A Three- dimensional Babcock-Leighton Solar Dynamo Model with Non-axisymmetric Convective Flows

Abstract

The observed convective flows on the photosphere (e.g., supergranulation, granulation) play a key role in the Babcock-Leighton (BL) process to generate large-scale polar fields from sunspots fields. In most surface flux transport (SFT) and BL dynamo models, the dispersal and migration of surface fields are modeled as an effective turbulent diffusion. We present the first kinematic 3D FT/BL model to explicitly incorporate realistic convective flows based on solar observations. The results obtained are generally in good agreement with the observed surface flux evolution and with non-convective models that have a turbulent diffusivity on the order of $3 \times 10^{12}$ cm$^2$ s$^{-1}$ (300 km$^2$ s$^{-1}$). However, we find that the use of a turbulent diffusivity underestimates the dynamo efficiency, producing weaker mean fields and shorter cycle.

2 pages,1 figure, to appear in Proceedings of IAU Symposium No. 340, 2018