Research Article

On a limitation of Zeeman polarimetry and imperfect instrumentation in representing solar magnetic fields with weaker polarization signal

¹ National Solar Observatory, 3665 Discovery Drive, 3rd Floor, Boulder, CO 80303, USA
² Stanford University, Stanford, CA 94305-4085, USA
³ ReSoLVE Centre of Excellence, Space Climate Research Unit, University of Oulu, POB 3000, 90014 Oulu, Finland
⁴ NorthWest Research Associates, 3380 Mitchell Lane, Boulder, CO 80301, USA
⁵ Institute for Space-Earth Environmental Research, Nagoya University, Furo-cho Chikusa-ku Nagoya, 464-8601 Aichi, Japan

^* Corresponding author: apevtsov@nso.edu

Received: 18 January 2020
Accepted: 13 January 2021

Abstract

Full disk vector magnetic fields are used widely for developing better understanding of large-scale structure, morphology, and patterns of the solar magnetic field. The data are also important for modeling various solar phenomena. However, observations of vector magnetic fields have one important limitation that may affect the determination of the true magnetic field orientation. This limitation stems from our ability to interpret the differing character of the Zeeman polarization signals which arise from the photospheric line-of-sight vs. the transverse components of the solar vector magnetic field, and is likely exacerbated by unresolved structure (non-unity fill fraction) as well as the disambiguation of the 180° degeneracy in the transverse-field azimuth. Here we provide a description of this phenomenon, and discuss issues, which require additional investigation.