Speaker
Description
First Name: Binghang
Last Name: Li
Affiliation: Beihang University
All Authors: Yukun Luo、Jie Jiang 、Binghang Li 、Zebin Zhang 、Ruihui Wang
Abstract: The evolution of the Sun’s large-scale surface magnetic field is well represented by surface flux transport (SFT) models, which can consequently provide a natural constraint for the outer boundary condition (BC) of Babcock–Leighton (BL) dynamo models. For the first time, this study proposes a zero radial diffusion boundary condition for BL dynamo models, enabling their surface field evolution to align consistently with SFT simulations. The derivation of this boundary condition is based on the MHD induction equation, and its effects are evaluated in comparison with two alternative approaches: (i) a radial outer BC, and (ii) a radial outer BC combined with strong near-surface radial pumping. The comparison is carried out both for the evolution of a single bipolar magnetic region and within a full BL dynamo model. The results show that the zero radial diffusion BC effectively suppresses radial diffusion across the surface, ensuring consistency between the bipolar magnetic region evolution in the BL dynamo and the SFT model. With this outer BC, the full BL dynamo model successfully reproduces the fundamental properties of the solar cycle. In addition, the model naturally produces a surface magnetic field that is not purely radial, in closer agreement with solar observations. The physically motivated zero radial diffusion boundary condition paves the way for deeper insight into solar and stellar cycles.