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1
Content available Integrated precipitable water from GPS observations and CIMEL sunphotometer measurements at CGO Belsk
Kruczyk M., Liwosz T., Pietruczuk A.
Reports on Geodesy and Geoinformatics
|
2017
|
Vol. 103
46--65
EN
This paper describes results of integrated precipitable water co-located measurements from two techniques: GPS solution and CIMEL-318 sun-photometer. Integrated Precipitable Water (IPW) is an important meteorological parameter and is derived from GPS tropospheric solutions for GPS station at Central Geophysical Observatory (CGO), Polish Academy of Sciences (PAS), Belsk and compared with sunphotometer (CIMEL-318 device by Cimel Electronique) data provided by Aerosol Robotic Network (AERONET). Two dedicated and independent GPS solutions: network solution in the sub-network of European Permanent Network (EPN) and precise point positioning solution have been made to obtain tropospheric delays. The quality of dedicated tropospheric solutions has been verified by comparison with EPN tropospheric combined product. Several IPW comparisons and analyses revealed systematic difference between techniques (difference RMS is over 1 mm). IPW bias changes with season: annual close to 1 mm IPW (and semi-annual term also present). IPW bias is a function of atmospheric temperature. Probable cause of this systematic deficiency in solar photometry as IPW retrieval technique is a change of optical filter characteristics in CIMEL.
2
Wpływ niepływowych efektów obciążeniowych na współrzędne punktów i realizację układu odniesienia w regionalnej sieci GPS
Liwosz T.
Prace Naukowe Politechniki Warszawskiej. Geodezja
|
2017
|
z. 56
3--125
PL
Efekty obciążeniowe wywołane niepływowym naciskiem atmosfery, oceanów i wody kontynentalnej na powierzchnię Ziemi powodują jej deformację. Przemieszczenia punktów z powodu tych efektów zwykle nie są uwzględniane podczas opracowania obserwacji GPS (ang. Global Positioning System). Celem pracy było przeanalizowanie wpływu modelowania niepływowych efektów obciążeniowych podczas opracowania obserwacji GPS na współrzędne punktów oraz na realizację geodezyjnego układu odniesienia w regionalnej sieci GPS. Analizy przeprowadzono na podstawie rozwiązań GPS, które otrzymano w wyniku spójnego opracowania ciągłych obserwacji dobowych GPS dla okresu 10 lat zarejestrowanych na 51 stacjach położonych w Europie. W analizach wykorzystano modele obciążeniowe, tworzone i udostępniane przez trzy różne instytucje, które stosowano na poziomie obserwacji (metoda a priori). W wyniku modelowania efektu niepływowego obciążenia powierzchni Ziemi atmosferą otrzymano średnią poprawę powtarzalności dobowych szeregów czasowych składowej wysokościowej o 6.3%, oceanami o 0.9%, a wodą kontynentalną o 2.1%. Łączne modelowanie wszystkich efektów spowodowało poprawę powtarzalności składowej wysokościowej o 9.8% dla rozwiązań dobowych i o 13.1% dla rozwiązań tygodniowych. Najlepszą zgodność współrzędnych pomiędzy rozwiązaniami, w których dla danego efektu wykorzystano modele z różnych instytucji, stwierdzono dla rozwiązań z modelowanym efektem obciążeniowym z powodu atmosfery. Dla większości stacji różnice współrzędnych nie przekraczały 1 mm w żadnej ze składowych. Niemniej, dla kilku stacji położonych w rejonie wybrzeża Morza Północnego i Morza Bałtyckiego, stwierdzono rozbieżności w dobowych szeregach czasowych współrzędnej wysokościowej dochodzące do 6 mm. Modelowanie efektu z powodu obciążenia powierzchni Ziemi wodą kontynentalną usunęło sygnał roczny z szeregu czasowego współczynnika skali sieci regionalnej. Modelowanie efektów obciążeniowych nie wpłynęło na układ odniesienia realizowany na podstawie 10-letnich obserwacji. Modelowanie wszystkich efektów łącznie spowodowało zmniejszenie błędów prędkości punktów GPS, które dla wszystkich składowych wyniosło 7% i aż 23%, jeśli podczas wyznaczania prędkości wyznaczano dodatkowe wyrazy opisujące sygnały o okresie rocznym i półrocznym obecne we współrzędnych GPS. W analizowanych szeregach czasowych współrzędnych punktów, oprócz sygnałów o okresie rocznym i półrocznym, stwierdzono także sygnały o okresie roku drakonicznego GPS (351.4 dni) i jego harmoniczne. Modelowanie efektów obciążeniowych me wpłynęło znacząco na okresowości zawarte w szeregach czasowych współrzędnych i na amplitudy sygnałów rocznych i