Numerical Simulation of Solar Magnetic Flux Emergence Using the AMR–CESE–MHD Code

Abstract

Magnetic flux emergence from the solar interior to the atmosphere is believed to be a key process in the formation of solar active regions and driving solar eruptions. Due to the limited capabilities of observations, the flux emergence process is commonly studied using numerical simulations. In this paper, we develop a numerical model to simulate the emergence of a twisted magnetic flux tube from the convection zone to the corona, using the AMR–CESE–MHD code, which is based on the conservation-element solution-element method, with adaptive mesh refinement. The results of our simulation agree with those of many previous studies with similar initial conditions, but by using different numerical codes. In the early stage, the flux tube rises from the convection zone, being driven by magnetic buoyancy, until it reaches close to the photosphere. The emergence is decelerated there, and with the piling up of the magnetic flux, the magnetic buoyancy instability is triggered, which allows the magnetic field to partially enter into the atmosphere. Meanwhile, two gradually separated polarity concentration zones appear in the photospheric layer, transporting the magnetic field and energy into the atmosphere through their vortical and shearing motions. Correspondingly, the coronal magnetic field is also reshaped into a sigmoid configuration, containing a thin current layer, which resembles the typical pre-eruptive magnetic configuration of an active region. Such a numerical framework of magnetic flux emergence as established will be applied to future investigations of how solar eruptions are initiated in flux emergence active regions.