On the Estimation of the Ionospheric Exit Regions of Magnetospheric VLF Radio Waves by the Use of Wave Energy Distribution in Wave Number Space
A new ground-based direction finding technique is proposed to estimate the ionospheric exit regions of magnetospheric VLF waves on the basis of wave energy distribution of those waves in wave number space which is evaluated by means of maximum entropy concept. This method is essentially different from the previous direction finding techniques by which the wave normal direction of an equivalent plane wave can be estimated. The solution by maximum entropy method, however, depends on the inversion model, or on the wave polarization included in the integration kernels, because TE- and TM-mode waves can independently propagate in free space. In this paper, the effectiveness and dependence of maximum entropy solutions on the inversion model are discussed for the investigation of the ionospheric transmission and magnetospheric propagation mechanisms of magnetospheric VLF waves.
KeywordsMaximum Entropy Method Polarization Model Inversion Model Spectral Matrix Wave Number Space
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- Hayakawa, M., Y. Tanaka, T. Okada and J. Ohtsu, Time scales for the formation, lifetime and decay of low latitude whistler ducts, Ann. Geophysicae, 1, 515, 1983.Google Scholar
- 9] Lefeuvre, F. and C. Delannoy, Analysis of random electromagnetic wave field by a maximum entropy method, Ann. Telecomm., 34, 204, 1979.Google Scholar
- Ohta, K. and H. Eguchi, The automatic observation of the polarization of whistlers at low latitudes, Trans. Inst. Electr. Comm. Engrs. Japan, J69-B, 967, 1986.Google Scholar
- Rycroft, M. J., Whistlers and discrete VLF/ELF emissions, in “ELF-VLF Radio Wave Propagation” ed. by J. A. Holtet, p.317, D. Reidel, 1974.Google Scholar
- 18] Shimakura, S., Study on signal analysis and estimation of the ionospheric exit regions of whistler waves, Doctoral thesis, Nagoya University, 1987.Google Scholar
- Shimakura, S. and M. Hayakawa, On the estimation of wave energy distribution of magneto- spheric VLF waves at the ionospheric base with ground-based multiple electromagnetic field components, Proc. Chapman Conf. on Plasma Waves and Instabilities in Magnetospheres and at Comets, Sendai, p. 238, 1987.Google Scholar
- 20] Shimakura, S., H. Suzuki, M. Hayakawa, F. Lefeuvre and D. Lagoutte, On the estimation of wave energy distribution of magnetospheric VLF waves at the ionospheric base with ground- based multiple electromagnetic field components, to be submitted to Planet. Space Sci., 1990.Google Scholar
- 21] Storey, L. R. O. and F. Lefeuvre, Analysis of a wave field in a magnetoplasma, 1. The direct problem, Geophys. J. Roy. Astron. Soc., 56, 255, 1979.Google Scholar