The fraction of interplanetary coronal mass ejections that are magnetic clouds: Evidence for a solar cycle variation

"Magnetic clouds" (MCs) are a subset of interplanetary coronal mass ejections (ICMEs) characterized by enhanced magnetic fields with an organized rotation in direction, and low plasma beta. Though intensely studied, MCs only constitute a fraction of all the ICMEs that are detected in the s...

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Bibliographic Details
Published in:Geophysical research letters 2004-09, Vol.31 (18), p.L18804.1-n/a
Main Authors: Richardson, I. G., Cane, H. V.
Format: Article
Language:English
Subjects:
Earth, ocean, space
Exact sciences and technology
Solar Physics
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Summary:"Magnetic clouds" (MCs) are a subset of interplanetary coronal mass ejections (ICMEs) characterized by enhanced magnetic fields with an organized rotation in direction, and low plasma beta. Though intensely studied, MCs only constitute a fraction of all the ICMEs that are detected in the solar wind. A comprehensive survey of ICMEs in the near- Earth solar wind during the ascending, maximum and early declining phases of solar cycle 23 in 1996 - 2003 shows that the MC fraction varies with the phase of the solar cycle, from approximately 100% (though with low statistics) at solar minimum to approximately 15% at solar maximum. A similar trend is evident in near-Earth observations during solar cycles 20 - 21, while Helios 1/2 spacecraft observations at 0.3 - 1.0 AU show a weaker trend and larger MC fraction.
ISSN:0094-8276
1944-8007
DOI:10.1029/2004GL020958