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Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 35, 701-710, 2017
https://doi.org/10.5194/angeo-35-701-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Regular paper
06 Jun 2017
Studying the variability in the diurnal and seasonal variations in GPS total electron content over Nigeria
Victor Adetayo Eyelade1, Adekola Olajide Adewale2, Andrew Ovie Akala2, Olawale Segun Bolaji2, and A. Babatunde Rabiu1 1Centre for Atmospheric Research, National Space Research and Development Agency, Anyigba, Nigeria
2Department of Physics, Faculty of Science, University of Lagos, Akoka, Lagos State, Nigeria
Abstract. The study of diurnal and seasonal variations in total electron content (TEC) over Nigeria has been prompted by the recent increase in the number of GPS continuously operating reference stations (CORSs) across Nigeria as well as the reduced costs of microcomputing. The GPS data engaged in this study were recorded in the year 2012 at nine stations in Nigeria located between geomagnetic latitudes – 4.33 and 0.72° N. The GPS data were used to derive GPS TEC, which was analysed for diurnal and seasonal variations. The results obtained were used to produce local GPS TEC maps and bar charts. The derived GPS TEC across all the stations demonstrates consistent minimum diurnal variations during the pre-sunrise hours 04:00 to 06:00 LT, increases with sharp gradient during the sunrise period (∼ 07:00 to 09:00 LT), attains postnoon maximum at about 14:00 LT, and then falls to a minimum just before sunset. Generally, daytime variations are found to be greater than nighttime variations, which range between 0 and 5 TECU. The seasonal variation depicts a semi-annual distribution with higher values (∼ 25–30 TECU) around equinoxes and lower values (∼ 20–25 TECU) around solstices. The December Solstice magnitude is slightly higher than the June Solstice magnitude at all stations, while March Equinox magnitude is also slightly higher than September Equinox magnitude at all stations. Thus, the seasonal variation shows an asymmetry in equinoxes and solstices, with the month of October displaying the highest values of GPS TEC across the latitudes.

Citation: Eyelade, V. A., Adewale, A. O., Akala, A. O., Bolaji, O. S., and Rabiu, A. B.: Studying the variability in the diurnal and seasonal variations in GPS total electron content over Nigeria, Ann. Geophys., 35, 701-710, https://doi.org/10.5194/angeo-35-701-2017, 2017.
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The study examined the diurnal and seasonal variations in total electron content (TEC) over Nigeria. The derived GPS TEC across all the stations demonstrated consistent minimum diurnal variations during the pre-sunrise hours, increased with a sharp gradient during the sunrise period, attained a postnoon maximum at about 14:00 LT, and then fell to a minimum just before sunset. The seasonal variation depicted a semi-annual distribution with higher values around equinoxes than solstices.
The study examined the diurnal and seasonal variations in total electron content (TEC) over...
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