Diurnal phase and amplitude variations of 12.1 kHz Omega signal along the auroral zone

摘要

The diurnal and seasonal variations in the phase and amplitude of Omega radio navigation signal at 12.1 kHz band (from Aldra in Norway) received at Tjornes in Iceland are analyzed in order to know the propagation mode of the VLF wave signal in high latitudes for a better understanding of the behavior of the lower ionosphere. It is found that the diurnal variation of the VLF phase and amplitude is closely correlated with solar zenith angle. A rapid change of VLF phase shift and VLF amplitude occurs at the times of sunrise and sunset during magnetically quiet period.