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Description
The ionosphere is a complex plasma medium characterised by electron density fluctuations spanning a wide range of spatial and temporal scales. Its dynamics are determined by complex interactions with the magnetosphere, solar wind, and thermosphere, forming a tightly coupled system. These external and internal factors cause variability that is often nonlinear and anisotropic, making it difficult to model the behaviour of the ionosphere. Achieving a realistic representation of ionospheric processes at all scales remains a key challenge for understanding the full range of interactions between the magnetosphere-ionosphere-thermosphere coupling.
Swarm is the Earth Observation mission of the European Space Agency (ESA) that consists of three identical satellites operating in Low Earth Orbit. Within the Swarm-VIP-Dynamic project, a set of data-driven statistical models has been constructed using Swarm measurements alongside heliogeophysical proxies. These models characterise ionospheric electron density and its variability across different geophysical regions (including polar, auroral, midlatitude, and equatorial regions), capturing plasma fluctuations at spatial scales between 100 km and 7.5 km. This multi-scale modelling framework provides new insights into the spatial structure and dynamics of ionospheric variability.
All three final versions of the Swarm-VIP-Dynamic models (v3.1, v3.2, and v3.3) have been systematically evaluated for their capability to reproduce climatological patterns in electron density (Ne) and its spatial gradients. This assessment utilises model outputs generated from the statistically independent evaluation dataset (SED), which was not used during model training or validation. Comparisons are made against Swarm satellite observations across four distinct ionospheric regions classified using the ionospheric region flag from the IPDxIRR_2F data product. The selected periods span different solar activity conditions: 2018–2019 represents a solar minimum phase, while 2023 corresponds to elevated solar activity, including the geomagnetic storm event of April 23–26, 2023.
This work is funded by ESA Solid Magnetic Science Cluster - Research Opportunities: 4D Ionosphere framework (ESA Contract No. 4000143413/23/I-EB). DK, YJ, and WM acknowledge funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (ERC Consolidator Grant 866357, POLAR-4DSpace).
