Ionosphere-magnetosphere simulation of small-scale structure and dynamics

This work presents first results and the numerical methods of a highly impr oved two-dimensional three-fluid simulation model of the ionosphere-magneto sphere system. The model considers ionization and recombination, ion-neutra l friction, the Hal term in Ohm's law, and various heat sources in the ener gy equations. The electrodynamic response and the evolution of the collisio n frequencies are treated self-consistently in the height-resolved ionosphe re. This model is the first and to our knowledge the only simulation model that can resolve the dynamic and nonlinear electromagnetic interaction betw een the ionosphere and the magnetosphere. The simulation is aimed at modeli ng fast temporal and small spatial scale ionospheric structures associated, for instance, with filamentary aurora and ionospheric heating experiments. The results presented in this paper focus on ion and electron heating by d ifferent sources, i.e., ion heating due to plasma-neutral friction, electro n heating resulting from energetic particle precipitation and by ohmic diss ipation in strong field-aligned currents. This work is motivated by a speci fic auroral event that was observed simultaneously with optical and radar i nstruments. A consistent explanation of sis event is possible in the presen ce of ohmic heating of electrons in a strong field-aligned electric current layer.