How did the solar wind structure change around the solar maximum? From interplanetary scintillation observation

K. Fujiki, M. Kojima, M. Tokumaru, T. Ohmi, A. Yokobe, K. Hayashi, D. J. McComas, H. A. Elliott

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

Observations from the second Ulysses fast latitude scan show that the global structure of solar wind near solar maximum is much more complex than at solar minimum. Soon after solar maximum, Ulysses observed a polar coronal hole (high speed) plasma with magnetic polarity of the new solar cycle in the Northern Hemisphere. We analyze the solar wind structure at and near solar maximum using interplanetary scintillation (IPS) measurements. To do this, we have developed a new tomographic technique, which improves our ability to examine the complex structure of the solar wind at solar maximum. Our IPS results show that in 1999 and 2000 the total area with speed greater than 700 km s-1 is significantly reduced first in the Northern Hemisphere and then in the Southern Hemisphere. For year 2001, we find that the formation of large areas of fast solar wind around the north pole precedes the formation of large polar coronal holes around the southern pole by several months. The IPS observations show a high level agreement to the Ulysses observation, particularly in coronal holes.

Original languageEnglish (US)
Pages (from-to)1257-1261
Number of pages5
JournalAnnales Geophysicae
Volume21
Issue number6
DOIs
StatePublished - Jun 2003
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Geology
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Keywords

  • Interplanetary physics (solar wind plasma)
  • Radio science (remote sensing)

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