Coupling between the neutral tidal wind and the ionospheric dynamo current

Abstract

A self-consistent model for the motions of the neutrals and the plasma within the dynamo region is presented. The mutual coupling between both components, the degree of energy dissipation of the wind and the modification of its horizontal and vertical structure due to the plasma, and finally the electric fields and currents generated by the fundamental diurnal and semidiurnal tidal winds are calculated. The main results are that the diurnal tidal (1, −1) mode, being an evanescent mode in the lower atmosphere, changes into a propagation mode with reduced attenuation within the dynamo region. On the other hand, the semidiurnal (2, 2) mode increases its attenuation there. The electric currents are driven mainly by the divergence-free part of the electric dynamo field v × B. The efficiency of the diurnal wind in generating dynamo currents reduces by a factor of about 2 if the mutual coupling between plasma and neutrals is taken into account.