engleski

Investigating the evolution and interactions of the September 2017 CME events with EUHFORIA

Coronal Mass Ejections (CMEs) are the primary source of strong space weather disturbances at Earth and other locations in the heliosphere. While their (geo-)effectiveness is largely determined by their dynamic pressure and magnetic field, phenomena such as the interaction with other transients (CMEs, CIRs…), or the pre- conditioning of interplanetary space due to preceding CMEs, can significantly alter the properties of single CME events and influence their (geo-)effectiveness. Investigating such phenomena via physics- based models is crucial to improve our understanding of interacting CME events, and to assess the prediction capability of extreme space weather events at various locations in the heliosphere. We present a comprehensive analysis of the CME events that erupted from AR12673 during the unusually active week of September 4-10, 2017, using the EUHFORIA heliospheric model. As AR12673 rotated on the solar disk, CMEs were launched over a wide range of longitudes, interacting with each other and paving the way for the propagation of following CMEs. CME signatures were observed at both Earth and Mars, and associated particle events were reported at Earth, Mars, and STEREO-A. At Earth, an intense geomagnetic storm triggered by a CME sheath interacting with a preceding ejecta was recorded on September 8, 2017. Using parameters derived from remote-sensing and multi-spacecraft observations of the CMEs and their source region, we simulate the events with both traditional cone CME model, and with a more realistic flux-rope CME model. We investigate how CME-CME interactions affect the spatial and temporal evolution of CME shocks, sheaths and ejecta in the heliosphere, and we compare simulation results with in-situ measurements at Earth and Mars. This study will not only benchmark current prediction capabilities in the case of complex CME events, but will also provide better insights on the large-scale evolution of complex CME events throughout the heliosphere.

coronal mass ejections, MHD simulations, space weather

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