Abstract :
A regional adaptive and assimilative three-dimensional (3D) ionospheric model is proposed. It is able to ingest real-time data from different ionosondes, providing the ionospheric bottomside plasma frequency ƒp over the Italian area. The model is constructed on the basis of empirical values for a set of ionospheric parameters Pi[base] over the considered region, some of which are assigned a variation ΔPi. The values for the ionospheric parameters actually observed at a given time at a given site will thus be Pi= Pi[base]+ΔPi. These Pi values are used as input of an electron density N(h) profiler. The latter is derived from the Advanced Ionospheric Profiler (AIP), which is software used by Autoscala as part of the process of automatic inversion of ionogram traces. The 3D model ingests ionosonde data by minimizing the root-mean-square deviation between the observed and modeled values of ƒp(h) profiles obtained from the associated N(h) values at the points where observations are available. The ΔPi values are obtained through such a minimization procedure. The 3D model is tested using data collected at the ionospheric stations of Rome (41.8 N, 12.5 E) and Gibilmanna (37.9 N, 14.0 E), and then comparing the results against data from the ionospheric station of San Vito dei Normanni (40.6 N, 18.0 E). The software developed is able to produce maps of the critical frequencies ƒoF2 and ƒoF1, and of ƒp at a fixed altitude, with transverse and longitudinal cross-sections of the bottomside ionosphere in a color scale. ƒp(h) and associated simulated ordinary ionogram traces can easily be produced for any geographic location within the Italian region. ƒp values within the volume in question can be also provided.
