On the Existence of the Kolmogorov Inertial Range in the Terrestrial Magnetosheath Turbulence

Abstract

In the solar wind, power spectral density (PSD) of the magnetic field fluctuations generally follow the so-called Kolmogorov spectrum f^-5/3 in the inertial range, where the dynamics is thought to be dominated by nonlinear interactions between counter-propagating incompressible Alfvén wave parquets. These features are thought to be ubiquitous in space plasmas. The present study gives a new and more complex picture of magnetohydrodynamics (MHD) turbulence as observed in the terrestrial magnetosheath. The study uses three years of in-situ data from the Cluster mission to explore the nature of the magnetic fluctuations at MHD scales in different locations within the magnetosheath, including flanks and subsolar regions. It is found that the magnetic field fluctuations at MHD scales generally have a PSD close to f^-1 (shallower than the Kolmogorov one f^-5/3) down to the ion characteristic scale, which recalls the energy containing scales of solar wind turbulence. The Kolmogorov spectrum is observed only away from the bow shock toward the flank and the magnetopause regions in 17% of the analyzed time intervals. Measuring the magnetic compressibility, it is shown that only a fraction (35%) of the observed Kolmogorov spectra were populated by shear Alfvénic fluctuations, whereas the majority of the events (65%) was found to be dominated by compressible magnetosonic-like fluctuations, which contrasts with well-known turbulence properties in the solar wind. This study gives a first comprehensive view of the origin of the f^-1 and the transition to the Kolmogorov inertial range; both questions remain controversial in solar wind turbulence.

21 pages, 7 figures

References in corpus (4)

• Solar wind turbulent spectrum at plasma kinetic scales
• Spectral Slope Variation at Proton Scales from Fast to Slow Solar Wind
• Ion kinetic energy conservation and magnetic field strength constancy in multi-fluid solar wind Alfvénic turbulence
• Nature of the MHD and kinetic scale turbulence in the magnetosheath of Saturn: Cassini observations

Cited by in corpus (6)

• Kinetic cascade in solar-wind turbulence: 3D3V hybrid-kinetic simulations with electron inertia
• Energy cascade rate measured in a collisionless space plasma with MMS data and compressible Hall magnetohydrodynamic turbulence theory
• Statistics of Kinetic Dissipation in Earth's Magnetosheath -- MMS Observations
• Kinetic Scale Slow Solar Wind Turbulence in the Inner Heliosphere: Co-existence of Kinetic Alfvén Waves and Alfvén Ion Cyclotron Waves
• Kinetic plasma turbulence: recent insights and open questions from 3D3V simulations
• The Ion Transition Range of Solar Wind Turbulence in the Inner Heliosphere: Parker Solar Probe Observations