Summary

International Symposium on Electromagnetic Compatibility

2009

Session Number:24S2

Session:

Number:24S2-1

Three-Dimensional VHF Observations of Positive Cloud-to-Ground Flashes in Summer Thunderstorm Season

Y. Nakamura,  T. Morimoto,  T. Ushio,  Z. Kawasaki,  M. Shimizu,  

pp.781-784

Publication Date:2009/7/20

Online ISSN:2188-5079

DOI:10.34385/proc.14.24S2-1

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Summary:
Lightning Research Group of Osaka University (LRGOU) and Chubu Electric Power Company (CEPCO) have been conducting a cooperative thunderstorm observations during the last few summers in Tono Aria (Gifu Pref., Japan). LRGOU has been developing two- (2D) and three-dimensional (3D) VHF source mapping system for electromagnetic (EM) waves emitted in association with lightning discharge progression based on a unique technique of the broadband digital interferometry. CEPCO has improved the location accuracy of lightning strokes by the lightning location and protection system (LLP system). At 2028:59 JST on 8 August, 2008, we observed the 3D spatiotemporal development channels of positive cloud to ground (CG) lightning flash with the VHF broadband digital interferometer (DITF) and the return stroke with the LLP system. This flash is divided before and after the return stroke. In the first stage, the lightning channel progresses about 16 km horizontally between 6 and 10 km high. The LLP system detects the return stroke near the initiation point of that channel. In the last stage, the negative breakdown run through the same channel before the return stroke. This positive lightning is accompanied by the bidirectional leader.