Ionospheric VLF waves and optical phenomena over active thunderstorms. Ph.D. Thesis
In 1987 and 1988, two campaigns, the Wave Induced Particle Precipitation campaign and the Thunderstorm 2 campaign, were conducted to investigate lightning-generated effects in the upper atmosphere and ionosphere. Two rockets (apogees 420km and 330km) and 6 balloons (float altitudes 30km) were launched near thunderstorms in these campaigns. Optical and electric signals from hundreds of lightning strokes were recorded by both the rockets and balloons. Using the data obtained in these two campaigns, the author has been able to study some problems about lightning-generated VLF waves in the ionosphere which have not been well investigated previously. In this dissertation, the author reports the following: the downward-looking optical detector on the rocket recorded some anomalous characteristic optical phenomena which had not been reported previously. This study shows that they occurred above the balloon altitude (30km), and the results are interpreted in terms of discharges at high altitudes. The author studied the relation between the amplitude of lightning-generated VLF waves in the ionosphere and the lightning current recorded by the SUNYA lightning network. This study shows that the amplitude of waves at frequencies below 5 kHz has linear response to the lightning current. Above 5 kHz, there is not a significant linear correlation between the wave amplitude and the lightning current. The author has been able to determine the propagation path of the lightning-generated VLF waves from the source to the rocket. The path is consistent with the leaky waveguide hypothesis in which waves travel in the waveguide to the vicinity of the rockets, and then propagate vertically through the ionosphere. The author has found that the amplitude of lightning generated VLF waves have maxima and minima at different altitudes instead of being attenuated monotonically with altitude as expected.
- Research Organization:
- Washington Univ., Seattle, WA (United States)
- OSTI ID:
- 237299
- Report Number(s):
- N-96-22528; NIPS-96-07451; TRN: 9622528
- Resource Relation:
- Other Information: TH: Ph.D. Thesis; PBD: Jan 1993
- Country of Publication:
- United States
- Language:
- English
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