Reynolds Number and Intermittency in the Expanding Solar Wind: Predictions Based on Voyager Observations

Abstract

The large scale features of the solar wind are examined in order to predict small scale features of turbulence in unexplored regions of the heliosphere. The strategy is to examine how system size, or effective Reynolds number, varies, and then how this quantity influences observable statistical properties, including intermittency properties of solar wind turbulence. The expectation based on similar hydrodynamics scalings, is that the kurtosis, of the small scale magnetic field increments, will increase with increasing Reynolds number. Simple theoretical arguments as well as Voyager observations indicate that effective interplanetary turbulence Reynolds number decreases with increasing heliocentric distance. The decrease of scale-dependent magnetic increment kurtosis with increasing heliocentric distance, is verified using a newly refined Voyager magnetic field dataset. We argue that these scalings continue to much smaller heliocentric distances approaching the Alfven critical region, motivating a prediction that the Parker Solar Probe spacecraft will observe increased magnetic field intermittency, stronger current sheets, and more localized dissipation, as its perihelion approaches the critical regions. Similar arguments should be applicable to turbulence in other expanding astrophysical plasmas.

References in corpus (9)

• Anisotropic scaling of magnetohydrodynamic turbulence
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• Fading Coronal Structure and the Onset of Turbulence in the Young Solar Wind
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• Nonuniversality and finite dissipation in decaying magnetohydrodynamic turbulence
• The scaling properties of dissipation in incompressible isotropic three-dimensional magnetohydrodynamic turbulence

Cited by in corpus (9)

• Intermittency in the Expanding Solar Wind: Observations from Parker Solar Probe (0.16au), Helios 1 (0.3-1au), and Voyager 1 (1-10au)
• Turbulence in the outer heliosphere
• Magnetic field intermittency in the solar wind: PSP and SolO observations ranging from the Alfven region out to 1 AU
• Helios 2 observations of solar wind turbulence decay in the inner heliosphere
• Taylor microscale and effective Reynolds number near the Sun from PSP
• Efficient kinetic Lattice Boltzmann simulation of three-dimensional Hall-MHD Turbulence
• Understanding the level of Turbulence by Asymmetric Distributions: a motivation for measurements in Space Plasmas
• De-Biasing Structure Function Estimates From Sparse Time Series of the Solar Wind: A Data-Driven Approach
• Isotropization and Evolution of Energy-Containing Eddies in Solar Wind Turbulence: Parker Solar Probe, Helios 1, ACE, WIND, and Voyager 1