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D. Halilovic, R. Weber:
"GNSS-based Regional Ionosphere Modeling";
Talk: Specialized Workshop on Space Geodesy and Ionosphere Research SGI 2019, Berlin, Germany; 2019-09-26 - 2019-09-27.

GNSS Dual-frequency observables allow for the calculation of the ionospheric total electron content (TEC) which characterises the integrated number of electrons along the signal path between rover and satellite. Therefore, the TEC, either mapped to the zenith (VTEC) or examined over the signal path (STEC), constitutes a main indicator of the ionospheric activity over a certain point on the Earth´s surface. TEC information enables to correct single-frequency measurements for the ionospheric delay, which is one of the main error sources in GNSS. While dual-frequency receivers are able to directly account for the predominate share of the ionospheric delay by means of building an ionosphere-free linear combination, numerous GNSS users operate just single-frequency receivers. Such receivers require external corrections, like ionosphere models, to mitigate the influence of the ionospheric delay. Further, corrected single-frequency measurements can be used to perform improved site positioning.
At the Department of Geodesy and Geoinformation (University of Technology, Vienna, TUW) regional IONEX files are established on a regular basis, using dual-frequency zero difference GNSS (GPS+Galileo) observations from around 35 IGS and Multi-GNSS permanent stations. The stations are located in the mid-latitude European region, covering a latitudinal range of 30° - 65° and longitudinal range of -15° - 45°. The modified single-layer (MSLM) mapping function is used to describe the deterministic component of the ionosphere, while the computation of the electron density is based on a spherical harmonics expansion. The resulting ionosphere maps have a spatial resolution of 0.5° and temporal resolution of 1h.
In this study we present also results of our contribution the GSA Galileo Reference Center-MS project. Different broadcast models (for example Klobuchar and NeQuick-Gal) and post-processed ionosphere models are compared to the TUW model. In addition, the given model range corrections are applied to single-frequency observations and are compared to ranges derived from dual-frequency receivers on chosen stations in the European mid-latitude region, in order to check their quality and performance.

regional ionosphere modeling, GNSS, TEC

https://publik.tuwien.ac.at/files/publik_281899.pptx