półrocznych. Modelowanie efektu z powodu obciążenia powierzchni Ziemi wodą kontynentalną pozwoliło lepiej zinterpretować szeregi czasowe współrzędnej wysokościowej, w których dla kilku stacji pojawił się zbyt duży (sztuczny) sygnał roczny wynikający z niewielkiego rozmiaru analizowanej sieci regionalnej (efekt sieci). Analiza szumowa szeregów czasowych współrzędnych GPS z modelowanym efektem obciążenia powierzchni Ziemi atmosferą wykazała zmniejszenie amplitud szumu potęgowego oraz zwiększenie amplitud szumu białego i indeksów spektralnych (uwydatnienie większej korelacji czasowej). Z kolei modelowanie efektu z powodu wody kontynentalnej spowodowało zmniejszenie wartości indeksów spektralnych (zmniejszenie korelacji czasowej). Modele obciążeniowe zastosowano również jako poprawki do uzyskanych w wyniku opracowania obserwacji GPS współrzędnych (metoda a posteriori). Uzyskano bardzo dobrą zgodność powtarzalności współrzędnych z metodą a priori (różnice nieistotne statystycznie). Przy czym, w różnicach współrzędnych z modelowanym efektem z powodu wody kontynentalnej uzyskanymi w tych dwóch metodach zaobserwowano sygnał roczny o maksymalnej amplitudzie 0.2 mm.
EN
Non-tidal loading effects due to atmosphere, ocean, and continental water cause deformation of the Earth's surface. Global Positioning System (GPS) observations are usually not corrected for the displacements due to these effects. The aim of this work was to analyse the impact of the non-tidal loading effects modelling during G PS data processing on station coordinates and a reference frame realization in a regional GPS network. The analyses were performed on the basis of GPS solutions, which were obtained from homogeneous processing of daily GPS data collected during a period of 10 years at 51 permanent stations evenly distributed in Europe. The non-tidal loading models, created by three different institutions, were applied at the observation level (a priori approach). Modelling the non-tidal loading effect due to the atmosphere improved the mean repeatability of daily time series of the height component by 6.3%, due to oceans by 0.9%, and due to continental water by 2.1 %. Modelling all the non-tidal loading effects improved the mean repeatability of the height component by 9.8% in case of daily solutions, and by 13.1% in case of weekly solutions. The best consistency between solutions, in which models from different institutions were applied, was obtained for the non-tidal atmospheric effect. However, for a few sites located at the North Sea and Baltic Sea shores, the differences in daily time series for the height component reached 6 mm. Modelling of the non-tidal loading effects did not affect a reference frame realized by 10-year solutions. Modelling all the non-tidal effects improved the velocity errors in all components by 7%, and by 23% when in addition also annual and semiannual signals that are present in site coordinate time series were estimated during the velocity estimation. In coordinate time series, in addition to annual and semiannual signals, also the GPS draconitic signal (351.4 days) and its harmonics were found. Modelling the non-tidal effects did not significantly influence the periodicities present in the GPS coordinate time series or annual and semiannual amplitudes. Modelling the continental water loading effect improved the interpretation of time series for some stations for which, due to a small size of the regional network (network effect), too high (spurious) annual signals were observed. Noise analysis of the GPS coordinate time series showed that modelling the non-tidal atmospheric loading decreased the power law amplitudes, and increased the white noise amplitudes and spectral indices (time correlation increased). On the other hand, modelling the continental water loading decreased the spectral indices of the coordinate time series for the height component (time correlation decreased). The non-tidal loading effects were also applied a posteriori, i.e., as corrections to the estimated coordinates. The comparison of a posteriori and a priori methods showed very high consistency in the repeatability of station coordinates (differences were not significant). In the difference time series between solutions in which the continental water loading effect was modeled, an annual signal was found, with a maximum amplitude of 0.2 mm.
