Bulg. J. Phys. vol.38 no.2 (2011), pp. 206-215

Effects of Solar Eclipse on Long Path VLF Transmission

S.S. De1, B.K. De2, B. Bandyopadhyay1, S. Paul1, S. Barui1, D.K. Haldar1, M. Sanfui1, T.K. Das1, G. Chattopadhyay1, P. Pal3
1Centre of Advanced Study in Radio Physics and Electronics, University of Calcutta 1, Girish Vidyaratna Lane, Kolkata 700 009, India
2Department of Physics, Tripura University, Tripura (West), Suryamaninagar 799 130, India
3Department of Physics, M. B. B. College, Agartala 799 004, Tripura, India
Abstract. The variations of phase and amplitude of a subionospheric transmitted signal at frequency 19.8 kHz from North West Cape, Australia (latitude: 21.82oS; longitude: 114.16oE) measured at Kolkata (latitude: 22.56oN, longitude: 88.5oE) during the period of solar eclipse (partial, 91.1%) on July 22, 2009 will be presented in this paper. The variations in amplitude are quite significant than the usual ambient values of the adjacent 5 days of the day of eclipse for the same period. During eclipse, the height of reflection of VLF (very low frequency) signal has been increased by 3 km. The conductivity parameter and the sharpness parameter are calculated using phase and amplitude variation of VLF signal. Plausible explanations of these changes in amplitude and phase are presented. The waveguide parameters, viz., conductivity parameter (ωr) and sharpness parameter (β) related to VLF propagation in the Earth-ionosphere waveguide are considered to be responsible for signal attenuation.

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