Anisotropy of Electric Field Fluctuations Spectrum of Solar Wind Turbulence

TL;DR

This study analyzes the anisotropy in electric field fluctuation spectra of solar wind turbulence, revealing directional differences and their dependence on solar activity using spacecraft data.

Contribution

It provides new insights into the anisotropic nature of electric field fluctuations in solar wind turbulence through wavelet analysis of Cluster spacecraft data.

Findings

Power and spectral index anisotropy observed between 0.01 Hz and 0.1 Hz

More power in parallel electric field fluctuations than perpendicular

Anisotropy varies with solar activity

Abstract

To investigate the power and spectral index anisotropy in the inertial range of solar wind turbulence, we use 70 intervals of electric field data accumulated by Cluster spacecraft in the free solar wind. We compute the electric field fluctuation power spectra using wavelet analysis technique and study its spectral index variation with the change in angle between the heliocentric radial direction and the local mean magnetic field. We find clear power and spectral index anisotropy in the frequency ranging from 0.01 Hz to 0.1 Hz, with more power in parallel fluctuations than perpendicular. We also report our study of anisotropy as a function of solar activity.