Correlation between Decay Rate and Amplitude of Solar Cycles as Revealed from Observations and Dynamo Theory

TL;DR

This study uncovers correlations between solar cycle amplitude, decay rate, and period, using observational data and dynamo models, highlighting the importance of meridional circulation fluctuations for solar cycle prediction.

Contribution

It demonstrates that fluctuations in meridional circulation are essential to reproduce observed solar cycle correlations in a flux transport dynamo model.

Findings

Linear correlation between cycle amplitude and decay rate

Correlation between current cycle amplitude and previous cycle decay rate

Anti-correlation between current cycle amplitude and previous cycle period

Abstract

Using different proxies of solar activity, we have studied the following features of solar cycle. (i) A linear correlation between the amplitude of cycle and its decay rate, (ii) a linear correlation between the amplitude of cycle $n$ and the decay rate of cycle $(n - 1)$ and (iii) an anti-correlation between the amplitude of cycle $n$ and the period of cycle $(n - 1)$. Features (ii) and (iii) are very useful because they provide precursors for future cycles. We have reproduced these features using a flux transport dynamo model with stochastic fluctuations in the Babcock-Leighton $\alpha$ effect and in the meridional circulation. Only when we introduce fluctuations in meridional circulation, we are able to reproduce different observed features of solar cycle. We discuss the possible reasons for these correlations.