Can the observable solar activity spectrum be reproduced by a simple dynamo model?

Abstract

The temporal spectrum of the solar activity is more than just the main cycle. It contains different timescales, which can be considered as continuous components of the activity spectrum. The possibility of finding a realistic spectrum of the solar magnetic activity variation is analysed for several versions of a simple model for solar activity based on the original idea of E. Parker. In particular, we study the original set of partial differential equations with two versions of suppression of the dynamo action and the fourth-order dynamical system obtained by truncating the Parker equations. We show that the effects included in the models, i.e. the nonlinear dynamo suppression and the dynamical chaos, as well as random fluctuations of the dynamo drivers, are quite sufficient to obtain the main solar cycle and the continuous components of the spectrum similar to the observed ones. However, the capabilities of the approach under consideration substantially vary from one model to another. Each model reproduces a continuous component of the spectrum in a specific parameter range. This study has confirmed the view that the examination of various solar dynamo models with the aim to find a reasonable combination of main activity cycle and continuous spectrum of solar activity can be used as an additional test of their validity.