Non-Gaussianity and cross-scale coupling in interplanetary magnetic field turbulence during a rope–rope magnetic reconnection event

摘要

In a recent paper (Chian et al., 2016) it was shown that magneticreconnection at the interface region between two magnetic flux ropesis responsible for the genesis of interplanetary intermittentturbulence. The normalized third-order moment (skewness) and thenormalized fourth-order moment (kurtosis) display a quadraticrelation with a parabolic shape that is commonly observed inobservational data from turbulence in fluids and plasmas, and islinked to non-Gaussian fluctuations due to coherent structures. Inthis paper we perform a detailed study of the relation between theskewness and the kurtosis of the modulus of the magnetic field|B| during a triple interplanetary magnetic flux ropeevent. In addition, we investigate the skewness–kurtosis relation oftwo-point differences of |B| for the same event. Theparabolic relation displays scale dependence and is found to beenhanced during magnetic reconnection, rendering support for thegeneration of non-Gaussian coherent structures via rope–ropemagnetic reconnection. Our results also indicate that a directcoupling between the scales of magnetic flux ropes and the scaleswithin the inertial subrange occurs in the solar wind.