The impacts of the ionospheric observable and mathematical model on the Global Ionosphere Model

Wenfeng Nie, Tianhe Xu, Adrià Rovira-Garcia, José Miguel Juan Zornoza, Jaume Sanz Subirana, Guillermo González-Casado, Wu Chen, Guochang Xu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

8 Citations (Scopus)


A high-accuracy Global Ionosphere Model (GIM) is significant for precise positioning and navigating with the Global Navigation Satellite System (GNSS), as well as space weather applications. To obtain a precise GIM, it is critical to take both the ionospheric observable and mathematical model into consideration. In this contribution, the undifferenced ambiguity-fixed carrier-phase ionospheric observable is first determined from a global distribution of permanent receivers. Accuracy assessment with a co-located station experiment shows that the observational errors affecting the ambiguity-fixed carrier-phase ionospheric observables range from 0.10 to 0.35 Total Electron Content Units (TECUs, where 1 TECU = 1016e-/m2and corresponds to 0.162 m on the Global Positioning System, GPS L1 frequency), indicating that the ambiguity-fixed carrier-phase ionospheric observable is over one order of magnitude more accurate than the carrier-phase leveled-code one (from 1.21 to 3.77 TECUs). Second, to better model the structure of the ionosphere, a two-layer GIM has been built based on the above carrier-phase observable. Preliminary global accuracy evaluation demonstrates that the accuracy of the two-layer GIM is below 1 TECU and about 2 TECUs during low and high solar activity periods. Third, the single-frequency point positioning experiment is adopted to test the ionosphere mitigation effects of the GIMs. Positioning results demonstrate that the single-frequency positioning accuracy can be improved by more than 30% using the undifferenced ambiguity-fixed ionospheric observable-derived two-layer GIM, compared with that using the carrier-phase leveled-code ionospheric observable-based single-layer GIM.
Original languageEnglish
Article number169
JournalRemote Sensing
Issue number2
Publication statusPublished - 1 Feb 2018


  • Ionospheric observable
  • Mathematical model
  • Two-layer
  • Undifferenced ambiguity-fixed mode

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)


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