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VLF Propagation In Earth-Ionosphere Waveguide Pinpoints Lightning

USING ONLY 30 LIGHTING SENSORS, worldwide lightning location (WWLL) has been successfully achieved via very-low-frequency (VLF) propagation in the Earth-ionosphere-waveguide (EIWG) atmospheric layer. To avoid ground propagation or mixed "sky" and ground propagation, the researchers demanded evidence of Earth-ionosphere waveguide dispersion. In addition, each lightning strike had to be within the perimeter defined by the lightning-sensor sites that were detecting the stroke. Under these conditions, the stroke's time and location could be determined along with root-mean-square (rms) errors.

To help to identify impulses from the same lightning stroke, the sensor was automatically adjusted to allow an average detection rate of three per second. Detection is thus limited to the strongest 4 percent of all lightning strokes. Currently, there are 30 WWLLnetwork lightning receiving sites distributed around the world in longitude and from the Antarctic to the Arctic in latitude. Coverage is achieved with one set of lightning sensors and redundant lightning data processors, which have the same design and software. Thanks to the use of VLF propagation in the EIWG layer, strong lightning strokes can be detected up to the imposed limit of 13.3 Mm (one-third of the way around the world). Such lightning detection is achieved in urban areas on a 1-m whip antenna with adequate signal-to-noise ratio.

Due to the global nature of this project, a large number of researchers took part in it: Richard Dowden and James Brundell from Low Frequency Electromagnetic Research Ltd. (Dunedin, NZ); Robert Holzworth, Abram Jacobson, Erin Lay, and James Weinman from the University of Washington; Craig Rodger and Neil Thomson from the University of Otago (Dunedin, NZ); Jnos Lichtenberger from Etvs Lorand University (Budapest, Hungary); Thomas Lyons from Australia's Murdoch University; Steven O'Keefe from Griffin University (Nathan, Australia); Zen Kawasaki from Osaka University; Colin Price from Tel Aviv University; Victor Prior from the Institute of Meteorology (Lisbon, Portugal); Pascal Ortga from the University of French Polynesia; Yuri Mikhailov from IZMIRAN (Moscow region, Russia); Oscar Veliz from the Geophysics Institute of Peru; Xiushu Qie from the Institute of Atmospheric Physics (Beijing, China); Gary Burns from the Australian Antarctic Division of Ice, Ocean, Atmosphere & Climate; Andrew Collier from Hermanus Magnetic Observatory in South Africa; Osmar Pinto Junior from Brazil's Chefe do Grupo de Electricidade Atmosfrica (ELAT); Ricardo Diaz from Universidad Nacional Tucuman in Argentina; Claudia Adamo from the Institute of Atmospheric Sciences and Climate (Rome, Italy); Earle Williams from Massachusetts Institute of Technology; Sushil Kumar from the University of the South Pacific (Suva, Fiji); G.B. Raga from the Universidad Nacional Autonoma de Mexico; Jose Rosado from the University of Puerto Rico; Eldo Avila from Argentina's Universidad Nacional de Cordoba; Mark Cliverd from the British Antarctic Survey's Physical Sciences Division; Thomas Ulich from Finland's Sodankyla Geophysical Observatory; Peter Gorham from the University of Hawaii; Thomas Shanahan from the British Geological Survey's Seismology and Geomagnetism Group; Thomas Osipowicz from the National University of Singapore; Gregory Cook from the UK's University of Sheffield; and Yang Zhao from the Chinese Academy of Sciences in Gansu. See "World-Wide Lightning Location Using VLF Propagation in the Earth-Ionosphere Waveguide," IEEE Antennas And Propagation Magazine, October 2008, p. 40.

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