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Multiscale Analysis of the Turbulent Ionospheric Medium

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P. De Michelis and R. Tozzi

The physical parameters which describe many fluid and plasma systems, such as density, velocity, temperature, and electric and magnetic fields, are often characterized by fluctuating values. When the fluctuations are observed over many spatial and temporal scales and a nonlinear transfer of energy occurs between the different scales, the system is generally said to be in a turbulent state. Several interplanetary space environments, such as solar wind, ion foreshock, the magnetosheath, and the magnetotail and, last but not least, the ionosphere, have been found to be in a turbulent state.

The Hurst exponent values obtained evaluating the first-order structure function for the considered dataset (i.e., the horizontal intensity of the magnetic field due to external sources recorded by Swarm A during a period of 2 years and quiet geomagnetic conditions). The Hurst exponent values are relative to the Northern high latitudes and are reported in magnetic local time and quasi dipole magnetic latitude in a polar representation. Dashed circles are drawn at magnetic latitudes of 50°, 60°, 70°, and 80°.

Turbulence crucially influences the cross-scale coupling of the dynamical processes: it can influence the transport of mass, momentum, and energy from solar wind and the magnetosphere to the ionosphere and can also perturb the equilibrium structure of the ionosphere, as well as the plasma dynamics and particle energization at many locations in the ionosphere. Here, we review some recent findings on the multiscale and turbulent character of the ionosphere, with a special emphasis on high-latitudes. In particular, we analyse some scaling features of magnetic field fluctuations, relating them to their spectral properties and the occurrence of intermittency phenomena.

Publication: P. De Michelis and R. Tozzi, “Multiscale Analysis of the Turbulent Ionospheric Medium”, Chapter 19 in “The Dynamical Ionosphere”, Editors: M. Materassi, B. Forte, A. Coster and S. Skone, Elsevier 2020.