AMHERST, Mass. - It’s been a busy season for University of Massachusetts electrical engineer Andrew Pazmany, from the "monster" tornadoes that ripped through Oklahoma on May 3, to a tiny twister that damaged a cypress tree and toppled gravestones in a Kansas cemetery late last week. Pazmany, a UMass alumnus, constructed the specialized radar which, during the massive early May storm, produced the highest-resolution data ever available on a tornado. He chases tornadoes along with colleagues at the University of Oklahoma, using a truck-mounted radar and a videocamera. A research faculty member with the University’s highly-regarded Microwave Remote Sensing Laboratory, Pazmany’s work is funded by the National Science Foundation.
Researchers are trying to determine what meteorological conditions enable a supercell, a large rotating thunderstorm, to drop a funnel ? particularly a dangerous tornado, which is classified as F4 or F5. By determining what conditions must exist for the formation of an especially fierce tornado, researchers hope to develop accurate predictions of when and where such a tornado may touch down, giving people time to evacuate. Pazmany notes that "some large, organized supercells develop strong rotation, a structure similar to tornadoes, but never drop a funnel ? and no one knows why." A photo he took of such a supercell hangs on his office wall.
Although Pazmany has traveled to Oklahoma for three consecutive tornado seasons, which run roughly from April through June in the Midwest, the May 3 storm offered him his first opportunity to see a twister close-up. The storm dropped several tornadoes, one of which came within a half-mile of the radar truck. Pazmany videotapes the tornadoes while scanning the narrow-beam radar across them. The radar signals bounce off raindrops and flying debris, enabling scientists to track the movement of parcels of wind ? some of it blowing more than 300 miles an hour.
The specialized radar transmits at a higher frequency than the Doppler radar seen in television weather reports. It focuses in on storms with an ultra-narrow radar beam, which allows measurements of the highest wind speeds in the tornado’s walls. The resulting radar images reveal a shape similar to hurricanes, but on a 100-times smaller scale. Pazmany and his colleagues will present their preliminary findings this summer at a meeting of the radar conference of the American Meteorological Society, he said.