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[1] This paper describes how the joint utilization of autoscaled data such as the F 2 peak critical frequency f o F 2 , the propagation factor M(3000)F 2 , and the electron density profile coming from two reference ionospheric stations (Rome and Gibilmanna), and the regional (Simplified Ionospheric Regional Model Updated) and global (International Reference Ionosphere) ionospheric models can provide a valid tool for obtaining a real-time threedimensional (3-D) electron density mapping of the ionosphere. Preliminary results of the proposed 3-D model are shown by comparing the electron density profiles given by the model with the ones measured at three testing ionospheric stations (Athens, Roquetes, and San Vito).Citation: Pezzopane, M., M. Pietrella, A. Pignatelli, B. Zolesi, and L. R. Cander (2011), Assimilation of autoscaled data and regional and local ionospheric models as input sources for real-time 3-D International Reference Ionosphere modeling, Radio Sci., 46, RS5009,

[1] A method for mapping of ionospheric conditions over Europe, suitable to be used in real time for operational applications, is described in this paper. The method is based on the Simplified Ionospheric Regional Model (SIRM), a regional model of the standard vertical incidence monthly median ionospheric characteristics that has been updated with real-time (automatic scaled) ionospheric observations to produce nowcasting maps over Europe. As substantial fluctuations from a monthly median regional ionospheric description occur on day-to-day basis, the SIRM results oversimplified a number of the ionospheric phenomena of real significance for radio communications applications. Therefore a rapid conversion of real-time data from four European digisondes (Digital Portable Sounders) to the driving parameters of the Simplified Ionospheric Regional Model is introduced as the real-time SIRM updating (SIRMUP). In this approach, values of the ionospheric characteristics from first-guess model parameters at measurement points are combined with real-time measurements. To assess the qualitative improvements achieved with the real-time SIRM update method, observations of foF2 parameter with SIRMUP predictions were compared for various ionospheric conditions. The simulation shows that the SIRMUP prediction results are much improved comparing to SIRM predictions, especially during large-scale ionospheric disturbances, as well as during quiet conditions, while there was a marginal improvement during localized ionospheric disturbances. In general, the results clearly demonstrate that the proposed procedure of updating SIRM with automatic scaling ionospheric parameters from the four European digisondes has the potential to be used in real time for nowcasting the standard ionospheric characteristics over Europe for operational applications.

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A simplified model of the key ionospheric characteristics of vertical incidence such as fo F2 M(3000)F2, h′F, foF1, and f0E that are used for prediction of operational parameters of HF telecommunication systems in a restricted area has been developed. The simplified ionospheric regional model (SIRM), is based upon the Fourier analysis of the monthly median values of these characteristics from seven ionospheric stations in Europe. It is shown that only 12 dominant Fourier coefficients, expressed as a function of local time (LT), solar activity and geographic latitude are sufficient to reproduce the main features of the diurnal, seasonal, and solar cycle behavior of the mid‐latitude ionosphere under median conditions. The model is in a very suitable form for digital computer calculation of the characteristics for a given position, instant of time, and solar activity.