Berdichevsky, D. and Piacentini, R. (2024) Prediction of the Amplitude and Main Characteristics of Solar Cycle 25.
Advances in Aerospace Science and Technology,
9, 191-200. doi: 10.4236/aast.2024.94015.
1. Introduction
This Report closely follows the work by Uzal, Piacentini, and Verdes [1] (from now on referred to as UPV) in predicting the number of sunspots maximum and
their date as well as the date at the end of the Solar Cycle 25 and at the start of the Solar Cycle 26 at its defining minimum. It is worth mentioning that the
predictions of the solar cycle often tend to be quite different, as can be seen in [2]. In particular, the forecasting of the intensity of the 24 solar cycle maximum,
obtained by UPV of the maximum Sunspot number equal to 78, was a prediction that was quite reasonable and, within that work, was estimated at one sigma
uncertainty of the measured Sunspot number of 116 (as given in SISLO: https://www.swpc.noaa.gov/products/predicted-sunspot-number-and-radio-flux). The
curvature method developed in UPV [1] then is no more than a numerical search technique attempting to maximize the chance of success in locating the time
and intensity of the Solar Maximum based on ideas pioneered by Waldmeier around the earlier 1930s [3], see also, e.g., Garg et al., 2019 [4].
We perform a numerical evaluation of a smoothed Sunspot number as a function of time, using as input the monthly Sunspot list since 1740 (to near present,
March 2023), obtained thanks to world-wide-web public access site provided by the WDC-SILSO service (https://www.sidc.be/SILSO/home).
The next section (Section 2) describes the numerical approach based on available algorithms instead of their personal development, as in our guiding technique
by UPV [1]. Section 3 presents our conclusions.
2. Method and Results
In our evaluation of the fastest ascent of Sunspots when past the solar minimum of the new cycle, we proceed to identify the curvature numerically of the
smoothed Sunspot number, i.e., the location of the fastest ascent with a technique described wholly in the Appendix and available from the numerical tools in
the literature of which we provide in detail the one we used in our work and which distinguish this tool from those employed by Uzal, Piacentini and Verdes (see
[1]) and which being self-developed are in general less simple to apply.
Figure 1. Solar sunspot number from the year 1740 to March 2023 plotted with a scale that extends until the start of the year 2025. The complete series is
indicated in blue and the smoothed series is running monthly and averaged using the neighboring 12-month values (in green). Reference of Sunspot number
data: WDC-SILSO service (https://www.sidc.be/SILSO/home).
The red curve in Figure 2 shows the value of the derivative and we proceed to smooth it in the same way that we did with the smoothing of the Sunspots
number, using the algorithm MATLAB “filtfilt”. The value is adjusted to an approximate reproduction in its intensity to all maxima in the Solar Cycle, since the start
of the eighteenth century. In this case, the adjustment factor has been ~6.25, which is, as the figure shows, the one used for the black curve (Adjusted Curvature).
It is quite consistent with the observed maximum average intensity in the number of sunspots, with an uncertainty that we indicate when we solely consider the
last 4 Solar Cycles.
Figure 2 shows the smoothed sunspots number, the first curvature evaluation and the smoothed curvature used to predict for Solar Cycle 25, the maxima for the
