Oblique Heating of the Auroral Ionosphere by LF/MF Transmitters,
ROYAL AEROSPACE ESTABLISHMENT FARNBOROUGH (UNITED KINGDOM)
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The paper describes the generation of ELF signals due to oblique heating of the auroral ionosphere by signals from ELF modulated LFMF radio transmitters. Apart from signals of natural origin, timing signals six pips which occurred on the hour were received. The pips of frequency 1 kHz, duration 1 05 ms and field strength -0.1 pT exhibit a favoured source location -1 50 km south-southeast of Sodankyla. The pips are shown to occur only when there is significant local magnetic activity and when the auroral electrojet is enhanced. The originating signals are demonstrated to be of Soviet origin and due to LFMF broadcast transmitters several hundred kilometers away from the ELF source location. Various mechanisms which could account for a localised generation region far from the transmitters are discussed. The favoured mechanism involves in-phase heating due to two or more transmitters.
- Atmospheric Physics
- Radiofrequency Wave Propagation