How accurately can we measure the Earth’s rotation?

The Earth Rotation Parameters (ERPs) belong to the fundamental transformation parameters linking the International Celestial Reference Frame (ICRF) and the International Terrestrial Reference Frame (ITRF). The ERPs are conventionally composed of the X and Y pole coordinates (polar motion, PM), their rates, UT1-UTC, and its rate called length-of-day (LoD). The Global Navigational Satellite System (GNSS) is one of the major satellite techniques, which delivers reliable information about ERPs.

ERPs are time-variable global geodetic parameters with a purely geophysical origin. Theoretically, the estimates of these parameters should be independent of the satellite constellation used in GNSS processing. Nonetheless, clear differences in the time series of ERPs are noticed when using different GNSS constellations. In this study, GPS, GLONASS, and Galileo estimates of ERP have been tested in search of system-specific signals.

The main motivation of this work was the presumption that the newly developed European system – Galileo could help with the mitigation of the known errors in the GPS-based ERP products. In the case of GPS, the orbital period equals 11h 58m, thus, it is in 2:1 resonance with the earth rotation. The corresponding resonances for GLONASS and Galileo are much weaker and equal to 17:8 and 17:10, respectively.

Since December 2018, the Galileo system constellation is composed of 24 usable satellites and is nearly fully operational together with the legacy GPS and GLONASS systems. Moreover, the detailed metadata containing optical and geometrical properties for the In Orbit Validation (IOV) and Fully Operational Capability (FOC) satellites have been released since 2017 by the European GNSS Service Centre. The metadata brought new perspectives for the advanced approaches for the orbit modeling based on the hybrid or semi-empirical models. Finally, Galileo is certainly a perfect system to check its suitability for ERP estimation and to confirm the hitherto results based on GPS and GLONASS systems.

The GPS-based polar motion estimates are of better quality than those based on GLONASS and Galileo, which are susceptible to deficiencies in the orbit modeling. On the other hand, we observe a systematic bias of GPS-based length-of-day (LoD) with respect to the reference series with a mean offset of −22.4 µs/day. The Galileo-based solutions are almost entirely free of this issue.

The spurious signals inherently influence the Galileo-based and GLONASS-based ERPs at the frequencies which arise from the resonance between the satellite revolution period and earth rotation, e.g., 3.4 days for Galileo and 3.9 days for GLONASS. These and the draconitic signals overshadow the GNSS-based ERP estimates. Although all the system-specific solutions are affected by the artificial signals, the combination of different GNSS mitigates most of the uncertainties and improves the ERP results.

Details of our study are presented in: Zajdel, R., Sośnica, K., Bury, G. Dach R., Prange L. (2020) System-specific systematic errors in earth rotation parameters derived from GPS, GLONASS, and Galileo. GPS Solut 24, 74 (2020). https://doi.org/10.1007/s10291-020-00989-w

This work was funded by the National Science Centre, Poland (NCN) grant UMO 2018/29/B/ST10/00382 („Determination of Global Geodetic Parameters using the Galileo Satellite System”).

 

Number of satellites used in the multi-GNSS processing by the particular analysis centers. The gaps in data reflect the unavailability of the products

How the advanced geodetic technologies could help us to measure the impact of earth’s tremors provoked by human mining activities

Most of us are used to thinking of earthquakes as devastating natural phenomena, but anthropological activities also can be responsible for some very serious earth shakes. One example of such an event relates to underground mining activity. Our study is focused on an event happened in Western Poland around Rudna Mine on 29 January, 2019. A collapse in the mine provoked an earthquake with Magnitude of 4.6. In order to estimate the severity and impact of the shock, we used several different sources of data – seismological and geodetic, and different data-processing strategies. From data recorded by a regional seismological network we estimated the source mechanism of the shock, which explains the parameters of the collapse that provoked the spread of the seismic waves in the ground surface. We used the records from a local seismological network to determine ground response in the short time after the moment of the collapse – peak ground acceleration, velocity and displacement (8mm horizontally and 1.5mm vertically). At a station for precise positioning (GNSS) located near to the epicenter of the shock (at Komorniki village) we detected changes in the position (coordinates) of this station for a short period of the shock. The result we interpreted as an alternative seismograph. We also revised a longer period of coordinate records for this station to validate the stable position of this point before and after the collapse. The other geodetic method that we applied in our study is based on satellite radar measurements (InSAR). They cover a period three months before and three months after the collapse and show the slow sinking (about 20cm/year before the shock and up to 50cm/year after the shock) due to the mining works in the range of the mine. For the time of the collapse these data revealed that the event affected an area of 2 square km and led to a subsidence of about 15 cm within six days.

