Magnetic Flux Transport at the Solar Surface

TL;DR

This paper reviews the surface flux transport model of the Sun's magnetic field, detailing how surface flows influence magnetic evolution and its implications for understanding solar dynamo processes.

Contribution

It provides a comprehensive review of the modeling of surface magnetic flux transport processes and discusses the model's successes and results.

Findings

The model successfully reproduces observed magnetic field evolution.

Surface flows significantly influence magnetic flux distribution.

The model offers insights into the solar dynamo mechanism.

Abstract

After emerging to the solar surface, the Sun's magnetic field displays a complex and intricate evolution. The evolution of the surface field is important for several reasons. One is that the surface field, and its dynamics, sets the boundary condition for the coronal and heliospheric magnetic fields. Another is that the surface evolution gives us insight into the dynamo process. In particular, it plays an essential role in the Babcock-Leighton model of the solar dynamo. Describing this evolution is the aim of the surface flux transport model. The model starts from the emergence of magnetic bipoles. Thereafter, the model is based on the induction equation and the fact that after emergence the magnetic field is observed to evolve as if it were purely radial. The induction equation then describes how the surface flows -- differential rotation, meridional circulation, granular, supergranular flows, and active region inflows -- determine the evolution of the field (now taken to be purely radial). In this paper, we review the modeling of the various processes that determine the evolution of the surface field. We restrict our attention to their role in the surface flux transport model. We also discuss the success of the model and some of the results that have been obtained using this model.