Periodic change of polarity of photospheric magnetic field

Fuente: arXiv
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Autori principali: Vernova, Elena, Tyasto, Marta, Baranov, Dmitrii
Natura: Preprint
Pubblicazione: 2025
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author Vernova, Elena
Tyasto, Marta
Baranov, Dmitrii
author_facet Vernova, Elena
Tyasto, Marta
Baranov, Dmitrii
contents The work is devoted to the study of periodic structures in the magnetic field of the photosphere. The polarity of the Sun's magnetic fields shows cyclicity with periods of 1-3 years, which is possibly due to quasi-biennial variations that are found in various parameters of solar activity, interplanetary space, and in cosmic rays. In this work, variations in weak magnetic fields of the photosphere were investigated, which required the use of special data processing methods. Synoptic maps of the photospheric magnetic field for the period 1978-2016 (NSO Kitt Peak) were used. To highlight the contribution of weak magnetic fields, the saturation threshold for synoptic maps was set at 5 G. Based on thus transformed synoptic maps, a time-latitude diagram was constructed. For the selected latitude intervals, smoothing, trend removal and Fast Fourier Transform (FFT) were performed. In the time-latitude diagram, 6 spatiotemporal regions with distinct cyclic structure were observed during 4 solar cycles (21-24). The periods ranged from 0.5 to 4 years with a maximum at 1.2 years. The amplitude of ripples is significantly higher for those intervals in which the polar field had positive sign. This effect confirms the connection of ripples variations with the polarity of the 22-year magnetic cycle.
format Preprint
id arxiv_https___arxiv_org_abs_2507_04912
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Periodic change of polarity of photospheric magnetic field
Vernova, Elena
Tyasto, Marta
Baranov, Dmitrii
Solar and Stellar Astrophysics
The work is devoted to the study of periodic structures in the magnetic field of the photosphere. The polarity of the Sun's magnetic fields shows cyclicity with periods of 1-3 years, which is possibly due to quasi-biennial variations that are found in various parameters of solar activity, interplanetary space, and in cosmic rays. In this work, variations in weak magnetic fields of the photosphere were investigated, which required the use of special data processing methods. Synoptic maps of the photospheric magnetic field for the period 1978-2016 (NSO Kitt Peak) were used. To highlight the contribution of weak magnetic fields, the saturation threshold for synoptic maps was set at 5 G. Based on thus transformed synoptic maps, a time-latitude diagram was constructed. For the selected latitude intervals, smoothing, trend removal and Fast Fourier Transform (FFT) were performed. In the time-latitude diagram, 6 spatiotemporal regions with distinct cyclic structure were observed during 4 solar cycles (21-24). The periods ranged from 0.5 to 4 years with a maximum at 1.2 years. The amplitude of ripples is significantly higher for those intervals in which the polar field had positive sign. This effect confirms the connection of ripples variations with the polarity of the 22-year magnetic cycle.
title Periodic change of polarity of photospheric magnetic field
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2507.04912