Jensen–Shannon Complexity Measurements in Solar Wind Magnetic Field Fluctuations

Abstract

Abstract Turbulent magnetic field fluctuations in the solar wind have been extensively investigated, but few studies have analyzed their complexity. Jensen–Shannon complexity maps of time series data provide a mathematical tool that can characterize fluctuations in laboratory experiments as stochastic, chaotic, or periodic phenomena. We apply this recently developed tool to characterize stochastic behavior in solar wind structures, including interplanetary coronal mass ejections (ICMEs), co-rotating interactions regions (CIRs), and turbulent magnetic fluctuation intervals. We find that the turbulent intervals observed by Helios, Wind, and Ulysses lie within the stochastic region of the complexity maps and that their complexity decreases while their normalized entropy increases with distance from the Sun. The complexity values associated with the fast solar wind (>550 km s−1) turbulence identified in Ulysses data beyond 5 au are highest at low latitudes (<10°) and lowest at latitudes above 20°. The Jensen–Shannon complexity maps show that fluctuations in the magnetic field, plasma flow, and density of the solar wind at 1 au are stochastic in ICMEs and CIRs identified in Wind data. Our analysis of Ulysses data between 1.4 and 5.4 au shows that the complexity of the ICMEs decreases with distance from the Sun, and the normalized entropy increases. Furthermore, the complexity values associated with magnetic field fluctuations in ICMEs identified in Ulysses data behave like the slow solar wind turbulence fluctuations within 4 au and take on values closer to the complexity values of the fast solar wind beyond 4 au.