By Jan TenBruggencate
Advertiser Science Writer
Several airline passengers are hurt almost every year when their planes are suddenly jerked up and down by an invisible force called clear-air turbulence.
One passenger was killed and 102 were injured on a 1997 flight from Narita, Japan, to Honolulu. Ten were hurt on a 1998 Los Angeles to Honolulu flight. And 22 were hurt in a 1999 Narita to Honolulu flight. Nine were hurt on one flight and eight on another last year flying from Tokyo to Honolulu.
Airlines and the Federal Aviation Administration are desperate for ways to detect these bumpy places in the skies. Among the technologies are temperature sensors that detect dangerous air masses or using infrared lasers beamed ahead of aircraft.
But many are banking on highly accurate weather forecasting to predict the locations of dangerous areas.
"If we can improve our knowledge of turbulence events, we will not only save lives but also thousands of dollars lost in fuel, flight rerouting and delays," said Jim Weyman, meteorologist in charge at the Honolulu forecast office of the National Weather Service.
This month, weather scientists are using the skies around Hawai‘i to gain an understanding of the process. A National Oceanic and Atmospheric Administration hurricane-hunter jet, a Gulfstream IV, is flying into the jet stream and into thunderstorms this month in the third year of its Severe Clear Air Turbulence — Colliding with Air Traffic (SCATCAT) program.
The jet is in the Islands to conduct reconnaissance on winter storms over the Pacific, and will do some turbulence studies.
The crew looks for areas where turbulence is likely and ejects instrument packages called drop-sondes into them, allowing researchers to measure the atmospheric conditions.
The program has already made one interesting finding: The jet stream is in many ways more like a turbulent sea than a flowing brook; it has vertical waves that can break like waves on the ocean, creating invisible but severe upheavals in the air flow.
SCATCAT manager Mel Shapiro said that researchers can make computerized models of what’s going on in the air, but they require actual tests like the ones conducted by the Gulfstream IV to test the models and find out whether they are accurate.
"Comparing the actual atmosphere to the model prediction is the key to improving aviation models that are used by · pilots for flight safety," Shapiro said.
The project is also refining the capabilities of measuring equipment, which ultimately can help in turbulence prediction, but will also feed into other climate programs, he said. One is the U.S. Weather Research Program, a consortium of the National Oceanic and Atmospheric Administration, the National Science Foundation, the Department of Defense and NASA.
The Weather Research Program is working to improve observation technologies to try to improve forecasts as a way of warning specific populations against imminent severe weather — and of cutting the costs associated with weather disruptions.
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