Characteristics of the solar wind at 1 a.u. in relation to Hale sector boundaries

Abstract

A study is made of the solar wind characteristics at 1 a.u. in the vicinity of Hale and anti-Hale sector boundaries (SBs), after isolating the SBs with solar activity related temporal flows and/or transient interplanetary structures (magnetic clouds) around them. It is found that, on average, the profile of the solar wind flow speed prior to SB passage and the minimum in flow speed at the SB do not differ for the two types of SBs. The flow speed 1–2 days after the passage of anti-Hale SB is found, however, to be significantly higher compared to Hale SB. The results indicate that the polarity configurations of the solar sectorial magnetic field structures with reference to the zonal (activity) structures influence the characteristics of coronal sources of high-speed streams, that accompany SB crossings at 1 a.u.