By JOSEPH B. VERRENGIA
AP Science Writer
Frustrated scientists carry an extra burden as they watch
wildfires torch southern California: Days ago, their instruments
told them this destruction would happen.
But once the fires ignited, their computers could not forecast
where or how long the fires would burn, or suggest where fire crews
might contain their spread.
Researchers say it will be several years before computer
programs will accurately forecast fire behavior the way TV
weathermen tell viewers where a hurricane or a blizzard is heading.
"Last Friday, we saw there would be very high winds over the
Simi Valley and San Diego," said geographer Dar Roberts, principal
investigator at the Southern California Wildfire Hazard Center at
the University of California-Santa Barbara.
By Tuesday fires had erupted in the area.
"It's a scary moment because you know that if somebody starts a
fire, it's going to be tough," Roberts said. "We could see this
happening."
Researchers at several universities and the National Interagency
Fire Center in Boise, Idaho, integrate information about weather,
fire dangers and available fire crews. Their reports go to
government land managers and city public safety departments,
especially in fire-prone western and southern states.
In addition to weather reports and data from hundreds of
automated ground-based climate stations, they use atmospheric
computer models that predict conditions above likely fire spots.
As fires burn, the agencies send updates on key factors, such as
when the Santa Ana winds might let up.
But what about whether a fire will jump a river or crest a
certain hillside in the next hour? Should a neighborhood be
evacuated? For those strategic decisions, fire managers cannot turn
to scientists and computers.
They still must rely on their own experience and frontline
reports from exhausted "ground-pounders" - their fire crews armed
with shovels and pickaxes.
Computer simulations of fires are "an extremely valuable tool
for lessons learned that can be applied to future fires, but it is
not an operational model," said Rich Wagoner of the National
Center for Atmospheric Research in Boulder, Colo.
Today's best wildfire models are so complicated they run only on
supercomputers normally reserved for calculations related to global
warming and nuclear weapons simulations.
They are called "coupled models" because they combine data
about the atmosphere and weather with data on fire conditions, such
as elevation and soil and plant moisture.
But models bog down on the details that really determine a
fire's behavior. Such as, whether a mountain slope is cool and
facing north, or warm and facing south. Or, whether the 60 mph
winds are gusty or constant. Or finer details, such as the
dimensions of leaves and needles on specific plants.
The best models crudely simulate wildfire over about a
half-square-mile. Want finer resolution? The models' accuracy drops
to an area equal to a few football fields.
And there is the speed issue. Supercomputers operate at
trillions of calculations per second, but they can't keep pace with
wildfires, which create their own hurricane-force winds at blast
furnace temperatures.
"It takes several days to run a model to get an hour or two of
forecast," Wagoner said.
Scientists say it will cost $25 million over five years to
develop a faster, portable wildfire model.
In September, researchers at NACR and the Rochester Institute of
Technology won a $300,000 federal grant to begin translating
remote-sensing data and satellite photographs into "mini-movies"
predicting a wildfire's behavior for 60 minutes. They hope fire
managers can download the animations on laptop computers at the
scene of a blaze.
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On the Net: NCAR: http://box.mmm.ucar.edu/fire/firehome.html
U.S. Forest Service: http://www.fs.fed.us/eng/rsac/