Parameters of the Ionospheric F2 Layer as a Source of Information on Trends in Thermospheric Dynamics

Abstract

The problem of determination of trends in thermospheric dynamics parameters (horizontal winds) on the basis of analysis of trends in various combinations of ionospheric F2-layer parameters is formulated. The previous attempts of the author 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) + 2h) are described. These trends are found higher than the hmF2 trends obtained ear- lier by various authors analyzing the hmF2 behavior at fixed moments of local time.