HOURLY VARIANCES OF FLUCTUATIONS IN THE HELIOSPHERIC MAGNETIC-FIELD OUT OF THE ECLIPTIC-PLANE

Magnetic field fluctuations at high heliographic latitudes are discuss ed in terms of the latitude and radial dependence of their variances, as observed by the Ulysses spacecraft. The increased level of transver se fluctuations in fast solar wind flows from the polar coronal holes is similar to that found in high speed streams near the ecliptic. Howe ver, 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 timesc ales, free from additional energy input from stream-stream interaction s or from coronal mass ejections and in the presence of a slowly evolv ing, low frequency Alfvenic population. The conclusion is that fluctua tions in the inertial range in the homogeneous polar coronal flows dec ay faster than predicted by the WKB approximation. However, even minor compression effects can increase the energy in these fluctuations.