Intermittency in Interplanetary Coronal Mass Ejections Observed by Parker Solar Probe and Solar Orbiter

TL;DR

This study investigates the intermittency and turbulence characteristics of interplanetary coronal mass ejections (ICMEs) using data from Parker Solar Probe and Solar Orbiter, revealing universal intermittency behavior and radial evolution of turbulence.

Contribution

It provides the first detailed analysis of intermittency in ICMEs across multiple heliocentric distances, highlighting the static nature of ICMEs and the development of turbulence in sheath regions.

Findings

Kurtosis shows universal intermittency behavior across all intervals.

ICMEs exhibit radially invariant intermittency levels.

Turbulence in sheath regions increases with distance from the Sun.

Abstract

Intermittency has been studied extensively in the fast and slow solar winds but to a far lesser extent in interplanetary coronal mass ejections (ICMEs). While ICMEs are often characterized by their relatively smooth, large-scale magnetic flux rope structures, a spectrum of fluctuations is nonetheless present at smaller scales. We have examined kurtosis and its scaling exponents at magnetohydrodynamic inertial scales in 49 ICMEs observed between 0.25 and 1 au by Parker Solar Probe and Solar Orbiter, and compared the results to those obtained for the ICME sheath regions and ambient solar wind intervals. Kurtosis behaves similarly in all intervals studied and presents a universal behavior typical of intermittent time series. The ICMEs displayed a radially invariant level of intermittency, suggesting that they are relatively static, well-developed turbulent environments. In the sheath regions, the level of intermittency increased with distance, indicating that the turbulence is not yet fully developed at small heliocentric distances. In addition to intermittent fluctuations related to turbulence, the sheath regions may possess a population of non-turbulent structures that increase the absolute value of kurtosis.