Electrical Coupling Between the E and F Regions and its Effect on Low-Latitude Electrodynamic Drifts Produced by the Atmospheric Dynamo

The global ionospheric electrostatic potential distribution is determined using a realistic first-principle ionosphere model and simple wind distributions. The low -latitude ion drifts are calculated for various wind distributions and for self-consistent plasma and potential distributions. These drifts are compared with the plasma drifts observed at Jicamarca, and show considerable improvement over previous dynamo models. The role of the F-region dynamo is determined to be significantly greater than previously assumed. The zonal neutral wind in the F region is shown to be the major source of low-latitude electric fields and the reversal of this wind is linked to the formation of enhanced electric fields in the post-sunset period. The reversal of this wind and the large size of the conductivity ratio, Sigma_sp{P}{E}/Sigma _sp{P}{E} are the principle factors which determine the behavior of the post-sunset enhancement of vertical ion drift at low latitudes.