Abstract
It is known that the solar radio flux is strongly correlated to the sunspot cycle and that the flux is nearly the same at every minimum. If 64 sfu is taken as the baseline for all cycles, then we can calculate the proxy sunspot number from the flux, and vice versa. Furthermore, we find that the fitted adjusted flux divided by the fitted sunspot number gives a strong marker for the start of Solar Cycle 25 in October 2019. The high resolution 2K (based on 2048×2048 pixels SDO images) sunspot number currently indicates a start in June 2019.
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Data Sources
Space Weather Prediction Center and NASA panel: https://www.weather.gov/news/190504-sun-activity-in-solar-cycle https://www.swpc.noaa.gov/news/solar-cycle-25-forecast-update
Source: WDC-SILSO, Royal Observatory of Belgium, Brussels. SILSO, World Data Center - Sunspot Number and Long-term Solar Observations, Royal Observatory of Belgium, online Sunspot Number catalogue: http://www.sidc.be/SILSO/, ‘year(s)-of-data 1947-2019’
Source 10.7 cm radio flux values (sfu): spaceweather.gc.ca
“NOAA, SWPC Space Weather Operations (SWO)”. “Original Ottawa data” “Solar Terrestrial Activity Report” or STAR World Data Center for Solar-Terrestrial Physics, Moscow Data World Data Center for Solar-Terrestrial Physics, Moscow
Acknowledgements
I thank the anonymous first and second reviewer and members of the editorial board for their useful comments and suggestions. I also thank the Chinese astronomer for his multiple comments.
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Geryl, P.P.A., Alvestad, J. A formula for the start of a new sunspot cycle. Astrophys Space Sci 365, 113 (2020). https://doi.org/10.1007/s10509-020-03800-x
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DOI: https://doi.org/10.1007/s10509-020-03800-x