Analysis of the Factors Affecting Ionospheric Total Electron Content in East Africa and Middle East

dc.contributor.advisorElfagd, Yitagesu (PhD)
dc.contributor.authorEshetu, Mulu
dc.date.accessioned2022-01-25T08:29:17Z
dc.date.accessioned2023-11-09T11:26:54Z
dc.date.available2022-01-25T08:29:17Z
dc.date.available2023-11-09T11:26:54Z
dc.date.issued2021-11-29
dc.description.abstractThe low latitude and equatorial ionospheric total electron content (TEC) variations are investigated using dual frequency GPS TEC data taken from 7 GPS stations in which 6 are found in East Africa and one is found in Saudi Arabia in the year of 2015. This GPS TEC data was used to study the diurnal, seasonal, geomagnetic and latitudinal variations of ionospheric TEC at these GPS stations as insu_cient research results of ionospheric variations are available for these areas. The results of the analysis showed that the ionospheric TEC undergoes diurnal, seasonal, geomagnetic (quiet and disturbed day) and latitudinal variations. With regard to the diurnal variation, the TEC value shows minimum at predawn and gradual increase with time of the day attaining a maximum in the afternoon and a gradual decrease after sunset. This is the result of photo ionization of the atmosphere due to the increased intensity of solar radiation during day. On the other hand during night electron loss processes (ion-electron recombination and electron attachment) dominate and the TEC value is decreased. The TEC value in March shows a very rapid decrease after sunset due to the high recombination rate that is proportional to the square of the high electron density in March. Moreover, the night time TEC value shows a secondary minima maxima near dawn which may be due to the Counter Electrojet (CEJ). The TEC value in the solstice months of June and December don't show plateau and secondary maxima. It simply increase till noon and then decreases slowly during afternoon and during night. The seasonal variation is caused by the relative position of the Earth with the sun which changes the solar zenith angle. The greatest TEC value occurred in the equinoctial month of March and the least occurred during the winter solstice month of December and intermediate TEC value is recorded in summer solstice month of June. The e_ects of geomagnetic storms on TEC values have been also considered in this study. The result reveals that the storm day TEC value is greater than the quiet day TEC value. This is due to the fact that high amount of solar particles reach the earth and there is more ionization during the storm period. The TEC value also vary with latitude. The highest TEC value is obtained for stations that are closer to the geomagnetic equator (MOIU in Kenya) in the southern hemisphere. This may be the result of the occurrence of highly radiation of the sun and the DEBK station in Ethiopia located around EIA crest region is due to the fountain e_ect. The least value of TEC is observed for stations far from the geomagnetic equator (SOLA in Saudi Arabia) which is located beyond the EIA region. Moreover, TEC value of January 3, 2015 (at perihelion) is greater than that of the July 3, 2015 (aphelion), 2015. For the future more research need on the perihelion and aphelion cases of ionospheric TEC.en_US
dc.identifier.urihttp://10.90.10.223:4000/handle/123456789/29624
dc.language.isoenen_US
dc.publisherAddis Ababa Universityen_US
dc.subjectTecen_US
dc.subjectIonosphereen_US
dc.subjectDiurnal Variationen_US
dc.subjectSeasonal Variationen_US
dc.subjectLatitudinalen_US
dc.subjectVariationen_US
dc.subjectGeomagnetic Storm Variationen_US
dc.subjectEquatorial Ionization Anomalyen_US
dc.subjectEast Africanen_US
dc.subjectLow Latitude /Equatorial Regionen_US
dc.subjectFountain Effecten_US
dc.titleAnalysis of the Factors Affecting Ionospheric Total Electron Content in East Africa and Middle Easten_US
dc.typeThesisen_US

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