NSF PR 98-59 - September 25, 1998
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Researcher Uses "Doppler on Wheels" to Stare Hurricane
Georges in the Eye
When a hurricane's spinning mass of rain, lightning
and wind reaches shore the last thing you want to
do is drive a truck directly into its path. Unless
you are atmospheric scientist Joshua Wurman, that
is, and you have mounted a large Doppler radar unit
on the back of your truck.
For the second time this summer, Wurman and a research
team from the University of Oklahoma will drive two
such "Doppler on Wheels" units into the face of a
hurricane reaching landfall--Hurricane Georges. With
funding from the National Science Foundation (NSF),
Wurman studies patterns in hurricane winds that may
help in forecasting the evolution of these storms
once they hit land.
"Hurricanes spawn damaging winds well inland," said
Wurman, "but they can also cause tornadoes and flooding.
We are trying to figure out how patterns of winds
and rain develop in hurricanes, and determine why
and where a storm will produce floods and funnel clouds."
For many years, meteorologists have used Doppler radar
at fixed locations to monitor weather patterns, as
seen in weather forecasts on television. Due to advances
in technology, Doppler radar has evolved to the point
where it can be mounted to mobile platforms like Wurman's
"Doppler on Wheels."
The vehicle itself is an odd-looking configuration
of generators, equipment and an operator cabin welded
to a large flatbed truck. The most prominent feature,
however, is the large conical base and wide dish of
the Doppler radar. "Considering that one radar unit
is pink and yellow, and the other is blue and green,
we do get our fair share of funny looks as we're heading
to a storm," said Wurman.
"The biggest advantage of 'Doppler on Wheels' is that
Wurman can collect more data with better precision,"
said Stephan Nelson, program manager in the NSF's
division of atmospheric sciences, which funds Wurman's
research. "Hurricanes rarely oblige to move in the
path of two correctly spaced Doppler systems. Since
we can't move the storm, it's awfully convenient that
we can move the radar."
In addition to studying hurricanes, these trucks have
also been used to study tornadoes. Since the project
began in 1995, researchers have taken advantage of
the mobility of "Doppler on Wheels" to map, for the
first time, tornado winds. With these Doppler maps
of tornadoes, they gained new insight into how tornadoes
form and evolve.
In August, Wurman's team took the mobile radar systems
to meet Hurricane Bonnie in North Carolina. While
riding through 12 hours of storm, these researchers
were the first to observe hurricane wind streaks,
intense bursts of wind over a short distance. The
wind streaks detected in Bonnie were similar to those
that Wurman initially observed during his first hurricane
mission in 1996. "These are probably the hallmarks
of a landing hurricane," said Wurman.
Wind streaks, he hypothesized, are probably caused
by boundary layer rolls, portions of the storm where
the wind is influenced by the friction between the
earth's surface and storm. Peak speeds of these wind
streaks can be as much as 50 miles per hour (mph)
higher than average winds. "Obviously, short bursts
of 120-mph winds can do a lot more damage to houses
and trees than 70-mph winds can," Wurman says.
Wurman will have another chance to collect data this
year as Hurricane Georges reaches the continental
United States.
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