The influence of ionization and recombination processes on the dynamics of ionospheric plasma clouds

The dynamics of a one-dimensional ionospheric irregularity interacting with the magnetosphere is studied by numerical simulation. The polarization electric field produced by charge separation within the irregularity propagates along magnetic field lines with the Alfvén velocity V_A and drives polarizational and field-aligned currents in the magnetosphere. Their values and localization are controlled by motion and deformation of the irregularity resulting from its electrostatic coupling to the background ionosphere. The pattern of the field-aligned currents varies with time and depends primarily on gradients of the polarization electric field. The latter is controlled by the ambient electric field, diffusion, recombination process, intensity of the initial perturbation, etc. Feedback effect of the magnetospheric conductance on the development of the irregularity is examined.