THE UNDERLYING MAGNETIC-FIELD DIRECTION IN ULYSSES OBSERVATIONS OF THE SOUTHERN POLAR HELIOSPHERE

Between April and November 1994 the Ulysses spacecraft explored heliographic latitudes above 60 degrees S in the southern polar heliosphere and had returned to 20 degrees S by February 1995. We have used hourly averages of the magnetic field measurements made by Ulysses to study the underlying heliospheric field direction. In contrast to data previously reported from lower latitudes, we find that above 60 degrees S neither the mean nor the most probable azimuthal angle of the magnetic field agree with that predicted by the Parker model, the most probable angle being of the order of 24 degrees more tightly wound than expected. The distribution of azimuth angles retains the high degree of asymmetry previously found at lower latitudes causing the mean angle to remain slightly less tightly wound than the prediction. In this high latitude region, the distribution of the meridional (north-south) angle is found to be symmetric with mean and most probable values close to the Parker prediction.