Origin of Multifractality in Solar Wind Turbulence: the Role of Current Sheets

TL;DR

This study investigates the multifractal nature of solar wind turbulence, highlighting the distinct roles of current sheets and correlations in shaping multifractality through advanced analysis methods.

Contribution

It introduces a multifractal framework combined with surrogate analysis to differentiate the effects of current sheets and correlations in solar wind turbulence.

Findings

Both series are strongly multifractal despite differences in extreme events.

Long-range correlations drive multifractality in current sheet-free series.

Heavy-tail distributions and nonlinear correlations contribute to multifractality with current sheets.

Abstract

In this work, a multifractal framework is proposed to investigate the effects of current sheets in solar wind turbulence. By using multifractal detrended fluctuation analysis coupled with surrogate methods and volatility, two solar wind magnetic field time series are investigated, one with current sheets and one without current sheets. Despite the lack of extreme-events intermittent bursts in the current sheet-free series, both series are shown to be strongly multifractal, although the current sheet-free series displays an almost linear behavior for the scaling exponent of structure functions. Long-range correlations are shown to be the main source of multifractality for the series without current sheets, while a combination of heavy-tail distribution and nonlinear correlations are responsible for multifractality in the series with current sheets. The multifractality in both time series is formally shown to be associated with an energy-cascade process using the p-model.