Electrodynamics of magnetosphere-ionosphere coupling and feedback on magnetospheric field line resonances

The model is applied to the excitation of field line resonances (FLRs) in dipolar and stretched geomagnetic fields in Earth's magnetosphere. Magnetosphere-ionosphere coupling is included by accounting for the closure of magnetospheric field-aligned currents (FACs) through Pedersen currents in the ionosphere.

A second new aspect is that the height-integrated Pedersen conductivity is treated as a dynamic parameter by electrodynamically coupling the two-dimensional finite element wave model "Topo" to the ionospheric ionization model "Global Airglow Model (GLOW)." We demonstrate that field line stretching brings the equatorial plasma β above unity, where the reduced MHD formulism for low-frequency plasma breaks down. As an application of our model, we study a specific FLR event observed on 31 January 1997, when the NASA FAST satellite was over the Canadian Auroral Network for the OPEN Program Unified Study (CANOPUS) Gillam station.