Effects of the interplanetary magnetic field on the twisting of the magnetotail: Global MHD results

Abstract

We used the global magnetohydrodynamic (MHD) simulation to investigate effects of the interplanetary magnetic field (IMF) on the twisting of the magnetotail. It is shown that the cross section of the magnetotail is elongated along a certain direction close to the IMF orientation. The elongated direction twists with the IMF orientation, magnitude, and the distance away from Earth, and the quantitative relationship has been given. In addition, the current sheet has a similar twisting behavior as the magnetotail magnetopause, with a smaller twisting angle. Our simulated results fall within the range that people have deduced from observations.