Intermittency of Magnetic Discontinuities in the Near-Sun Solar Wind Turbulence

Abstract

The intermittency domain is in the magnetohydrodynamic inertial range but just above the dissipation range and contains the intermittent structures that influence the spectral index. However, the nature of these structures is still under debate and how they affect the higher-order scaling behavior in the near-Sun solar wind turbulence remains to be investigated. Here we use the magnetic field data measured by Parker Solar Probe in the near-Sun solar wind. We identify the intermittency by partial variance of increments method and conduct the multiorder structure functions analyses in the intermittency domain before and after removing the intermittency. We also perform for the first time the scaling analyses on the fluctuations of magnetic field direction given by the rotational angle θ = cos − 1 ( B 1 · B 2 ) / ∣ B 1 ∣ ∣ B 2 ∣ , in which B 1 and B 2 are the magnetic fields measured at two instants. We find that the multifractal scaling of the magnetic field could be predicted by the log-Poisson intermittency model with 2D sheetlike structures and a simple Kolmogorov −5/3 monoscaling recovers after the removal of the intermittency. We also find a similar behavior for the scalings of θ, suggesting that magnetic discontinuities are involved in the energy transfer process of solar wind turbulence.

Effect of Spherical Polarization on the Magnetic Spectrum of the Solar Wind

“…Salem et al (2009) used numerical methods to remove discontinuities, and recovered α B = 2/3, with a scaling exponent of 1/2 for the velocity. Wu et al (2023b) recovered monofractal scaling with α B = 2/3 for a near-perihelion PSP observation after numerically removing discontinuities, while Wu et al (2023a) excluded convective structures from PSP observations from one coronal hole to obtain α B = 1/2. Discontinuities in the solar wind have been found to be mostly rotational, with some being tangential (Neugebauer 2006).…”