3
Content available Verification of the Polish geodetic reference frame by means of a new solution based on permanent GNSS data from the years 2011-2014
Liwosz T., Ryczywolski M.
Reports on Geodesy and Geoinformatics
|
2016
|
Vol. 102
52--66
EN
The new solution for the Polish geodetic primary GNSS network was created to verify the currently used reference frame (PL-ETRF2000). The new solution is based on more GNSS data (more daily observation sessions included, a longer data timespan, GLONASS observations added) which were processed in a newer reference frame (IGb08) according to up-to-date methodology and using the latest version of Bernese GNSS Software. The new long-term solution (spanning 3.7 years) was aligned to the IGb08 reference frame using a minimum constraints approach. We categorized Polish reference stations into two categories according to their data length. We obtained good agreement of the new solution with the PL-ETRF2000: for most stations position differences did not exceed 5 mm in horizontal, and 10 mm in vertical components. However, for 30 stations we observed discontinuities in position time series, mostly due to GNSS equipment changes, which occured after the introduction of PL-ETRF2000. Position changes due to the discontinuities reached 9.1 mm in horizontal components, and 26.9 mm in vertical components. The new solution takes into account position discontinuities, and in addition also includes six new stations which were installed after the introduction of the PL-ETRF2000. Therefore, we propose to update the currently-used reference frame for the Polish geodetic primary network (PL-ETRF2000) with the new solution. The new solution was also accepted by the EUREF Technical Working Group as a class A solution (highest accuracy) according to EUREF standards.
4
Content available Geodetic and geodynamic studies at Department of Geodesy and Geodetic Astronomy WUT
Brzeziński A., Barlik M., Andrasik E., Izdebski W., Kruczyk M., Liwosz T., Olszak T., Pachuta A., Pieniak M., Próchniewicz D., Rajner M., Szpunar R., Tercjak M., Walo J.
Reports on Geodesy and Geoinformatics
|
2016
|
Vol. 100
165--200
EN
The article presents current issues and research work conducted in the Department of Geodesy and Geodetic Astronomy at the Faculty of Geodesy and Cartography at Warsaw University of Technology. It contains the most important directions of research in the fields of physical geodesy, satellite measurement techniques, GNSS meteorology, geodynamic studies, electronic measurement techniques and terrain information systems.
5
Content available Assessment of continental hydrosphere loading using GNSS measurements
Zygmunt M., Rajner M., Liwosz T.
Reports on Geodesy and Geoinformatics
|
2016
|
Vol. 101
36--53
EN
Presented paper is dedicated to problems of deformation of the Earth's crust as a response to the surface loading caused by continental waters. The aim of this study was to specify areas particularly vulnerable to studied deformation and to compare calculated and observed displacements. Information of the continental water volume was taken from the WaterGAP Global Hydrological Model. Calculated values of the deformations were verified with the results obtained with programs SPOTL and grat. Vertical deformations were almost 10 times higher than the deformation in the horizontal plane, for which reason later part of the paper focuses on the former. In order to check agreement of the calculated and observed deformation 23 stations of International GNSS Service (IGS) were selected and divided into three groups (inland, near the shoreline and islands). Before comparison outliers and discontinuities were removed from GNSS observations. Modelled and observed signals were centred. The analysed time series of the vertical displacements showed that only for the inland stations it is possible to effectively remove displacements caused by mass transfer in the hydrosphere. For stations located in the coastal regions or islands, it is necessary to consider additional movement effects resulting from indirect ocean tidal loading or atmosphere loading.
6
Content available Integrated Precipitable Water Vapour measurements at Polish Polar Station Hornsund from GPS observations verified by aerological techniques
Kruczyk M., Liwosz T.
