Three laureates of the Minister’s scholarship for outstanding young scientists

The Ministry of Education and Science has announced the results of scholarships for outstanding young scientists. In this year’s edition, 217 scholarships were awarded to outstanding young scientists, including 52 doctoral students, selected in a competition by experts from the Advisory Team.

Three members of the SpaceOS were awarded the scholarship: dr Kamila Pawłuszek-Filipiak, dr Paweł Hordyniec and Radoslaw Zajdel. The winners will receive very high scholarships – PLN 5,390.00 per month for a period of three years. Detailed information on the website of the Ministry of Science and Higher Education.


The high-frequency motion of the Earth pole on the basis of observations from 80 GNSS satellites and 100 ground stations

Scientists from the Institute of Geodesy and Geoinformatics, UPWr and the Astronomical Institute of the University of Bern in Switzerland have proven that GNSS observations from GPS, GLONASS and Galileo satellites are able to provide high-quality information on high-frequency changes in the Earth rotation with periods from several to several hours. Therefore, for the first time it was possible to determine the model of the sub-daily Earth polar motion using as many as 80 satellites: GPS, GLONASS and Galileo. All previous determinations of the empirical GNSS models were based on the GPS system, which caused problems due to exactly 2 revolutions of GPS satellites per day, translating into the risk of recognizing orbital errors of GPS satellites as pole movements.

A new method of integrating GNSS data from satellites with different revolution periods allows the development of independent empirical models describing changes in the Earth rotation caused by ocean tides. The very first model of sub-diurnal changes in the movement of the Earth pole which is free from most of the disadvantages of solutions based solely on the GPS system is now described by Zajdel et al. (2021). The model is based on 3 years of continuous observations from 100 ground GNSS stations located on all continents and recording data from 80 GNSS satellites.

Read more about the determination of high-frequency changes in the motion of the Earth Pole in the latest article in the Journal of Geodesy:

Zajdel, R., Sośnica, K., Bury, G. Dach, R., Prange, L., Kaźmierski, K. (2021) Sub-daily polar motion from GPS, GLONASS, and Galileo. Journal of Geodesy 95, 3. -020-01453-w

1st and 2nd GATHERS Roadshows

The Institute of Geodesy and Geoinformatics at UPWr will host two online Roadshows to promote the EU funded GATHERS project. The project is focused on Earth’s surface deformation monitoring and is realized in cooperation with teams from the leading European universities of TU Delft, TU Wien, and La Sapienza-Rome.

During the events the participants will learn how different geodetic techniques as InSAR, LiDAR and GNSS seismology are used for efficient analysis of deformations of the Earth’s surface. Also, more details about the GATHERS’ MSc and PhD trainings on InSAR, LiDAR, and GNSS seismology for studying the man-made hazards will be presented.

The two dates of the events are:

– Friday, November 27, 2020 at 9am – 11:30 a.m. and

– Monday, December 14, 2020 at 9am – 11:30 a.m.

The registration is open on

Radio occultation observations help studying tropical cyclones

Tropical cyclones (TCs) are destructive natural phenomena related not only to low pressure systems and extremely strong winds, but also to copious rainfall and dense clouds. TCs cause catastrophic damage to both human lives and health and socioeconomic situation. The economic losses associated with tropical cyclones are rising every year in the USA. Memorable Hurricane Katrina in 2005 caused more than $80 billion damage and killed almost 2 000 people.

Therefore, any technique, which can improve prediction, observation, and modelling tropical cyclones is extremely valuable. One of this techniques is radio-occultation (RO). RO is an active limb viewing technique, which uses the phase and amplitude of two L-band electromagnetic signals transmitted from Global Navigation Satellite System (GNSS) satellites and received by low earth orbit satellites. The Earth’s atmosphere affects the propagating GNSS signal resulting in the signal delay and bending, which eventually can be transformed into high quality meteorological profiles of temperature, pressure, and water vapour using appropriate processing techniques.

A set of high quality RO profiles during TCs is presented by the team of researchers from the Institute of Geodesy and Geoinformatics at WUELS, the University of Graz, and the University of Padova in their newest work. Observations from over a dozen RO satellite missions were processed and collocated with the TC best tracks in 2001-2018 and eventually collected in a handy archive in the NetCDF files. The final dataset is freely available at:

The RO-TC record contains information about TC location and intensity, vertical meteorological and climatological RO profiles, and other useful information such as spatial and temporal differences between TC centres and mean tangent points position of the collocated RO profiles. More details on the archive content, application, and study case as well as statistical analyses are demonstrated in the newest issue of Earth System Science Data journal:

Lasota, E., Steiner, A. K., Kirchengast, G. and Biondi, R.: Tropical cyclones vertical structure from GNSS radio occultation: an archive covering the period 2001–2018, Earth Syst. Sci. Data, 12(4), 2679–2693, doi:10.5194/essd-12-2679-2020, 2020.

