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On the multifractal features of low-frequency magnetic field fluctuations in the field-aligned current ionospheric polar regions: Swarm observations

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G. Consolini, P. De Michelis, T. Alberti, F. Giannattasio, I. Coco, R. Tozzi, and T. T. S. Chang

In this work we have characterized the magnetic field fluctuations in the high latitude ionosphere by means of high resolution magnetic measurements (50 Hz) from the European Space Agency Earth’s observation mission Swarm.

A sketch of coherent field-aligned flux tubes in a quasi force-free equilibrium. The current is aligned along magnetic structures. The colors refer to different directions of the field-aligned currents.

We found anomalous spatiotemporal scaling features of magnetic field fluctuations in regions where field‐aligned currents occur, at spatial scales in the range 0.8–80 km (timescales in the range 0.1–10 s). The nature of these fluctuations is multifractal, suggesting a highly complex structure of the field‐aligned currents. Our results support the hypothesis that field‐aligned currents are filamentary in nature, and this paves the way to new perspectives in the comprehension of the physical processes responsible for the magnetospheric‐ionospheric coupling.

Publication: G. Consolini, P. De Michelis, T. Alberti, F. Giannattasio, I. Coco, R. Tozzi, and T. T. S. Chang, On the multifractal features of low-frequency magnetic field fluctuations in the field-aligned current ionospheric polar regions: Swarm observations, J. Geophys. Res.: Space Physics, 125, 2020.
https://doi.org/10.1029/2019JA027429