Low-Latitude Sunspot Group Tilt Angles in 15-24 Activity Cycles

Abstract

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 $\overline{\gamma }$ and the slope $\mu$ from latitude $\theta$ 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 ${\theta }_{cut}$ at which the highest correlation is observed with the strength of the next activity cycle for active regions with latitude $\theta <{\theta }_{cut}$. It was found that for magnetic field measurement data, the highest correlation of the parameters $\overline{\gamma }$ and $\mu$ with the strength of the next solar activity cycle is characteristic of bipoles in the equatorial zone with $\theta <{\theta }_{cut}\approx 14.2^o$. For white light observation data, ${\theta }_{cut}\approx 8.5^o$ for Mount Wilson observatory and ${\theta }_{cut}\approx 9.4^o$ for Kodaikanal observatory.

11 pages, 4 figures, 2 tables

References in corpus (20)

• The Solar Cycle
• The new Sunspot Number: assembling all corrections
• Solar cycle prediction
• Sunspot group tilt angles and the strength of the solar cycle
• Visualization of the challenges and limitations of the long-term sunspot number record
• The cause of the weak solar cycle 24
• Re-calibration of the Sunspot Number: Status Report
• The Effect of "Rogue" Active Regions on the Solar Cycle
• Recovering Joys Law as a Function of Solar Cycle, Hemisphere, and Longitude
• Limits to solar cycle predictability: Cross-equatorial flux plumes
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• Surface Flux Transport on the Sun
• Source of a Prominent Poleward Surge During Solar Cycle 24
• Nonlinear mechanisms that regulate the solar cycle amplitude
• Re-examining Sunspot Tilt Angle to Include Anti-Hale Statistics
• Comparison of Debrecen and Mount Wilson/Kodaikanal sunspot group tilt angles and the Joy's law
• Tilt of sunspot bipoles in Solar Cycles 15 to 24
• Sunspot group tilt angles from drawings for cycles 19-24
• Dependence of North--South Difference in the Slope of Joy's Law on Amplitude of Solar Cycle
• Relationship Between the Tilt Angle of Sunspot Group and the Properties of the Next Solar Cycle