Turbulence and Anomalous Resistivity inside Near-Earth Magnetic Clouds

TL;DR

This study analyzes turbulence and anomalous resistivity inside near-Earth magnetic clouds associated with CMEs, revealing significant turbulence levels and resistivity enhancements that influence CME energetics.

Contribution

It provides the first comprehensive survey of turbulence amplitudes and anomalous resistivity inside near-Earth magnetic clouds using in-situ Wind spacecraft data.

Findings

Proton density fluctuation modulation index ranges from 0.13 to 0.16.

Magnetic field fluctuation modulation index ranges from 0.04 to 0.05.

Anomalous resistivity exceeds Spitzer resistivity by 500-1000 times.

Abstract

We use in-situ data from the Wind spacecraft to survey the amplitude of turbulent fluctuations in the proton density and total magnetic field inside a large sample of near-Earth magnetic clouds (MCs) associated with coronal mass ejections (CMEs) from the Sun. We find that the most probable value of the modulation index for proton density fluctuations ($\delta n_{p}/n_{p}$) inside MCs ranges from 0.13 to 0.16, while the most probable values for the modulation index of the total magnetic field fluctuations ($\delta B/B$) range from 0.04 to 0.05. We also find that the most probable value of the Mach number fluctuations ($\delta M$) inside MCs is $\approx 0.1$. The anomalous resistivity inside near-Earth MCs arising from electron scattering due to turbulent magnetic field fluctuations exceeds the (commonly used) Spitzer resistivity by a factor of $\approx 500-1000$. The enhanced Joule heating arising from this anomalous resistivity could impact our understanding of the energetics of CME propagation.