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On long-term periodicities in the sunspot recordSunspot records are systematically maintained, with the knowledge that an 11 year average period exists since about 1850. Thus, the sunspot record of highest quality and considered to be the most reliable is that of cycle eight through the present. On the basis of cycles 8 through 20, various combinations of sine curves were used to approximate the observed R sub MAX values (where R sub MAX is the smoothed sunspot number at cycle maximum). It is found that a three component sinusoidal function, having an 11 cycle and a 2 cycle variation on a 90 cycle periodicity, yields computed R sub MAX values which fit, reasonably well, observed R sub MAX values for the modern sunspot cycles. Extrapolation of the empirical functions forward in time allows for the projection of values of R sub MAX for cycles 21 and 22. For cycle 21, the function projects a value of 157.3, very close to the actually observed value of 164.5. For cycle 22, the function projects a value of about 107. Linear regressions applied to cycle 22 indicate a long-period cycle (cycle duration 132 months). An extensive bibliography on techniques used to estimate the time dependent behavior of sunspot cycles is provided.
Document ID
19840026317
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Wilson, R. M. (NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
September 4, 2013
Publication Date
July 1, 1984
Subject Category
Solar Physics
Report/Patent Number
NAS 1.15:86458
NASA-TM-86458
Accession Number
84N34388
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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