Model simulations of the magnetic field intensity by the BATSRUS global MHD model for dipole tilts ϕ of (a) +35°, (b) 0 and (c) −35°. Each plot is for simulation run time t = 90 min. The open-closed field line boundary is shown in each case and the black dot gives the location of the magnetopause reconnection site. The mauve lines are open magnetospheric field lines separated by 7° along the moon-midnight cross section of the ionospheric polar caps. A summary of model inputs is given in Table 1.