A fully three-dimensional (3D), time-dependent, MHD interplanetary global model (3D IGM) has been used, for the first time, to study the relationship between different forms of solar activity and transient variations of the north-south component, B-z, of the interplanetary magnetic field (IMF) at 1 AU. One form of solar activity, the hare, is simulated by using a pressure pulse at different locations near the solar surface and observing the simulated IMF evolution of B-theta (= - B-z) at 1 AU. Results show that, for a given pressure pulse, the orientation of the corresponding transient variation of B-z has a strong relationship to the location of the pressure pulse and the initial conditions of the IMF. Two initial IMF conditions are considered: a unipolar Archimedean spiral with outward polarity and a flat heliospheric current sheet (HCS) with outward polarity in the northern hemisphere and which gradually reverses polarity in the solar equatorial plane to inward polarity in the southern heliospheric hemisphere. The wave guide effect of the HCS is also demonstrated.
ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES