Influence of the IMF Bx on the geometry of the bow shock and magnetopause

Abstract

The solar wind-magnetosphere interaction is still an open problem under the influences of the Bx component of the interplanetary magnetic field (IMF). We have performed a series of 3D global magnetohydrodynamic simulations and demonstrated the quantitative effects of the IMF Bx component on the locations and shapes of the bow shock and magnetopause during northward IMF. The IMF Bx can greatly change the configurations of the bow shock and the magnetosphere, and bring north-south asymmetries in the noon-midnight meridian plane. The larger magnetosonic Mach number in the northern hemisphere makes the northern part of the bow shock closer to the Earth, while the situation is opposite in the south. In the downstream of the southern bow shock, the magnetic fields get greatly compressed in the southern magnetosheath, leading to a drastic increased magnetic pressure above the magnetopause. As a result, the southern part of the magnetopause becomes closer to the earth while its northern part has a little change. Moreover, it is found that the subsolar points of the bow shock and magnetopause are not sensitive to the IMF Bx during northward IMF.