Sensitivity of ring analysis to near-surface magnetism

TL;DR

This paper reviews how near-surface magnetic fields influence local helioseismology measurements, particularly ring-diagram analysis, and discusses implications for detecting magnetic activity precursors.

Contribution

It provides a comprehensive review of recent advances in understanding the sensitivity of ring analysis to near-surface magnetism.

Findings

Magnetic fields can bias local helioseismology results.

Ring-diagram analysis helps detect subsurface magnetic changes.

Magnetic effects are crucial for interpreting helioseismic data.

Abstract

While magnetic field has only second order effects on global sound waves, it can affect the mode frequencies and flow fields inferred using local helioseismology. A strong localized field can bias our results when one try to infer global scale flows such as the meridional circulation. On the other hand, one important object of research in this area is to determine whether one can detect changes in frequencies or sub-surface flow fields that could be a precursor of surface magnetic events. In this paper we review recent development in this area focusing on results obtained with the ring-diagram analysis technique.