Electron density fluctuations from Swarm as a proxy for ground-based scintillation data: A statistical perspective

The Swarm satellite mission has been used for numerous studies of the ionosphere. Here we use a global product, based on electron density measurements from Swarm that characterises ionospheric variability. The IPIR (Ionospheric Plasma IRregularities product) provides characteristics of plasma density structures in the ionosphere, of plasma irregularities in terms of their amplitudes, gradients and spatial scales and assigns them to geomagnetic regions. Ionospheric irregularities and fluctuations are often the cause of error in position, navigation, and timing (PNT) based on Global Navigation Satellite Systems (GNSS), in which signals pass through the ionosphere. IPIR dataset also provides an indication, in the form of a numerical value index (IPIR index), on their severity for the integrity of trans-ionospheric radio signals and hence, the accuracy of GNSS positioning.

We analysed two datasets from Swarm A and from ground-based scintillation receivers. Time intervals when Swarm A passes over the field of view of the ground-based GPS receiver are compared to ground-based scintillation data, collecting an azimuthal selection of the GNSS data relevant to the Swarm satellite overpass. We provide validations of the IPIR product against the ground-based measurements from 23 ground-based receivers, focusing on GPS TEC and scintillation data in low, auroral and polar regions, and in different longitudinal sectors. We have determined median, mean, maximum and standard deviation of a parameter’s values, for both datasets, for each conjunction point and observe a weak trend of stronger scintillations with an increasing IPIR index.

This work was carried out in the framework of the ISWAT group "Ionospheric Plasma Irregularities and Their Impact on Trans-ionospheric Radio Waves" and reflects the effect of irregularities on the passage of trans-ionospheric signals. This work was supported by the Research Council of Norway grant number 267408, 275655 and it is a part of the 4DSpace Strategic Research Initiative at the University of Oslo. WJM and DK also acknowledge funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (ERC Consolidator Grant agreement No. 866357, POLAR-4DSpace)