Simulation of the propagation of lightning electromagnetic pulses in the Earth–ionosphere waveguide using the fdtd method in the 2‐D spherical coordinate system

• Published in: IEEJ transactions on electrical and electronic engineering Vol. 15; no. 3; pp. 335 - 339
• Main Authors: Yamamoto, Junya, Baba, Yoshihiro, Tran, Thang Huu, Rakov, Vladimir A.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-03-2020; Wiley Subscription Services, Inc
• Subjects: Computer simulation; Coordinates; Electric fields; Electrical resistivity; Electromagnetic pulses; FDTD method; Finite difference time domain method; Ionosphere; Ionospheric propagation; Lightning; lightning electromagnetic pulse; Mathematical analysis; Pulse propagation; Return strokes (lightning); spherical coordinate system; Spherical coordinates; Time domain analysis; Wave propagation; Waveforms
• ISSN: 1931-4973; 1931-4981
• DOI: 10.1002/tee.23060

The finite‐difference time domain (FDTD) method in the two‐dimensional (2‐D) spherical coordinate system was used to compute waveforms of vertical electric field on the ground surface at distances of 280, 450 and 958 km produced by negative lightning return strokes. The use of the FDTD method in the 2‐D spherical coordinate system allowed us to represent the Earth's curvature. Note that the flat‐ground approximation is inadequate beyond a distance of 300 km or so. The lightning source was represented by the modified transmission‐line model with linear current decay with height (MTLL model). The conductivity of the atmosphere was assumed to increase exponentially with height. Skywaves (reflections from the ionosphere) were identified in computed waveforms and used for the estimation of apparent ionospheric reflection height. It was found that our model better reproduces the electric field waveforms measured at distances of up to about 1000 km by Qin et al. (2017) than the flat‐ground model. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.