Developing New Technologies to Increase Tornado Warning Time

Though this year’s tornado season in Georgia was not as active as the past few years, researchers at Georgia Tech are busy analyzing the weather data they collected from several twisters that hit the state this past spring. They hope this information will help them improve current storm detection technology, while they also create new methods to increase warning time.

Researchers at the Severe Storms Research Center (SSRC) at Georgia Tech completed their first tornado season since installing three state-of-the-art Warning Decision Support Systems (WDSS) in metro Atlanta early this year – two at Georgia Tech and one at the National Weather Service office in Peachtree City, Ga. Researchers are using these systems to determine if the WDSS tornado recognition logic can be better “tuned” to the tornadoes of the Southeast.

“Tornadoes in Georgia and elsewhere in the Southeast are often short-lived events,” says Gene Greneker, director of the SSRC. “Here, tornadoes can come and go in 10 minutes, as opposed to an hour in Kansas.”

WDSS technology – which includes advanced image processing, artificial intelligence, neural networks and other algorithms that use Doppler radar data – was developed at the National Severe Storms Laboratory in Norman, Okla. There, studies showed a 50 percent increase in warning time for tornadoes, severe thunderstorms and flash floods in Great Plains states.

“Another goal of the SSRC is to fund the development of new technologies that may be able to detect the early formation of tornadoes,” Greneker says. “If we are successful, these technologies could complement the Doppler radars operated by the National Weather Service.”

Complementary technologies being developed by Georgia Tech researchers are:

• early detection of tornadoes based on the “acoustic signatures” they produce and on the correlation between tornado occurrence and pre-storm thunder activity. Dr. Krishan Ahuja, a professor of aerospace engineering and a Regents Researcher at Georgia Tech Research Institute (GTRI), is trying to determine whether there is a correlation between tornado sound and the rotational speed of tornadoes as they materialize. If so, researchers could determine an “acoustic signature” that would predict tornadoes before they actually form.
   
• early detection of tornadoes based on a pattern of increasing electrical discharges produced by cloud-to-cloud lightning strikes. Dr. Tom Pratt, a senior research engineer at GTRI, has developed a first-generation lightning detection system that provides range, direction and radio frequency signatures associated with lightning activity in severe thunderstorms. He plans to fine tune the system by integrating additional sensors, including acoustic devices, into the system, and by developing advanced processing and analysis capabilities to improve total lightning detection and discrimination.
   
• a more meaningful 3-D severe thunderstorm display that is designed with human perception capabilities in mind. GTRI principal research scientist Nick Faust has created an integrated visualization of 3-D Doppler radar and global, high-resolution terrain – representing the first time such data have been displayed together in real time. This system also provides integrated browsing and analysis, and integration of relevant data, such as buildings and maps. The latter capability will grow in importance as researchers develop sophisticated models of storm development that yield rules for how storms behave in the presence of hills or mountains and other features, Faust reports.
   
• high-resolution documentation of tornado tracks based on storm path and duration information gathered at the scene. Research scientist Dr. Jim St. John, of the School of Earth and Atmospheric Sciences, is creating a detailed database called the Tornado Track Survey. The database contains tornado start and end points, as well as detailed descriptions of damage caused by the storm. St. John uses global positioning system receivers to pinpoint locations along the storm track, and he shoots digital images to record damage at each point. This information is then available to other researchers for comparison to radar or other data to investigate characteristics and evolution of tornadoes.
   
• more effective tornado detection algorithms than are currently part of WDSS. Principal research engineer Dr. Mark Richards and senior research engineer Vince Sylvester, both of GTRI, want to make radar smarter using advanced signal processing techniques. These will clarify the system’s often-indistinct display of a tornado’s rotating wind pattern. The researchers are also applying new target recognition methods to detect tornadoes and their precursors. In addition, they are studying potential sites for an experimental radar station in north Georgia, parts of which are underserved by existing stations, the researchers say.

“While these technologies are experimental, they are promising,” Greneker says. “They will continue to be tested.”

After the WDSS technology has been tested in north Georgia, it will be exported to south Georgia as funding permits, Greneker says.

The SSRC’s research is being funded by the Georgia Emergency Management Agency, the Federal Emergency Management Agency, the Georgia General Assembly and a grant from BellSouth Business Systems.