km	O
.	O
</s>
<s>
And	O
,	O
although	O
FIRETEC	O
and	O
WFDS	O
carry	O
prognostic	O
conservation	O
equations	O
for	O
the	O
reacting	O
fuel	O
and	O
oxygen	O
concentrations	O
,	O
the	O
computational	O
grid	O
cannot	O
be	O
fine	O
enough	O
to	O
resolve	O
the	O
reaction	O
rate-limiting	O
mixing	O
of	O
fuel	O
and	O
oxygen	O
,	O
so	O
approximations	O
must	O
be	O
made	O
concerning	O
the	O
subgrid-scale	O
temperature	O
distribution	O
or	O
the	O
combustion	B-Application
reaction	O
rates	O
themselves	O
.	O
</s>
<s>
These	O
models	O
also	O
are	O
too	O
small-scale	O
to	O
interact	O
with	O
a	O
weather	B-General_Concept
model	I-General_Concept
,	O
so	O
the	O
fluid	O
motions	O
use	O
a	O
computational	O
fluid	O
dynamics	O
model	O
confined	O
in	O
a	O
box	O
much	O
smaller	O
than	O
the	O
typical	O
wildfire	O
.	O
</s>
<s>
The	O
morphing	O
EnKF	O
combines	O
the	O
ideas	O
of	O
data	O
assimilation	O
with	O
image	B-Algorithm
registration	I-Algorithm
and	O
morphing	O
to	O
provide	O
both	O
additive	O
and	O
position	O
correction	O
in	O
a	O
natural	O
manner	O
,	O
and	O
can	O
be	O
used	O
to	O
change	O
a	O
model	O
state	O
reliably	O
in	O
response	O
to	O
data	O
.	O
</s>
<s>
Thus	O
,	O
while	O
more	O
complex	O
models	O
have	O
value	O
in	O
studying	O
fire	O
behavior	O
and	O
testing	O
fire	O
spread	O
in	O
a	O
range	O
of	O
scenarios	O
,	O
from	O
the	O
application	O
point	O
of	O
view	O
,	O
FARSITE	O
and	O
Palm-based	O
applications	O
of	O
BEHAVE	O
have	O
shown	O
great	O
utility	O
as	O
practical	O
in-the-field	O
tools	O
because	O
of	O
their	O
ability	O
to	O
provide	O
estimates	O
of	O
fire	O
behavior	O
in	O
real	O
time	O
.	O
</s>
<s>
Also	O
,	O
although	O
they	O
have	O
reached	O
a	O
certain	O
degree	O
of	O
realism	O
when	O
simulating	O
specific	O
natural	O
fires	O
,	O
they	O
must	O
yet	O
address	O
issues	O
such	O
as	O
identifying	O
what	O
specific	O
,	O
relevant	O
operational	O
information	O
they	O
could	O
provide	O
beyond	O
current	O
tools	O
,	O
how	O
the	O
simulation	O
time	O
could	O
fit	O
the	O
operational	O
time	O
frame	O
for	O
decisions	O
(	O
therefore	O
,	O
the	O
simulation	O
must	O
run	O
substantially	O
faster	O
than	O
real	O
time	O
)	O
,	O
what	O
temporal	O
and	O
spatial	O
resolution	O
must	O
be	O
used	O
by	O
the	O
model	O
,	O
and	O
how	O
they	O
estimate	O
the	O
inherent	O
uncertainty	O
in	O
numerical	B-General_Concept
weather	I-General_Concept
prediction	I-General_Concept
in	O
their	O
forecast	O
.	O
</s>
