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1

Integrated precipitable water from GPS observations and CIMEL sunphotometer measurements at CGO Belsk

Kruczyk M., Liwosz T., Pietruczuk A.

Reports on Geodesy and Geoinformatics

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2017

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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

Określenie opóźnienia troposferycznego z użyciem sensora GPS w transporcie lotniczym

Krasuski K., Jafernik H.

Autobusy : technika, eksploatacja, systemy transportowe

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2017

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R. 18, nr 6

826--829, CD

PL

W artykule omówiony został problem wyznaczenia parametru opóźnienia troposferycznego z użyciem obserwacji GPS w obszarze implementacji techniki GNSS w transporcie lotniczym. Parametr opóźnienia troposferycznego został wyznaczony na podstawie programów CSRS-PPP, GAPS i magicPPP. W artykule dokonano porównania wartości opóźnienia troposferycznego dla uzyskanych wyników badawczych. W eksperymencie badawczym wykorzystano dane GPS z odbiornika Topcon HiperPro zamontowanego na pokładzie samolotu Cessna 172.

EN

The article discussed the problem of the designation of tropospheric delay parameter using GPS observations in the area of implementation of GNSS technology in air transport. Tropospheric delay parameter has been set on the basis of CSRS-PPP, GAPS and magicPPP softwares. The article compares the values of tropospheric delay for the results presented in the research. In experiment the GPS data from Topcon Hiper Pro receiver that was installed on the aircraft Cessna 172, were used.

3

Metody korekcji wpływu troposfery na dokładność określania lokalizacji w systemach GNSS

Wroński J. W.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2016

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nr 6

455--458, CD

PL

W ostatnich latach systemy GNSS znajdują zastosowanie w technologiach M2M (automatyczna nawigacja samochodowa), czy w najnowszych zastosowaniach technologii internetowych: Internecie Rzeczy lub Przedmiotów (IoT – Internet of Things), lub Internecie Wszechrzeczy (IoE - Internet of Everything), czyli sieci ludzi, procesów, danych i rzeczy podłączonych do Internetu. Sygnały z satelity przechodząc przez warstwę troposfery ulegają opóźnieniu, co ma wpływ na dokładność określania pozycji odbiornika. W referacie przedstawiono modele troposfery pozwalające na korekcję jej wpływu na dokładność lokalizacji odbiorników systemów GNSS.

EN

With the free availability of GNSS signal and the availability of cheap GNSS receivers, the GNSS technology is having a pervasive use in civil, industrial, scientific and military areas. GNSS localization plays the most important role in nowadays technologies such machine-to-machine communication and Internet of Things. RF signals are delayed when travelling from the transmitter to the receiver through the troposphere due to variability of the refractive index of the troposphere layer. This article describes methods used in GNSS systems to correct localization precision due to signal delay in the troposphere layer.

4

Long series of GNSS Integrated Precipitable Water as a climate change indicator

Kruczyk M.

Reports on Geodesy and Geoinformatics

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2015

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Vol. 99

1--18

EN

This paper investigates information potential contained in tropospheric delay product for selected International GNSS Service (IGS) stations in climatologic research. Long time series of daily averaged Integrated Precipitable Water (IPW) can serve as climate indicator. The seasonal model of IPW change has been adjusted to the multi-year series (by the least square method). Author applied two modes: sinusoidal and composite (two or more oscillations). Even simple sinusoidal seasonal model (of daily IPW values series) clearly represents diversity of world climates. Residuals in periods from 10 up to 17 years are searched for some long-term IPW trend – self-evident climate change indicator. Results are ambiguous: for some stations or periods IPW trends are quite clear, the following years (or the other station) not visible. Method of fitting linear trend to IPW series does not influence considerably the value of linear trend. The results are mostly influenced by series length, completeness and data (e.g. meteorological) quality. The longer and more homogenous IPW series, the better chance to estimate the magnitude of climatologic IPW changes.

5

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

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2015

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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.

6

Evaluation of the possibility of using the predicted tropospheric delays in real time GNSS positioning

Kalita J. Z., Rzepecka Z., Krzan G.

Artificial Satellites : Journal of Planetary Geodesy

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2014

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Vol. 49, No. 4

179--189

EN

Among many sources of errors that influence Global Navigation Satellite System (GNSS) observations, tropospheric delay is one of the most significant. It causes nonrefractive systematic bias in the observations on the level of several meters, depending on the atmospheric conditions. Tropospheric delay modelling plays an important role in precise positioning. The current models use numerical weather data for precise estimation of the parameters that are provided as a part of the Global Geodetic Observation System (GGOS). The purpose of this paper is to analyze the tropospheric data provided by the GGOS Atmosphere Service conducted by the Vienna University of Technology. There are predicted and final delay data available at the Service. In real time tasks, only the predicted values can be used. Thus it is very useful to study accuracy of the forecast delays. Comparison of data sets based on predicted and real weather models allows for conclusions concerning possibility of using the former for real time positioning applications. The predicted values of the dry tropospheric delay component, both zenith and mapped, can be safely used in real time PPP applications, but on the other hand, while using the wet predicted values, one should be very careful.

7

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

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2012

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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.

8

Results of the application of tropospheric corrections from different troposphere models for precise GPS rapid static positioning

Wielgosz P., Paziewski J., Krankowski A., Kroszczyński K., Figurski M.

Acta Geophysica

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2012

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Vol. 60, no. 4

1236-1257

EN

In many surveying applications, determination of accurate heights is of significant interest. The delay caused by the neutral atmosphere is one of the main factors limiting the accuracy of GPS positioning and affecting mainly the height coordinate component rather than horizontal ones. Estimation of the zenith total delay is a commonly used technique for accounting for the tropospheric delay in static positioning. However, in the rapid static positioning mode the estimation of the zenith total delay may fail, since for its reliable estimation longer observing sessions are required. In this paper, several troposphere modeling techniques were applied and tested with three processing scenarios: a single baseline solution with various height differences and a multi-baseline solution. In specific, we introduced external zenith total delays obtained from Modified Hopfield troposphere model with standard atmosphere parameters, UNB3m model, COAMPS numerical weather prediction model and zenith total delays interpolated from a reference network solution. The best results were obtained when tropospheric delays derived from the reference network were applied.

9

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

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2006

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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.