4. STATISTICAL ANALYSES
The statistical analyses presented in this paper are based
on the 1992-2001 CN Tower lighting current data
measured using the old Rogowski coil. During this 10-
year period, the CN Tower current measurement system
recorded a total of 160 lightning flashes, containing 508
current impulses (current impulses having wavefront
peaks lower than 2 kA have not been used or counted in
the analysis presented in this paper). The overwhelming
majority of these flashes, 156 out of 160 (97.5%), were
negative. Only two 3-stroke flashes (1.25%) were found to
be bipolar, each containing one positive stroke.
Furthermore, two single-stroke positive flashes (1.25%)
were recorded at the tower during the reporting period.