On the Long-Term Modulation of Solar Differential Rotation
Abstract
Long-term modulation of solar differential rotation was studied with data from Mt. Wilson and our original observations during Solar Cycles 16 through 23. The results are that i) the global B-value (i.e. latitudinal gradient of differential rotation) is modulated with a period of about six or seven solar cycles, ii) the B-values of the northern and southern hemispheres are also modulated with a period similar to the global one, but iii) they show quasi-oscillatory behavior with a phase shift between them. We examined the yearly fluctuations of the B-values in every solar cycle with reference to the phase of the sunspot cycle and found that the B-values in the sunspot-minimum years show large and erratic variations, while those in the sunspot-maximum years show small fluctuations. Positive correlation between the former B-values and the latter was found. We discuss the independent long-term behavior of solar differential rotation between the northern and southern solar hemispheres and the implication for the solar dynamo.
- Publication:
-
Solar Physics
- Pub Date:
- November 2014
- DOI:
- 10.1007/s11207-014-0576-9
- arXiv:
- arXiv:1407.5735
- Bibcode:
- 2014SoPh..289.4021S
- Keywords:
-
- Rotation;
- Solar cycle;
- observations;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 12pages,6figures