A Modified Spheromak Model Suitable for Coronal Mass Ejection Simulations

Abstract

Coronal mass ejections (CMEs) are some of the primary drivers of extreme space weather. They are large eruptions of mass and magnetic field from the solar corona and can travel the distance between Sun and Earth in half a day to a few days. Predictions of CMEs at 1 au, in terms of both its arrival time and magnetic field configuration, are very important for predicting space weather. Magnetohydrodynamic modeling of CMEs, using flux rope-based models, is a promising tool for achieving this goal. In this study, we present one such model for CME simulations, based on spheromak magnetic field configuration. We have modified the spheromak solution to allow for independent input of poloidal and toroidal fluxes. The motivation for this is the possibility of estimating these fluxes from solar magnetograms and extreme ultraviolet data from a number of different approaches. We estimate the poloidal flux of CME using post-eruption arcades and toroidal flux from the coronal dimming. In this modified spheromak, we also have the option to control the helicity sign of flux ropes, which can be derived from the solar disk magnetograms using the magnetic tongue approach. We demonstrate the applicability of this model by simulating the 2012 July 12 CME in the solar corona.