Ionospheric TEC variations during the ascending solar activity phase at an equatorial station, Uganda

The total electron content (TEC) is a vital and most dominant ionospheric parameter that can cause Global Positioning System (GPS) signal delays, signal degradation and in extreme cases loss of lock. This results into inefficient operations of ground and space based Global Navigation Satellite Syste...

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Bibliographic Details
Published in:Indian journal of radio & space physics 2013-02, Vol.42 (1), p.7-17
Main Authors: Oron, S, D'ujanga, F M, Ssenyonga, T J
Format: Article
Language:English
Subjects:
Global navigation satellite system
Global Positioning System
GNSS
Ionospherics
Latitude
Longitude
Scintillation
Solar activity
Stations
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Summary:The total electron content (TEC) is a vital and most dominant ionospheric parameter that can cause Global Positioning System (GPS) signal delays, signal degradation and in extreme cases loss of lock. This results into inefficient operations of ground and space based Global Navigation Satellite System (GNSS) applications. The study of TEC variability is, therefore, useful for GNSS users in order to minimize errors where high levels of accuracy in measurements are required. This paper presents the diurnal, seasonal and solar activity dependence of TEC at the GPS-SCINDA (ScIntillation Network Decision Aid) station in Kampala, Uganda (geographic coordinates: latitude 0.3[degrees]N, longitude 32.6[degrees]S; and geomagnetic coordinates: latitude -9.3[degrees], longitude 104.2[degrees]) for the years 2010 and 2011. The results obtained show that the diurnal variability in TEC at this station has a pre-dawn minimum followed by an early morning steady increase, an afternoon maximum and then a post sunset gradual reduction in TEC, with the equinoctial months depicting nighttime enhancements more prominently at around 2000 hrs UT (2300 hrs LT). Scintillation occurrence, a consequence of TEC fluctuations, was observed from about 1800 hrs UT (2100 hrs LT) to local midnight giving S sub(4) index values above 0.4, with the equinox months recording higher occurrences than other seasons. TEC variations were also seen to exhibit solar activity dependence. The sunspot numbers and the F10.7 solar flux exhibited a good correlation with TEC recorded over the two years.
ISSN:0367-8393