Speaker
Description
First Name: Jie
Last Name: Jiang
Email Address: jiejiang@buaa.edu.cn
Affiliation: Beihang University, China
All Authors: Jie Jiang
Abstract: Over 40 years of detailed solar magnetic field observations have shown that the original Babcock–Leighton (BL) dynamo scenario proposed in the 1960s could capture the essential physics of the global solar dynamo. That is the surface magnetic field, including the polar field, plays a central role in driving the solar cycle. In the past decade, major progress has been made in understanding the evolution of the solar surface magnetic field and incorporating this knowledge into dynamo modeling. The cycle dependence and stochastic properties of sunspot emergence, including their latitudes and tilt angles, have emerged as key sources of nonlinear and stochastic modulation of the solar cycle. When the observed surface magnetic field evolution is used to constrain the outer boundary condition of BL dynamo models, the resulting behavior differs fundamentally from the long-held flux transport dynamo framework developed in 1990s. Rather than relying on an equatorward meridional flow in the tachocline, the equatorward migration of the toroidal field arises naturally from the time- and latitude-dependent regeneration of toroidal flux, driven by latitudinal differential rotation together with the evolving surface field. Within this framework, the polar field strength becomes the primary regulator of the cycle period. In addition, the Lorentz force associated with the cyclic magnetic field produced by the dynamo naturally reproduces both the poleward and equatorward branches of the observed torsional oscillations.