Observational results hinting at the coupling of the thermosphere with the ionosphere/magnetosphere system and with the middle atmosphere

Total density data based on CACTUS microaccelerometer measurements have been analysed between 220 and 700 km altitudes at low latitudes in the time interval 1975–79. Instantaneous residual density values with respect to atmospheric models for quiet as well as for disturbed days have been investigated as a function of local solar time (LST). It has been found that the density residuals present conspicuous increases of the variance in several LST intervals as well as a general broadening which can be in connection with various coupling mechanisms between the thermosphere and the ionosphere/magnetosphere on the one hand, and the middle atmosphere on the other. An attempt is made to select those mechanisms responsible for the observed features.