FDTD Analysis of ELF Wave Propagation in Inhomogeneous Subionospheric Waveguide Models
Keywords:
FDTD Analysis of ELF Wave Propagation in Inhomogeneous Subionospheric Waveguide ModelsAbstract
The space formed by the ground and ionosphere is known to act as a resonator for extremely low frequency (ELF) waves. Lightning discharges trigger this global resonance, which is known as Schumann resonances at the frequencies of 8, 14, 21Hz etc. Even though the inhomogeneity (like day-night asymmetry, local perturbation etc.) is important for such subionospheric ELF propagation, the previous analyses have been always made by some approximations because the problem is too complicated to be analyzed by exact full-wave analysis. This paper presents the first application of the conventional FDTD method to such subionospheric ELF wave propagation, in which any kinds of inhomogeneities can be included in the analysis, to be compared with the observational results. We show the application of FDTD to our problem and present a few numerical computational results to be compared with those by the pre-existing analysis method.
Downloads
References
E. R. Williams. The Schumann resonance: A
global tropical thermometer. Science, 256,
-1187, 1992.
D. J. Boccipio, E. R. Williams, S. J. Heckman,
W. A. Lyons, I. T. Baker and R. Boldi. Sprites,
ELF transients, and positive ground stroke.
Science, 269, 1088-1091, 1995.
J. R. Wait. Electromagnetic Waves in Stratified
Media. Perganion Press, Oxford, 1962.
J. Galejs. Terrestrial Propagation of Long
Electromagnetic Waves. Pergamon Press,
Oxford, 1972.
P. V. Bliok, A. P. Nikolaenko and
Yu. F. Filippov, Schumann Resonances in the
Earth-Ionosphere Cavity, Peter Pergrinus Ltd.,
W. O. Schumann. On the radiation free self-
oscillations of a conducting sphere, which is
surrounded by an air layer and an ionospheric
shell [in German]. Zeitschrift fur
Naturforschung, 7, 149-154, 1952.
T. Madden and W. Thompson. Low frequency
electromagnetic oscillations of Earth-
ionosphere cavity. Rev. Geophys., 3, 211-254,
A. P. Nickolaenko and M. Hayakawa,
Resonances in the Earth-Ionosphere Cavity,
Kluwer Academic Publishers, Dordrecht, 2002.
R. Holland. THREDS: A finite-difference time-
domain EMP code in 3D spherical coordinates IEEE Trans. Nuclear Science, NS-30(6), 4592-
, 1983.
D. D. Sentman. Schumann resonances. In
Handbook of Atmospheric Electrodynamics, Ed.
by H. Volland, vol. 1, 267-310, CRC Press,
A. P. Nickolaenko and M. Hayakawa. Natural
electromagnetic pulses in the ELF range.
Geophys. Res. Lett., 25(16), 3103-3106, 1998.
A. P. Nickolaenko, M. Hayakawa,
I. G. Kudintseva, S. V. Myand and
L. M. Rabinowicz. ELF sub-ionospheric pulse
in time domain, Geophys. Res. Lett., 26(7),
-1002, 1999.
C. E. R. Bruce and R. H. Golde. The lightning
discharge. J. Inst. Electr. Eng., 88, 487, 1941.
C. Greifinger and P. Greifinger. Approximate
method for determining ELF eigenvalues in the
earth-ionosphere waveguide. Radio Science, 13,
, 1978.
V. C. Mushtak and E. R. Williams. ELF
propagation parameters for uniform models of
the Earth-ionosphere waveguide. J. Atmos.
Soler-terr. Phys., 18, 1989-2001, 2002.
K.Kunz and R.J. Luebbers. The Finite
Difference Time Domain Method for
Electromagnetics, CRC Press, Boca Raton,
USA, 1993.
