Wednesday, November 6, 2002

University of Hawaii

UH researchers help NASA
better predict lightning

Their work will help NASA save money
and improve safety for its shuttle launches

By Helen Altonn

Costly delays and cancellations of shuttle launches from Florida may be reduced because of a method developed by University of Hawaii scientists to forecast lightning.

Steven Businger, professor of meteorology, and one of his graduate students, Robert A. Mazany, improved warnings of lightning strikes from thunderstorms with a Lightning Index.

The Index combines meteorological data with data on the amount of water vapor in a cloud from Global Positioning System (GPS) receiver sites.

It improved the lead time for forecasting lightning strikes at Kennedy Space Center by nearly 10 percent in initial testing.

Benefits, NASA said, include safety of personnel outside, protection for the $10 billion rocket launching systems and space shuttle, and huge savings. Costs can range from $90,000 for a 24-hour delay to $1 million if the shuttle has to land at another facility and be transported back to Kennedy Space Center, the agency said.

A leading researcher on frontal cyclones, hurricanes and severe thunderstorms, Businger pioneered use of GPS in atmospheric sciences with Michael Bevis, Hawaii Institute of Geophysics and Planetology professor.

"We were the first scientists to actually get water vapor data from a network of GPS receivers in the field," Businger said.

Their first experiments with GPS receivers in 1994 drew the interest of the National Oceanic and Atmospheric Administration (NOAA) and other federal agencies.

The GPS comprises 24 satellites that transmit radio signals for multiple purposes, such as tracking trucks across highways, Businger said.

GPS also is being applied increasingly for weather and climate observations because it can be used to measure precipitable water -- "essentially how much water is there in the atmosphere above the receiver," Businger said.

"This has huge implications for weather forecasting," said Businger, explaining the amount of water vapor signals the kind of weather that can be expected.

More water vapor, for example, means warm, very humid weather, while less relates to dry, cold conditions, he said.

Nearly 75 percent of all space shuttle launches between 1981 and 1994 were delayed or canceled, with about half due to weather, according to a report on the Lightning Index in the October issue of the American Meteorological Society's Weather and Forecasting.

One GPS receiver is located at Kennedy Space Center on Florida's East Coast, which has one of the highest lightning flash densities in the nation, the article said.

This makes the new index extremely valuable, said Mazany, who earned a master's degree last year with a thesis on the GPS atmospheric research. He is now a captain in the U.S. Air Force and flight commander of Satellite Operations, 17th Operational Weather Squadron, in Honolulu.

A space shuttle cannot be launched in rain, lightning or strong winds, and Florida "is the thunderstorm capital of the country," Businger said. Southwest winds over Florida tend to deliver warmer, more unstable air packing more moisture for lightning strikes.

The major weather challenge for shuttle launches is to forecast lightning 90 minutes before a first strike and within a 20-mile radius of the launch site, according to the American Meteorological Society report.

Data from the 1999 summer thunderstorm season was used to test the index, Businger said.

It combines four prediction elements: atmospheric electric charge, the amount of water vapor detected in a cloud or air mass, change in the amount of water vapor over nine hours, and a scale that predicts how unstable the air will become.

Businger said research is continuing at Kennedy Space Center on the Lightning Index.

"They are investigating and refining it."

He is also still working with GPS.

"The next step is to create a flash flood index for Hawaii," he said, adding that he is working on a proposal to NOAA to fund the project.

Businger, of the UH School of Ocean & Earth Science & Technology (SOEST), and other UH and National Weather Service scientists have collaborated on research to improve observations and forecasting of flash flood hazards in the tropical Pacific.

He is part of a research group led by Bevis using a growing number of GPS receivers in Hawaii to measure water vapor. He has done extensive research on development of cyclones in polar air masses and has led investigations applying GPS for remote sensing of the atmosphere.

The Lightning Index work was supported by NOAA, the U.S. Air Force Air Weather program, NASA, the Department of the Navy and the Office of Naval Research under the Pacific STARNET program.

University of Hawaii

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