The ionosphere, on a global scale, is reasonably well understood from a climatology perspective. However, the storm dynamics of the ionosphere are not fully understood. This partly arises from the complex response function of the Thermosphere-Ionosphere(T-I) system but also from the uncertainty in the space and time dynamics of the magnetospheric inputs to the ionosphere. In the context of M-I coupling, the ionosphere responds to magnetospheric electrodynamic forcing by altering the conductivity in the ionosphere and by plasma transport. Phenomenologically,we understand how to let the ionospheric conductivity evolve in response to local precipitation and how to transport plasma in the collision media of the thermosphere, but we are unable to complete the global coupling because the magnetospheric drivers cannot be defined on the appropriate scales.
The magnetospheric drivers in question are the magnetospheric electric field and the particle (auroral) precipitation. A need for dynamic models of both these drivers exists. Unfortunately, no eminent theoretical, magnetospheric breakthrough is likely which would enable these sources to be defined from knowledge of a few solar wind parameters (e.g. a magnetospheric convection model that responds to IMF and solar wind pressure changes as well as the ensuing storm and substorm dynamics). Hence, it rests upon improved observation techniques and data handling to make progress in the M-I coupling issue. Specific suggestions are to use more global imagers to monitor the precipitation in order to infer boundary locations and particle energy input and to make extensive in situ observations of the plasma convection on a global scale. The Motorola Iridium project with its 77 polar satellites a ~800 km altitude would be an ideal platform for this latter objective.
Sojka, J. J., Magnetospheric shortcomings in ionospheric-magnetospheric coupling: An ionospheric perspective, Solar-Terrestrial Predictions - IV, proceedings of a Workshop at Ottawa, Canada (ed. J. Hruska et al.), 544-548 1994.