Waveform parameters of fields generated by lightning strokes to the CN tower and to objects in its vicinity

Since 1991, broadband, high-resolution measurement systems have simultaneously captured the lightning current derivative at the CN tower and the corresponding lightning-generated electric and magnetic fields 2 km north of the tower. Extensive cumulative statistics of waveform parameters (peak, 10% to 90% risetime to peak and pulse width at the 50% level of the peak) of electric and magnetic field signals, generated by lightning return-strokes to the CN Tower during the past eleven years (1992-2002), have been derived and are presented in this paper. Furthermore, waveform parameters of electric fields radiated from lightning strikes to the CN Tower and to other objects in its vicinity are compared. It is shown that the risk from electromagnetic interference (EMI) due to the lightning-generated electromagnetic pulse (LEMP) is substantially elevated near a tall structure. The presented statistical results will assist in the establishment of more sophisticated protective measures against interference due to lightning-generated electromagnetic pulses, especially those generated from lightning occurring at tall structures.