Solar Differential Rotation of Sunspot Groups with Different Magnetic Types during Solar Cycles 22–25

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Abstract
This study systematically examines differential rotation of α- type (unipolar), β- type (bipolar), and βx- type (complex) sunspot groups (SGs) using 1986–2025 RGO/USAF/NOAA data across solar cycles (SCs) 22–25. Methods include daily displacement measurements for rotation rates, outlier removal, binomial fitting for differential rotation profiles, and comparisons across magnetic types, cycles, and hemispheres. Our key findings are as follows: βx- type SGs exhibit the most pronounced differential rotation and significant cycle-dependent variations, with stronger differential rotation in active cycles (22–23) and weaker in less active ones (24–25); α- and β- type SGs show similar stable profiles. A comparison of near-equatorial low-latitude (10°) rotation rates across SCs reveals that both α- and β- type SGs are ordered as follows: SC 25 > SC 24 > SC 23 > SC 22; in contrast, βx- type SGs exhibit a different sequence: SC 25 > SC 23 > SC 22 > SC 24. The rotational rates of βx- type SGs exhibit inconsistent hemispheric dominance across different cycles; the north–south hemispheric differences in rates between α- and β- type SGs are relatively weak.
Funding Information
  • 河南省科学技术厅 ∣ Natural Science Foundation of Henan Province (Grant No. 242300420253)
  • MOST ∣ National Natural Science Foundation of China (Grant No. 12463009)
  • MOST ∣ National Natural Science Foundation of China (Grant No. 12505122)
  • MOST ∣ National Key Research and Development Program of China (Grant No. 2025YFF0510701)
  • MOST ∣ National Natural Science Foundation of China (Grant No. 12673064)
  • Yunnan Revitalization Talent Support Program Innovation Team Project (202405AS350012)
  • China Postdoctoral Science Foundation (2021M690932)
  • Postgraduate Education Reform and Quality Improvement Project of Henan Province (YJS2024JD32)
  • Climbing Program of NSSC (E6PD3001)

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