This is an investigation into the association between ionospheric absorption caused
by electron precipitation and ELF:3 Hz-3 kHz and VLF:3 kHz-30 kHz, chorus.
Ionospheric absorption was measured using the chain of riometers in Finland and
related to chorus events recorded simultaneously at SANAE (L=4.2), Antarctica. The
displacement in longitude of the Finnish riometers from SANAE’s conjugate point made
it impossible to establish a clear relationship between chorus and riometer absorption.
The diurnal variation of chorus has been established for the years 2002, 2004 and
2005 and it is shown that chorus can occur at any Local Time(LT) but has a well
defined maximum probability of occurring between 0800 LT to 0900 LT.
To study the occurrence of chorus automatically we have developed an Index of
ELF/VLF activity which enables us to identify chorus and distinguish it from other
emissions such as hiss and whistlers.
This index of VLF Activity was established by computing the standard deviation
of the VLF signal amplitude and it has been observed that the index is larger for the
chorus signature as opposed to the hiss which is low and does not vary widely due to
the hiss’ steady signal. This index is called ASD index of “VLF Activity”. / 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:10413/8311 |
| Date | January 2009 |
| Creators | Musumpuka, Remmy. |
| Contributors | Hughes, Arthur R. W., Collier, Andrew B. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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