Spatiotemporal Analysis of Ionospheric Total Electron Content and Equatorial Plasma Bubbles over East Africa Based on GNSS Observations

Amsalu, Hundesa

dc.contributor.author	Amsalu, Hundesa
dc.date.accessioned	2026-08-18T07:41:52Z
dc.date.available	2026-08-18T07:41:52Z
dc.date.issued	2026-01
dc.identifier.uri	http://ir.bdu.edu.et/handle/123456789/17010
dc.description.abstract	This dissertation explores the spatiotemporal variations of ionospheric Total Electron Content (TEC) and the characteristics of Equatorial Plasma Bubbles (EPBs) over East Africa, based on a comprehensive analysis of global navigation satellite system (GNSS) TEC gathered from 2012 to 2016. Understanding these phenomena is essential for enhancing the accuracy of satellite-based navigation, communication, and positioning systems, particularly in regions like East Africa that are vulnerable to ionospheric disturbances. Employing Ordinary Kriging (OK), geostatistical interpolation technique, this research meticulously quanti es the spatial and temporal behavior of TEC across various geographic regions within Ethiopia. The results indicate signi cant diurnal variations, with TEC values consistently peaking around noon (approximately 12: 00 UT) and showing marked di erences across latitudes. For instance, northern regions often display elevated TEC levels compared to southern areas, highlighting a pronounced north-south gradient that aligns with variations in solar and geomagnetic in uences. In addition to TEC analysis, the study employs GNSS- derived parameters such as the Rate of TEC Index (ROTI) and slant TEC (sTEC) to characterize the occurrence and dynamics of EPBs during geomagnetically quiet conditions. The ndings reveal that EPB activity predominantly occurs between 17:00 and 22:00 UT, with peak occurrences aligned with equinox seasons. This pattern underscores the in uence of solar terminator alignment with the geomagnetic meridian, which facilitates the generation of EPBs through enhanced vertical plasma drift and subsequent Rayleigh-Taylor instability. Furthermore, the research establishes correlation between TEC variability and EPB occurrences, suggesting that increased TEC prior to sunset enhances the likelihood of EPB formation. The insights gained from this study contribute to a deeper understanding of equatorial ionospheric dynamics and the complex interactions between solar activity, geomagnetic conditions, and ionospheric structure. Overall, this dissertation not only advances the scienti c knowledge of ionospheric behaviors in East Africa but also emphasizes the e ectiveness of geostatistical modeling techniques in enhancing predictive capabilities for TEC variability and EPB dynamics. By providing a detailed analysis of these crucial phenomena, this work aims to support improved forecasting and mitigation strategies for the impacts of space weather on technological systems reliant on accurate ionospheric data	en_US
dc.language.iso	en_US	en_US
dc.subject	Physics	en_US
dc.title	Spatiotemporal Analysis of Ionospheric Total Electron Content and Equatorial Plasma Bubbles over East Africa Based on GNSS Observations	en_US
dc.type	Dissartation	en_US