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Paper: Analyses of the Evolution and Interaction of Multiple Coronal Mass Ejections and Their Shocks in July 2012
Volume: 484, Outstanding Problems in Heliophysics: From Coronal Heating to the Edge of the Heliosphere
Page: 241
Authors: Wu, S. T.; Wu, C.; Liou, K.; Plunkett, S.; Dryer, M.; Fry, C. D.
Abstract: The Sun has become more active since 2010 after a long-lasting solar minimum (2007-2009) between Cycle 23 and 24. Many Coronal Mass Ejections (CMEs) have been detected by current orbiting instruments on-board SOHO/LASCO and STEREO-A and B. During the period of July 2012 three consecutive CMEs were observed on July 17 (∼13:54UT), July 18 (∼06:24UT) and July 19 (∼05:39UT) from three different source regions on the solar surface located at S23W61, N18W180 and S17W92. Their corresponding average speeds were 802, 713, and 1160 km s-1, respectively. Multiple interplanetary (IP) shocks and CMEs arrived at the twin STEREO-A/B, SOHO/LASCO, ACE and WIND spacecraft where STEREO-A and STEREO-B were orbiting near 121 degrees West and 114 degrees East of the Sun-Earth line. The orbit of ACE and SOHO/LASCO were at L1 and WIND was near the Sun-Earth line. This unique line-up gave us opportunity to test the simulation of CMEs propagation and its induced IP shocks. Thus, we have used a well-developed global three-dimensional magnetohydrodynamic (MHD) model (Wu et al. 2007a) to perform forward MHD modeling to investigate the evolution of these CMEs and IP shocks. Using simulation results together with observations we found that an IP shock driven by the July 18 CME arrived at STEREO-B first, another IP shock driven by the July 19 CME arrived at STEREO-A, then the flank of an IP shock driven by the July 17 CME arrived at Earth. The observations from both coronal images and in-situ solar wind measurements are used to assess the reality of the IP shock arrival time from the simulation.
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