Investigation of intermittency in solar wind turbulence: scale-dependent kurtosis

A well known feature of turbulence is the existence of intermittency, a feature which has been widely studied in solar wind. The issue of intermittency is investigated by studying the behavior of scale-dependent kurtosis in the solar wind using magnetic field measurements from the ACE and Cluster spacecraft at 1 AU. It is also analyzed numerically with high-resolution magnetohydrodynamic (MHD) spectral simulations. Kurtosis increases with filter wavenumber, implying the presence of coherent structures at the smallest scales. This phase-coupling is related to intermittency in solar wind turbulence and the emergence of non-Gaussian statistics. However, it is inhibited by the presence of upstream waves and other phase-randomizing structures, which act to reduce the growth of kurtosis.