The Sun’s surface poloidal and toroidal magnetic field were constructed for the last 4 solar cycles using observations from multiple instruments, and were then reproduced using the updated Babcock-Leighton model.
Super-synoptic map is constructed using SDO/HMI’s synoptic magnetic maps of each Carrington rotation, covering the period of May 2010 to December 2017. Polarity reversals can be clearly seen in the map.
The dipole, quadrupole, and octupole components of the Sun’s magnetic field are calculated and visualized, covering the last 22 years of the Sun’s activities.
The dipole moment observed by the WSO during the pre-minimum years of the last 4 solar cycles are used to establish a relation with the sunspot numbers of the following maximum years. The relation is then used to calculate the dipole moment for all the past cycles.
A more comprehensive time-distance helioseismic method is developed to derive the Sun’s meridional circulation, and a 3-layer flow structure is found through the convection zone.
Numerical simulations of solar rotation and dynamo have been performed over the last decades with the aim of understanding the physics of the solar interior. Here we briefly discuss two main approaches, namely, mean-field modeling and global simulations. We also present recent results of hydrodynamic global simulations which reveal interesting aspects of stellar rotation.
Subsurface meridional flow speed shows an anti-correlation with the magnetic flux being transported poleward above the latitude of 35°. In the lower latitude, the residual meridional flow, after a long-time mean profile is subtracted, shows converging flow toward the activity belts.