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.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Bruevich, E.A., Bruevich, V.V., Yakunina, G.V.: Changed relation between Solar 10.7-cm radio flux and some activity indices which describe the radiation at different altitudes of atmosphere during cycles 21–23. J. Astrophys. Astron. 35, 1–15 (2014). https://doi.org/10.1007/s12036-014-9258-0.
Clette, F., Lefèvre, L.: The new sunspot number: assembling all corrections. Sol. Phys. 291, 2629 (2016). https://doi.org/10.1007/s11207-016-1014-y.
Clette, F., Lefèvre, L., Cagnotti, M. et al.: The revised Brussels–Locarno sunspot Nnmber (1981–2015) Sol. Phys. 291, 2733 (2016). https://doi.org/10.1007/s11207-016-0875-4
Covington, A.E.: Solar radio emission at 10.7 cm. J. R. Astron. Soc. Can. 63, 125 (1969). 1969 SAO/NASA Astrophysics Data System (ADS) http://adsabs.harvard.edu/full/1969JRASC..63..125C
Dudok de Wit, T., Lefèvre, L., Clette, F.: Uncertainties in the sunspot numbers: estimation and implications. Sol. Phys. 291, 2709 (2016). https://doi.org/10.1007/s11207-016-0970-6.
Hathaway, D.H., Wilson, R.M., Reichmann, E.J.: Group sunspot numbers: sunspot cycle characteristics. Sol. Phys. 211, 357 (2002). https://doi.org/10.1023/A:1022425402664.
Johnson, R.W.: Power law relating 10.7 cm flux to sunspot number. Astrophys. Space Sci. 332, 73 (2011). https://doi.org/10.1007/s10509-010-0500-1.
Labitzke, K., van Loon, H.: Space Sci. Rev. 80, 393 (1997). https://doi.org/10.1023/A:1004907126955.
Lampropoulos, G., Mavromichalaki, H., Tritakis, V.: Possible estimation of the Solar Cycle characteristic parameters by the 10.7 cm Solar radio flux. Sol. Phys. 291, 989–1002 (2016). https://doi.org/10.1007/s11207-016-0859-4
Leamon, R.J., McIntosh, S.W., Chapman, S.C., et al.: Timing terminators: forecasting sunspot Cycle 25 onset. Sol. Phys. 295, 36 (2020). https://doi.org/10.1007/s11207-020-1595-3
Okoh, D., Okoro, E.: On the relationships between sunspot number and Solar radio flux at 10.7 centimeters. Sol. Phys. 295, 1 (2020). https://doi.org/10.1007/s11207-019-1566-8
Prölss, G.: Physics of the Earth’s Space Environment: An Introduction. Springer, Berlin (2004). https://www.springer.com/gp/book/9783540214267. 978-3-642-97123-5
Svensmark, H.: Influence of cosmic rays on earth’s climate. Phys. Rev. Lett. 81(22), 5027–5030 (Nov 1998). https://doi.org/10.1103/PhysRevLett.81.5027.
Tapping, K.F.: 10.7 cm Solar radio flux. Space Weather 11(7), 394–406 (2013). https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/swe.20064
Tapping, K., Morgan, C.: Changing relationships between sunspot number, total sunspot area and \(F_{10.7}\) in Cycles 23 and 24. Sol. Phys. 292, 73 (2017). https://doi.org/10.1007/s11207-017-1111-6.
Tapping, K.F., Morton, D.C.: The next generation of Canadian Solar flux monitoring. J. Phys. Conf. Ser. 440(1), 012039 (2013). https://iopscience.iop.org/article/10.1088/1742-6596/440/1/012039/meta
Tapping, K.F., Valdés, J.J.: Did the Sun change its behavior during the decline of Cycle 23 and into Cycle 24? Sol. Phys. 272, 337 (2011). https://doi.org/10.1007/s11207-011-9827-1
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.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Electronic Supplementary Material
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
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
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s10509-020-03800-x