Reports on Geodesy and Geoinformatics
|
2015
|
Vol. 98
1--17
EN
We present results of the comparison of integrated precipitable water measurements from GPS solution and aerological techniques: CIMEL-318 sun-photometer and radiosoundings (RAOB). Integrated Precipitable Water (IPW) - important meteorological parameter is derived from GPS tropospheric solutions by known procedure for GPS station at Polish Polar Station, Hornsund (Svalbard). The relation between 2 m temperature and the mean temperature of atmosphere above, used to convert from wet part of tropospheric delay (ZWD) to IPW, has been derived using local radiosonde data at Ny Alesund. Sunphotometer data have been provided by AERONET. Quality of dedicated tropospheric solutions has been verified by comparison with EPN tropospheric combined product. Several IPW comparisons and analyses lead to determination of systematic difference between techniques: GPS IPW and sunphotometer data (not present in case of RAOBs). IPW measured by CIMEL is on average 5% bigger (0.5 mm) than IPW from GPS. This bias changes seasonally and is a function of atmospheric temperature what signals some systematic deficiencies in solar photometry as IPW retrieval technique. CIMEL IPW show some temperature dependent bias also in relation to radiosoundings.
7
Content available remote Effect of the GLONASS-specific receiver antenna phase center corrections on the results of european regional GNSS network
Liwosz T.
Artificial Satellites : Journal of Planetary Geodesy
|
2013
|
Vol. 48, No. 4
191--203
EN
In the paper I investigated the effect of the GLONASS-specific receiver antenna phase center corrections on the results of a regional permanent GNSS network. I made analysis, using Bernese GPS Software 5.0, of GPS-only and GPS-GLONASS (GNSS) observations collected at permanent sites in Europe. Two types of GNSS solutions were computed: with GPS phase center corrections used for observations of both systems, and with the system specific corrections for observations of the respective system. The Bernese software was modified accordingly to use GLONASS specific corrections for GLONASS measurements. The results, i.e., coordinates and tropospheric zenith delays were analyzed and compared between computed solutions. Introducing GLONASS-specific receiver antenna phase center corrections did not improve the repeatability of the GNSS coordinate time series. Differences of coordinates between the two GNSS solutions were highly repeatable but offsets (biases) were observed; maximum bias for horizontal component was 1 mm and 4 mm for up component. Similar biases were observed for stations with the same antenna models. Periodic signal with a period of 1/3-year was found in difference time series between GPS and GNSS solutions for north component with a maximum peak-to-peak amplitude 2.8 mm. The periodic signal was attributed to GLONASS.
8
Content available Tropospheric delay from EPN reprocessing by WUT LAC as valuable data source - in comparison to operational EPN products and aerological data
Kruczyk M., Liwosz T.
Reports on Geodesy
|
2012
|
z. 1/92
109--122
EN
Standard EPN tropospheric products still show some discrepancies, prominent especially before GPS week 1400. It was one of the motives of massive reprocessing projects organised in the frame of both IGS and EPN. WUT LAC is one of Analysis Centers actively participating in EPN Reprocessing Campaign. Both operational tropospheric products and reprocessing campaign were manifold analysed. Properties of information carried in ZTD estimates were investigated both in ZTD solutions and in the form of IPW (Integrated Precipitable Water). Independent aerological data sources - radiosounding and CIMEL-318 sunphotometer were used for external verification. Authors demonstrate some results convincingly demonstrating value of reprocessed tropospheric product. Tropospheric solutions from reprocessing compared to meteorological data demonstrate better conformity. Most important application of long series ZTD’s of uniform quality is climatology. Search for climate change signal in IPW series is possible only with a reliable tropospheric solution. Reprocessing campaign results meet this requirement.
9
Content available Studies of crustal deformation due to hydrological loading on GPS height estimates
Rajner M., Liwosz T.
