  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.
