MID-LATITUDE MEASUREMENTS OF THE THERMOSPHERIC NEUTRAL WIND DURING THE ALADDIN PROGRAM

During the 24-h ALADDIN rocket programme at Wallops Island (37° 50'N, 75° 29'W) on 29 and 30 June 1974 [Philbrick, C.R., ALADDIN '74 Handbook, AFCRL, (1974)], six measurements of the neutral wind profile were successfully made using chemical release techniques. The wind measurements cover 16 h of observations and allow the tentative identification of the propagating diurnal tidal mode (1,1) at the lower altitudes (90-120 km). A very strong evanescent oscillation between 150 and 200 km, with an amplitude greater than 100 m s-1, is identified as the (1, -2) mode. During the night-time period (30 June 0000-0800 UT) there was a moderate level (Kp 3-4) of geomagnetic activity with several discrete polar substorms. The magnitude of a generally south-westward wind after local midnight, of 150-200 m s-1, and its depth of penetration into the lower thermosphere (below 150 km) at the latitude of Wallops Island (~38°N), probably reflects a strong enhancement of the quiet day thermospheric circulation by geomagnetic heating and acceleration processes in the sunlit polar cap at the summer solstice. This series of wind measurements provides the first continuous measurements of vector neutral wind through the night-time period, between about 130 and 200 km, and the 16-h period of observations was possible through tracking of two lithium trail releases during daytime. © 1979.