Abstract/Summary

In this work, we have, for the first time, applied the interpretation of multiple ghost-fronts to two synthetic CMEs propagating within a structured solar wind using the HUXt solar wind model. The two coronal mass ejections (CMEs) occurred on 2012 June 13-14 showing multiple fronts in images from STEREO HIs. The HUXt model is used to simulate the evolution of these CMEs across the inner heliosphere as they interacted with structured ambient solar wind. The simulations reveal that the evolution of CME shape is consistent with observations across a wide range of solar latitudes and that the manifestation of multiple `ghost-fronts' within HIs field of view is consistent with the positions of the nose and flank of the same CME structure. This provides further conformation that the angular separation of these features provides information on the longitudinal extent of a CME. For one of the CMEs considered in this study, both simulations and observations show that a concave shape develops within the outer CME front. We conclude that this distortion results from latitudinal structure in the ambient solar wind speed. The work emphasizes that the shape of the CME cannot be assumed to remain a coherent geometrical shape during its propagation in the heliosphere. Our analysis demonstrates that the presence of `ghost' CME fronts can be used to infer the distortion of CMEs by ambient solar wind structure as a function of both latitude and longitude. Those information have potential to improve the forecasting of space weather events at Earth.