What the Sunspot Record Tells Us About Space Climate

By D. Hathaway, R. Wilson. 2004

147 citations recorded by the source corpus.

The records concerning the number, sizes, and positions of sunspots provide a direct means of characterizing solar activity over nearly 400 years. Sunspot numbers are strongly correlated with modern measures of solar activity including: 10.7-cm radio flux, total irradiance, X-ray flares, sunspot area, the baseline level of geomagnetic activity, and the flux of galactic cosmic rays. The Group Sunspot Number provides information on 27 sunspot cycles, far more than any of the modern measures of solar activity, and enough to provide important details about long-term variations in solar activity or “Space Climate.” The sunspot record shows: 1) sunspot cycles have periods of 131± 14 months with a normal distribution; 2) sunspot cycles are asymmetric with a fast rise and slow decline; 3) the rise time from minimum to maximum decreases with cycle amplitude; 4) large amplitude cycles are preceded by short period cycles; 5) large amplitude cycles are preceded by high minima; 6) although the two hemispheres remain linked in phase, there are significant asymmetries in the activity in each hemisphere; 7) the rate at which the active latitudes drift toward the equator is anti-correlated with the cycle period; 8) the rate at which the active latitudes drift toward the equator is positively correlated with the amplitude of the cycle after the next; 9) there has been a significant secular increase in the amplitudes of the sunspot cycles since the end of the Maunder Minimum (1715); and 10) there is weak evidence for a quasi-periodic variation in the sunspot cycle amplitudes with a period of about 90 years. These characteristics indicate that the next solar cycle should have a maximum smoothed sunspot number of about 145 ± 30 in 2010 while the following cycle should have a maximum of about 70 ± 30 in 2023.

Subfields: Astronomy and Astrophysics, Oceanography

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In Astronomy and Astrophysics

1. D. Hathaway
2. I. Usoskin
3. P. Gilman
4. M. Dikpati
5. R. Wilson
6. F. Clette
7. J. Vaquero
8. Dibyendu Nandy

In Oceanography

1. D. Hathaway
2. P. Gilman
3. M. Dikpati
4. I. Usoskin
5. R. Wilson
6. J. Vaquero
7. F. Clette
8. L. Svalgaard

Citations in the corpus

• A History of Solar Activity over Millennia (2008, unknown): “For details see the review on sunspot numbers and solar cycles (Hathaway and Wilson, 2004; Hathaway, 2008).”
• Does the F10.7 index correctly describe solar EUV flux during the deep solar minimum of 2007-2009? (2011, background): “[2] Solar activity presented by sunspot number varies over different timescales [e.g., Frick et al., 1997; Hathaway and Wilson, 2004; Lundstedt et al., 2005; Usoskin, 2008;Wilson, 1988].”
• A History of Solar Activity over Millennia (2008, background): “For details see the review on sunspot numbers and solar cycles (Hathaway and Wilson, 2004; Hathaway, 2010).”
• Geomagnetic activity indicates large amplitude for sunspot cycle 24 (2006, methodology): “The recent (October 2003) peak in aaI indicates a sunspot number maximum for cycle 24 of about 160 ± 14. This prediction is very much in line with the predictions of a large cycle 24 by Hathaway and Wilson [2004] and by Dikpati et al. [2006] but in contrast to the prediction of a small cycle 24 by”
• From the Wolf number to the International Sunspot Index: 25 years of SIDC (2007, background): “…it provides a base index of the solar forcing on the Earth climate and of secular evolutions of the radiative, corpuscular and magnetic flux interacting with the Earth atmosphere and magnetosphere (Frö hlich and Lean, 2004; Hathaway and Wilson, 2004; Solanki et al., 2005; Wang et al., 2005).”
• Simulating and Predicting Solar Cycles Using a Flux-Transport Dynamo (2006, background): “This finding is in agreement with the predictions by Hathaway & Wilson (2004) andTsirulnik et al. (1997), but in contrast to that of Svalgaard et al. (2005) and Schatten (2005).”
• Sunspot cycle 24: Smallest cycle in 100 years? (2005, background): “, 2002], but not all [Tsirulnik et al., 1997; Hathaway and Wilson, 2004], also seem to indicate lower solar activity for the coming cycle(s).”
• Historical sunspot observations: A review (2007, background): “Table 5 Decalogue of Hathaway and Wilson (2004) on important results for space cli”