INTERMITTENT BEHAVIOR IN AXISYMMETRICAL MEAN-FIELD DYNAMO MODELS IN SPHERICAL-SHELLS

Axisymmetric mean-field dynamo models in spherical shells are shown to be capable of producing temporally intermittent behaviour. This is of potential importance since (i) it is, as far as we are aware, the fir st time such behaviour has been produced internally by a mean-field dy namo model in a spherical shell, without requiring any additional assu mptions or truncations, and (ii) it may be characteristic of the type of behaviour observed in the long-term record of solar activity, such as Maunder minima. We also show that these types of behaviour persist when the functional form of the alpha quenching is altered and also oc cur over intervals of the shell thickness and the dynamo number.