Kriging‐based ionospheric TEC, ROTI and amplitude scintillation index ( <i>S</i> <sub>4</sub> ) maps for India
In this study, an attempt is made to develop regional ionospheric total electron content (TEC), rate of TEC index (ROTI) and amplitude scintillation index (S 4) maps using data from 26 dual-frequency global positioning system (GPS) receivers under GPS aided geo-stationary earth orbit augmented navigation programme over Indian region. One-minute spatial TEC maps are generated for the entire Indian region covering 65–100°E geographic longitudes, 5–40°N geographic latitudes with 2° × 2° grid separation using Kriging method. Also, the ROTI and amplitude scintillation index (S 4) maps for every 5 min are generated. The performance of the generated regional TEC maps is evaluated during a severe geomagnetic storm condition. Patterns of equatorial ionisation anomaly (EIA) TEC structures are investigated for St. Patrick's storm between the days 15 and 20 March 2015 with the generated TEC maps. The proposed TEC maps depict the northern crest of EIA features in latitudinal extent and TEC strength. The kriging method detects the suppressed and downshift of EIA features on 18 March 2015. The movement of plasma bubbles are analysed over Indian latitudes during the transition period of a geomagnetic storm on 17 March 2015.