Influence of the Severe Geomagnetic Activity over the Performance of the Real-Time Global Ionosphere Maps

The severe geomagnetic activities pose significant affect in modification of the electron concentrations of the ionospheric layer, especially along the equatorial and polar regions, causing challenging environments considering positioning perspectives. The recent availability of the Real-Time Global Ionosphere Maps (RT-GIMs) by some specialized IGS associated analysis centers such as Centre National d’Etudes Spatiales (CNES), Chinese Academy of Sciences (CAS), Universitat Politècnica de Catalunya (UPC), and Wuhan University (WHU), provides exciting opportunity to comprehend the ionospheric modification under these geomagnetic influences in real-time, while the RTGIMs can be integrated to the real-time precise point positioning (RT-PPP) to reduce the convergence time. Therefore, we perform the accuracy evaluation of these RT-GIM under the presence of a severe G-4 class geomagnetic storm during the year 2024. The performance of these RT-GIM products is evaluated by comparing the RT-GIM vertical Total Electron Content (VTEC) values with Final GIMs provided by Center for Orbit Determination in Europe (CODE) over land and Jason-3 altimetry satellite over oceans. The CNES RT-GIMs undergoes severe accuracy degradation across all continents recording a significant -20 to -40 TECU bias offset compared to the final CODE GIMs (CODGs) during the main phase of the geomagnetic storm. Similarly, the performance of the WHU RTGIMs sightly deteriorates upto -10 TECU along the equatorial, south pacific, and south pole regions. However, CAS and UPC RT-GIMs show a relatively consistent performances during the initial and main phase of the severe geomagnetic storm. However, during the final phase of the geomagnetic storm, both WHU and CAS RTGIMs exhibit overperformances of more than 10 TECU over the Antarctica compared to the final CODGs. Additionally, on the comparison with the Jason-3, the CNES and WHU RTGIMs shows worst performances once again with the average deviations of 10-15 TECU over the oceans during the high intensity period of the geomagnetic storm. Meanwhile, UPC RT-GIM remain the most consistent and stable performer (both, globally and over oceans) that provides accurate global ionospheric information, almost similar to the final GIMs, which is promising for their applications in real-time precise GNSS positioning.