A Mechanism of Helicity Variations on the Sun
Abstract
Helicity of solar magnetic fields plays an important role in dynamo theories of the solar cycle. The helicity has been known to vary with the main 11-year period (Hale's cycle). Recent observations have revealed significant helicity variations on a shorter time scale, with a characteristic period of approximately 2 years. We suggest an explanation for the observed variations of the magnetic helicity, based on our model of the double magnetic cycle of solar activity. The quasi-biennial variations of the helicity are the consequence of the influence of erupted magnetic fields of the main cycle on the helicity in the regions of generation of the high-frequency component of magnetic field. This model suggests that the low-frequency component of is generated at the base of the convective zone due to large-scale radial shear of angular velocity. The high-frequency component may be generated in the subsurface region due to latitudinal shear or due to the radial shear in this region.
- Publication:
-
SOHO-9 Workshop on Helioseismic Diagnostics of Solar Convection and Activity
- Pub Date:
- 1999
- Bibcode:
- 1999soho....9E..42B