Vol52,3,2009 437 ANNALS OF GEOPHYSICS, VOL. 52, N. 3/4, June/August 2009 1. Introduction The need for more reliable and efficient communications services, especially those in- volving ionospheric HF communications and navigational systems, imposes increasing de- mand for a better knowledge of the effects im- posed by the Earth’s upper atmosphere and ways to mitigate disturbing effects. Temporal and spatial changes in the upper atmosphere act to limit and degrade the performance of terres- trial and Earth-space radio systems in many dif- ferent ways and this is why mitigation activities must involve several topics like ionospheric monitoring and modeling, development of new hardware for communication systems and new propagation simulator, measurements and mod- eling of ionospheric Total Electron Content (TEC) and ionospheric scintillations, using in particular the Global Positioning System (GPS). The European ionospheric community has long been aware that cooperation research on an international basis is essential to deal with such complex issues. In particular, interna- tional cooperation is required for the collection of data, in both the real-time and in retrospec- tive modes, the development and verification of new methods to improve the performance of both operational and future terrestrial and Earth-space communication systems and the exchange of expertise on space plasma effects on Global Navigation Satellite Systems (GNSS). In this context the COST 296 Action MIERS on the «Mitigation of Ionospheric Ef- fects on Radio Systems» has made a significant impact in a number of areas. 2. The major achievements of COST 296 a) A study dedicated to the improvement of the NeQuick model for Galileo users has been performed to identify the weaknesses of the model at mid-latitudes. b) Neuro-fuzzy modelling based methods to predict foF2 1-24 hours in advance have been presented. c) An analytical model has been developed for mid-scale ionospheric inhomogeneities oc- curring either as patches in the high-latitude ionosphere or bubbles in the low latitude/equa- torial ionosphere in order to investigate and pre- dict their scintillation effects. d) The day-to-day variability in TEC is greater than in foF2 and exhibits its higher val- ues during the nighttime hours. The slab thick- ness variability shows a similar pattern with that of TEC or of foF2 variability. e) The Prompt Ionospheric Database has been improved (http://www.wdc.rl.ac.uk/cgi- COST 296 MIERS: conclusion Alain Bourdillon (1), Ljiljana R. Cander (2) and Bruno Zolesi (3) (1) IETR, Université de Rennes 1, France (2) STFC, Rutherford Appleton Laboratory, Chilton, UK (3) Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italy A brief summary is given here of the major achievements of the COST 296 Action MIERS. Mailing address: Dr. Alain Bourdillon, IETR, Univer- sité de Rennes 1, 35042 Rennes, France; e-mail: alain.bour- dillon@univ-rennes1.fr Vol52,3,2009 20-09-2009 19:06 Pagina 437 438 A. Bourdillon, L.R. Cander and Bruno Zolesi bin/digisondes/cost_database.pl). This is 24/7 on-line service that is based on the contribu- tions of a number of COST 296 participating institutions. f) The RWC-Warsaw/IDCE web service (http://www.cbk.waw.pl/rwc/idce and ftp:// www.cbk.waw.pl/idce) provides on line access to the 24-hours ahead forecast of foF2 and M(3000)F2 for quiet as well as disturbed condi- tions based on data of continuous monitoring of regional ionospheric conditions from all avail- able sites. The list of available forecasting mod- els. g) The structure of a heterogeneous array has been proposed for HF direction finding pur- pose with advantages resulting from its sensi- bility to the incident polarization. h) Research has been directed at exploiting MIMO techniques for long-range communica- tions within the HF band. Several HF-MIMO measurement campaigns were performed using different antenna array configurations at both the transmitter and receiver ends of the link. i) Time-of-flight measurements (TOF) over the radio link between Uppsala (Sweden) and Bruntingthorpe (U.K.) have been performed and compared with the TOF provided by the long-term prediction models SIRM. l) A long-term interference prediction mod- el for the HF spectrum is being developed. This model could be used in the absence of system capability to assess interference background in real time or near real time. m) An operational service for space-plasma and space-weather monitoring has been devel- oped (Space Weather Applications Center Ionosphere, http://w3swaci.dlr.de/). n) The role of higher order ionosphere er- rors (the term in f-3 due to the effect of the ge- omagnetic field; the three f-4 terms (i) due to the curvature of the path in the plane of inci- dence, (ii) curvature perpendicular to the plane of incidence and (iii) due to the actual distribu- tion of electron density along the path) is under consideration. o) The monitoring of ionospheric scintilla- tion activity has been continued in different parts of the world. The database has been ana- lyzed and the development of forecasting mod- els has been initiated 3. Proposal for a follow-on Action Since 1991, the COST 238, COST 251, COST 271 and COST 296 Actions relating to ionospheric radio propagation have been par- ticularly useful in creating a critical mass of researchers in projects where the initial em- phasis was on long-term ionospheric predic- tion and retrospective ionospheric modeling over Europe. The COST 238 Action PRIME (Prediction and Retrospective Ionospheric Modeling over Europe) was a four year research project with objectives to develop regional maps and mod- els over the European ionosphere that are more accurate than internationally available global maps and models. It involved the participation of some 72 scientists and engineers from 17 countries. The work encompassed the produc- tion of regional monthly median maps and al- gorithms for generating «instantaneous» snap- shot maps of the standard vertical-incidence ionospheric characteristics from coordinated sounding measurements within Europe. Addi- tional studies involved height profiles of elec- tron density, the vertical total electron content up to an altitude of 1000 km and research lead- ing to an improved understanding and thus po- tential for better modeling of ionospheric storm morphologies. Work conducted within COST 238 was continued in the follow-on project COST 251 IITS (Improved quality of service in Ionospheric Telecommunication Systems planning and Operation) on the appli- cation of PRIME results in the improved qual- ity of service in ionospheric telecommunica- tion systems planning and operation. Both projects yielded significant results, but they also identified further areas where future development was needed. The topics for more research included: hour-to-hour and day-to-day variability prediction capabilities in the topside ionosphere, upgrading of the current models to include scintillation effects, the prediction of the ionospheric and plasmaspheric effects on navigational systems and the development of methods for calculating the reliability and com- patibility of HF radio systems using digital modulation techniques and over the horizon HF backscatter radars. Vol52,3,2009 20-09-2009 19:06 Pagina 438 439 COST 296 MIERS: conclusion The COST 271 Action «Effects of the upper atmosphere on terrestrial and Earth-space com- munications» was then established to examine a range of relevant research areas within four broad groupings by considering the impact of variability of space environment on communi- cations, to assess space plasma effects for satel- lite applications, to consider the ionospheric ef- fects on terrestrial communications and the space plasma effects on Earth-space and satel- lite-to-satellite communications. The COST 296 Action MIERS is now fin- ishing and it is clear that with the development of GPS applications, the coming Galileo system and the more frequent use of HF communica- tion systems with commercial aircraft, on polar routes for instance, there is a strong require- ment for improved understanding of ionospher- ic effects on such systems and better modeling of the ionosphere itself. This is the reason why the ionospheric COST community envisages proposing a new Action. 4. Conclusion The COST 296 Action has been very suc- cessful in bringing together in collaborative studies researchers who represent most of the available European expertise on the effects and mitigation of ionospheric effects on radio sys- tems. The significant results and advances in knowledge obtained during COST 296 have been summarized here. In addition a new pro- posal is currently under consideration. Vol52,3,2009 20-09-2009 19:06 Pagina 439