Diurnal and seasonal variation of GPS-TEC during a low solar activity period at EIA region (Bhopal)

The ionosphere near the equatorial ionization anomaly crest region in the Indian ionospheric sector was studied from May 2016 to April 2017, a solar minimum period. Total electron content (TEC) recorded using the multiple frequency GPS receivers at Bhopal (23.2° N, 77.4° E & MLAT 14.2° N) is used for the study. The diurnal variation shows that the day minimum in TEC is attained around 06:00 hours LT, and the day maximum occurs at about 16:00 hours LT. A similar diurnal pattern was observed in all months across various seasons. During the period of study, it was observed that Seasonal variation of TEC was minimal in winter, whereas highest during equinox and summer months. The variation of TECmax with EEJ shows a positive correlation between the parameters for all the months. The highest correlation (0.8398) was observed in January 2017, while it was lowest (0.4004) in March 2017 and the results were compared with earlier observations, and a possible mechanism was discussed.