| dc.description.abstract | In the electron density distribution at the low-latitude ionosphere, equatorial electrodynamics plays a critical role such as forecasting the dynamics and fluctuations of ionospheric plasma densities. The equatorial electrojet (EEJ) and the equatorial ionization anomaly (EIA) are two major phenomena of equatorial electrodynamics. Studies have been carried out on the strength of EEJ as well as the EIA. However, the following gaps still exist: most studies have been done in Indian and American regions during maximum solar years; yet ionospheric dynamics have a dependence on the longitude; correlations have also not been done during both geomagnetically quiet and disturbed conditions. The correlation between EEJ and EIA was required since EEJ is one of the systems that lift plasma in equatorial regions, causing Equatorial Ionization Anomaly, which suggests a connection between EEJ and EIA. Since it is necessary to get a complete picture during both geomagnetically quiet and disturbed conditions, therefore, the problem of the study is that strong scintillations affect communication and navigation systems. Thus, there is a need to investigate the relationship between EEJ and EIA since they are important for ionospheric space weather and also this will help the development of models that can be used to forecast or nowcast scintillations. Based on the aforesaid knowledge gap the problem of this study is on EEJ's impact on the development of the EIA during the low solar activity period over the East African region. Based on this problem the objectives of the study were (i) To determine the strength of EEJ, (ii) To quantify the strength of EIA and (iii) To analyze the correlation between EEJ and EIA. This study used a pair of International Real-time Magnetic Observatory Network (INTERMAGNET) magnetometers located in Addis Ababa (geographic 9.05°N, 38.76°E, geomagnetic 0.16°N, 110.45°E), the African Meridian B-field Education and Research (AMBER) station in Adigrat (geographic 14.26°N, 39.45°E, geomagnetic 6.1°N, 111.04°E) both in Ethiopia and the total electron content (TEC) derived from a set of International Global Navigation Satellite System (GNSS) signals (IGS) receivers within the East African region. The data used during this period was for both geomagnetically disturbed and quiet conditions. The difference in the horizontal component of the geomagnetic field seen by two ground-based magnetometers was used to estimate the EEJ strength. In determining the EIA strength over the region, TEC over the crest to that above the trough was determined to be in a certain ratio. The peak value of EEJ is 110nT and it occurs between 10:00 and 14:00 LT for geomagnetically quiet conditions. This is due to the high rate of photoionization during this period. These variations in the amplitude of EEJ with time and months is attributed to the monthly movement of the Sq foci northward and equatorward in a given year. The EIA’s peak during geomagnetically quiet days is 1.45 and it was recorded between 20:00 – 22:00LT while the peak of EIA during geomagnetically disturbed days is 1.2 and it occurred at 20:00LT. The correlation coefficients were found to vary from moderate to strongest during geomagnetically quiet conditions, ranging from 0.58 to 0.74. During geomagnetically disturbed conditions, the correlation coefficient ranges from 0.28 to 0.45. The significant linear link between EEJ and EIA is caused by the independent increase in the eastward electric field and photo-ionization on TEC. Most panels showed that the ratio of Crest (CT) to trough (TEC) > 1. This research presents patterns in the EEJ and EIA strength over East Africa during the solar minimum period. Since EEJ and EIA influences the occurrence of ionospheric irregularities which in turn lead to scintillations of communication and navigation signals, we recommend simultaneous analysis of EEJ, EIA and scintillation data. This would reveal the influence of EEJ and EIA on the occurrence of scintillations. | en_US |
