Multiple forms of intermittency in partial differential equation dynamo models

We find concrete evidence for the presence of crisis-induced and Pomeau-Manneville type-I intermittencies in an axisymmetric partial differential equation (PDE) mean-field dynamo model. These findings are of potential importance for two different reasons. First, as far as we are aware, this is the first time detailed evidence has been produced for the occurrence of these types of intermittency for such deterministic PDE models. And second, despite the rather idealized nature of these models, the concrete evidence. for the occurrence of more than one type of intermittency in such models makes it in principle possible that different types of intermittency may occur in different solar-type stars or even in the same star over different epochs. In this way a multiple intermittency framework may turn out to be of importance in understanding the mechanisms responsible for grand-minima type behavior in the Sun and solar-type stars and in particular in the interpretation of the corresponding observational and proxy evidence. [S1063-651X(99)08811-X].