Abstract
It is well known that the polar magnetic field is at its maximum during solar minima, and that the behaviour during this time acts as a strong predictor of the strength of the following solar cycle. This relationship relies on the action of differential rotation (the Omega effect) on the poloidal field, which generates the toroidal flux observed in sunspots and active regions. We measure the helicity flux into both the northern and the southern hemispheres using a model that takes account of the Omega effect, which we apply to data sets covering a total of 60 years. We find that the helicity flux offers a strong prediction of solar activity up to five years in advance of the next solar cycle. We also hazard an early guess as to the strength of Solar Cycle 25, which we believe will be of similar amplitude and strength to Cycle 24.
Highlights
In this article we investigate the suitability of the magnetic-helicity flux as a predictor of solar activity.Solar activity and its associated phenomena and drivers are known to have wide-ranging effect on the heliosphere, including how cosmic rays pass through said regions (Ferreira and Potgieter, 2004)
In this study we choose to neglect the second component, and we focus on the contribution due to the Omega effect, which is the main contributor to large-scale helicity flux
Given that the polar field is more directly related to the Omega effect being described by our helicity flux, as well as a good measure of the dipole moment, we choose to compare the effectiveness of magnetichelicity predictions with this benchmark
Summary
In this article we investigate the suitability of the magnetic-helicity flux as a predictor of solar activity. The Omega effect is typically attributed to the polar magnetic-field lines, which move slower than those at the Equator due to differential rotation As a consequence, they wrap themselves around the solar axis, generating toroidal field. A small (relatively) flow of positive helicity exits the southern interior, which gives an overall build-up of positive helicity in the southern hemisphere This model can be succinctly described by the following formulae (Berger and Ruzmaikin, 2000): dHV N dt. We analyse the data provided by the Wilcox Solar Observatory using a variety of techniques described within This includes hemispherical splitting, and a direct comparison with the prediction capabilities of the polar field, which is currently the most commonly used precursor indicator of the solar cycle.
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