DYNAMICS OF AXISYMMETRICAL TRUNCATED DYNAMO MODELS

An important question regarding the study Of mean field dynamo models is how to make precise the nature of their underlying dynamics. This i s difficult both because relatively little is known about the dynamica l behaviour of infinite dimensional systems and also due to the numeri cal cost of studying the related partial differential equations. As a first step towards their understanding, it is useful to consider the c orresponding truncated models. Here we summarise some recent results o f the study of a class of truncated axisymmetric mean field dynamo mod els. We find conclusive evidence in these models for various types of intermittency as well as multiple attractors and final state sensitivi ty. We also find that the understanding of the underlying dynamics of such dynamo models requires the study of a new class of dynamical syst ems, referred to as the non-normal systems. Current work demonstrates that these types of systems are capable of a novel type of intermitten cy and also of relevance for the understanding of the full axisymmetri c PDE dynamo models.