Modeling Of Tec Variations Based On Signals From Near Zenith Gnss Satellite Observed By Dense Regional Network

Currently the substantial successes in high-resolution ionospheric mapping is declared in many publications. Nevertheless, up to now there are no examples of dynamic visualization of TEC disturbances on regional scale with as high resolution as tropospheric models.Over the years, ionosphere has been modeling basing on the simple assumption, that it is a thin layer, which surrounds the Earth at some arbitrary height. However, the choice of this height was also a subject of special investigations and up to now has not been clearly defined. Ambiguity of this choice leads to uncertainty of coordinates of ionospheric pierce points (IPP). Usage of various heights of ionospheric layer substantially changes the configuration of IPPs of all-in-view satellites.In such a way, the model will be different for different layer heights and model will be distorted.Dense network of GNSS receivers makes it possible to mapping the regional ionosphere basing on data from observations of one satellite. In this case, IPPs are uniquely determined and the model is similar, independently of layer height, except some displacements and variations of scale. In the case of satellite passing through near zenith, the model is practically self-similar for elevations more 70 degrees. Each regional STEC variation map in this study was produced from observation data using one near zenith satellite, in contrast to the conventional approach which is based on usage of all-in-view ones.Two-dimensional total electron content (STEC) perturbations over Poland are mapped using ASG-EUPOS GNSS permanent network, with spatial resolution of 50 kilometers. These regional maps of TEC with such a high resolution allow revealing structures and evolutions of ionospheric disturbances at the mid-latitudes.A preliminary result of the STEC perturbation mapping indicates that it could be a strong tool to investigate the ionospheric structures in details.