Comparison of VTEC due to GPS and assimilation of the IRI-Plas model during a geomagnetic storm condition over Indian region

Ionosphere is one of the largest sources of error for single frequency GNSS (Global Navigation Satellite Systems) users. The IRI-Plas is the widely used ionospheric and plasmaspheric climatic model for estimating VTEC (Vertical Total Electron Content) globally. This paper focuses on the performance of the IRI-Plas-2017 model with ingestion of GIM-TEC (Global Ionospheric Maps) input option at two low latitude stations, Hyderabad (Lat:17.2°N; Lon:78.5°E) and Bangalore (Lat: 12.9°N; Lon: 77.6°E) over the Indian region. The predicted TEC due to the model is compared with GPS TEC (Global Positioning System).The analysis is carried out for 7^th, 8^th and 9^th September 2017 (Pre storm, Storm and post storm days). In this work, Symmetric Kullbacke Leibler Distance (SKLD), Cross Correlation (CC) coefficient and the metric norm (L2N) methods are used to evaluate the performance of IRI-Plas-TEC (with and without TEC input) with GPS TEC. From the results it is observed that TEC predicted by the assimilation option produced smaller estimation errors and substantial improvement of the model performance for ionospheric disturbances.