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NOTE TO USERS : NCEI Termination of Data.

SSNe for Solar Cycles 23-25

Note: This plot is updated during the first week of each month. Follow me for hourly SSNe updates.

This plot provides a look at the progression of the smoothed NWRA effective sunspot number (SSNe) for solar cycles 23, 24, and 25. The heavy solid curve is the smoothed SSNe (centered 13-month average), the light solid curve is the monthly average SSNe, and the dashed curve is a sunspot number calculated from the smoothed F10.7 solar flux. The foF2 data used in the SSNe calculations were obtained from the National Centers for Environmental Information (NCEI), and the 10.7cm solar flux data were obtained from the Dominion Radio Astrophysical Observatory (DRAO).

The red curves extending beyond the current date are based on the latest prediction for Cycle 25 issued by the NOAA SWPC. What is wanted here is a projection for SSNe that is consistent with the SWPC SSN prediction. The peak smoothed sunspot number (using the v2.0 scaling) for Cycle 24 was 115 and the smoothed SSNe was 90, and the smoothed predicted SSN and observed SSNe for the past solar minimum were 0 and -7.5, respectively. A scaling relationship of SSNePred = (97.5/115.0)*SSNPred - 7.5 was applied to the SWPC SSN prediction released on 15 July 2020 to produce the three red curves: the solid red curve is the SWPC prediction scaled by this factor, and the two dashed curves are the "high" and "low" predictions scaled by this same factor.

Please note that the SSNe values plotted here were calculated in near real-time from a limited data set. If you are interested in post-analysis SSNe values calculated from a more representative data set, please contact NWRA.

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