Over the last decade, we have learned a lot about ionospheric physics and radio propagation over Europe. It is a complex topic where overall picture is assembled from intense research by many individual institutions in Europe, by their joint work within the COST (Co-operation in the Field of Scientific and Technical Research) Actions 238 on ‘Prediction and Retrospective Ionospheric Modelling over Europe’ and 251 on ‘Improved Quality of Service in Ionospheric Telecommunication Systems Planning and Operation’ and by lively discussions of these results at European scientific meetings. At the beginning of the follow-on COST271 Action on ‘Effects of the Upper Atmosphere on Terrestrial and Earth-Space Communications’ a first priority was to prepare a state-of-the-art documents of the current...