R. Raghavarao et al., NEUTRAL TEMPERATURE ANOMALY IN THE EQUATORIAL THERMOSPHERE - A SOURCEOF VERTICAL WINDS, Geophysical research letters, 20(11), 1993, pp. 1023-1026
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.