Magnetic Reconnection and Intermittent Turbulence in the Solar Wind

Abstract

A statistical relationship between magnetic reconnection, current sheets, and intermittent turbulence in the solar wind is reported for the first time using in situ measurements from the Wind spacecraft at 1 AU. We identify intermittency as non-Gaussian fluctuations in increments of the magnetic field vector B that are spatially and temporally nonuniform. The reconnection events and current sheets are found to be concentrated in intervals of intermittent turbulence, identified using the partial variance of increments method: within the most non-Gaussian 1% of fluctuations in B, we find 87%-92% of reconnection exhausts and ∼9% of current sheets. Also, the likelihood that an identified current sheet will also correspond to a reconnection exhaust increases dramatically as the least intermittent fluctuations are removed from the data set. Hence, the turbulent solar wind contains a hierarchy of intermittent magnetic field structures that are increasingly linked to current sheets, which in turn are progressively more likely to correspond to sites of magnetic reconnection. These results could have far reaching implications for laboratory and astrophysical plasmas where turbulence and magnetic reconnection are ubiquitous.

Observations of turbulence in a Kelvin‐Helmholtz event on 8 September 2015 by the Magnetospheric Multiscale mission

“…Turbulence allows for the scale‐to‐scale transfer of fluctuation energy within a system. In many systems the direction of this energy transfer is from large to small scales and therefore turbulence can play a key role in driving the kinetic‐scale phenomena observed in space plasmas and dissipating large‐scale energy [ Matthaeus and Lamkin , ; Servidio et al , ; Donato et al , ; Wan et al , ; Stawarz et al , ; Osman et al , , , ; Kiyani et al , ]. While information about the small‐scale magnetic and electric field behavior has been well studied, for example, in the solar wind [e.g., Bale et al , ; Sahraoui et al , ], information about the kinetic‐scale velocity fluctuations (for both the ions and electrons) is more difficult to obtain.…”

Influence of intermittency on the anisotropy of magnetic structure functions of solar wind turbulence

“…The intermittency may be anisotropic in nature. Osman et al [, ] showed that scaling behavior is non‐Gaussian and globally scale invariant when measuring along the local mean magnetic field, which is distinct from the classic multifractal scaling behavior seen when local mean magnetic field vector is transverse to the flow direction. The original solar wind turbulence with intermittency usually illustrates spectral anisotropies with an increase of the power‐law index from about −2 to about −1.5 when the sampling direction changes from longitudinal to transverse [ Horbury et al , ; Podesta , ; Wicks et al , ; He et al , ].…”

Observational Evidence for Self-generation of Small-scale Magnetic Flux Ropes from Intermittent Solar Wind Turbulence

“…Various approaches have been utilized to identify these structures mostly as incremental changes in magnetic field from in-situ time-series data (e.g., Bruno et al 2001;Vasquez et al 2007;Borovsky 2008;Greco et al 2009a;Greco et al 2010;Miao et al 2011;Osman et al 2014;Greco et al 2016). However there generally lacks a synergy between the analyses of these two types of coherent structures, and the analysis method for the smallscale magnetic flux ropes is outdated.…”