Effects of propagation on the rise times and the initial peaks of radiation fields from return strokes

Abstract

The theoretical solution to the problem of radiation from a pulsed vertical dipole over a flat homogeneous earth is employed to study the changes in rise times and the attenuation of the initial peaks of the radiation fields from lightning constructed according to the most recent experimental data on lightning return stroke radiation fields. Expected changes in rise times and the attenuation of the initial peaks for different values of distances and conductivities are presented. It is shown that for a given initial rise time there is a spread in distant rise times due to the variability of the shapes of the radiation fields. The expected spread in distant rise times for different values of distances and conductivities is calculated. The results show the importance of taking into account the propagation effects in any attempt to estimate return stroke current parameters such as rise time, rate of rise, and peak current from radiation fields which propagated over land. The predictions are compared with the available experimental data, and a good agreement is found between them.

Wavelet analysis of lightning return stroke

“…Knowledge about the frequency spectrum is also important once it is known to be related to electric field waveform used to locate lightning and analyze its properties. For example, it is well known that the high-frequency content is attenuated due to propagation effects resulting in attenuation of electric field waveform amplitude (Uman et al, 1976;Lin et al, 1979;Krider, 1980, 1984;Cooray and Lundquist, 1983). To understand lightning some studies in the frequency domain have been done (e.g.…”

FDTD simulation of LEMP propagation over lossy ground: Influence of distance, ground conductivity, and source parameters

“…A number of approximate expressions in both frequency and time domains have been used [e.g., Cooray and Lundquist, 1983;Cooray, 1992Cooray, , 2002Rubinstein, 1996;Shoory et al, 2005;Barbosa and Paulino, 2007] to account for the field propagation effects. Recently, the finite difference time domain (FDTD) method [Yee, 1966] for solving Maxwell's equations has been used in studying lightning electromagnetic pulses (LEMPs) at close and far distances with the propagation path being over lossy ground [e.g., Baba and Rakov, 2014].…”

Propagation effects on radiation field pulses generated by cloud lightning flashes

“…Most of the available studies on the propagation effects on lightning generated electromagnetic fields are confined to the case of lightning flashes striking flat ground (Uman et al, 1976;Gardner, 1981;Cooray and Lundquist, 1983;Le Vine et al, 1986;Cooray, 1987;Cooray and Ming, 1994;Cooray and Perez, 1994;Ming and Cooray, 1994;Cooray et al, 2000;Cooray, 2005;Cooray et al, 2005;Pavenello et al, 2005). These studies, the subject matter of which was confined to return strokes, were motivated by the importance of furthering the knowledge of propagation effects in research work related to (a) the remote sensing of lightning parameters, (b) the interaction of lightning generated electromagnetic fields with power lines and electrical installations and (c) the location of lightning flashes through magnetic bearings and time of arrival techniques.…”