The paper presents the results of research related to the application of GNSS solutions in short observational periods in geodynamical investigations. Authors used the 3-hour solution appointed from hour-long interval of about 30 chosen stations on mountainous terrains from over 100 which were worked out. The main aim was to check the correctness of such solutions by the comparison with the daily ones. Some outliers in East component could testify, that tropospheric or ionospheric models used in the data adjustment are not sufficient for so short-time solutions. The second principal problem, which was considered in the present work is the ability to detect diurnal and sub-diurnal oscillations in changes of permanent stations’ coordinates. Results show unambiguously, that such oscillations appear in all analysed stations. In the paper there are examples of stations with dominant oscillations in different frequencies. The clear homogeneous in the frequencies was not found among any group of stations. It is therefore difficult to affirm, if their origin comes purely from the geodynamical phenomena., Andrzej Araszkiewicz, Janusz Bogusz, Mariusz Figurski and Karolina Szafranek., and Obsahuje bibliografii
a1_The aim of this paper is to present the strategy of determination of the reference solution for the ASG-EUPOS (Active Geodetic Network - European Position Determination System) coordinate monitoring system. ASG-EUPOS is a network of permanent GNSS (Global Navigation Satellite System) stations controlled by the Polish Head Office of Geodesy and Cartography (HOGC), which main role is to realize the ETRS89 (European Terrestrial Reference System) in the territory of Poland. The Centre of Applied Geomatics (CAG) of the Military University of Technology (MUT) performs a control processing of the network and it is the leader of the ASG+ (the supporting modules for ASG-EUPOS system real-time services) project within which the coordinate monitoring system was developed. The coordinate monitoring is aimed to assess the actual performance of the GNSS stations and the reliability of the system and its services. The Polish realization of the ETRS89 is also controlled, where the deviation of the actual coordinates from the reference values are monitored. Furthermore, the monitoring enables the analysis of factors that degrade the individual GNSS stations and assess the solution stability which has impact on the quality of the determined geodynamic parameters. The reference solutions (coordinates and their changes over time) were determined according to the recommendations of the IAG sub-commission for the European Reference Frame concerning densification of EUREF. The paper presents the determination of the reference cumulative solution and the results of the processing of a few years long series of GNSS observations. The analysis are performed by the Bernese 5.0 and CATREF software. The results consists of daily and subdaily ASG-EUPOS reference solutions. They are also considered as input data for geodynamic studies to determine the horizontal and vertical velocity fields., a2_Estimation of the individual station velocities is of crucial importance for the ETRF (European Terrestrial Reference Frame) reference frame maintenance to assess the compatibility of the current station position with its catalogue (reference) value and apply coordinate correction if necessary., Karolina Szafranek, Janusz Bogusz and Mariusz Figurski., and Obsahuje bibliografii
The results presented in this paper concern investigation of environmental influences to GNNS coordinates on the example of ASG-EUPOS network. The problem of the impact of environmental effects is crucial for observing gravity. Satellite systems are not as susceptible to changes in local hydrology or atmospheric effects, although significant influences are clearly visible in the change of coordinates. The authors analyzed daily and sub-daily solutions (geocentric coordinates) in the context of different disturbances to eliminate sites suffering from poor quality for further researches (e.g. data from the most reliable ASG-EUPOS stations will be used for investigating the correlation of their movements with the lithosphere deformations on territory of Poland). There are many doubts regarding proper antennas’ placement - as they are mostly placed on the roofs, there were questions if data from these sites can be used for scientific purposes like velocity estimations or geodynamical researches. Analysis of daily solutions was supposed to prove that the majority of Polish sites give fully valuable data. Some factors that may cause a precision decreasing can be avoided or eliminated in the future. Taking into consideration that GLONASS will be soon fully operational and it will be an alternative for commonly used GPS, the authors made separate elaboration of GPS and GLONASS data. Usage of two different satellite systems holds the potential to increase of solutions’ reliability and eliminate errors that could be possibly related to the specific satellite system. Base on time series of coordinates residual values, systematic errors that could prove geophysical and geodynamical influence on GNSS measurements were investigated. In this elaboration only post-processing observations were taken into account, but the monitoring of the network in the near real-time by means of coordinates’ stability is under development., Janusz Bogusz, Mariusz Figurski, Krzysztof Kroszczyński and Karolina Szafranek., and Obsahuje bibliografii
The paper concerns analysis of solutions obtained during common processing of data from GNSS permanent stations situated on mountainous terrain: the Western Carpathians, the Sudetes Mountains and adjacent areas. As the outcome daily and weekly solutions (ellipsoidal coordinates) of forty Polish, Czech, Slovak, Ukrainian and German sites were obtained. Weekly solutions were used to determine velocity field and vertical movements, daily solutions enabled quality and precision of sites’ coordinates estimation to check if permanent GNSS sites can be used as a stable reference frame for geodetic, geological and geodynamical measurements in the mountainous area. First investigations concerning data from permanent GNSS stations in the Sudetes Mountains were made in 2007 using daily solutions from EPN sites obtained in test reprocessing of the whole regional network performed in Centre of Applied Geomatics. Since that time, national systems became operational increasing density of GNSS network, so the data can be used for wider range of investigations. As the majority of examined stations started to gather data in 2008, analysis were based on relatively short observation period, so they rather play a role of tests for further investigations and they give the preliminary estimation of individual sites’ activity., Mariusz Figurski, Karolina Szafranek, Janusz Bogusz and Paweł Kamiński., and Obsahuje bibliografii