The study of outer radiation belt dynamics has been ongoing for over 5 decades. Outer radiation belt
dropouts involve the rapid lost of electron fluxes at the main phase of a storm and subsequent recovery.
The characteristics of the dropouts are many and varied. This study examines the Geosynchronous
Earth Orbit (GEO) and the ionospheric responses during Stream Interface (SI) andMagnetic Cloud (MC)
events, using a combination of ground based and satellite instruments. SI- and MC-driven dropout events
were inspected from summary plots of the Synchronous Orbit Particle Analyser (SOPA) instruments from
the year 1996 to 2007. Comprehensive studies were done on six selected events. Analysis of the data
from the instruments indicate that SIs and MCs are important lost drivers with significant differences
in GEO and ionospheric environment. To validate the data and test for consistent response of the
events, the Superposed Epoch Analysis (SEA) technique was used. The ground based measurements also
revealed how the absorption peaks in the ionosphere correlated with dropouts and geophysical activity.
Ionospheric absorption during SI associated dropouts was enhanced for 5 < L < 6, while significant peaks
in ionospheric absorption extended to lower L during MC driven dropouts. Wave-particle interactions
and southward Interplanetary Magnetic Field (IMF-Bz) are apparent causes for the precipitation. This
analysis showed that, within the confines of the selected events, SI driven dropouts were more dominant
at the declining phase of the solar cycle while the MC driven dropouts were more dominant during solar
maximum. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/10442 |
| Date | January 2011 |
| Creators | Ogunjobi, Olakunle. |
| Contributors | Collier, Andrew B. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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