HR: 1330h
AN: AE22A-1119    [PDF]
TI: Full Wave Analysis and Observation of Spherics Generated by Lightning
AU: * Nakamura, Y
EM: nakamura@reg.ec.t.kanazawa-u.ac.jp
AF: Graduate School of Natural Science and Technology, Kanazawa University, 2-40-20 Kodatsuno, Kanazawa, 920-8667 Japan
AU: Nagano, I
AF: Graduate School of Natural Science and Technology, Kanazawa University, 2-40-20 Kodatsuno, Kanazawa, 920-8667 Japan
AU: Yagitani, S
AF: Graduate School of Natural Science and Technology, Kanazawa University, 2-40-20 Kodatsuno, Kanazawa, 920-8667 Japan
AU: Ozaki, M
AF: Graduate School of Natural Science and Technology, Kanazawa University, 2-40-20 Kodatsuno, Kanazawa, 920-8667 Japan
AU: Ozaki, M
AF: Department of Information and Systems Engineering, Kanazawa University, 2-40-20 Kodatsuno, Kanazawa, Kanazawa, 920-8667 Japan
AB: We have developed a simple and cheap system with just a single VLF electromagnetic (EM) receiver to locate lightning discharges, which can determine both the direction and range of each lightning return stroke. With this system, we observe wave forms of two horizontal magnetic fields and of one vertical electric field of VLF spherics.\ The wave form of each VLF spheric usually consists of a couple of sequential pulses. The first pulse comes directly from a lightning return stroke, and is used for the direction finding of the stroke.\ The second and later pulses represent the multiple reflections of the first pulse between the ionosphere and the ground.\ The difference in the time-of-arrival of each set of adjacent pulses is determined by the difference in their multi-hop propagation path lengths in the Earth-ionosphere waveguide.\ By using the time-of-arrival differences between two or more pulses, we can inversely estimate both the reflection height of the ionosphere and the range of the lightning stroke. In this study, in order to quantitatively evaluate the observed spheric wave forms, we compute the propagation of the electromagnetic pulses\ (EMP) radiated by lightning current strokes by using the full wave method including the ionosphere and the ground, and compare their characteristics with the actual observations.
DE: 3304 Atmospheric electricity
DE: 3324 Lightning
DE: 3337 Numerical modeling and data assimilation
DE: 3360 Remote sensing
DE: 3394 Instruments and techniques
SC: Atmospheric and Space Electricity [AE]
MN: 2003 Fall Meeting