Solar magnetic field reversal as seen at Ulysses

Abstract

The rapid motion of the Ulysses spacecraft from high southern to high northern latitudes in 2000-2001 provided an excellent opportunity to make inferences regarding the solar magnetic dipole's behaviour around solar maximum. A simple dipole model is fitted to Ulysses measurements of the polarity of the heliospheric magnetic field mapped back to the solar wind source surface. Although higher order components of the field are ignored, the gradual reversal in orientation of the dipole field component can be followed during solar maximum, with the dipole axis crossing the solar equator during early 2000-early 2001. The dipole appears to exhibit a rotation at a slower rate than the Carrington frame of reference, similar to previous measurements made around solar maximum in the solar equatorial regions.