Authors: Dinesha V. Hegde (Department of Space Science, The University of Alabama in Huntsville), Talwinder Singh (Center for Space Plasma and Aeronomic Research (CSPAR), The University of Alabama in Huntsville), Tae K. Kim (Center for Space Plasma and Aeronomic Research (CSPAR), The University of Alabama in Huntsville), NIkolai V. Pogorelov (Department of Space Science, The University of Alabama in Huntsville)

On August 20, 2018, a relatively slower and smaller Coronal Mass Ejection (CME) led to the third most powerful geomagnetic storm of solar cycle 24, occurring on August 26, 2018, during the cycle’s declining phase. This occurrence was particularly intriguing since geomagnetic storms are typically initiated by larger, faster CMEs. Previous studies suggest that the associated flux rope with this CME experienced a complex rotation in the interplanetary medium before arriving at Earth. In this work, we simulate the propagation of this CME via the time-dependent, data-driven ambient solar wind using a magnetohydrodynamic model based on constant-turn flux ropes.  We constrain the characteristics of the associated flux rope by fitting the coronagraphic observations of this CME including the STEREO-A/HI data.  We characterize the simulated CME using the Marubashi force-free flux-rope fitting in order to examine the rotation of this CME in the inner heliosphere. Our research highlights the significance of accurate modeling of CME and ambient solar wind in order to understand the dynamics of CME and solar wind interactions.