Contact:  Jeanne Kouhestani, NOAA Corps    FOR IMMEDIATE RELEASE    
          NOAA Corps                       9/9/97
          Frank Lepore,                    
          National Hurricane Center   
          Dr. Hugh Willoughby,
          Hurricane Research Division

Hurricane forecasting took a big step forward recently with the successful testing of new and improved instruments that are dropped from "hurricane hunter" aircraft to measure temperature, pressure, humidity, and wind speed and direction. The experiment, carried out in August during Hurricane Guillermo, produced the most complete and detailed portrait of a hurricane ever seen, said scientists from the Commerce Department's National Oceanic and Atmospheric Administration.

The successful test enabled scientists to deploy the instruments during September's Hurricane Erika from NOAA's new Gulfstream-IV jet in its first operational mission, and from the agency's two WP-3D Orion aircraft. The resulting data caused forecasters at NOAA's National Hurricane Center, who plotted the data in real time, to improve their hurricane track prediction.

During the Guillermo experiment, scientists from NOAA's Hurricane Research Division and NOAA Corps pilots and civilian technical crews from the Aircraft Operations Center flew two research WP-3D aircraft into the Category 5 (most intense) hurricane, which was raging over the eastern Pacific Ocean. The aircraft carry Doppler radars that measure winds throughout the hurricane's domain, from the ocean surface to 10 kilometers above.

Nearly a hundred newly developed instruments called Global Positioning System dropwindsondes -- were deployed from the aircraft with an outstanding success rate.

The NOAA ship Ronald H. Brown, one of the most advanced research ships in the world, was south of the storm's center and also released weather balloons periodically to supplement the dropwindsonde data. Weather balloon-borne instruments are similar to dropwindsondes, only they go up instead of down. Collaborating university scientists simultaneously acquired and analyzed NOAA satellite imagery over a larger area around the hurricane, helping put the dropwindsonde data into context.

"Hurricane Guillermo provided an ideal proving ground for the Vortex Motion and Evolution Experiment," said Hugh Willoughby, chief of the Hurricane Research Division. "Together the radars, dropwindsondes, ship data, flight level instruments and satellites produced the most complete and detailed portrait of a hurricane to date. Observations of this kind enable tropical meteorologists to further improve forecasts of hurricane motion and address the problem of skillfully forecasting hurricane intensity."

The dropwindsondes were developed as the primary scientific payload of NOAA's new Gulfstream-IV jet, which flies up to 45,000 feet around hurricanes in the steering currents, and for the lower flying P-3 aircraft that penetrate the hurricanes for research purposes. The new dropwindsondes replace 1970's technology.

"We are extremely pleased with the performance of the dropwindsondes," said Capt. George Player, director of the Aircraft Operations Center in Tampa, Fla., which is part of the Office of NOAA Corps Operations. "Engineers in AOC's Science and Engineering Division have extensively tested the instruments and corrected problems with the manufacturer's original design. Now we're getting the results we want."

The aircraft are equipped with computer systems that "talk" to the dropwindsondes, and that create graphic images. This technology allows scientists to actually see the physical processes of hurricanes, and measures wind, temperature and humidity every five meters as the dropwindsonde falls.

The hurricane vortex experiment was designed to look at how whirlpools and currents of wind cause a storm to move or how the environment controls the motion and intensity of the storm. Though hurricane track forecasting has improved steadily over the years, the new dropwindsondes technology, coupled with other land-, ship-, aircaft- and satellite-based technology, will help scientists better understand the physics that determine hurricane intensity. The ultimate payoff will be more precise intensity forecasts that will help prevent overwarning and the adverse economic impact (as much as $660,000 per mile) caused by unnecessary evacuations. The most destructive hurricanes form by the processes of rapid deepening that may convert a 90 miles-per-hour hurricane into one with 150 miles-per-hour winds in less than a day. Understanding how hurricanes work will help forecasters anticipate sudden changes in intensity and motion.

"The bottom line is that each time our ability to predict hurricanes improves, we can better protect American lives and property," Willoughby said.

The experiment, and the highly successful first operational flights in the environment of a major hurricane, Hurricane Erika, were the culmination of a multi-year effort that involved NOAA's Aircraft Operations Center, Hurricane Research Division, Geophysical Fluid Dynamics Laboratory, National Centers for Environmental Protection, and National Hurricane Center; and, outside NOAA, the National Center for Atmospheric Research in Boulder, Colo.

The Hurricane Research Division is part of NOAA's Atlantic Oceanographic and Meteorological Laboratory in Miami, Fla. The Office of NOAA Corps Operations, which includes civilians and commissioned officers, manages and operates the agency's fleet of aircraft and ships. The NOAA Corps is the nation's smallest uniformed service.