A search for geomagnetic storm evidence of the reversal of the solar dipole magnetic field and interplanetary Bz

The axis of the solar dipole magnetic field is aligned to within 30° of the solar rotational axis for up to 2 years during solar minima. Coronal mass ejections (CMEs) during those periods arise from the equatorial streamer belts and should share the magnetic orientation of the dipole field. If those field orientations are maintained in interplanetary space, CMEs producing geomagnetic storms should be characterized by southward B z during minima when the fields point outward in the northern solar hemisphere and by northward B z at alternate minima when the solar dipole is reversed. Since southward B z is an important factor in producing geomagnetic storms, we should expect that storms during minima characterized by southward B z are significantly larger than those during the alternate minima. Storm data from 10 solar minima are used to test this hypothesis. The test yields a null result.