Geophys. Res. Lett., 23, 595-598, 1996
Abstract:
Magnetic field fluctuations at high heliographic latitudes are
discussed in terms of the latitude and radial dependence of their variances,
as observed by the Ulysses spacecraft. The increased level of transverse
fluctuations in fast solar wind flows from the polar coronal holes is
similar to that found in high speed streams near the ecliptic. However,
continuous observations in the fast solar wind both southward and northward
of the solar equatorial plane has allowed the determination of the radial
dependence of fluctuations on hourly and shorter timescales, free from
additional energy input from stream-stream interactions or from coronal mass
ejections and in the presence of a slowly evolving, low frequency Alfvénic
population. The conclusion is that fluctuations in the inertial range in the
homogeneous polar coronal flows decay faster than predicted by the WKB
approximation. However, even minor compression effects can increase the
energy in these fluctuations.
For copies of this paper, please contact us.