TURBULENT MAGNETOHYDRODYNAMIC DYNAMO FOR INTENSE MAGNETIC-FIELDS AS THE ORIGIN OF SUNSPOTS

The formation of intense magnetic fields in the solar convection zone, which are the origin of sunspots, has been studied based on the concept of a turbulent magnetohydrodynamic dynamo. In this dynamo, the cross helicity, or magnetic-field/velocity correlation, plays a central role in connecting the magnetic field with the rotational motion of an electrically conducting fluid, instead of the helicity or velocity-vorticity correlation that has long been regarded as being a primary dynamo mechanism. Based on this analysis, the mechanisms of some important properties associated with sunspots can be discussed: the formation of intense magnetic fields of a few thousand Gauss; the restriction of sunspots to the lower latitude region; the poleward meridional flow.