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Determination of interplanetary coronal mass ejection geometry and orientation from ground-based observations of galactic cosmic rays

journal contribution
posted on 2023-05-17, 00:34 authored by Kuwabara, T, Bieber, JW, Evenson, P, Munakata, K, Yasue, S, Kato, C, Fushishita, A, Tokumaru, M, Duldig, ML, John Humble, Silva, MR, Dal Lago, A, Schuch, NJ
We have developed a method for determining interplanetary coronal mass ejection (ICME) geometry from galactic cosmic ray data recorded by the ground-based muon detector network. The cosmic ray density depression inside the ICME, which is associated with a Forbush decrease, is represented by an expanding cylinder that is based on a theoretical model of the cosmic ray particle diffusion. ICME geometry and orientation are deduced from observed time variations of cosmic ray density and density gradient and are compared with those deduced from a magnetic flux rope model. From March 2001 to May 2005, 11 ICME events that produced Forbush decreases >2% were observed, and clear variations of the density gradient due to ICME passage were observed in 8 of 11 events. In five of the eight events, signatures of magnetic flux rope structure (large, smooth rotation of magnetic field) were also seen, and the ICME geometry and orientation deduced from the two methods were very similar in three events. This suggests that the cosmic ray-based method can be used as a complementary method for deducing ICME geometry especially for events where a large Forbush decrease is observed.


Publication title

Journal of Geophysical Research-Space Physics










School of Natural Sciences


Amer Geophysical Union

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2000 Florida Ave Nw, Washington, USA, Dc, 20009

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Copyright © 2009 American Geophysical Union.

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