LOW-LATITUDE PLASMA DRIFTS FROM A SIMULATION OF THE GLOBAL ATMOSPHERIC DYNAMO

The results of a simulation of the global atmospheric dynamo are presented and compared to observations of the ion drift at Jicamarca and the drifts calculated from previous dynamo models. This simulation procedures a global plasma distribution which is self-consistent with the global potential distribution. We examine the dynamo-generated potential distribution and the associated E x B drifts induced upon the plasma for two F region winds and a (1,-2) tide in the E region. By using simple diurnal winds and tides and making the plasma and potential distributions self-consistent, the agreement of the calculated E x B with the observed drifts at Jicamarca is improved. The use of an F region wind derived from the DE 2 satellite (Herrero and Mayr, 1986) ran further improve the agreement between the calculated E x B drifts and the observed low-latitude plasma drifts. These results lead to the conclusion that the F region dynamo is a very important source of electric fields at low latitudes at all local times. Based on these results, we propose that the postsunset enhancement of the vertical ion drift at Jicamarca is primarily due to a local time gradient in the F region zonal wind in conjunction with the conductivity gradient at the dusk terminator.