Behavior of parameters of the ionospheric F2 layer at the edge of the centuries: 2. Height of the layer

The trends in the height of the ionospheric F 2 layer, hmF 2, for the period from the end of the 1990s to the beginning of the 2010s are considered. It is shown that for a majority of the considered situations (time of the day plus season) negative trends are obtained for all stations for which series of initial data satisfying the requirements were found. They vary from −1.2 to −3.1 km per year. The trends in the daytime are slightly higher than in the postsunset period which apparently manifests the influence of the contraction of the upper atmosphere on changes in the hmF 2 value.