Solar wind velocity structure around the solar maximum observed by interplanetary scintillation

Abstract

Ulysses observed a latitude structure of solar wind in its second fast latitude scan and found that the global structure of solar wind near the solar maximum is significantly different from that in the solar minimum. Also soon after the solar maximum, Ulysses measured that the fast solar wind which has magnetic polarity of the new solar cycle appeared at high latitude in northern hemisphere. This fast wind appeared and disappeared a few times. We introduced a new tomographic algorithm, time‐series tomography, to reconstruct IPS velocity map using all data observed in the year from 1998 to 2001 and analyzed the variation of the solar wind structure through these four year. Especially in 2001, we compared the Ulysses’ fast latitude scan data. As results, it is found that disappearance and recovery of the fast solar wind around the north pole precedes that around the south pole for several months. And also found that the IPS observation shows high level agreement to the Ulysses observation especially for high latitudes.