Multiscale Features of Magnetic Field Fluctuations and Field-Aligned Currents in the Polar Ionosphere: A Case Study

Complexity is a typical feature of space plasmas that may involve the formation of multiscale
coherent magnetic and plasma structures. The winding features (pseudo-polarization) of magnetic
field fluctuations at different spatial scales are a useful quantity in this framework for investigating
complexity in space plasma. Indeed, a strong link between pseudo-polarization, magnetic/plasma
structures, turbulence and dissipation exists. We present some preliminary results on the link between
the polarization of the magnetic field fluctuations and the structure of field-aligned currents
in the high-latitude ionosphere. This study is based on high-resolution (50 Hz) magnetic field data
collected on board the European Space Agency Swarm constellation. The results show the existence
of a clear link between the multiscale coarse-grained structure of pseudo-polarization and intensity
of the field-aligned currents, supporting the recent findings according to which turbulence may be
capable of generating multiscale filamentary current structures in the auroral ionosphere. This feature
is also examined theoretically, along with its significance for the rate of energy deposition and heating
in the polar regions.