This plot provides a look at the progression of the smoothed NWRA effective sunspot number (SSNe) for solar cycles 23 and 24. 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 and 10.7cm solar flux data used in these calculations were obtained from the NOAA Space Weather Prediction Center (SWPC).
The red curves extending beyond the current date are rough predictions based on the notional prediction for Cycle 25 provided by the NOAA SWPC. This prediction (as of April 2019) gives an expected solar minimum in 'late 2019 or 2020', a maximum occurring between 2023 and 2026, and a sunspot range of 95 to 130. The upper curve shown here uses the higher sunspot number of 130 with a maximum year of 2023, and the lower curve uses the lower sunspot number of 95 with a maximum year of 2026. Both curves assume that the solar minimum will occur in Dec 2019. These two curves represent a current best-estimate of the range of SSNe over the next two years.
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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