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Abstract:
The accuracy and precision of the Global Navigation Satellite Systems (GNSS) based positioning can be degraded by sudden and significant ionospheric disturbances. The various indices can characterize the temporal and spatial changes of the ionospheric state. For instance, the Gradient Ionospheric indeX (GIX) provides the magnitude of the total electron content (TEC) spatial gradients. On the other hand, the Sudden Ionospheric Disturbance indeX (SIDX) or the Rate Of Tec Index (ROTI) describes the temporal changes of TEC. The knowledge of distinct capabilities and characteristics of indices can help choosing the right index for an application and thus may guarantee adequate safety for GNSS-based systems.In this study, we present how GIX, SIDX, and ROTI indices differ during the severe geomagnetic storm on 17th March 2015 and how their magnitude and variations are related to the GNSS precise positioning. We focused on absolute and differential positioning approaches, and code pseudorange and carrier phase-based results. Our analyses were conducted for selected GNSS stations located at different latitudes and regions in Europe and South America. We also discuss the advantages and drawbacks of the indices and their potential use for highly accurate positioning.
