A Model of the Double Magnetic Cycle of the Sun

It has been argued that the solar magnetic cycle consists of two main periodic components: a low-frequency component (Hale's 22 yr cycle) and a high-frequency component (quasi-biennial cycle). The existence of the double magnetic cycle on the Sun is confirmed using Stanford, Mount Wilson, and Kitt Peak magnetograph data from 1976 to 1996 (solar cycles 21 and 22). In the frame of the Parker's dynamo theory, a model of the double magnetic cycle is presented. This model is based on the idea of two dynamo sources separated in space. The first source of the dynamo action is located near the bottom of the convection zone, and the second operates near the top. The model is formulated in terms of two coupled systems of nonlinear differential equations. It is demonstrated that in the case of a weak interaction between the two dynamo sources, the basic features of the double magnetic cycle, such as the existence of two components and the observed temporal variations of the high-frequency component, can be reproduced.