Long-Term Trends in the Upper Atmosphere – Recent Progress

Abstract

Anthropogenic emissions of greenhouse gases influence the atmosphere at nearly all altitudes between ground and space, thus affecting not only life on the surface, but also the space-based technological systems on which we increasingly rely. Long-term changes and trends in the upper atmosphere (mesosphere, thermosphere and ionosphere) are affected also by other drivers, stratospheric ozone depletion, changes in atmospheric wave forcing, changes in water vapour concentration, long-term changes of geomagnetic activity, and secular changes of Earth’s magnetic field. The global trend scenario in the upper atmosphere is presented. It forms a consistent pattern of global change at heights above 50 km. The upper atmosphere is generally cooling and contracting, and related changes in chemical composition (minor components) are affecting the ionosphere. A significant progress reached in the last few years in the three areas, which did not fit the global scenario of trends in the upper atmosphere, is described in more detail.