Low-Latitude Sunspot Group Tilt Angles in 15-24 Activity Cycles
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arXiv
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866916964872486912 |
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| author | Tlatov, Andrey |
| author_facet | Tlatov, Andrey |
| contents | An analysis of the tilt angles of the active regions in 15-24 activity cycles was performed. We used data from measurements of magnetic fields in the sunspot umbra in the period 1918 -2019 at the Mount Wilson Observatory, as well as the tilt angles of active regions in 'white' light at the Kodaikanal and Mount Wilson observatories in activity cycles 15-21. The mean tilt angles of active regions $\overlineγ$ and the slope $μ$ from latitude $θ$ in the activity cycles are considered. Low-latitude bipoles are the most important in predicting the strength of solar cycles. In this work, we selected the cutoff latitude $θ_{cut}$ at which the highest correlation is observed with the strength of the next activity cycle for active regions with latitude $θ<θ_{cut}$. It was found that for magnetic field measurement data, the highest correlation of the parameters $\overlineγ$ and $μ$ with the strength of the next solar activity cycle is characteristic of bipoles in the equatorial zone with $θ<θ_{cut}\approx 14.2^o$. For white light observation data, $θ_{cut}\approx 8.5^o$ for Mount Wilson observatory and $θ_{cut}\approx 9.4^o$ for Kodaikanal observatory. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_19217 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Low-Latitude Sunspot Group Tilt Angles in 15-24 Activity Cycles Tlatov, Andrey Solar and Stellar Astrophysics An analysis of the tilt angles of the active regions in 15-24 activity cycles was performed. We used data from measurements of magnetic fields in the sunspot umbra in the period 1918 -2019 at the Mount Wilson Observatory, as well as the tilt angles of active regions in 'white' light at the Kodaikanal and Mount Wilson observatories in activity cycles 15-21. The mean tilt angles of active regions $\overlineγ$ and the slope $μ$ from latitude $θ$ in the activity cycles are considered. Low-latitude bipoles are the most important in predicting the strength of solar cycles. In this work, we selected the cutoff latitude $θ_{cut}$ at which the highest correlation is observed with the strength of the next activity cycle for active regions with latitude $θ<θ_{cut}$. It was found that for magnetic field measurement data, the highest correlation of the parameters $\overlineγ$ and $μ$ with the strength of the next solar activity cycle is characteristic of bipoles in the equatorial zone with $θ<θ_{cut}\approx 14.2^o$. For white light observation data, $θ_{cut}\approx 8.5^o$ for Mount Wilson observatory and $θ_{cut}\approx 9.4^o$ for Kodaikanal observatory. |
| title | Low-Latitude Sunspot Group Tilt Angles in 15-24 Activity Cycles |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2509.19217 |