A model of the solar magnetic cycle with a meridian stream closed inside the convective zone

Abstract

A dynamo model of the solar cycle suggesting a relatively new mechanism for generation of poloidal magnetic fields is studied. This model considers the meridian motion in which the material rises at the equator and sinks at the poles and allows the magnetic fields from the solar surface to be transferred to the generation layer at the base of the convective zone. In addition to the surface stream of material and large-scale magnetic field from the equator to the poles, we assume the looping of a new poloidal magnetic field near the poles. At the base of the convective zone, thin meridian streams transfer the end of that loop from the poles to the equator. The loop consists of poloidal fields on the top and at the bottom of the stream near the base of the convective zone. Thus, new poloidal magnetic fields, which are opposite in sign to the poloidal fields of the current solar cycle, are generated in the depth of the convective zone. New poloidal fields on the top of the stream become the fields of a new 11-year cycle. At the bottom of the meridian stream, the direction of the poloidal magnetic field is the same as the direction of the poloidal field of the current solar cycle. The lifetime of the deep-seated poloidal field is much longer than 11 years, due to the motion of the material which keeps it from rising too rapidly. The meridian loop of the subsequent solar cycle has a poloidal field opposite in direction to the poloidal field at the base of the convective zone. This counterbalances the poloidal field at the bottom of the meridian stream. The numerical model calculates the magnetic fields in the surface and bottom layers of the convective zone.