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Galactic Cosmic Ray Intensity Response to Interplanetary Coronal Mass Ejections/Magnetic Clouds in 1995 - 2009


Richardson, IG and Cane, HV, Galactic Cosmic Ray Intensity Response to Interplanetary Coronal Mass Ejections/Magnetic Clouds in 1995 - 2009, Solar Physics: A Journal for Solar and Solar-Stellar Research and The Study of Solar Terrestrial Physics, 270, (2) pp. 609-627. ISSN 0038-0938 (2011) [Refereed Article]

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Copyright 2011 Springer Science+Business Media B.V.

DOI: doi:10.1007/s11207-011-9774-x


We summarize the response of the galactic cosmic ray (CGR) intensity to the passage of the more than 300 interplanetary coronal mass ejections (ICMEs) and their associated shocks that passed the Earth during 1995 – 2009, a period that encompasses the whole of Solar Cycle 23. In ∼80% of cases, the GCR intensity decreased during the passage of these structures, i.e., a "Forbush decrease" occurred, while in ∼10% there was no significant change. In the remaining cases, the GCR intensity increased. Where there was an intensity decrease, minimum intensity was observed inside the ICME in ∼90% of these events. The observations confirm the role of both post-shock regions and ICMEs in the generation of these decreases, consistent with many previous studies, but contrary to the conclusion of Reames, Kahler, and Tylka (Astrophys. J. Lett. 700, L199, 2009) who, from examining a subset of ICMEs with flux-rope-like magnetic fields (magnetic clouds) argued that these are "open structures" that allow free access of particles including GCRs to their interior. In fact, we find that magnetic clouds are more likely to participate in the deepest GCR decreases than ICMEs that are not magnetic clouds.

Item Details

Item Type:Refereed Article
Keywords:Interplanetary coronal mass ejections · Magnetic clouds · Cosmic rays · Solar wind plasma · Interplanetary magnetic field · Coronal mass ejections
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:High energy astrophysics and galactic cosmic rays
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Cane, HV (Dr Hilary Cane)
ID Code:75082
Year Published:2011
Web of Science® Times Cited:93
Deposited By:Mathematics and Physics
Deposited On:2012-01-09
Last Modified:2017-11-01

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