Surface Flux Transport 2D documentation

Radiative and energetic output on our host star is primarily governed by the surface plasma and magnetic field dynamics. Hence, it is essential for us to understand the magnetic field distribution on the solar surface. However, with our current observational capabilities, we can only observe half of the solar surface routinely. Even direct observations are not reliable near high latitudes due to the forshortening effect. In this context the unobserved farside of the Sun also poses increased uncertainity on the estimation of global surface magnetic flux estimates. Such problems are more pronounced for observations of other magnetically active stellar objects due to short observating window and low resolving power.

Magnetic fields generated in the interior of a star manifests on the surface due to bouyancy subjected to large scale plasma flows on the surface. This phenomena distributes the magnetic field globally along with possible flux cancellation processes. With the available observations and our theoretical understanding, we can numerically model this flux transport process by solving the magnetic induction equation. Such modelled global distribution of the surface magnetic field is essential for understanding and forecasting solar/stellar activity and evolution. Sun is magnetically active and this activity cycle lasts for about 11 years during which the magnetic field distribution on the solar surface – the photosphere, evolves and generates a vast range of events e.g., emergece and decay of sunspots, solar flares, coronal mass ejections, flow of solar wind and energetic particles into the heliosphere etc. Surface flux transport model solves the radial component of the magnetic induction equation on the solar surface by using prescribed flow profiles, flux cencellation process and source terms. This code suite provides a numerical model of SFT developed in PYTHON.

Link to the GitHub repository: https://sr-dash.github.io/SFT2D/.

Note

The code is under active development and is not yet ready for production use. Please report any issues on the GitHub repository.

Last Updated on 2025-10-30.

Contents:

• Quick Start
  • Acknowledgments
  • System Requirements
  • A Brief Description of the SFT 2D code
• Surface flux transport (SFT) simulation Notebook
  • Import sft2d package and check teh latest version.
  • Load BMR property for a solar cycle for a test run
  • Compute and plot the solar cycle parameters
  • To-Do List
• Theoretical background
  • Magnetic field evolution on the solar surface
  • Bipolar Magnetic Region (BMR) Flux Injection — Theoretical Explanation
• API Reference
  • sft2d.calculate_advection
  • sft2d.calculate_diffusion
  • sft2d.calculate_time_step
  • sft2d.create_grid
  • sft2d.initialize_field
  • sft2d.meridional_flow
  • sft2d.differential_rotation
  • sft2d.calculate_usflx
  • sft2d.calculate_dm
  • sft2d.calculate_polar_field
  • sft2d.calculate_polar_flux
  • sft2d.plot_bfly
  • sft2d.plot_mag