[P-EM09] Space Weather and Space Climate

[PEM09-24] Cosmic ray variation at the Earth caused by flank-side or backside coronal mass ejections

*Yuki Hayashi¹, Chihiro Kato¹, Kazuoki Munakata¹, Yoshiki Masuda¹, Ryuho Kataoka², Akira Kadokura^2,3, Masayoshi Kozai³, Shoko Miyake⁴, Kazumasa Iwai⁵, Rafael Mendonça⁶, Carlos Roberto Braga⁷, Ezequiel Echer⁶, Alisson Dal Lago⁶, M. Rockenbach⁶, N. J. Shcuch⁶, H. K. Al Jassar⁸, Madan M. Sharma⁸, José Valentin Bageston⁶, Ismail Sabbah¹¹, Marc Duldig⁹, J. E. Humble⁹, Paul Evenson¹⁰ (1.Shinshu University, 2.National Institute of Polar Research, 3.Polar Environment Data Science Center, Joint Support-Center for Data Science Research, Research Organization of Information and Systems, 4.National Institute of Technology, Ibaraki College, 5.Institute for Space-Earth Environmental Research, Nagoya University, 6.National Institute for Space Research, 7.George Mason University, 8.Kuwait University, 9.University of Tasmania, 10.University of Delaware, 11. College of Technological Studies, Public Authority for Applied Education and Training)

Keywords:flank-side or backside CMEs, the galactic cosmic-ray (GCR) intensity variations

The galactic cosmic-ray (GCR) intensity at Earth sometimes shows transient variations related to solar activity, such as coronal mass ejections (CMEs). We have observed the transient GCR intensity variations using the Global Muon Detector Network (GMDN) for decades. The largest-amplitude transient GCR variations are the so-called Forbush decrease events, which are caused by fast CMEs coming to Earth. However, the possible GCR variations associated with flank-side or backside CMEs have been poorly understood. We report the initial analysis of such candidate events, including January and July 2012 CME events, to discuss the possibility of diagnosing the meso-scale cosmic ray distributions in the inner heliosphere.