Long-Term Variations in the Solar Differential Rotation

摘要: Using Greenwich data (1879–1976) and SOON/NOAA (1977–2002) on sunspot groups we found the following results: (i) The Sun's mean (over all concerned cycles during 1879–1975) equatorial rotation rate (A) is significantly larger (≈0.1%) in odd-numbered (ONSCs) than even-numbered (ENSCs). (≈10%) more differential ONSCs ENSCs. North–south difference latitude gradient of significant ENSCs insignificant ONSCs. (ii) known very large decrease A from cycle 13 to 14 confirmed. amount this was about 0.017 μrad s−1. Also, find that decreased 17 18 by 0.008 s−1 21 22 0.016 From northern hemisphere southern hemisphere, it opposite later two epochs. time gap between consecutive drops 44 years, suggesting existence a `44-yr' or `double Hale cycle' A. drops, viz., 22, 90 years (Gleissberg cycle). We predict next drop (moderate) will be occurring 25 26 followed relatively large-amplitude activity. (iii) Existence 90-yr seen cycle-to-cycle variation (B). weak 22-yr modulation B seems superposed strong modulation. (iv) coefficient varies only has maximum amplitude order 0.01 around activity minima. (v) There exists good anticorrelation ENSCs, `22-yr' periodicity B. 0.05 (vi) It well-known Gnevyshev Ohl rule solar applicable also 20, but 12 (in data) both hemispheres, seem violate And (vii) All aforesaid statistically variations related approximate 179-yr cycle, 1811–1989, motion center mass system.