by Clayton
DeKorne
It could be a Ford F250 Crew Cab or a Dodge 2500 Ram Van. You'll
know it by the bright orange, 5,500-pound trailer in tow, and the
mad glint in the driver's eyes. As the rig pulls up in a coastal
neighborhood, the yellow-slickered agents spilling out aren't
exactly Ghost Busters, but they do intend to capture accurate wind
data by erecting a portable weather station. In less than half
anhour, the crew will erect a 33-foot steel-lattice tower sporting
an array of whirligigs— anemometers capable of measuring
gusts traveling up to 200 mph — anda bank of weather sensors.
They will fire up a generator, which powers a linked
uninterruptible power supply, then boot up the rig's computer,
which will send real-time measurements of the storm over the
Internet to meteorologists from the National Oceanic and
Atmospheric Administration (NOAA) and analysts contracted bythe
Federal Emergency Management Agency (FEMA). With one last look to
make sure all systems are go, the researchers will speed off,
keeping their fingers crossed that there might still be time to
erect another tower before the storm makes landfall.
During a guster, this scenario is typical for the crews working on
the Florida Coastal Monitoring Project (FCMP), a collaboration of
students and professors from the University of Florida, Florida
Institute of Technology, ClemsonUniversity, and Florida
International University seeking to quantify near-surface hurricane
behavior and to evaluate the actual loads on residential buildings.
Theproject includes 32 homes that have been outfitted with
instruments to measure windpressures in single-family homes.
Instruments on six of these homes standing inthe paths of
Hurricanes Frances and Ivan measured — for the first time
ever— the true impact of hurricane-force winds.
In less than half an hour, a tower is up and ready to send
real-timeweather data direct from a neighborhood in line with a
hurricane.
"It's the first real look we've had," says Forrest Masters, an
assistant professor of civil engineering at Florida
InternationalUniversity who heads the tower-erection teams. Prior
to FCMP's first deployment,hurricane information was gathered
primarily from stations at inland airfields oron offshore buoys.
Or, it's been gathered by reconnaissance aircraft flyingmiles above
the storm. However, the peak pressures that load a house are deeply
sensitive to ground-level turbulence, which depends on the
roughness of the terrain,explains Masters. Wind traveling over the
smooth surface of an airfield, or over the ocean, behaves very
differently than wind moving over and around the trees andhouses in
a neighborhood.
The project includes installing sensors housed in protective
aluminum pans to measure wind pressures on critical areas of a
roof.
The FCMP studies may have a profound impact on our understanding of
how homes perform in hurricanes. The loads referenced in current
building codesare based on the analysis of winter storms and
thunderstorms, which Masters saysmay be very different animals. New
data may give engineers a fine-grained view ofthe gusts spawned by
hurricanes, which in turn may suggest new hurricane-resistant
building practices. If anything, coastal codes may get stricter:
Preliminary datasuggest that tropical cyclones are much "gustier"
than storm models basedon winter storms and thunderstorms. —
Clayton DeKorne