Solar cycle asymmetry as a consequence of fluctuations in dynamo parameters

TL;DR

This paper explains the asymmetry in solar cycle durations as a result of fluctuations in dynamo parameters, supported by a model and recent solar cycle data.

Contribution

It introduces a dynamo model with fluctuating parameters that reproduces observed solar cycle asymmetries and predicts a correlation with polar field reversal delays.

Findings

Model shows increased asymmetry with higher fluctuation amplitude and coherence time.

Data from recent solar cycles confirm the predicted correlation.

The asymmetry is linked to fluctuations in the solar dynamo process.

Abstract

The duration of activity growths in solar cycles is on average shorter than the duration of its declines. This asymmetry can result from fluctuations in dynamo parameters. A solar dynamo model with fluctuations in the $\alpha$-effect shows the statistical asymmetry which increases with both fluctuation amplitude and coherence time. An interpretation for the asymmetry origin is suggested, which predicts a correlation between the asymmetry measure and delay of the polar field reversals relative to the activity maxima. Data on the twelve latest solar cycles confirm such a correlation.