Very Low Frequency (VLF) radio waves propagate within the Earth-ionosphere
waveguide with very little attenuation. Modifications of the waveguide geometry affect the propagation
conditions, and hence, the amplitude and phase of VLF signals. Changes in the ionosphere,
such as the presence of the D-region during the day, or the precipitation of energetic particles,
are the main causes of this modification. Using narrowband receivers monitoring remote VLF
transmitters, the amplitude and phase of these signals are recorded. A multivariate data analysis
technique, Principal Component Analysis (PCA), is applied to the data in order to determine parameters
such as seasonal and diurnal changes which affect the variation of these signals. Data was
then analysed for effects from extragalactic gamma ray bursts, terrestrial gamma ray flashes and
solar flares. Only X-rays from solar flares were shown to have an appreciable affect on ionospheric
propagation. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2009.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/8323 |
| Date | January 2009 |
| Creators | Bremner, Sherry. |
| Contributors | Collier, Andrew B. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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