1. 1st VarSITI General Symposium 6-11 June 2016 Albena, Bulgaria
On the Spatio-temporal Variation of GPS Measured Total Electron Content over Nigeria within Equatorial Ionospheric Anomaly Region
1A.B.Rabiu, 1V.A.Eyelade, 2O.S.Bolaji, 2A.O Adewale,
1Centre for Atmospheric Research, National Space Research & Development Agency, Anyigba, Nigeria.
2Department of Physics, University of Lagos, Akoka, Nigeria.
1st VarSITI General Symposium June Albena, Bulgaria

2. 1st VarSITI General Symposium 6-11 June 2016 Albena, Bulgaria
Introduction
TEC observed on ground has become a proxy for monitoring ionospheric responses to magnetic activity as well as Space Weather in general
Quantitative study of spatial distribution of TEC has been hindered over the years in Nigeria due to the lack of distributed GPS facility,.
Deployment of a network of Nigeria GNSS Reference Network (NIGNET) by the Nigerian Office of Surveyor General provides an essential foundation for this study
1st VarSITI General Symposium June Albena, Bulgaria

3. 1st VarSITI General Symposium 6-11 June 2016 Albena, Bulgaria
Main objectives
This paper examined the spatial and temporal variations of the ionospheric Total Electron Content (TEC) over Nigeria
a country within the equatorial ionospheric anomaly region,
using the GPS data obtained from 11 stations of the Nigeria GNSS Network (NIGNET) in the year 2012 during the ascending phase of solar activity.
1st VarSITI General Symposium June Albena, Bulgaria

4. Magnetic Equator over Africa
Broad range of magnetic equator over land
EIA width
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5. Distribution of the NIGNET Stations used for the Study
Geographic Latitude (degree N)
Geographic Longitude (degree E)
1st VarSITI General Symposium June Albena, Bulgaria

6. Geographic Longitude (degree E)
On NIGNET data
Geographic Latitude (degree N)
Geographic Longitude (degree E)
Primarily meant for land mapping and surveying
RINEX files were accessed and 1st used for ionospheric studies by Rabiu et al., (2014)
It’s a project fully supported by the Office of Surveyor General of the Federal Government of Nigeria (OSGoF)
1st VarSITI General Symposium June Albena, Bulgaria

7. Spatial variation of TEC at 07:00LT (Sunrise)
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8. Spatial variation of TEC at 17:00LT (about Sunset)
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9. Diurnal variation of TEC
across the latitudes
At different stations
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10. variation of noontime TEC across the Latitudes
an asymmetric semiannual pattern across the latitudes
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11. Semiannual variation of TEC
Uniform pattern at all stations irrespective of distance from the magnetic equator
Equinoctial maximum with minimum in solstices
Asymmetrical equinoctial maximum as March Equinox has greater value than September
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Conclusions
At sunrise at about 07:00 LT, TEC decreases westwards across all the latitudes.
at about sunset (around 17:00 LT), TEC decreases eastwards across all latitudes
This variability pattern is attributed to the changes in the ionization in consistency with phot-ionization theory due to the relative motion of the earth and the Sun.
Generally, daytime values of TEC are observed to be greater than the nighttime values
Daytime TEC value is found to be consistently weakest at sunrise and maximized between 1200 & 1400 LT across all latitudes
Seasonal variation with semiannual pattern gave equinoctial maximum across all latitudes
1st VarSITI General Symposium June Albena, Bulgaria

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Acknowledgements
The GPS RINEX data were obtained from Office of the Surveyor General of the Federal Government of Nigeria, which is the mapping agency of Nigeria responsible for operation and maintenance of the Nigerian GNSS reference network NIGNET CORS
Dr. Gopi Krishna Seemala and the Institute for Scientific Research, Boston College, Boston, MA, USA for making the GPS- TEC analysis software available
1st VarSITI General Symposium June Albena, Bulgaria

14. Thank You