Parameters of the ionospheric F2 layer as a source of information on trends in thermospheric dynamics

The problem of determining trends in thermospheric dynamics parameters (horizontal winds) based on analysis of trends in various combinations of ionospheric F2-layer parameters is formulated. The previous attempts of the authors in this direction are briefly described. It is shown that all studied parameters lead to the same result: after the “boundary date” (approximately 1980) a systematic change in these parameters (a long-term trend) is observed, this fact manifesting changes in the dynamical regime of the thermosphere because of cooling and contraction of the entire middle and upper atmosphere. The results of a search for trends in the hmF2 height for the moment (T(ss) + 2 h) are described. These trends are found higher than the hmF2 trends obtained earlier by various authors analyzing the hmF2 behavior at fixed moments of local time.