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Title Simultaneous Measurement of Lightning Parameters for Strokes to the Toronto Canadian National Tower

Author(s) A.M. Hussein, W. Janischewskyj, J.-S. Chang, V. Shostak, W.A. Chisholm, P. Dzurevych and Z.-I. Kawasaki

Journal J. of Geophysical Research, 100, D5, 8853-8861 (1995)

Abstract Successful simultaneous measurements of significant parameters for lightning strikes to the Canadian National (CN) Tower in Toronto have been performed since the summer of 1991. Three 10-bit 10-ns computer-controlled double-channel digitizers, with long segmented memory, have simultaneously captured the current derivative at the CN Tower and the corresponding electric and magnetic fields 2.0 km north of the tower. Lightning flashes to the tower were videotaped from two mutually perpendicular directions for the purpose of constructing a three-dimensional image of the lightning path. Furthermore, the return stroke velocity, a parameter also needed for the analysis of lightning radiation models, has been measured by a computer-controlled photodiode system. In this paper all relevant parameters for a CN Tower lightning stroke, observed on August 17, 1991, are shown and analyzed.

Title Luminous Propagation of Lightning Attachment to CN Tower

Author(s) D. Wang, Z.-I. Kawasaki, K. Yamamoto, K. Matsuura, J.S. Chang, W. Janischewskyj

Journal J. of Geophysical Research, 100, D6, 11661-11667 (1995)

Abstract Using an eight-channel photodiode system, we resolved in time and space the luminous propagation of lightning attachment to the CN tower. Approximately 60 lightning discharges were recorded during 1991 and 1992. Most of these discharges demonstrated simultaneous, bidirectional propagation starting at several tens of meters above the top of the CN tower. Propagation speeds ranged from 8×100 to 287×106 m/s. The observed bidirectional propagation suggests the presence of space leaders or the reilluminations following these space leaders during the initial stage of development of upward leaders from the CN tower. A few of the bidirectional discharges were found to have the return stroke speeds and these might be deduced to be manifestations of the bidirectional propagation processes of return strokes which occurred after the connection of a downward leader and an upward connection leader. We also recorded portions of seven ordinary dart leader - return stroke sequences. The dart leader speeds ranged from 7×106 to 23×106 m/s; the velocities of the return strokes ranged from 88×106 to 143×106 m/s. These values are in excellent agreement with the previous results by other authors. Positive correlations are found among the return stroke velocity, the leader velocity, and the leader light intensity. However, it also is observed that even in the case of a very tall structure, when a dart leader approaches the CN tower, it is highly possible that no apparent connecting leader is initiated before the ensuing return stroke.

Title	Simultaneous Measurement of Lightning Parameters for Strokes to the Toronto Canadian National Tower
Author(s)	A.M. Hussein, W. Janischewskyj, J.-S. Chang, V. Shostak, W.A. Chisholm, P. Dzurevych and Z.-I. Kawasaki
Journal	J. of Geophysical Research, 100, D5, 8853-8861 (1995)
Abstract	Successful simultaneous measurements of significant parameters for lightning strikes to the Canadian National (CN) Tower in Toronto have been performed since the summer of 1991. Three 10-bit 10-ns computer-controlled double-channel digitizers, with long segmented memory, have simultaneously captured the current derivative at the CN Tower and the corresponding electric and magnetic fields 2.0 km north of the tower. Lightning flashes to the tower were videotaped from two mutually perpendicular directions for the purpose of constructing a three-dimensional image of the lightning path. Furthermore, the return stroke velocity, a parameter also needed for the analysis of lightning radiation models, has been measured by a computer-controlled photodiode system. In this paper all relevant parameters for a CN Tower lightning stroke, observed on August 17, 1991, are shown and analyzed.

Title	Luminous Propagation of Lightning Attachment to CN Tower
Author(s)	D. Wang, Z.-I. Kawasaki, K. Yamamoto, K. Matsuura, J.S. Chang, W. Janischewskyj
Journal	J. of Geophysical Research, 100, D6, 11661-11667 (1995)
Abstract	Using an eight-channel photodiode system, we resolved in time and space the luminous propagation of lightning attachment to the CN tower. Approximately 60 lightning discharges were recorded during 1991 and 1992. Most of these discharges demonstrated simultaneous, bidirectional propagation starting at several tens of meters above the top of the CN tower. Propagation speeds ranged from 8×100 to 287×106 m/s. The observed bidirectional propagation suggests the presence of space leaders or the reilluminations following these space leaders during the initial stage of development of upward leaders from the CN tower. A few of the bidirectional discharges were found to have the return stroke speeds and these might be deduced to be manifestations of the bidirectional propagation processes of return strokes which occurred after the connection of a downward leader and an upward connection leader. We also recorded portions of seven ordinary dart leader - return stroke sequences. The dart leader speeds ranged from 7×106 to 23×106 m/s; the velocities of the return strokes ranged from 88×106 to 143×106 m/s. These values are in excellent agreement with the previous results by other authors. Positive correlations are found among the return stroke velocity, the leader velocity, and the leader light intensity. However, it also is observed that even in the case of a very tall structure, when a dart leader approaches the CN tower, it is highly possible that no apparent connecting leader is initiated before the ensuing return stroke.