Weaker solar wind from the polar coronal holes and the whole Sun

D. J. McComas, R. W. Ebert, H. A. Elliott, B. E. Goldstein, J. T. Gosling, N. A. Schwadron, R. M. Skoug

Research output: Contribution to journalArticlepeer-review

404 Scopus citations


Observations of solar wind from both large polar coronal holes (PCHs) during Ulysses' third orbit showed that the fast solar wind was slightly slower, significantly less dense, cooler, and had less mass and momentum flux than during the previous solar minimum (first) orbit. In addition, while much more variable, measurements in the slower, in-ecliptic wind match quantitatively with Ulysses and show essentially identical trends. Thus, these combined observations indicate significant, long-term variations in solar wind output from the entire Sun. The significant, long-term trend to lower dynamic pressures means that the heliosphere has been shrinking and the heliopause must be moving inward toward the Voyager spacecraft. In addition, our observations suggest a significant and global reduction in the mass and energy fed in below the sonic point in the corona. The lower supply of mass and energy may result naturally from a reduction of open magnetic flux during this period.

Original languageEnglish (US)
Article numberL18103
JournalGeophysical Research Letters
Issue number18
StatePublished - Sep 28 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Geophysics
  • General Earth and Planetary Sciences


Dive into the research topics of 'Weaker solar wind from the polar coronal holes and the whole Sun'. Together they form a unique fingerprint.

Cite this