The source surface and photospheric magnetic field models

It is possible to reproduce the configuration of the neutral line on the solar source surface by the axial dipole at the center of the Sun and a few fictitious dipoles on the photosphere. In this paper, the authors attempt to identify the nature of such fictitious dipoles in the photospheric magnetic fields. It is shown that large-scale photospheric dipole fields can be identified clearly at the locations indicated by the fictitious dipoles when the photospheric field is very simple. They are found to be active regions.