Ulysses observations of the irregularly structured mid‐latitude solar wind during the approach to solar maximum

Abstract

The Ulysses spacecraft reached 45°S heliolatitude in its second polar orbit on 5 February 2000. Solar wind observations over the first portion of Ulysses' second orbit have been remarkably different from those taken at mid‐latitudes throughout its first orbit. During these portions of its first orbit, Ulysses crossed back and forth between the fast and slow solar wind and encountered a persistent corotating interaction region (CIR) on each solar rotation. In contrast, as Ulysses climbed to mid‐latitudes in its second orbit, it observed highly irregular solar wind with much less periodic CIRs, and no entries thus far into the fast solar wind. In addition, the recent data include a higher frequency of coronal mass ejections (CMEs) than observed in Ulysses' previous orbit, as well as numerous interplanetary shocks associated with both the CMEs and CIRs. These observations demonstrate that the mid‐latitude solar wind structure becomes increasingly complex as solar activity increases and coronal streamers, small‐scale coronal holes, and CMEs arise at increasingly high latitudes.