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1

Estimation of height changes of GNSS stations from the solutions of short vectors and PSI measurements

Krynski J., Zak L., Ziolkowski D., Cisak J., Lagiewska M.

Geodesy and Cartography

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2017

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Vol. 66, no. 1

73--88

EN

Time series of weekly and daily solutions for coordinates of permanent GNSS stations may indicate local deformations in Earth’s crust or local seasonal changes in the atmosphere and hydrosphere. The errors of the determined changes are relatively large, frequently at the level of the signal. Satellite radar interferometry and especially Persistent Scatterer Interferometry (PSI) is a method of a very high accuracy. Its weakness is a relative nature of measurements as well as accumulation of errors which may occur in the case of PSI processing of large areas. It is thus beneficial to confront the results of PSI measurements with those from other techniques, such as GNSS and precise levelling. PSI and GNSS results were jointly processed recreating the history of surface deformation of the area of Warsaw metropolitan with the use of radar images from Envisat and Cosmo-SkyMed satellites. GNSS data from Borowa Gora and Jozefoslaw observatories as well as from WAT1 and CBKA permanent GNSS stations were used to validate the obtained results. Observations from 2000–2015 were processed with the Bernese v.5.0 software. Relative height changes between the GNSS stations were determined from GNSS data and relative height changes between the persistent scatterers located on the objects with GNSS stations were determined from the interferometric results. The consistency of results of the two methods was 3 to 4 times better than the theoretical accuracy of each. The joint use of both methods allows to extract a very small height change below the level of measurement error.

2

The use of GPS data at T-T Zone for the verification of the recent terrestrial reference frames considering possible geodynamic processes

Godah W., Krynski J., Cisak J.

Geoinformation Issues

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2012

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Vol. 4, no. 1(4)

5--13

EN

The interpretation of the geodynamic phenomena with the use of GPS observations strongly depends on the quality of the terrestrial reference frame. The aim of this contribution is to verify station velocities from recent ITRF/ETRF solutions as well as to evaluate the possible geodynamic processes by using long time series of GPS data from four permanent GNSS stations operating in T-T zone. The components of four baselines were calculated with the use of the Bernese v.5.0 GPS software using GPS observation data from 2004–2012. Time variations of baseline components and baseline length were analysed and their linear trends were estimated by applying linear regression analysis. The obtained results have indicated that the variations are within the range from –0.2 to 0.3 mm/year in X–component, from –0.6 to –0.3 mm/year in Y–component, from –0.2 to 0.2 mm/year in Z–component and from –0.2 to 0.6 mm/year for the baseline length. The estimated linear trends of baselines components variations fit substantially better to the respective ones derived from ITRF2008/ETRF2000 (R8) than to the ones from ITRF2005/ETRF2000 (R5).

PL

Możliwość interpretowania zjawisk geodynamicznych na podstawie analizy obserwacji GPS w dużej mierze zależy od jakości ziemskiego układu odniesienia. Celem niniejszej pracy jest zweryfikowanie prędkości stacji uzyskanych ze współczesnych rozwiązań ITRF/ETRF, a także ocena ewentualnych procesów geodynamicznych przy użyciu długiego szeregu czasowego obserwacji na stacjach permanentnych GNSS położonych w rejonie strefy Teisseyre’a-Tornquista. Składowe czterech wektorów obliczono przy użyciu programu Bernese v.5.0 z obserwacji GPS z lat 2004–2012. Poddano analizie zmiany czasowe składowych tych wektorów oraz ich długości; przy wykorzystaniu analizy regresji wyznaczono trendy liniowe tych zmian. Rezultaty analiz wskazują na zmiany w przedziałach -0.2 do 0.3 mm/rok w składowej X, -0.6 do -0.3 mm/ rok w składowej Y, -0.2 to 0.2 mm/ rok w składowej Z oraz -0.2 do 0.6 mm/ rok w długości wektora. Wyznaczone trendy liniowe zmian składowych wektorów wykazują znacząco lepszą zgodność z odpowiednimi zmianami otrzymanymi z rozwiązań w układach ITRF2008/ETRF2000 (R8) niż ze zmianami z rozwiązań w układach ITRF2005/ETRF2000 (R5).

