MHD simulations of the global solar corona around the Halloween event in 2003 using the synchronic frame format of the solar photospheric magnetic field

摘要

We performed two time-relaxation magnetohydrodynamics (MHD) simulations of the solar corona: one uses the boundary map representing the solar surface magnetic field distribution before the Halloween event in 2003, and the other uses map representing the postevent distribution. The aims of this study are to test a new concept of a solar surface magnetic field map capable of representing a particular time of interest and to examine the coronal responses to the solar photospheric magnetic field changes occurring over a few days. We used a new mapping scheme named “synchronic frame” that can include the longitudinal shift caused by the solar differential rotation and the solar surface variations occurring at the time of interest. These two time-relaxation MHD simulations using the two maps are separately performed to numerically obtain the quasi steady states of the solar corona before and after the Halloween event. Comparisons of the simulated coronal magnetic field structures to the SOHO/EIT measurements show that the combinations of our mapping method and simulation model reproduce the changes of the coronal structures well. We also find that the consequences of solar surface variations can be seen in the plasma quantities in the solar corona. These results show the capability and importance of the solar surface magnetic field mapping scheme for better reconstruction of global coronal structures, parts of which are sensitive to the solar surface magnetic field variations.