The issue of the Iodissee ANR Project is to help the design of the monitoring station network enabling to fulfill Galileo mission requirement, and to quantify the performance of the system. Traditional available software to help the engineers in this task are based on phenomenological or statistical models. We propose to build a complementary model which can work in synergy with the existing ones. We then suggest to build a complete ionospheric model coupled to an electromagnetic propagation module. This can be realized using traditional modelings. However, some recent scientific experiments and the knowledge acquired from GPS satellites and their communications to ground stations allow to confirm and to enhance the models by real data. To achieve this aim, we break up our work plan into seven tasks, completed by two general ones (namely Task 0 and Task 8, which respectively concerns the project management and the consortium agreement).

The first task is concerned with the definition of the needs. The purpose of this task is to detail the needs in terms of scintillation modeling necessary to carry on the Galileo performance assessment, to characterize the limitations of the current GIMS model in terms of ionosphere representativity and to iterate with physics experts in order to derive the set of specifications and of axes of improvement aiming at answering the Galileo system needs. The second and third tasks can be gathered together in a broader action which can be labeled as "model/data interactions". The objectives are to improve the models by comparison with experiments and measurements and with those feedbacks to adjust some parameters and coefficients in the model. Task 2 focuses on rare events and is devoted to the understanding of morphogenesis of new plasma depletions discovered by Demeter mission. The task 3 is concerned with the "standard ionosphere" and proposes to use GPS data to improve the physical model. Obviously, those tasks need to exchange their knowledge and their feedbacks.

The fourth and fifth tasks are gathered in the action named "Development of tools and numerical methods". Each task has to develop new numerical modules. The task 4 focuses on the electromagnetic propagation one which is necessary to evaluate the propagation of electromagnetic waves and signals in the disturbed ionosphere. Task 5 aims at building the main model and the numerical schemes and methods which are the core of the proposal. The methods need to be efficient and precise. Every adjustment which can come from task 2 or 3 need to be immediately transposed and strong exchanges between those tasks are obviously necessary.

Task 6 and 7 are concerned with the production of tools for the purpose of engineers. They are obviously strongly dependent on the previous tasks.