Electrodynamics of the equatorial evening ionosphere: 1. Importance of winds in different regions

摘要: The importance of winds at different altitudes and latitudes for the electrodynamics low-latitude evening ionosphere is examined with a model global coupled ionosphere-thermosphere system. reproduces main observed features equatorial plasma vortex prereversal enhancement (PRE) vertical drift. driven primarily by zonal wind forced diurnally varying pressure-gradient force. lags force owing to inertia. When ion drag important, time lag behind pressure gradient shortened, high-altitude turns eastward earlier than lower altitudes, where less important. Therefore, shear tends develop around transition between small large bottom F region. This closely associated in convection velocity that part vortex. Unlike previous studies, we find driving PRE lie mainly on field lines apexes above peak layer, extend magnetic latitude out nearly 30° encompass entire ionization anomaly Contrary suggestions, westward bottomside found weaken, rather strengthen, PRE. Daytime have relatively little influence electrodynamics.