3

Stare, ale jare

Cisak J.

Geodeta : magazyn geoinformacyjny

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2010

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nr 8

8-10

4

Study on the influence of ionosphere on GPS positioning results for antarctic stations

Cisak J., Kryński J., Zanimonskiy Y., Wielgosz P.

Reports on Geodesy

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2003

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z. 2/65

213-220

EN

The recent research developments within the framework of the project "Atmospheric impact on GPS observations in Antarctica" are presented in the paper. The effects of both ionospheric and tropospheric disturbances on GPS solutions are discussed. The GPS data, usually those provided by permanent GPS station arrays, are commonly used to investigate the structure and dynamic of ionosphere. First results of the project address the influence of the ionosphere over the Arctic and Antarctic regions on the repeatability of co-ordinates of vectors of different length during the quiet and disturbed ionosphere (ionospheric storms).

5

Polska sieć geodynamiczna, 1997 - epoka 0

Dobrzycka M., Cisak J.

Prace Instytutu Geodezji i Kartografii

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2001

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T. 48, z. 103

61--81

PL

W artykule opisano prace nad założeniem, pomiarem i wynikami opracowania obserwacji GPS w Polskiej Sieci Geodynamicznej (PSG). Otrzymane współrzędne punktów tej sieci porównano z wynikami wcześniejszych kampanii EUREF-POL i POLREF służącymi do utworzenia katalogu współrzędnych punktów podstawowej osnowy geodezyjnej kraju. Stwierdzono przy tym różnice o wyraźnie systematycznym charakterze. Omawiając możliwe źródła ujawnionych rozbieżności, zwrócono szczególną uwagę na efekt modelowania wysokości centrów fazowych anten, organizując specjalną, dwudobową kampanię testową na Krajowej Bazie Długościowej Warszawa-Bemowo.

EN

Reflecting natural and man-induced tectonics the position of the network points do change in time. Their motion can be monitored by repetitive measurements using modern geodetic methods. According to current trends and international recommendations the so called geodynamic network was established in Poland, aiming at monitoring coherency and stability of the primary control network, contributing to regional and global geodynamic investigations and providing unified frame for local geodynamic programs. The geodynamic network was set up in the first half of 90-ties. It consists of 36 points. Most of them (33) were chosen from nearly 400 – points of primary network that was in the process of fundamental modernisation. Location of points (Fig.1), consulted with geologists, gives coverage to main and subordinate crustal blocks. Monumentation of points (not fully uniform) is shown in Fig.2. The geodynamic network includes five permanent GPS stations of the “GPS Permanent EUREF Network” and seven remaining 0-order EUREF points, serving as an extension of ETRS system. 0-epoch GPS campaign in the Polish Geodynamic Network (PSG) was carried out in September 1997, in five three-day sessions, using eight sets of Leica receivers. The observations were processed and adjusted in co-operation with WUT Analysis Centre of the „GPS Permanent EUREF Network” program, using Bernese 4.0 software, according to presently valid standards. As the reference points served all five Polish GPS permanent stations, as well as five stations in neighbouring countries. Vectors used in adjustment are shown in Fig. 4. The results of 0 - epoch campaign were compared to those from former campaigns: EUREF-POL (1992) and POLREF (1994–1995). The differences obtained in latitude, longitude and ellipsoidal height are shown in Table 1 and illustrated in Fig. 5, in order to better indicate their systematic character that is especially significant in the height component. Looking for reasons of such results several possible sources were considered, among them steadily changing, different ITRF frame parameters, used for elaboration of different campaigns (91 for EUREF-POL, 94 for POLREF and 96 for PSG), as well as different versions of computing program, methods of adjustment and ties selections. Special attention however, was paid to the antenna phase centre effect. In both POLREF (1994–1995) and PSG (1997) campaigns 8 Leica SR299 and SR399 receivers were used. At the reference points different sets of instruments were operating and different antenna characteristics were used: old and new, provided by manufacturers and recommended by IGS, model IGS 01/1996. Differences between old and new characteristics of the selected antenna types are shown in Table 2. To test the validity of the antenna heights used in PSG measurements, two day's long GPS campaign on the Polish Standard Baseline Warszawa-Bemowo was conducted (see Fig.6), with use of the majority of GPS antenna applied in the PSG campaign. On the first day instruments were installed in direct while on the next day in the reverse order. Differences in calculated height and distance between each pair of antennas in both setting orders, were compared with standard values (accuracy better than 2mm, obtained from multiple precise EDM measurements and geometric levelling). The results shown in Table 3 may suggest erroneous value of height component for Leica and - smaller – for DM model T antenna phase centre, while four other antenna types show very good agreement. Authors present one more possible source of discrepancies between results of different campaigns, reflected in rather regular, periodic variations of point positions. Not yet modelled, they are well documented by observations at permanent GPS stations (see Fig. 7) and possibly caused by not enough sufficient modelling of tidal effects. The reliable interpretation of results from different GPS campaigns is not easy, it needs very detailed information about instruments, methods and options of program used. Sometimes, when considering sophisticated tasks, re-computation might be appropriate.

