NEUTRAL TEMPERATURE ANOMALY IN THE EQUATORIAL THERMOSPHERE - A SOURCEOF VERTICAL WINDS

Data obtained from the WATS (Wind and Temperature Spectrometer) instru ment on DE-2 (Dynamics Explorer) during high solar activity, show new evidence for the presence of vertical winds of a significant magnitude in the equatorial thermosphere. They reveal a latitudinal structure t hat can be related to the recently discovered phenomena of the Equator ial Temperature and Wind Anomaly (ETWA). In the local evening hours, t he vertical winds usually are downward around the dip equator and coll ocated with the temperature minimum of ETWA. In general, they are upwa rd at about 24-degrees dip latitude away from the dip equator and are collocated with the ETWA temperature crests. The magnitude of the vert ical winds is in the 10-40 m/s range. It is proposed that the temperat ure and pressure ridges, formed by the excess ion drag on the zonal wi nds around the two crests and ordered by the relatively lower ion drag at the trough of the well known Equatorial Ionization Anomaly (EIA), drive a new wind system in the meridional plane and that the measured vertical winds form part of this wind system.