How to find the Earth’s center of mass using GNSS?

The Earth’s center of mass – as a whole planet – cannot be measured directly. However, precise knowledge about its motion is crucial both in engineering practice and the study of the environmental changes in the planet Earth. To find the Earth’s center of mass, we have to use indirect techniques and universal laws of physics. One of Kepler’s laws says that all celestial bodies orbit in circles or ellipses, with the main body at one of the two foci. Therefore, satellites orbiting the Earth and precise observations of their motion can be used to measure the center of the Earth, the so-called geocenter coordinates. In the latest article in GPS Solutions, scientists from the Institute of Geodesy and Geoinformatics UPWr used for the first time in the world observations of up to 80 artificial navigational satellites (GNSS, Global Navigational Satellite Systems) to determine geocenter coordinates. Three constellations of satellites were used, including GPS, GLONASS, and Galileo. To date, such research was not feasible because Galileo reached the number of 24 active satellites at the end of 2018. That makes the research innovative and breakthrough in determining the center of the Earth’s center of mass with a millimeter level accuracy.

Formal errors of the GCC-Z estimates in mm. The β angles for all the orbital planes of the corresponding GNSS constellations are shown using dashed gray lines. Vertical cyan lines point to the epochs of minimum and maximum errors for each of the GPS, GLONASS, and Galileo. Note a different vertical axis scale for GLO

Origin of the geocenter motion

Most of the processes in the Earth’s atmosphere, oceans, and ice cover are connected with the transport of huge masses. Along with the movement of masses in the Earth system, their natural center, the so-called geocenter, also moves. The precise description of the movement of the natural center of the Earth’s masses is crucial for orbit modeling of artificial satellites and the interpretation of the climate changes on Earth. One should keep in mind that all artificial satellites of the Earth orbit around the same natural Earth’s center of mass. In attempting to imagine the practical consequences of incorrect interpretation of the geocenter motion, we can point out that an error in the determination of the geocenter equal to 3 mm translates into an inaccurate estimate of the loss of mass of glaciers in Antarctica equivalent to 200 billion tons of ice.

Problems with the geocenter motion in GNSS research

The description of the geocenter motion using the GPS system has been a research problem for years. It is worth noting that we describe the millimeter movement of the center of the planet’s masses, observing the motion of the satellites about 20 000 km above the Earth’s surface. The main problem is to model the forces acting in space on a satellite and to separate them from the movement of the geocenter. Satellites are susceptible to the non-gravitational perturbing forces – mainly solar radiation pressure, which acts on the solar panels and the satellite’s body. In this article IGiG scientists described how the orbit modeling of GPS, GLONASS and the latest Galileo system influences the determination of geocenter coordinates. The most problematic component of the geocenter coordinates turned out to be the Z-axis component, which is directed to the North Pole. When satellite orbit and solar radiation pressure are not well modeled, the Z component of the geocenter motion contains more errors than the actual geophysical signal caused by the circulation of masses between the northern and southern hemispheres. Researchers also pointed out that precise metadata on the satellites’ optical and physical parameters, which has been officially published in 2017 by the European Space Agency, improve the quality of orbit modeling and the possibility to describe the geocenter motion.

The failure at the start of Galileo proves to be crucial in the determination of the geocenter

In the case of the Galileo constellation, a very unusual phenomenon can be observed. One pair of the Galileo satellites have been launched into highly eccentric orbit instead of circular. These satellites have never been classified as fully operational but transmit signals, which can be tracked by the ground stations. Interestingly, a pair of satellites in an incorrect orbit improves the determination of the geocenter coordinates using the Galileo constellation.

The analysis also revealed that the geocenter coordinates are best determined using two constellations: GPS and Galileo. The article shows that the GLONASS constellation is currently not suitable for determining the geocenter motion because regardless of the adopted orbit modeling strategy, the errors resulting from solar radiation pressure modeling are more significant than the movement of the geocenter itself.

For more information about the GNSS-derived geocenter coordinates, please refer to the latest article published in GPS Solutions:

Zajdel, R.; Sośnica, K.; Bury, G. (2021) Geocenter coordinates derived from multi-GNSS: a look into the role of solar radiation pressure modeling. GPS Solut 25, 1 (2021).

