A Model Hierarchy for Ionospheric Plasma Modeling∗

Received (Day Month Year) Revised (Day Month Year) Communicated by (xxxxxxxxxx) This paper deals with the modeling of the ionospheric plasma. Starting from the two-fluids Euler-Maxwell equations, we present two hierarchies of models. The MHD hierarchy deals with large plasma density situations while the dynamo hierarchy is adapted to lower density situations. Most of the models encompassed by the dynamo hierarchy are classical ones, but we shall give a unified presentation of them which brings a new insight into their interrelations. By contrast, the MHD hierarchy involves a new (at least to the authors) model, the massless MHD model. This is a diffusion system for the density and magnetic field which could be of great practical interest. Both hierarchies terminate with the 'classical' striation model, which we shall investigate in detail.