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Modern Maximum

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History of sunspot number observations showing the recent elevated activity.

The Modern Maximum was found by Sami Solanki, Ilya G. Usoskin and colleagues[1] as the period of unusually high solar activity[2] which began with solar cycle 15 in 1914. It reached a maximum in solar cycle 19 during the late 1950s and may have ended with the peak of solar cycle 23 in 2000, as solar cycle 24 is recording, at best, very muted solar activity.[3][failed verification] Another proposed end date for the maximum is 2007, with the decline phase of Cycle 23.[citation needed] In any case the low solar activity of solar cycle 24 in the 2010s marked a new period of reduced solar activity.

This maximum period is a natural example of solar variation, and one of many that are known from proxy records of past solar variability. The Modern Maximum reached a double peak once in the 1950s and again during the 1990s.


  1. ^ Solanki, Sami K.; Usoskin, Ilya G.; Kromer, Bernd; Schüssler, Manfred; Beer, Jürg (2004). "Unusual activity of the Sun during recent decades compared to the previous 11,000 years" (PDF). Nature. 431 (7012): 1084–7. Bibcode:2004Natur.431.1084S. doi:10.1038/nature02995. PMID 15510145. S2CID 4373732. Retrieved 17 April 2007., "11,000 Year Sunspot Number Reconstruction". Global Change Master Directory. Retrieved 2005-03-11.
  2. ^ Usoskin I.G. (2017). "A History of Solar Activity over Millennia". Living Reviews in Solar Physics. 14 (3): 3. arXiv:0810.3972. Bibcode:2017LRSP...14....3U. doi:10.1007/s41116-017-0006-9. S2CID 195340740. PDF Copy
  3. ^ Rigozo, N. R.; Echer, E.; Vieira, L. E. A.; Nordemann, D. J. R. (2001). "Reconstruction of Wolf Sunspot Numbers on the Basis of Spectral Characteristics and Estimates of Associated Radio Flux and Solar Wind Parameters for the Last Millennium". Solar Physics. 203 (1): 179–191. Bibcode:2001SoPh..203..179R. doi:10.1023/A:1012745612022. S2CID 117574927.