ON THE LARGE-SCALE DIFFUSE MAGNETIC-FIELD OF THE SUN

Although the sunspots migrate towards the equator, the large-scale wea k diffuse magnetic fields of the Sun migrate poleward with the solar c ycle, the polar field reversing at the time of the sunspot maxima. We apply the vector model of Dikpati and Choudhuri (1994, Paper I) to fit these observations. The dynamo layer at the base of the convection zo ne is taken to be the source of the diffuse field, which is then evolv ed in the convection zone subject to meridional circulation and turbul ent diffusion. We find that the longitudinally averaged observational data can be fitted reasonably well both for positive and negative valu es of the alpha-effect by adjusting the subsurface meridional flow sui tably. The model will be extended in a future paper to include the dec ay of active regions as an extra source of the diffuse field, which ma y be necessary to explain the probable phase lag between B-tau and B-p hi at lower latitudes.