Abstract
In this work, we present results of a time-dependent data-driven numerical simulation developed to study the dynamics of coronal active region magnetic fields. The evolving boundary condition driving the model, the photospheric electric field, is inverted using a time sequence of vector magnetograms as input. We invert three distinct electric field datasets for a single active region. All three electric fields reproduce the observed evolution of the normal component of the magnetic field. Two of the datasets are constructed so as to match the energy input into the corona to that provided by a reference estimate. Using the three inversions as input to a time-dependent magnetofrictional model, we study the response of the coronal magnetic field to the driving electric fields. The simulations reveal the magnetic field evolution to be sensitive to the input electric field despite the normal component of the magnetic field evolving identically and the total energy injection being largely similar. Thus, we demonstrate that the total energy injection is not sufficient to characterize the evolution of the coronal magnetic field: coronal evolution can be very different despite similar energy injections. We find the relative helicity to be an important additional metric that allows one to distinguish the simulations. In particular, the simulation with the highest relative helicity content produces a coronal flux rope that subsequently erupts, largely in agreement with extreme-ultraviolet imaging observations of the corresponding event. Our results suggest that time-dependent data-driven simulations that employ carefully constructed driving boundary conditions offer a valuable tool for modeling and characterizing the evolution of coronal magnetic fields.
Highlights
Coronal mass ejections (CMEs) – large-scale eruptive events originating in the solar corona (e.g., Webb and Howard, 2012) – have a large impact on the plasma environment from the corona out to the heliosphere (e.g., Kilpua, Koskinen, and Pulkkinen, 2017)
We present the results from our time-dependent data-driven modeling approach applied to NOAA active region (AR) 11504
While the AR is active prior to June 11 (e.g. M-class flares on June 9 and 10), the degradation of the quality of the vector magnetogram data towards the limb (Hoeksema et al, 2014; Sun and Norton, 2017) does not allow to include this phase in the modeling
Summary
Coronal mass ejections (CMEs) – large-scale eruptive events originating in the solar corona (e.g., Webb and Howard, 2012) – have a large impact on the plasma environment from the corona out to the heliosphere (e.g., Kilpua, Koskinen, and Pulkkinen, 2017) These energetic events occur frequently, on average several times a day (week) during solar maxima (minima) (e.g., Webb and Howard, 1994; Yashiro et al, 2004) and are accompanied by other transient events such as flares (e.g., Gosling et al, 1976; Yashiro et al, 2008; Murray et al, 2018) and solar energetic particle events (e.g., Reames, 1999). Characterizing the structure and dynamics of the coronal magnetic field is key to understanding the processes governing the formation and eruption of coronal mass ejections
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