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Establishing atmospheric turbulence thresholds for reliable ground-based solar magnetograms.

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Title: Establishing atmospheric turbulence thresholds for reliable ground-based solar magnetograms.
Authors: Alzate Betancur, Miguel1 (AUTHOR) malzateb1@eafit.edu.co, Vargas Domínguez, Santiago2 (AUTHOR), Campos Rozo, José Iván2,3 (AUTHOR), Restrepo Gómez, René1 (AUTHOR) rrestre6@eafit.edu.co
Source: Advances in Space Research. Jun2026, Vol. 77 Issue 12, p12754-12766. 13p.
Subjects: Atmospheric turbulence, Solar magnetic fields, Sun observations, Astrophysical spectropolarimetry, Solar activity
Abstract: Continuous monitoring of solar magnetic activity is essential for understanding eruptive events that can disrupt human technology. Although space-based observatories provide high-quality data, their cost limits sustained global coverage, motivating low-cost ground-based alternatives. However, atmospheric turbulence degrades the Stokes parameters required for magnetic-field reconstruction through inversion techniques. This paper proposes a methodology to determine the maximum terrestrial atmospheric aberration that still permits reliable inference of sunspot magnetic fields with opposite polarity, used to compute critical parameters for solar flare prediction models, such as the distance between magnetic barycenters of opposite polarity. The stability of the magnetic-field magnitude, inclination, azimuth, and line-of-sight component is also evaluated, since many flare-forecasting methods rely on predictors derived from the full photospheric vector magnetic field. The deviation of the barycenter distance and the structural similarity of the vector magnetic field maps under increasing turbulence, characterized by the Fried parameter r 0 , serve as quantitative quality criteria. The methodology was validated using spectropolarimetric data from NOAA AR 11504 acquired by the Helioseismic and Magnetic Imager (HMI; 14 cm aperture, 495 cm focal length). The analysis shows that, under static turbulence, reliable inference of magnetic barycenter distances is preserved down to r 0 ≈ 3 cm, with relative errors below 5%. Under dynamic turbulence, temporal variability increases dispersion and polarization crosstalk, reducing the stability of the barycenter distance across the full r 0 range. In contrast, direct analysis of the vector magnetic field maps reveals greater sensitivity to turbulence, as structural similarity and reconstruction errors stabilize only for r 0 > 7 cm, indicating a more restrictive threshold for reliable full-vector recovery. These results establish a practical turbulence threshold above which low-cost ground-based stations can still deliver magnetograms suitable for solar flare prediction models. The proposed framework provides a quantitative criterion for site selection and performance assessment of future ground-based solar monitoring networks. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:Continuous monitoring of solar magnetic activity is essential for understanding eruptive events that can disrupt human technology. Although space-based observatories provide high-quality data, their cost limits sustained global coverage, motivating low-cost ground-based alternatives. However, atmospheric turbulence degrades the Stokes parameters required for magnetic-field reconstruction through inversion techniques. This paper proposes a methodology to determine the maximum terrestrial atmospheric aberration that still permits reliable inference of sunspot magnetic fields with opposite polarity, used to compute critical parameters for solar flare prediction models, such as the distance between magnetic barycenters of opposite polarity. The stability of the magnetic-field magnitude, inclination, azimuth, and line-of-sight component is also evaluated, since many flare-forecasting methods rely on predictors derived from the full photospheric vector magnetic field. The deviation of the barycenter distance and the structural similarity of the vector magnetic field maps under increasing turbulence, characterized by the Fried parameter r 0 , serve as quantitative quality criteria. The methodology was validated using spectropolarimetric data from NOAA AR 11504 acquired by the Helioseismic and Magnetic Imager (HMI; 14 cm aperture, 495 cm focal length). The analysis shows that, under static turbulence, reliable inference of magnetic barycenter distances is preserved down to r 0 ≈ 3 cm, with relative errors below 5%. Under dynamic turbulence, temporal variability increases dispersion and polarization crosstalk, reducing the stability of the barycenter distance across the full r 0 range. In contrast, direct analysis of the vector magnetic field maps reveals greater sensitivity to turbulence, as structural similarity and reconstruction errors stabilize only for r 0 > 7 cm, indicating a more restrictive threshold for reliable full-vector recovery. These results establish a practical turbulence threshold above which low-cost ground-based stations can still deliver magnetograms suitable for solar flare prediction models. The proposed framework provides a quantitative criterion for site selection and performance assessment of future ground-based solar monitoring networks. [ABSTRACT FROM AUTHOR]
ISSN:02731177
DOI:10.1016/j.asr.2026.03.070