A breakthrough in the protection of location data privacy

            The ubiquitous computing gives unlimited possibilities to create intelligent solutions that increase efficiency in many areas of life. For example, the location of smartphones informs where and when the user was located, which allows you to simulate scenarios of the spread of infectious diseases, develop efficient contingency plans and quickly anticipate the emerging congestion. These solutions, although groundbreaking, often meet with criticism related to the protection of personal data privacy. Privacy protection and legal regulations prevent the widespread use of such data in creating innovative solutions.

            Privacy protection at the expense of data potential or vice versa, sacrificing people’s privacy for the purpose of creating new solutions will soon be no longer a problem. The solution for that was recently presented by scientists from the Wrocław University of Life Sciences in cooperation and the University of Auckland in their latest article published in the Computers, Environment and Urban Systems journal. The presented solution provides full-potential data on the location of the population, which can be used in almost any field related to human mobility, while protecting the privacy of the population. The idea is based on the generation of artificial movement trajectories whose characteristics are similar to the original data used to calibrate the data generating model. In this way, artificial trajectories do not coincide with the real movement of the population, but provide the same information.

            The developed model, called WHO-WHERE-WHEN (3W) is at the same time a human mobility model. During the calibration phase it creates an image of the mobility of a given area, so that it is also possible to generate hypothetical scenarios. For example, it is possible to assess the impact of adding the new residential area in the suburbs of large urban centers on the formation of congestion. Compared to the best solutions in this field, the 3W model has obtained 35% better accuracy in replicating movement trajectory characteristics while increasing the flexibility of the solution and the range of reflected population mobility characteristics.

Fig 1. Map showing a comparison of population density at a selected moment in the New York State area, calculated from generated data (left panel) and real data (right panel). Author of the map: Barbara Kasieczka.

            The conflict between the Internet of Things and privacy is the greatest constraint on the further development of many areas. The 3W model is expected to solve this problem in the future by creating universal access to location data, thus opening up a new market for mobility-based services, where the possibility of participation will not be limited by the unavailability of data, and equalizing the opportunities for corporations, small and medium-sized companies and academic entities.

            Article “Population mobility modelling for mobility data simulation”, authors: Kamil Smolak, Witold Rohm, Krzysztof Knop and Katarzyna Siła-Nowicka, is available at DOI:10.1016/j.compenvurbsys.2020.101526.

GNSS observations in mining tremors analysis

Among earthquakes, natural and anthropogenic ones can be distinguished. The Republic of Poland is located in an intraplate area where natural earthquakes are very rare. On the other hand, areas with a high density of active underground mining are threatened with induced seismicity. Seismic tremors occur regularly in the underground mining areas, and there are several hundred events annually with magnitudes greater than 2, with maximum magnitudes reaching 4. As mining tremors are shallow and very frequent, they cause damage to infrastructure.

Mining tremors are mainly monitored with seismological instruments, however, the progress in the field of satellite observations allows to observe them also with the high-rate GNSS observations, which are more and more often used to observe vibrations during large earthquakes and in structural monitoring, e.g. bridge vibrations. In contrary to classical GNSS observations, in vibrations monitoring the observations’ sampling rate is up to 100 Hz, which are processed in kinematic mode, resulting in epoch-to-epoch positions. The infrastructure that is developed within the EPOS-PL project led us to record one of the biggest mining tremors on the LGOM area, that occurred on January 29, 2019, with magnitude 3.7. Due to the optimal localisation of GNSS stations co-located with seismological instruments we were able to analyse the agreement between observations recorded with both techniques. With noise filtering technique, the positions processed in the relative and absolute Precise Point Positioning approaches were compared with seismological displacements. The comparison between GPS and SM derived displacements exhibited a Pearson’s correlation value ranging from 0.61 to 0.94 for horizontal displacements and the peak ground displacements reached 16 mm, with the accuracy of determination of approx. 2 mm for the horizontal plane and 4 mm for the vertical plane.

This is one of the first studies to analyse mining tremor using the high-rate GNSS technique, here limited to GPS data. Other studies have concerned natural earthquake analysis with HR-GNSS, and if they addressed induced shocks, it was only in the area of long-term displacements. The published research results show that also small, shallow tremors might be registered with GNSS observations, which can be supplementary in the seismological analysis.

Time variability of Pearson’s correlation coefficient of band-pass filtered DD displacements (left) and PPP displacements (right) in comparison with seismological data for station KOMR/LES1.

