Ionospheric characteristics of low latitude anomaly zone over Indian region by ground based GPS, radio occultation and SPIM model predictions

The present paper deals with investigation of ionospheric electron density over low latitude Indian region from seven ground based dual frequency global positioning system (GPS) stations across Indian region. The electron density in terms of total electron content (TEC) is estimated from the parameters of GPS observation at different locations and compared with international GNSS service global ionosphere map (GIM) as well as standard international reference ionosphere (IRI) and standard plasmasphere-ionosphere model (SPIM) predictions for both geomagnetic quiet and disturbed periods.