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Cross modulation of VLF and LF waves by gravity waves
Author(s) -
Rumi G. C.
Publication year - 1983
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs018i005p00738
Subject(s) - amplitude , physics , ionosphere , amplitude modulation , modulation (music) , very low frequency , specular reflection , absorption (acoustics) , nocturnal , phase (matter) , optics , computational physics , frequency modulation , geophysics , acoustics , telecommunications , radio frequency , astronomy , quantum mechanics , computer science
Some experimental data concerning amplitude and phase of two waves, one on 16 kHz and the other on 60 kHz, emitted in Rugby and received in Turin, are first presented. The amplitudes are affected by almost sinusoidal undulations; the oscillations of the 60‐kHz amplitudes are synchronous with those of the 16‐kHz amplitudes; furthermore, when the 60‐kHz amplitude increases, the 16‐kHz amplitude decreases in a specular fashion. This trend is explained in terms of a cross modulation imposed by traveling gravity waves that progressively modulate the ionization profile in the nocturnal D region of the ionosphere and hence affect the absorption of the VLF and LF waves. From this phenomenon, information about the lower tail of the nocturnal ionospheric D region can be obtained.