Dynamic Evolution of Dayside Magnetopause Reconnection Locations and Their Dependence on IMF Cone Angle: 3-D Global Hybrid Simulation

We study the dynamic evolution of dayside magnetopause reconnection locations and their dependence on the interplanetary magnetic field (IMF) cone angle via 3-D global-scale hybrid simulations. Cases with finite IMF B_x and B_z but IMF B_y = 0 are investigated. It is shown that the dayside magnetopause reconnection is unsteady under quasi-steady solar wind conditions. The reconnection lines during the dynamic evolution are not always parallel to the equatorial plane even under purely southward IMF conditions. Magnetopause reconnection locations can be affected by the generation, coalescence, and transport of flux ropes (FRs), reconnection inside the FRs, and the magnetosheath flow. In the presence of an IMF component B_x, the magnetopause reconnection initially occurs in high-latitude regions downstream of the quasi-perpendicular bow shock, followed by the generation of multiple reconnection regions. In the later stages of the simulation, a dominant reconnection region is present in low-latitude regions, which can also affect reconnection in other regions. The global distribution of reconnection lines under a finite IMF B_x is found to not be limited to the region with maximum magnetic shear angle.