Predictability of the solar cycle over one cycle

TL;DR

This paper develops a method to predict the strength of the upcoming solar cycle by modeling sunspot emergence and magnetic field evolution, accounting for inherent randomness and uncertainty, over a single cycle.

Contribution

It introduces a probabilistic scheme that combines statistical sunspot emergence models with flux transport simulations to predict solar cycle strength after three years of observation.

Findings

Predicted cycle 25 maximum strength range: 93-155 with 95% probability.

The method accounts for randomness in sunspot emergence, improving prediction reliability.

Cycle predictions become feasible after three years of ongoing cycle observation.

Abstract

The prediction of the strength of future solar cycles is of interest because of its practical significance for space weather and as a test of our theoretical understanding of the solar cycle. The Babcock-Leighton mechanism allows predictions by assimilating the observed magnetic field on the surface. But the emergence of sunspot groups has the random properties, which make it impossible to accurately predict the solar cycle and also strongly limit the scope of cycle predictions. Hence we develop the scheme to investigate the predictability of the solar cycle over one cycle. When a cycle has been ongoing for more than 3 years, the sunspot group emergence can be predicted along with its uncertainty during the rest time of the cycle. The method for doing this is to start by generating a set of random realizations which obey the statistical relations of the sunspot emergence. We then use a surface flux transport model to calculate the possible axial dipole moment evolutions. The correlation between the axial dipole moment at cycle minimum and the subsequent cycle strength and other empirical properties of solar cycles are used to predict the possible profiles of the subsequent cycle. We apply this scheme to predict the large-scale field evolution from 2018 to the end of cycle 25, whose maximum strength is expected to lie in the range from 93 to 155 with a probability of 95\%.