The detailed research information is presented in the paper entitled “High-rate GPS positioning for tracing anthropogenic seismic activity: The 29 January 2019 mining tremor in Legnica- Głogów Copper District, Poland” by Iwona Kudłacik1, Jan Kapłon1, Grzegorz Lizurek2, Mattia Crespi3, Grzegorz Kurpiński4, developed in cooperation of the Institute of Geodesy and Geoinformatics Wrocław University of Environmental and Life Sciences (1), Institute of Geophysics, Polish Academy of Sciences (2), Geodesy and Geomatics Division, DICEA-Sapienza University of Rome (3) and KGHM CUPRUM Sp. z.o.o. (4). The manuscript was published in Measurements:

This work was carried out within EPOS – the European Plate Observing System, co-financed by the European Union from the funds of the European Regional Development Fund, POIR.04.02.00-14-A0003/ 16. GNSS data was partially provided courtesy of KGHM Cuprum Sp. z. o. o. and the University of Warmia and Mazury, co-financed by the National Centre for Research and Development, POIR.04.01.04-00-0056/17.

Recent advancements in real-time GNSS meteorology

Accuracy of real-time ZTD against IGS Final product

GNSS remote sensing of the troposphere, called GNSS meteorology, delivers the zenith total delay (ZTD), which can be assimilated into numerical weather prediction (NWP) models, thus improving the quality of forecasts.

Major developments in GNSS, including new constellations, precise real-time satellite products, advanced troposphere mapping functions, have a positive impact on the quality of derived ZTD. However, neither are these achievements combined in a single processing strategy, nor is the impact of other processing parameters on ZTD accuracy analysed. Hadas et al. (2020) investigate the sensitivity of real-time troposphere products on various processing parameters, i.e., functional model, GNSS selection and combination, inter-system weighting, elevation-dependent weighting function, and gradient estimation. They define the advanced strategy dedicated to real-time GNSS meteorology, which combines recommended processing parameters. Although all four GNSSs, i.e. GPS, GLONASS, Galileo and BeiDou can provide real-time ZTD solutions independently, a multi-GNSS solution with intersystem weighting reduces the a posteriori standard deviation of estimated ZTD by up to 37%. The advanced strategy allows to estimate real-time ZTD with accuracy varying from 5.4 to 10.1 mm, which legitimates for assimilation into NWP.

ZTD periodograms (top) and differential peaks in power spectrum between real-time GPS-only and Galileo-only solutions with selected periods of expected orbit-related artificial signals for GPS (green) and Galileo (blue) (bottom).

Hadas and Hobiger (2020) focus on the contribution of Galileo to real-time GNSS meteorology. The slightly worse performance of Galileo-only solution than GPS-only solution over the entire year 2019 is attributed to fewer operational satellites, Galileo outage in July 2019 and missing antenna phase centre corrections for a second Galileo frequency. However, a combined GPS+Galileo solution leads to significantly better results than a GPS-only solution. Processing of nearly twice as much observations decreases the ZTD standard deviation by a factor of 1.5–2.0. The accuracy with respect to the final ZTD products improves by 3.7% to 8.5%. Finally yet importantly, the combined solution suppresses orbit-related artificial signals of high frequency.

For details we refer to:

Hadaś T, Hobiger T., Hodryniec P. (2020): Considering different recent advancements in GNSS on real-time zenith troposphere estimates. GPS Solutions Vol. 24, No. 99, Berlin – Heidelberg 2020, pp. 1-14,

Hadaś T, Hobiger T. (2020): Benefits of Using Galileo for Real-Time GNSS Meteorology. IEEE Geoscience and Remote Sensing Letters, pp. 1-5,

Research have received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 835997 (see also

The onboard Galileo atomic clocks can correct the wrong position of satellites

In the recent article published in GPS Solutions, scientists from IGG show how ultra-accurate atomic clocks can correct a total error in satellite positioning and navigation. This was impossible with GPS or GLONASS due to the low accuracy of onboard atomic clocks. The Galileo satellites are equipped with very stable atomic rubidium clocks and hydrogen masers. These clocks are so accurate that they can correct errors in the satellite positions. Although the total error of the signal including position and time should increase, it drops from 2.2 cm to 1.6 cm after using the atomic clocks onboard the Galileo satellites. This result is very surprising because at the stage of development of the satellite systems it was not planned to correct the position with data from atomic clocks. The total error of the Galileo signal is 1.6 cm, which is currently the most accurate of all navigation systems. The same error is 2.3 cm and 5.2 cm, in the case of GPS and GLONASS, respectively. Thus, the European Galileo system already provides the highest signal quality, despite the constellation incompleteness.