Geodesy and Cartography
|
2011
|
Vol. 60, no 2
135-144
EN
The paper deals with large-scale crustal deformation due to hydrological surface loads and its influence on seasonal variation of GPS estimated heights. The research was concentrated on the area of Poland. The deformation caused by continental water storage has been computed on the basis of Water GAP Hydrological Model data by applying convolution of water masses with appropriate Green's function. Obtained site displacements were compared with height changes estimated from GPS observations using the Precise Point Positioning (PPP) method. Long time series of the solutions for 4 stations were used for evaluation of surface loading phenomena. Good agreement both in amplitude and phase was found, however some discrepancies remain which are assigned to single point positioning technique deficiencies. Annual repeatability of water cycle and demanding procedure for computing site displacements for each site, allowed to develop a simple model for Poland which could be applied to remove (or highly reduce) seasonal hydrological signal from time series of GPS solutions.
PL
Celem niniejszej pracy jest analiza wpływu zmian wielkoskalowych stosunków wodnych na deformacje skorupy ziemskiej. Przedstawiona jest również możliwość monitorowania tego efektu przy pomocy geodezyjnych technik satelitarnych. Na podstawie zmiennego rozkładu mas hydrosfery lądowej (do tego celu wykorzystano model hydrologiczny WGHM) oraz wykorzystując informacje dotyczące właściwości skorupy ziemskiej (tzw. funkcje Greena) zostały obliczone modelowe zmiany wysokości wybranych punktów na terenie Polski. Wyniki te zostały porównane ze zmianami wysokości wyznaczonymi dla czterech stacji permanentnych GNSS, które dysponują długimi ciągami obserwacyjnymi, tj. Borowa Góra, Borowiec, Józefosław oraz Lamkówko. Do opracowania obserwacji GPS wykorzystana została metoda Precise Point Positioning (PPP), czyli obserwacje dla każdej stacji były opracowywane niezależnie. Pozwoliło to na odseparowanie sygnałów właściwych dla danej stacji pomiarowej i prawidłowa interpretacje geodynamiczna. Wyniki te dobrze zgadzają się co do amplitudy i fazy z modelowym efektem. Przyczyny widocznych rozbieżności również zostały przedyskutowane. Wyraźna, roczna powtarzalność deformacji wynikających ze zmiennego rozkładu mas wodnych, pozwoliła na skonstruowanie prostego dwuparametrowego modelu dla terenu Polski, który pozwala znacznie zredukować wpływ tego efektu bez konieczności złożonych obliczeń.
10
Content available Determination of the deformation of the Earth's crust in Poland
Bogusz J., Kujawa L., Liwosz T., Rogowski J. B., Jarosiński M., Kłęk M.
Reports on Geodesy
|
2008
|
z. 2/85
19-29
11
Content available Current activities of the astro-geodetic observatory in Jozefosław
Rogowski J., Bogusz J., Figurski M., Liwosz T., Kruczyk, M. M., Kujawa L., Kłęk M.
Reports on Geodesy
|
2006
|
z. 2/77
39-46
12
Content available remote CERGN 2003 solution and its relation to CERGN 1994-2001 campaign results
Hefty J., Stangl G., Cristea E., Kratochvil R., Liwosz T.
Reports on Geodesy
|
2006
|
z. 4/79
359-366
EN
Analysis strategy and results from CEGRN epoch campaign in 2003. Combined product based on individual network solutions by four analysis centres and its comparison with CEGRN 2001 coordinates. Time evolution of coordinates at some long-term observed CEGRN sites during seven epoch campaigns since 1994.
13
Content available Automatic system for GPS tropospheric delay estimation, on-line GPS processing user service and analysis of the results
Kruczyk M., Liwosz T., Rogowski J. B.
Reports on Geodesy
|
2006
|
z. 1/76
139-151
EN
This paper describes automatic system for GPS tropospheric delay estimation developed at the Institute of Geodesy and Geodetic Astronomy of the Warsaw University (WUT) LAC. The system is based on BPE (Bernese Processing Engine) and utilizes UltraRapid orbits and EUREF weekly coordinates. We describe processing strategies used in this application and report various experiences leading to start of NRT tropospheric service. We have made many statistical quality analysis of the resulting solutions. Accurate comparisons with ZTD combined product (EPN and IGS) and radiosounding data has been made. The poster presents also other research areas on the GPS data processing performed especially the Internet based service for an on-line GPS processing of the users data. Finally we present some other ideas of our interest how to use tropospheric delay in meteorology and climatology.
