Technology Examined For Weather Threat

Looking for ways to prevent air crashes that have claimed hundreds of lives, including '50s singing stars Buddy Holly and Ritchie Valens, researchers are testing a pair of radars they hope will detect icing conditions. Using the radars together should help determine the amount of tiny droplets of water in the air, too small for most radars, that are colder than freezing but still liquid. Marcia Politovich, director of the icing program at the National Center for Atmospheric Research (NCAR) in Boulder (CO) said Wednesday that the icing research experiment is continuing through the end of March. The team attached a small Ka-band radar to a large S-band unit, similar to the radars used by the National Weather Service. The researchers hope to report their findings later in the year.

"This will take out a lot of the guess work," explained Politovich. "We think it will show exactly where the water is. That information could ultimately turn into an important warning system for pilots."

While they can detect normal rain, it's hard for the longer wavelength S-band radars to detect the tiny water drops, 1/10th the size of a raindrop, that form in these deadly icing clouds. The Ka-band signals are absorbed by liquid water, Politovich explained, but not by ice or snow. So by comparing the signals from the two radars, the scientists hope to be able to calculate the presence of the tiny liquid water drops, so they can warn pilots to avoid dangerous areas.

The test unit operates from the ground near Boulder, she said, and if the system works, Ka-band units could easily be added to National Weather Service and airport radars.

In addition, Politovich said, it may be possible to pair Ka-band radar with the units on aircraft and develop a similar method to detect areas of icing danger. Combining the names of the radar types, S-Pol for polarized S-band radar and the Ka-band radar, the researchers are calling their test unit S-Polka.

In addition to the 1959 Iowa crash that killed Holly, Valens and J. P. Richardson, who was known as the Big Bopper, other icing-related crashes have included:

• An American Eagle ATR-72 en route to Chicago that went into a high-speed dive and crashed near Roselawn (IN) on October 31,1994. None of the 68 people aboard survived.
• A Comair Embraer 120 en route from Cincinnati that crashed on approach to the Detroit airport on January 9, 1997, killing all 29 people on board.

If NCAR's testing proves successful, this list will remain as is, with little or no growth.

FMI: www.ncar.ucar.edu