Characteristics of nearby lightning discharges observed at Singapore

Abstract

An analysis is performed of the parameters of nearby lightning discharges. Vertical electric and two perpendicular horizontal magnetic field components were recorded in the frequency range from 300 Hz to 13 kHz. Observations were performed at Singapore on 26 February, 1991. Data were stored in the ‘Elektronika-85’ computer memory that worked with a sampling frequency of 100 kHz. The source bearing was obtained using the horizontal components of the Poynting vector. These were calculated from the field components of the pulse signal directly in the time domain. The source distance was also estimated using the phase spectra of the wave impedance. Six events were chosen for the final processing that originated from predominantly vertical strokes observed visually during the data acquisition. Coordinates deduced from the electromagnetic records agree with the visual observations. Spectra of the current moments of the strokes were calculated from the records after the source distance was established. Experimental results are compared with the model representations for median return stroke.