Ulysses' second fast-latitude scan: Complexity near solar maximum and the reformation of polar coronal holes

Abstract

Ulysses second fast latitude scan, near solar maximum, comprises a complicated mixture of solar wind flows from a variety of sources at high southern as well as low heliolatitudes. In contrast, observations northward of ∼40° N show the reformation of relatively steady fast solar wind flows, which are virtually indistinguishable from the polar coronal hole winds observed at high latitudes over Ulysses' first orbit. These high-speed flows predominantly display the opposite magnetic polarity from that observed in the northern hemisphere during the previous orbit, indicating that the Sun's dipole has reversed. The recent restructuring of the high-latitude solar wind, so soon after solar maximum, suggests that the heliospheric chaos around maximum occupies a unique and relatively shorter-lived portion of the solar cycle with the majority of the cycle maintaining the simple bimodal solar wind structure associated with large, persistent polar coronal holes.