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Validation of the Cooray‐Rubinstein (C‐R) formula for a rough ground surface by using three‐dimensional (3‐D) FDTD
Author(s) -
Li Dongshuai,
Zhang Qilin,
Liu Tao,
Wang Zhenhui
Publication year - 2013
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2013jd020078
Subject(s) - lightning (connector) , finite difference time domain method , rough surface , mathematics , root mean square , fractal , geometry , mathematical analysis , electric field , physics , optics , materials science , quantum mechanics , power (physics) , composite material
Abstract In this paper, we have extended the Cooray‐Rubinstein (C‐R) approximate formula into the fractal rough ground surface and then validate its accuracy by using three‐dimensional (3‐D) finite‐difference time‐domain (FDTD) method at distances of 50 m and 100 m from the lightning channel. The results show that the extended C‐R formula has an accepted accuracy for predicting the lightning‐radiated horizontal electric field above the fractal rough and conducting ground, and its accuracy increases a little better with the higher of the earth conductivity. For instance, when the conductivity of the rough ground is 0.1 S/m, the error of the peak value predicted by the extended C‐R formula is less than about 2.3%, while its error is less than about 6.7% for the conductivity of 0.01 S/m. The rough ground has much effect on the lightning horizontal field, and the initial peak value of the horizontal field obviously decreases with the increase of the root‐mean‐square height of the rough ground at early times (within several microseconds of the beginning of return stroke).