Magnetosphere–ionosphere coupling by Alfvén waves: Beyond current continuity

Many numerical models of magnetospheric dynamics treat the ionosphere as an inner boundary condition. These models have traditionally used the current continuity condition, treating the ionosphere as a sheet current in which the electric field is electrostatic. A more general boundary condition is suggested that not only is more complete, but also straightforward to implement. Results from a model using this boundary condition applied to the excitation of field line resonances in the magnetosphere are presented.