Kolmogorov and Irosnikov-Kraichnan scaling in the anisotropic turbulent solar wind

TL;DR

This paper investigates the anisotropic turbulence in the solar wind at 1AU, revealing two coexisting components with distinct scaling laws: Irosnikov-Kraichnan and Kolmogorov, linked to different physical processes.

Contribution

It demonstrates the linear decomposition of solar wind turbulence into perpendicular and parallel components, each exhibiting different spectral scalings, advancing understanding of solar wind turbulence.

Findings

Perpendicular component aligns with Irosnikov-Kraichnan scaling.

Parallel component exhibits Kolmogorov scaling.

Both components are observed in energy densities and fluxes.

Abstract

Solar wind turbulence is dominated by Alfv\'{e}nic fluctuations but the power spectral exponents somewhat surprisingly evolve toward the Kolmogorov value of -5/3, that of hydrodynamic turbulence. We show that at 1AU the turbulence decomposes linearly into two coexistent components perpendicular and parallel to the local average magnetic field. The first of these is consistent with propagating Alfv\'{e}n wavepackets and shows the scaling expected of Alfv\'{e}nic turbulence, namely Irosnikov- Kraichnan. The second shows Kolmogorov scaling which we also find in the number and magnetic energy density, and Poynting flux.