NOAA 99-R525
Contact:  Erica Van Coverden                   FOR IMMEDIATE RELEASE
          (305) 361-4541                       9/3/99
	  Hurricane Dennis Yields More than Longevity, 
               NOAA Hurricane Scientists Say 

  Hurricane Dennis might be the storm that just won't go away, but it has
proven to be a fertile testing ground for new measurement technology. The
result?  Improved observations and forecasts of sea-level winds in
hurricanes, say hurricane forecasters at the National Oceanic and
Atmospheric Administration NOAA's Hurricane Research Division (HRD) and
Aircraft Operations Center successfully transmitted sea-level wind
measurements on Aug. 29 from Hurricane Dennis, using an experimental
instrument aboard NOAA's P-3 "hurricane hunter" aircraft.

     The measurements were incorporated into HRD's real-time hurricane wind
analysis system, combined with conventional winds from buoys, ships, Global
Positioning System dropwindsondes, and satellite cloud tracking to determine
the storm's wind field. Forecasters at the National Hurricane Center then
used the wind field as guidance to distribute warnings of gale force winds
(40 mph or higher) over coastal North and South Carolina.

     "What this new set of data provides is continuous measurement of wind
speed over a large area," says NOAA hurricane wind field expert Mark Powell.
"Based on successful comparison to the observations such as buoys and
coastal weather stations, the data from the new instrument was accepted by
the HRD analysis system, in real-time and used by the National Hurricane

     The technology in this experiment features a stepped frequency
microwave radiometer (SFMR), a sensor built by the University of
Massachusetts and Quadrant Engineering in Amherst, Mass., which is currently
flown aboard a NOAA hurricane hunter aircraft. The SFMR measures the signal
returned by the ocean surface beneath the aircraft as it is churned up by
hurricane winds. This technology has been in use for research purposes for a
number of years, but has never been available in real-time for forecasting.

     The measurements from the SFMR provide a critical addition to existing
tools for wind speed measurements, said Powell. Dropwindsondes deployed from
aircraft flying through and around a hurricane have been instrumental in
providing point observations within a storm, sending information every half

     Winds measured at flight level (about 10,000 ft.) by the U.S. Air Force
and NOAA hurricane reconnaissance aircraft are used in atmospheric models to
estimate surface winds. Estimating wind speeds from that altitude have
resulted in as much as 20 percent uncertainty. By incorporating the SFMR
wind speeds, scientists hope to reduce that uncertainty to provide more
accurate forecasts for coastal communities.

     "The SFMR gives us much more complete storm coverage at the surface
than the sondes, and at a fraction of the cost," said Peter Black, the HRD
scientist who helped develop the SFMR. "Eventually, we hope to see this
instrument on all hurricane hunter aircraft."

     The Hurricane Research Division is located at the Atlantic
Oceanographic and Meteorological Laboratory in Miami, Fla. It is one of
NOAA's 12 environmental research laboratories across the nation.

     NOAA's mission is to predict and describe changes in the Earth's
environment and to conserve and manage wisely the nation's coastal and
marine resources.


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