Statistical analysis of VLF radio emissions triggered by power line harmonic radiation and observed by the low-altitude satellite DEMETER
Abstrakt
DEMETER was a low-altitude satellite in operation between 2004 and 2010 in a circular polar orbit. One of its main scientific objectives was to study ionospheric perturbations related to man-made activity.
This paper investigates electromagnetic emissions triggered by Power Line Harmonic Radiation (PLHR), the man-made waves emitted at harmonics of 50 or 60 Hz. They look like rising tones or hooks with a starting frequency associated to a parent line with the frequency equal to a multiple of 50 or 60 Hz.
They occur preferentially during daytime in a frequency band between 1 and 4 kHz. It is shown that these emissions are rather frequent at high latitudes (3 < L < 6) above industrialized areas during periods of moderate magnetic activity.
Their average intensity is of the order of 10 mu V-2 m(-2) Hz(-1). PLHR propagates in the magnetosphere and triggers emissions due to wave-particle interactions in the equatorial region.