14
Content available Analysis of CEGRN 2005 as the eighth of CERGOP observing campaigns
Hefty J., Gerhatova L., Stangl G., Haslinger C., Krauss S., Becker M., Drescher R., Grenerczy G., Kratochvil R., Liwosz T.
Reports on Geodesy
|
2006
|
z. 1/76
39-46
EN
Strategy of analysis and results from solution of CEGRN epoch campaign in 2005 Combined solution of CEGRN 2005 based or individual solutions from six an: centres and its comparison with CEGRN 2003 coordinates. Time evolution of coordinates at some long-term observed CEGRN sites obtained during epoch camp since 1994 and the related problems.
15
Content available remote Geodynamic programmes conducted at Jozefoslaw Observatory
Rogowski J. B., Bogusz J., Figurski M., Kruczyk M., Kujawa L., Kurka W., Liwosz T.
Reports on Geodesy
|
2005
|
z. 2/73
159-170
16
Content available remote CEGRN 2003 solution and its relation to CEGRN 1994-2001 campaign results
Hefty J., Gerhátová L'., Stangl G., Cristea E., Kratochvíl R., Liwosz T.
Reports on Geodesy
|
2005
|
z. 2/73
33-40
EN
Analysis strategy and results from CEGRN epoch campaign in 2003. Combined product based on individual network solutions by four analysis centres and its comparison with CEGRN 2001 coordinates. Time evolution of coordinates at some long-term observed CEGRN sites during seven epoch campaignssince 1994.
17
Content available remote Some aspects of GPS tropospheric delay behavior, usefulness and estimation
Kruczyk M., Liwosz T., Rogowski J. B.
Reports on Geodesy
|
2004
|
nr 2/69
235--242
EN
Our paper highlights some different areas of our research in GPS meteorology. We have made many statistical quality analysis of the many standard tropospheric solutions and ZTD combined product (EPN and IGS). This work can be useful for both combined product users and improved processing strategy guidelines. The core of our interest is tropospheric delay estimation and usage in practical activity such as permanent network and epoch campaign adjustment. We report current works leading to start of NRT tropospheric service in WUT LAC. Finally we present some interesting ideas how to use tropospheric delay in meteorology and climatology (e. g. long IPW series for different dimate conditions, IPW distribution maps, correlation of IPW series for different stations and other parameters, comparisons with radiosounding profiles, IPW derivation).
18
Content available remote Research programe of the astrogeodetic observatory in Józesław
Rogowski J. B., Bogusz J., Figurski M., Kłęk M., Kruczyk M., Kujawa L., Kurka W., Liwosz T.
Reports on Geodesy
|
2004
|
nr 2/69
213--233
EN
Astrogedodetic Observatory Józefoslaw was joined to the IGS in 1991 and started to the permanent service in 1993. To day GPS stations JOZE and JOZE working in the frame IGS/EUREF. JOZ2 station participate in IGLOS an EUREF IP pilot projects. Results of tidal gravimetric observations; absolute gravity measurements; changes of the vertical, based on the gravimetric measurements and astrometric observations; hydrological and meteorological observations are the base for study of local deformations model. The results of practical test of RTK and DGPS measurements using mobile phone for data transmission performed since 1998 are also presented in the paper. WUT EUREF Local Analysis Centre, one of the 16 Local Analysis Centres acting in Europe, is a very important part of the Observatory. The Centre makes continuous service of one-week solution in the frame of EUREF network, processes national and international GPS campaigns, models ionosphere and troposphere parameters. The part of this Centre is automatic service for GPS data processing. The results of mentioned above work are presented in the paper.
19
Content available remote Central European intraplate velocities from CEGRN campaigns
Becker M., Cristea E., Figurski M., Gerhatova L., Grenerczy G., Hefty J., Kenyeres A., Liwosz T., Stangl G.
Reports on Geodesy
|
2002
|
z. 1/61
83-91
20
Content available remote WUT LAC status report
Bogusz J., Figurski M., Kruczyk M., Kujawa L., Liwosz T., Pfeil M., Rogowski J.
Reports on Geodesy
|
2001
|
z. 3/58
67-72
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