Prediction of even and odd sunspot cycles

TL;DR

This study develops a method to predict sunspot cycle amplitudes and durations by analyzing even and odd cycles separately, using specific precursors, and forecasts an increasing trend in solar activity for the coming decades.

Contribution

The paper introduces a novel approach to predict sunspot cycles by separately analyzing even and odd cycles with specific precursors, improving prediction accuracy.

Findings

Accurate prediction of sunspot cycle parameters using precursor data.

Cycle 25 predicted to have an amplitude of 171 +/- 23.

Cycle 26 likely stronger than cycle 25, indicating rising solar activity.

Abstract

Here we study the prediction of even and odd numbered sunspot cycles separately, thereby taking into account the Hale cyclicity of solar magnetism. We first show that the temporal evolution and shape of all sunspot cycles are extremely well described by a simple parameterized mathematical expression. We find that the parameters describing even sunspot cycles can be predicted quite accurately using the sunspot number 41 months prior to sunspot minimum as a precursor. We find that the parameters of the odd cycles can be best predicted with maximum geomagnetic aa index close to fall equinox within a 3-year window preceding the sunspot minimum. We use the found precursors to predict all previous sunspot cycles and evaluate the performance with a cross-validation methodology, which indicates that each past cycle is very accurately predicted. For the coming sunspot cycle 25 we predict an amplitude of 171 +/- 23 and the end of the cycle in September 2029 +/- 1.9 years. We are also able to make a rough prediction for cycle 26 based on the predicted cycle 25. While the uncertainty for the cycle amplitude is large we estimate that the cycle 26 will most likely be stronger than cycle 25. These results suggest an increasing trend in solar activity for the next decades.