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
This paper describes the researches upon the precise short-time GPS solutions made in the Centre of Applied Geomatics, Military University of Technology. The data from ASG-EUPOS (Polish Active Geodetic Network) was processed using Bernese 5.0 software and EPN (EUREF Permanent Network) standards and models. In this study, the adopted 3-hour observation window is shifted every hour obtaining geocentric coordinates in ITRF2005 reference frame. The adjusted network consisted of over 130 stations from Poland and the neighbouring countries, the period covered observations collected from 8.06.2008 to 18.06.2010. These two years of observations allowed to examine short-period oscillations which we found as closely related to the tidal (dynamic) frequencies. The analysis of the residua from IERS2003 tidal model was performed using least squares method with the Eterna software upon the idea of Chojnicki. It confirmed existence of the significant energy in the frequencies corresponding to S1, K1 and K2. The effects in S1 frequency reflect thermal influences, but the reasons of K1 and K2 existence could be both: dynamic (liquid core resonance and non-linearity of K1 are very difficult for modelling as well as the annual modulation of S1) or artificial (GPS satellites’ orbiting period, dynamic changes of satellites’ constellation and network geometry, multipath, residual tropospheric and ionospheric errors etc.). Since the phase of K1 for all 130 sites is very inconsistent the local effects could be also taken into account as one of the possible reasons. The paper describes the idea of the data processing and analysis, presents the results of vertical (Up component) oscillations in main tidal frequency bands, but also includes the discussion on the possible explanation of existence of short period oscillations in GPS precise solutions., Janusz Bogusz and Jan Hefty., and Obsahuje bibliografii
This paper contains the studies of the noise level in GPS (Global Positioning System) time series. As the data for this research the authors used changes of the geodetic coordinates of the ASG-EUPOS and associated (Slovak and Czech) sites. The method of precise GPS observations processing in short-time intervals was worked out in the Centre of Applied Geomatics, Military University of Technology. The authors focus on the diurnal and sub-diurnal frequency bands (tidal) as the tidal effects influence the sites’ positions at the most and the model used in the standard processing software does not contain geodetic coefficients. Thus the residual values of the geodetic coordinates time series should hold some information in the shape of coloured noise. The paper comprise short description of the Earth tides phenomenon, the concept of the tidal parameters determination, character of the white and coloured noise and the assessment of the noise estimation from GPS data. As the processed network contains 130 sites the spatial distribution of the noise’s parameters is also investigated., Janusz Bogusz and Bernard Kontny., and Obsahuje bibliografii