Reproduction of electromagnetic field waveforms and tower currents associated with return strokes struck Tokyo Skytree

Abstract

Observation of lightning current by using Rogowski coils started in February 2012 at Tokyo Skytree, which is a 634-m high freestanding broadcasting tower. Electromagnetic field waveforms are also observed by capacitive antennas at several tens of kilometers from the tower. Lightning current and electric field waveforms simultaneously observed in May 2012 are reproduced by using an electromagnetic model of a return stroke with the help of NEC-4. Observed lightning current waveforms are well reproduced by modeling the tower with small number of thin wires. Electromagnetic field waveforms also are reproduced by an inclined lightning channel model reconstructed from still photographs.