HR: 0830h
AN: AE21A-1104    [PDF]
TI: Lightning Current Parameters of Upward Lightning Flashes Observed at the 200-m Fukui Chimney in Winter
AU: * Wada, A
EM: jun@criepi.denken.or.jp
AF: Central Research Institute of Electric Power Industry, 2-11-1, Iwado Kita, Komae-shi, Tokyo, 201-8511 Japan
AU: Asakawa, A
AF: Central Research Institute of Electric Power Industry, 2-11-1, Iwado Kita, Komae-shi, Tokyo, 201-8511 Japan
AU: Miki, M
AF: Central Research Institute of Electric Power Industry, 2-11-1, Iwado Kita, Komae-shi, Tokyo, 201-8511 Japan
AU: Shindo, T
AF: Central Research Institute of Electric Power Industry, 2-11-1, Iwado Kita, Komae-shi, Tokyo, 201-8511 Japan
AB: For over twenty years we have been observing the lightning flashes at the 200-m-tall chimney in the Fukui thermal power plant in winter in Japan. The local IKL (thunderstorm days) is about 40 in this area and the lightning flashes at the chimney are recorded about 40 times in a winter season. When the lightning strikes the 5-m lightning rod on top of the chimney, lightning currents are measured by using coaxial shunt-resistors installed at the base of the lightning rod. Lightning progressing features was measured by the 40X40 pin photodiode array system. The system records luminosity changes in the lightning channel by measuring the differences between signals from different photodiodes. At a distance of 630 m from the chimney, a vertical lightning channel of 1000 m is divided by using 40 diode elements. Electromagnetic field changes that accompany lightning flashes are also measured by using several types of antennas. These simultaneous measurements classified the behavior of winter lightning flashes. All recorded lightning flash was the lightning discharge initiated by the upward leader from the chimney. Most lightning (about 90 percent) was the lightning discharge initiated by the upward-moving positively charged leader. The lightning initiated by the upward-moving negatively charged leader was only about 10 percent. Some of the lightning produced the subsequent discharge processes following the upward leader development. There are many differences between the lightning current parameters of upward lightning flashes and the downward lightning flashes. Interestingly, the upward leader currents observed at the chimney are big compared to the downward leader currents estimated by the several methods. We will report the properties of lightning current parameters based on the data collected at the 200-m-tall chimney in winter. These statistical data of lightning current parameters are classified especially from the point of view of lightning discharge types.
DE: 3304 Atmospheric electricity
DE: 3324 Lightning
SC: Atmospheric and Space Electricity [AE]
MN: 2003 Fall Meeting