A representation of the magnetic neutral line on the solar source surface in terms of the Sun's axial dipole at the center and two equatorial dipoles in the photosphere

Abstract

It is shown that the basic features of the neutral line configuration on the source surface (a concentric sphere of 2.5 solar radii) and their variations during a sunspot cycle can be represented fairly well in terms of an axial main dipole at the center of the Sun and two (or at most three during a very limited time period) antipodal dipoles on the photosphere. This representation is not unique, but may be physically more meaningful than the harmonic analysis results. The nature of the photospheric dipoles is also discussed. The results may have some application to the Earth's magnetic field and its variations.