Is Cycle 24 the Beginning of a Dalton-Like Minimum?

TL;DR

This study analyzes historical solar cycle data to assess whether Cycle 24 signals a Dalton-like minimum, finding that the accumulation of spotless days suggests a potential minimum around 2012, informing solar dynamo models.

Contribution

It provides a comparative analysis of spotless days across solar cycles from 1798-2010, offering a new method to predict solar minima based on spotless day accumulation.

Findings

Cycle 24's spotless days resemble those of past minima.

Approximately 20 spotless days remain before the next maximum.

Predicted last spotless day around December 2012 with 11 months uncertainty.

Abstract

The unexpected development of cycle 24 emphasizes the need for a better way to model future solar activity. In this article, we analyze the accumulation of spotless days during individual cycles from 1798-2010. The analysis shows that spotless days do not disappear abruptly in the transition towards an active sun. A comparison with past cycles indicates that the ongoing accumulation of spotless days is comparable to that of cycle 5 near the Dalton minimum and to that of cycles 12, 14 and 15. It also suggests that the ongoing cycle has as much as 20 \pm 8 spotless days left, from July 2010, before it reaches the next solar maximum. The last spotless day is predicted to be in December 2012, with an uncertainty of 11 months. This trend may serve as input to the solar dynamo theories.