Orbit and clock error

Positioning with navigation satellites is based on measuring the difference in the time of sending signal by satellite and the time of receiving this signal. To calculate the receiver position it is, therefore, necessary to know the exact position of the satellite at the time of sending the signal and the time of emission determined by the onboard atomic clock. The error in the clock or the position of the satellite directly affects the position of the GNSS receiver. The so-called SISRE (signal-in-space ranging error) parameter was used to assess how the satellite position error and the clock error translate into the signal error in space. SISRE consists of two parts: a satellite position error (orbit error) and a clock error.

Orbit and clock error

Positioning with navigation satellites is based on measuring the difference in the time of sending signal by satellite and the time of receiving this signal. To calculate the receiver position it is, therefore, necessary to know the exact position of the satellite at the time of sending the signal and the time of emission determined by the onboard atomic clock. The error in the clock or the position of the satellite directly affects the position of the GNSS receiver. The so-called SISRE (signal-in-space ranging error) parameter was used to assess how the satellite position error and the clock error translate into the signal error in space. SISRE consists of two parts: a satellite position error (orbit error) and a clock error.

The total SISRE containing an error of a satellite position and the clock is smaller for Galileo than the SISRE of the position itself. It means that the atomic clock effectively corrects systematic errors in the calculated position. Typically, errors should add up according to Gauss law. In the case of GLONASS, the satellite signal error increases from 3.9 cm (position-only error) to 5.1 cm (position and clock error). However, the onboard clock readings may have a similar value to the satellite position error, only the opposite sign for very accurate clocks. Position and clock are highly correlated in calculating the total effect on the satellite signal. It is the case for the Galileo satellites, where the clock corrects the orbit. The same happens in the Chinese BeiDou IGSO satellites, but the total error remains at 3.9 cm. The results of research conducted by scientists from IGG are quite a surprise and constitute an important step in understanding the way how navigation systems work and how their future can look like.

For more information on this and the evolution of changes in the accuracy of the GPS, GLONASS, Galileo, and BeiDou orbits and clocks, see:

Kazmierski, K., Zajdel, R. Sośnica, K. (2020) Evolution of orbit and clock quality for real-time multi-GNSS solutions. GPS Solut 24, 111 (2020).

Open PostDoc Position in the field of Satellite Geodesy

The Institute of Geodesy and Geoinformatics (IGG UPWr) announces an open PostDoc position that will be funded by the Polish National Science Center in the framework of the project “Integrated terrestrial reference frames based on SLR measurements to geodetic, active LEO, and GNSS satellites” (project number: 2019/35/B/ST10/00515).

Main tasks:

  • Combination of Lunar Laser Ranging (LLR) and Satellite Laser Ranging (SLR) for deriving Earth Rotation Parameters
  • Analysis of systematic effects in SLR and LLR observations with a focus on range biases, signature effects, and atmospheric refraction
  • Comparison of parameters based on GNSS, VLBI, SLR, and LLR analysis
  • Publishing scientific papers and presentation of results at scientific conferences
  • Assist in education of master and Ph.D. students


  • Ph.D. University degree in geodesy, informatics, physics, mathematics, aerospace engineering, or a similar discipline acquired between October 2013 and October 2020.

(the Ph.D. degree must be obtained outside the host institution that is outside the Wrocław University of Environmental and Life Sciences)

  • Proficiency in programming (e.g., in C++, Perl, Fortran, Python)
  • Experience in the time series analysis of geodetic parameters, e.g., Earth rotation parameters, station coordinates, troposphere delays and/or SLR or LLR data processing
  • Excellent record of scientific achievements, including publications as the first author in high-level journals, such as Journal of Geodesy, GPS Solutions, Journal of Geophysical Research, Geophysical Research Letters, or similar
  • Proficiency in English (oral and written)
  • Capability to work independently and timely, enjoying to participate actively in meetings of international teams and to present complex research matter concisely and appealingly (oral and written).

Required documents:

  • Application with the motivation letter
  • CV
  • list of publications (track record)
  • copy of the doctoral degree (Ph.D. diploma)

Application deadline: October 15, 2020

Salary: 10000,00 PLN per month (gross), which is equal to about 2270,00 EUR per month (gross)

Contract: 24 months

Contact: Univ. Prof. Dr. Krzysztof Sośnica, e-mail:

We offer working opportunities in the inspiring, young, international team of the SPace And Close Earth Observation Sciences (SpaceOS) Working Group (see ). More information about the project can be found at the website:

Applications and the selection procedure will follow the regulations from Annex to NCN Council Resolution No 90/2019 of 12 September 2019 amending the Regulations on awarding funding for research tasks funded by the National Science Centre as regards research projects:
The Wroclaw University of Environmental and Life Sciences is an equal opportunity employer. Applications from women for the PostDoc position will be strongly encouraged.