Modeling a Coronal Mass Ejection as a Magnetized Structure with EUHFORIA

Abstract

We studied an Earth-directed coronal mass ejection (CME) that erupted on 2015 March 15. Our aim was to model the CME flux rope as a magnetized structure using the European Heliospheric Forecasting Information Asset (EUHFORIA). The flux rope from eruption data (FRED) output was applied to the EUHFORIA spheromak CME model. In addition to the geometrical properties of the CME flux rope, we needed to input the parameters that determine the CME internal magnetic field like the helicity, tilt angle, and toroidal flux of the CME flux rope. According to the FRED technique geometrical properties of the CME flux rope are obtained by applying a graduated cylindrical shell fitting of the CME flux rope on the coronagraph images. The poloidal field magnetic properties can be estimated from the reconnection flux in the source region utilizing the post-eruption arcade method, which uses the Heliospheric Magnetic Imager magnetogram together with the Atmospheric Imaging Assembly (AIA) 193 Å images. We set up two EUHFORIA runs with RUN-1 using the toroidal flux obtained from the FRED technique and RUN-2 using the toroidal flux that was measured from the core dimming regions identified from the AIA 211 Å images. We found that the EUHFORIA simulation outputs from RUN-1 and RUN-2 are comparable to each other. Overall using the EUHFORIA spheromak model, we successfully obtained the magnetic field rotation of the flux rope, while the arrival time near Earth and the strength of the interplanetary CME magnetic field at Earth are not as accurately modeled.