Vol52,3,2009 edited by ALAIN BOURDILLON, LJILJANA R. CANDER and BRUNO ZOLESI A N N A L S OF GEOPHYSICS A N N A L I D I G E O F I S I C A Vol52,3,2009 20-09-2009 19:05 Pagina III Vol52,3,2009 20-09-2009 19:05 Pagina IV V ANNALS OF GEOPHYSICS, VOL. 52, N. 3/4, June/August 2009 Preface This issue of Annals of Geophysics contains a series of papers which form the Fi- nal Report of the COST (European Cooperation in Science and Technology) 296 Ac- tion on the Mitigation of Ionospheric Effects on Radio Systems (MIERS). It is impor- tant to recognize that COST is one of the longest running European instruments sup- porting cooperation among scientists and researchers across Europe. Prior to the COST 296 Action, strong collaboration in the field of ionospheric research and appli- cations had already been established under three previous actions on Prediction and Retrospective Ionospheric Modelling over Europe (PRIME), on Improved Quality of Service in Ionospheric Telecommunication Systems Planning and Operation, and Ef- fects of the Upper Atmosphere on Terrestrial and Earth-Space Communications. The MIERS main objective was to broaden our knowledge of the effects imposed by the ionosphere on practical radio systems, and for the development and implementation of techniques to mitigate the deleterious effects of the ionosphere on such systems. As a result of all these activities, more than 130 researchers from about 40 institutions in 26 countries all over the world currently belong to the ionospheric COST community. All the papers in this supplement are in the format employed in the international scientific literature. They describe the principle results achieved in the COST 296 Action. In addition to these scientific papers, an introductory paper briefly covers the background, the objectives as defined in the Memorandum of Understanding, the management structure and architecture of the action, and the technical work pro- gramme. An overview of COST 296 activities has been included together with a con- cluding paper summarising the overall outcomes and looking forward to further in- vestigations in a follow-on Action. We would like to thank all the participants of this Action, the Working Group and Package leaders, the secretary of the Action Mrs. Angela Vernon, and all the local organizers of the different Workshops and Management Committee meetings. Lastly, we also wish to acknowledge Prof. Enzo Boschi, President of the Istituto Nazionale di Geofisica e Vulcanologia, for supporting the publication of this issue of Annals of Geophysics. ALAIN BOURDILLON LJILJANA R. CANDER BRUNO ZOLESI Vol52,3,2009 22-09-2009 14:16 Pagina V