Study of the ionospheric scintillation and TEC characteristics at solar minimum in a West African equatorial region using Global Positioning System (GPS) data

Ionospheric scintillation is a rapid variation in the amplitude and phase of trans-ionospheric radio signal resulting from density irregularities in the ionosphere. It is referred to us by the index S4. The data used are the scintillation index (S4) and the vertical TEC (VTEC) recorded at the SCINDA (Scintillation Network Decision Aid) GPS station of Abidjan (Latitude = 5.34° N, Longitude = 3.90° W). This work covers the period from January 2008 to January 2009, two years of low solar activity with R12 equal to 2.8 and 4.2 respectively. The results show that the scintillation is not intense with S4 values lower than 1 in most of the cases and during the course of the day. However, from 2000 to 0200 there are relatively high values of S4 confirming that scintillation is primarily a nighttime observed phenomenon. The scintillation shows a seasonal effect characterized by intense value in the equinoctial months compare to that of the solstice season. The VTEC in general exhibits a diurnal variation as a function of the solar zenith angle. Higher VTEC values are observed around 1100 and 1800 local time and have the same seasonal variation with the S4 index.