Thermospheric density variations associated with auroral electrojet activity

Thermospheric density variations observed during the time period of August 6–8, 1968, are studied in relation to auroral electrojet activity. In situ density measurements were obtained by the accelerometer experiment on the Air Force low-altitude density research satellite OV1-15. Density profiles were obtained in the altitude region 155–250 km and between 30° and 90°N geographic latitude. Densities at 134 km obtained from the orbital decay of satellite 1968-64A are compared with the accelerometer measurements. Enhanced density variations at high latitudes are observed and are found to be associated with auroral electrojet activity. The latitude of maximum density enhancement points to the existence of an auroral heat source. Furthermore, the appearance of a wavelike structure on several density profiles is apparently connected with intensifications of the electrojet current.