Simultaneous Measurements of Return Stroke Current, Electric and Magnetic Fields at Three Distance Ranges Associated with Lightning Strikes to The CN Tower

In this paper, simultaneous GPS time-stamped measurements of the electric and magnetic fields at three distances and of the return stroke current associated with lightning strikes to the Toronto CN Tower during the Summer of 2005 are reported. The lightning return-stroke current was measured using a Rogowski coil installed at a height of 474 m AGL (above ground level). The vertical component of the electric field and the azimuthal component of the magnetic field were measured simultaneously at distances of 2.0 km (Pratt building of the University of Toronto), 16.8 km (Environment Canada Building), and 50.9 km (Grimsby, ON) from the CN Tower. Preliminary discussion on the current-field relation and propagation effects is also provided.