6

DGPS with Navi GSM

Cisak J., Kryński J., Sekowski M.

Reports on Geodesy

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2000

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z. 9/55

33-41

EN

The GPS system may be applied in numerous branches of state economy, service sector, navigation as well as in surveying projects as an inexpensive and highly reliable system providing near real time positioning at 1m level of accuracy. DGPS corrections generated by the permanent base station could fulfill the needs of the system users all over a medium size European country wherever the GSM signal is available. The tests conducted at the Institute of Geodesy and Cartography with DGPS with Navi GSM show the wide spectrum of usefulness of the system.

7

Preliminary analysis of the GPS derived vector Borowa Góra - Józefosław

Kryński J., Cisak J.

Prace Instytutu Geodezji i Kartografii

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2000

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T. 47, z. 100

35--50

PL

W pracy wykorzystano materiał obserwacyjny z 25 dni uzyskany z permanentnych obserwacji GPS na stacjach w Borowej Górze i w Józefosławiu. Dane GPS zostały opracowane w następujących po sobie sesjach 4–godzinnych dla dwóch kątów obcięcia horyzontu 5°i 15°. Wyniki obliczeń w postaci szeregów czasowych utworzonych dla poszczególnych składowych wektora BOGO–JOZE oraz ich błędów standartowych zostały poddane analizie. Przeprowadzono analizę statystyczną oraz dokonano wstępnej analizy widmowej zaobserwowanych szeregów czasowych z uwzględnieniem wpływu kąta obcięcia horyzontu. Stwierdzono okresowość zmian składowych wektora wyrażające się wyraźnym 12 h okresem i słabszym okresem 24 h. Wyznaczono również parametry modeli matematycznych funkcji opisujących procesy zmienności w czasie poszczególnych składowych badanego wektora oraz oszacowano błędy poszczególnych modeli. Poddano również analizie wpływ kąta obcięcia horyzontu na jakość wyników.

EN

Permanent GPS station BOGO at Astronomic–Geodetic Observatory at Borowa Góra operates since 1996. Data collected by means of Ashtech ZXII3 receiver is transferred on daily basis (from November 1998 on hourly basis as well) to the Local IGS Computing Centre at Graz (Cisak et al., 1999). This data together with data from other permanent GPS stations is used in international programmes such as computation of precise ephemeris in "almost real time" for GPS satellite orbits and investigation on ionosphere and troposphere. Moreover, data collected at BOGO station is widely accessible and is frequently used for processing GPS data from various GPS campaigns. An estimate of the quality of the data from BOGO station is therefore a matter of interest. It is very fortunate that the other IGS permanent station operates in Józefosław (JOZE) only 42 km away from Borowa Góra. Relatively short vector BOGO–JOZE can be reliably monitored and its analysis could provide valuable contribution to evaluate the quality of GPS data from BOGO station (Cisak et al., 1999) as well as to estimate the reliability of co–ordinates derived from this data. In addition the location of Borowa Góra at a stable east-european tactonic plate and Józefosław close to the edge of Teisseyre– Tornquist tectonic zone adds up additional interesting features to such an analysis.

8

Hourly data upload at Bogo permanent GPS station and preliminary attempt toward estimate the quality of collected data

Cisak J., Kryński J., Witkowski T.

Reports on Geodesy

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1999

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z. 5/46

114-125