The free electron content of the Earth's ionosphere plays an important role in com­ munication and navigation systems. On the other hand, ionospheric electron density irreguli1rities can hamper communication technology applications through scintilla­ tion (rapid and random fluctuation in the amplitude and phase of signals) effects. This suggests the need for research into the prediction of the ionospheric variabil­ ity and the various phenomena that affect it. In this thesis, ground magnetometer data of the geomagnetic field horizontal (H) intensity from a location (Addis Ababa: 9.02 o N, 38.77 o E geographic, magnetic dip O.l7oE, and Adigrat: 14.28°N, 39.46°E ge­ ographic, magnetic dip 6 0 E) have been used to determine the EEJ strength at the electrojet zone (Addis Ababa). Further, vertical total electron content (vTEC) and amplitude scintillation intensity (54) from a dual frequency GPS receiver which is situated at Addis Ababa (within the electrojet zone) and functional under the inter­ national SCINDA program of the US Air Force have been utilized to examine the time variations of (vTEC) and 54 in relation to the variations in the EEJ strength. Relations between the variables have been dictated through correlation analysis by taking peak values of EEJ on geomagnetically quiet days during August to November 2008. A negative or less correspondence between EEJ and the variables 54 and vTEC has been observed over the Ethiopian electrojet station, Addis Ababa.