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Equatorial ionospheric irregularities using GPS TEC derived index

2012; Elsevier BV; Volume: 92; Linguagem: Inglês

10.1016/j.jastp.2012.09.019

1879-1824

O.A. Oladipo, Torben Schüler,

Geophysics and Gravity Measurements

We have used the rate of change of TEC (ROT) derived fluctuation index to study irregularities in the ionosphere at Franceville in Gabon (Lat.= −1.63°, Long.=13.55°, Geomag. Lat.= −0.71°), an equatorial station in the African sector. Based on a preliminary study at two equatorial stations at different longitude an average ROTI index which gives the fluctuation level over half an hour at a particular station was put forward. This index eliminates the noise spikes or extreme value usually present in ROTI index estimate. The new index ROTIAVE was used to study ionospheric irregularity occurrence at Franceville. As far as we know, this is the first time irregularity occurrence study is being done at this station using GNSS data. The results obtained showed that ionospheric irregularity season at Franceville is from March to November and that there is a kind of minimum around June. Very low irregularities activity is also observed around January. Pre-midnight fluctuation is observed to be more pronounced at Franceville during the period studied.