Evolution and Interaction of Six Coronal Mass Ejections in March 2012

The solar activity, vis-à-vis Earth's response, reached a peak in 2012 during the early period of solar cycle 24. Many severe geomagnetic storms (e.g., geomagnetic index Dst < -80 nT) occurred in 2012 while interplanetary coronal mass ejections (ICMEs) and their driven shocks encountered the Earth. Six CMEs were observed on the 04th, 05th, 07th, 9th, 10th, and 13th of March 2012. While these CMEs were passing through the Earth, they caused four geomagnetic storms with Dst dropped to -78, -143, -51, and -80 nT on the 7th, 9th, 12th, and 15 of March 2012, respectively. To study the evolution and interaction between these CME events, we use a global, three-dimensional (3-D) magnetohydrodynamic (MHD) numerical model and a kinematic model (HAFv.2), with inputs based on the actual solar observations and constraints based on in situ measurements of solar wind parameters (density, velocity, magnetic field, and temperature) at Wind and STEREO-A/B. The detailed simulation results will be presented. For example, we will compare simulated CME images and in-situ solar wind parameters with observed CME images (from LASCO/SOHO, STEREO-A/B) and in-situ solar wind plasma and IMF observations (from Wind/ACE, STEREO-A/B). Work of CCW and SP were supported by ONR 6.1 program