An Early Prediction of the Amplitude of Solar Cycle 25

• Published in: Solar physics 2018-07, Vol.293 (7), p.1-10, Article 112
• Main Authors: Pesnell, W. Dean, Schatten, Kenneth H.
• Format: Article
• Language: English
• Subjects: Amplitudes; Astrophysics and Astroparticles; Atmospheric Sciences; Irradiance; Magnetic fields; Physics; Physics and Astronomy; Precursors; Solar activity; Solar cycle; Solar flux; Solar magnetic field; Solar minimum; Solar Physics; Solar spectral irradiance; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Sunspot cycle; Sunspot numbers; Sunspots; Wavelet transforms
• ISSN: 0038-0938; 1573-093X
• DOI: 10.1007/s11207-018-1330-5

A “Solar Dynamo” (SODA) Index prediction of the amplitude of Solar Cycle 25 is described. The SODA Index combines values of the solar polar magnetic field and the solar spectral irradiance at 10.7 cm to create a precursor of future solar activity. The result is an envelope of solar activity that minimizes the 11-year period of the sunspot cycle. We show that the variation in time of the SODA Index is similar to several wavelet transforms of the solar spectral irradiance at 10.7 cm. Polar field predictions for Solar Cycles 21 – 24 are used to show the success of the polar field precursor in previous sunspot cycles. Using the present value of the SODA index, we estimate that the next cycle’s smoothed peak activity will be about 140 ± 30 solar flux units for the 10.7 cm radio flux and a Version 2 sunspot number of 135 ± 25. This suggests that Solar Cycle 25 will be comparable to Solar Cycle 24. The estimated peak is expected to occur near 2025.2 ± 1.5 year. Because the current approach uses data prior to solar minimum, these estimates may improve as the upcoming solar minimum draws closer.