NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Galactic Cosmic Ray Intensity Response to Interplanetary Coronal Mass Ejections/Magnetic Clouds in 1995-2009We 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 approx.80% of cases, the GCR intensity decreased during the passage of these structures, i.e., a "Forbush decrease" occurred, while in approx.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 approx.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. 1. 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.
Document ID
20110023418
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Richardson, I. G.
(Maryland Univ. College Park, MD, United States)
Cane, H. V.
(Tasmania Univ. Hobart, Australia)
Date Acquired
August 25, 2013
Publication Date
May 12, 2011
Publication Information
Publication: Solar Physics
Volume: 270
Issue: 2
Subject Category
Astrophysics
Report/Patent Number
GSFC.JA.5412.2011
Funding Number(s)
CONTRACT_GRANT: NNG06EO90A
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available