How the Effects of Winds and Electric Fields in F2-layer Storms Vary with Latitude and Longitude : a Theoretical Study

The effects of thermospheric winds and electric fields on the ionospheric FZlayer are controlled by the geometry of the magnetic field, and so vary with latitude and longitude. We adopt a simple model of the daytime F2-layer and study the effects at midlatitudes (25O-65” geographic) of three processes that accompany geomagnetic storms : (i) thermospheric changes due to aurora1 heating; (ii) equatorward winds that tend to cancel the quiet-day poleward winds; and (iii) the penetration of magnetospheric electric fields. At * 65”, the effects of heating and electric fields are strongest in the longitudes towards which the geomagnetic dipole is tilted, i.e. the North American and the South Indian Ocean sectors. Because of the proximity of the geomagnetic equator to the East Asian and South American sectors, the reverse is true at +25”.