Magnetic Helicity with Solar Dynamo

Abstract

The research on solar dynamo can be said to begin with the discovery of the 11-year cycle from the statistical observation of sunspot activity and to explore the reasons for its formation. The observation results of the full solar disk magnetic field have enabled to discover the overall migration law of the large-scale longitudinal magnetic field on the surface of the sun for 22 years (see Fig. 6.1). The 11-year sunspot cycle is half of Babcock–Leighton’s recommended 22-year solar dynamo cycle, which corresponds to an oscillatory exchange of energy between toroidal and poloidal solar magnetic fields. At this point in the dynamo cycle, it is believed that within the convection zone forces emergence of the toroidal magnetic field through the photosphere, giving rise to pairs of sunspots, roughly aligned east-west with opposite magnetic polarities. The magnetic polarity of sunspot pairs changes every solar cycle, and this phenomenon is called the Hale cycle.