Currently, the International GNSS Service (IGS) has a well-developed global station network that includes over 500 stations in total, from which more than 360 allow tracking multi-GNSS signals. There is also a large number of permanent GNSS stations around the world operating within regional and national networks. The largest number of stations of global networks, e.g., those operated by the IGS, are located in Europe and America, as opposed to the Africa, Asia, or Oceania regions. The determination of global geodetic parameters, such as Earth rotation parameters, coordinates of the Earth’s center of mass, orbit determination, and realization of a terrestrial reference frame using GNSS observations require the use of a global, evenly distributed network of permanent GNSS stations. The selection of a proper network is a prerequisite for the representation of the Earth in the form of a discrete global grid and has a profound impact on the geophysical interpretation of information behind the temporal changes of the estimated parameters. New open-source software solving problems related to the proper selection of the GNSS station network has been developed at IGiG UPWr and made available to users.
Proper selection of GNSS stations
Most frequently, information about the station selection algorithm used in the specific case study is simply missing and probably performed manually based on the researcher’s experience. In the case of IGS Analysis Centers (ACs), which deliver official GNSS-based products, the station selection is often based on the priority list agreed upon between the ACs, such as IGS Repro3 priority list or EPN station classification document, considering aspects, such as co-location sites with other space-geodetic techniques, long history of the time series of observations. For the Center for Orbit Determination in Europe (CODE) AC, the global distribution, availability, and content of observation files are also evaluated prior to the definitive station selection. In the case of the IGS products provided by GFZ, the station selection is based on the pre-selection and station classification complemented with checks for formal correctness and consistency of the RINEX files with the official site logs. However, there is a lack of details on how this task is performed. New open-source software solving problems related to the proper selection of the GNSS station network has been developed at IGiG UPWr and made available to users.
Novel open-source software for GNSS network solutions
In a paper published in SoftwareX scientific journal by IGIG researchers provide the first free software for automatic station selection based on geometric and qualitative criteria is presented. The proposed solution is a novel approach to solving scientific problems related to global network selection, focusing on supporting the determination of global geodetic parameters. The application of the proposed algorithms can form the basis for research on the impact of permanent station network selection on the quality of global geodetic parameters. The software, due to its openness, can be connected to data centers such as the Crustal Dynamics Data Information System (CDDIS) or support the regional computing centers, e.g., those of EUREF Permanent GNSS Network (EPN), or IGS by supplementing their GNSS data analysis services.
Please find more details in the original paper:
Gałdyn, F., Zajdel, R., & Sośnica, K. (2023). RINEXAV: GNSS global network selection open-source software based on qualitative analysis of RINEX files.
SoftwareX, 22, 101372. https://doi.org/10.1016/j.softx.2023.101372
This work was realized in the frame of the grant funded by the Polish National Science Centre (NCN) Grant UMO-2021/42/E/ST10/ 00020. The APC is financed by Wrocław University of Environmental and Life Sciences (UPWr). Part of the research was carried out during the student internship funded by UPWr statutory research funding.