A Relationship between the Solar Rotation and Activity Analysed by Tracing Sunspot Groups

Abstract

The sunspot position from Greenwich Photoheliographic Results (GPR), US Air Force Solar Optical Observing Network and National Oceanic and Atmospheric Administration (USAF/NOAA), and Debrecen Photoheliographic Data (DPD) data bases in the period 1874 to 2016 were used to calculate yearly values of the solar differential-rotation parameters $A$ and $B$. The calculated differential-rotation parameters were compared with the solar-activity level. We found that the Sun rotates more differentially at the minimum than at the maximum of activity during the 1977 - 2016 epoch. An inverse correlation between equatorial rotation and solar activity was found using the recently revised sunspot number. The secular decrease of equatorial rotation rate accompanying the increase of activity stopped in the last part of the 20th century. It was noted that when a significant peak of equatorial rotation velocity is observed during minimum of activity, the strength of the next maximum is smaller than the previous one.

13pages, 3 figures

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Cited by in corpus (6)

• Measurements of Solar Differential Rotation Using the Century Long Kodaikanal Sunspot Data
• Long-Term Variations in Solar Differential Rotation and Sunspot Activity, II: Differential Rotation Around the Maxima and Minima of Solar Cycles 12-24
• Determination of the Solar Rotation Elements and Period from Ruđer Bošković's Sunspot Observations in 1777
• Bošković's method for determining the axis and rate of solar rotation by observing sunspots in 1777
• On the Determination of the Solar Rotation Elements i, Ω and Period using Sunspot Observations by Ruđer Bošković in 1777
• Long-term Evolution of the Solar Corona Using PROBA2 Data