Downbursts to be studied by scientists

Press, 31 May 1982, Page 10

Downbursts to be studied by scientists

More than 100 researchers in the United States and Britain will soon start, an intensive study of . microbursts, small intense downward and outward bursts of air that have been a big factor in several aircraft accidents and are of great concern to airlines and private pilots. The principal object of the study, termed J.A.W.S. for Joint Airport Weather Studies, is to get a better understanding of meteorological conditions that emanate from thunderstorms, including microbursts which often are associated with such storms. The researchers will try to learn how microbursts can be detected and predicted and their relationship to aviation safety. The $2.2 million project will be conducted near Denver, Colorado, for three months, and started on May 15.

The project will be managed by the National Centre for Atmospheric Research (N.C.A.R.) in Boulder, Colorado, and the University of Chicago, with funds from and sponsorship by the National Science Foundation (N.S.F.). Additional support will come from the National Oceanic and Atmospheric Administration (N.0.A.A.), the

National Aeronautics and Space Administration (N.A.S.A.) and the Federal Aviation Administration (F.A.A.). British participation will include a research airplane from the Royal Aircraft Establishment in Bedford, England.

Dr John McCarthy and James Wilson . of N.C.A.R. and Dr Theodore Fujita of the University of Chicago are the principal investigators. Besides the University of Chicago, researchers from the following institutions will participate in J.A.W.S.: Colorado State University, the Massachusetts Institute of Technology, University of Wyoming, and the University of Tennessee. While J.A.W.S. will concentrate on basic research, Dr McCarthy said, a big effort will be directed to applied research results.. These centre on the downburst and outflows of winds that occasionally emanate from thunderstorms and from clouds that are much smaller than thunderstorm clouds which often appear innocuous. Because these events sometimes occur in clear air, pilots landing or taking off can encounter unexpected downdrafts or sudden tailwinds or headwinds that abruptly change air speed,

possibly inducing stalls and sometimes crashes.

The most notable of such crashes occured at Kennedy Airport in New York in 1975, an event in which 113 people lost their lives. A similar event occured at Denver’s Stapleton Airport six weeks later, when 15 persons were injured.

“Thunderstorms unleash awesome power,” Dr McCarthy said. “Much is yet to be learned about how thunderstorms develop and why they occur where they do. how to predict when and where they will happen, and most importantly, how to warn the public of accompanying severe weather in sufficient time to take necessary action.

“Denver is an ideal location to study this type of phenonomenon. This area has one of the highest frequencies of thunderstorms in the United States. Moreover, Denver’s airport is the busiest commercial airport in the United States, and a detailed understanding of the downburst environment will be of great value to all aircraft operations here.”

In addition to the basic studies of low-level convective storm winds, J.A.W.S. will test seven wind-shear detection and warning systems to evaluate and com-

pare their performance. J.AW.S, will also study aircraft* performance in windshear conditions and the usefulness of Doppler radars for detecting conditions which may spawn wind shear. Using J.A.W.S. results, scientists can then make recommendations to private and commercial pilots, the aviation industry, and other interested groups about how the specific conditions that cause wind shear can be better detected and avoided. Researchers will co-ordi-nate field operations from three Doppler radar sites using a sophisticated communications system to change radar scanning strategies and to guide seven different research aircraft into or around storms of interest.

g Following the J.A.W.S. field experiment, the scientists will spend two years analysing the data, that will have been generated.. ''.<L

“This will be the most complete set of data yet gathered on downbursts,” Dr McCarthy said, “and it will take a great deal of work to unravel all the puzzles the data will reveal. In the end, we can expect to have results of great scientific interest as well as practical value.”—United States National Science Foundation.