Details of our study are presented in the paper “Combined Study of a Significant Mine Collapse Based on Seismological and Geodetic Data—29 January 2019, Rudna Mine, Poland” by Maya Ilieva1, Łukasz Rudziński2, Kamila Pawłuszek-Filipiak1, Grzegorz Lizurek2, Iwona Kudłacik1, Damian Tondaś1 and Dorota Olszewska2

Published in Remote Sensing (Special Issue Remote Sensing in Applied Geophysics) 2020, 12(10), 1570; https://doi.org/10.3390/rs12101570

1 Institute of Geodesy and Geoinformatics, Wrocław University of Environmental Life and Sciences

2 Institute of Geophysics, Polish Academy of Sciences

Funding: This study was conducted under the umbrella of the EPOS-PL project, POIR.04.02.00-14-A003/16,funded by the Operational Program Smart Growth 2014–2020, Priority IV: Increasing research potential, Action 4.2:Development of modern research infrastructure in the science sector. It was co-financed by the European Regional Development Fund. GNSS station LES1 was established as part of the EPOS-PL scientific geodetic infrastructure. This work was also partially financed by the Polish Ministry of Science and Higher Education in Poland as a part of its statutory activity No 3841/E-41/S/2020

Workshop on environmental remote sensing

On 18-20 March 2020, UPWr, together with RUS Copernicus and ESA, will organize a workshop on environmental remote sensing https://www.upwr.edu.pl/research/49016/geoworkshops.html. The programme includes: 4 hours of lectures (18 March), 5 practical exercises in the field of: land deformations related to the exploitation of natural resources, deformations related to earthquakes, crop monitoring and urban land use monitoring. The lecturers will be given by experienced ESA (Dr. F. Sarti and Dr. M. Fitrzyk) and RUS Copernicus (Miguel Castro Gómez and Tereza Šmejkalová) employees. Participation in the event is free of charge and the number of places is limited to 24. The application can be submitted on the website: https://rus-training.eu/training/rus-copernicus-at-the-apm-remote-sensing-of-the-environment-workshop/apply.

The event is part of the academic cooperation project between UPWr, TU Wien, TU Dresden and Imperial College London “Interdisciplinary international cooperation as the key to excellence in science and education (INCREaSE)”, funded by NAWA.

GATHERS H2020 kick-off meeting – summary

The kick-off meeting of the Twinning Project “GATHERS – Integration of Geodetic and imAging TecHniques for monitoring and modelling the Earth’s surface defoRmations and Seismic risk” has been held at The Wrocław University of Environmental and Life Sciences (UPWr) on December 4th-5th, 2019

The main purpose of GATHERS project is to enlarge the number of research-intensive actions in the field of geospatial sciences at UPWr, represented by the Institute of Geodesy and Geoinformatics (IGiG), foster development of leaders to form Lead Research Working Group in InSAR, LiDAR and GNSS seismology, and finally, to establish strong networks with the best Universities in Europe to generate competitive research applications in H2020. The main partners of the project are TU Delft (the Netherlands), TU Wien (Austria) and Sapienza University of Rome (Italy).

H2020 WIDESPREAD TWINNING programme initiatives are aimed at filling networking and partnership gaps that institutions in the Widening countries suffer from. Their cooperation with leading institutions from EU will develop activities for education, staff exchanges, initiation of collaboration in scientific fields, publications and life-long cooperation.

One of the key scientific disciplines at UPWr are geospatial sciences, represented by Institute of Geodesy and Geoinformatics (IGiG). IGiG aims at the development of new area of expertise, i.e. integrated multi-technique monitoring of ground deformations and seismicity using modern techniques, such as Interferometric Synthetic-Aperture Radar (InSAR), Light Detection and Ranging (LiDAR) and Global Navigation Satellite System (GNSS) seismology. Current challenges in the field related to the deformation rate and scale, a non-linear character of terrain movements, seismic magnitude, and differentiation between the sources of surface deformations, require an enhancement of the methodological approaches as well as substantial expertise in the interpretation of the results.

UPWr’s IGiG ambition is to be amongst the top research institutions of geospatial sciences in the coming years, and to become one of the leading centres of excellence in the Central and Eastern Europe.

GATHERS kick-off meeting day was opened by Dr. Maya Ilieva (Project Coordinator from UPWr). The purpose of the first official meeting was the team building, establishing of personal contacts and focus on the project goals. Participants discussed project governance and procedures, and finally voted for the project logo.

The kick-off meeting was accompanied by a B2B event in which over 30 carefully selected experts and companies from Europe took part. The B2B meeting started with two Keynote talks: “InSAR for mining industry” by Davide Colombo (TRE Altamira, Italy) and “Mining tremors – current challenges to the industry” by Prof. Grzegorz Mutke (GIG, Poland). The second part of the meeting was dedicated to the presentation of the techniques and challenges represented by GATHERS partners with the presentations of Prof. Ramon Hanssen (TU Delft), DI Michael Wimmer (TU Wien) and Prof. Mattia Crespi (Sapienza University of Rome). The B2B event concluded with a “World Café” to discuss the challenges in InSAR, LiDAR and GNSS seismology moderate d by experts with the participation of business partners.

This Project has received funding from the European Union‘s Horizon 2020 research and innovation programme under grant agreement No 857612.

This Project has received funding from the European Union‘s Horizon 2020 research and innovation programme under grant agreement No 857612.

Invitation for the kick-off meeting of the H2020 project

Kick-off meeting of the Twinning Project “GATHERS – Integration of Geodetic and imAging TecHniques for monitoring and modelling the Earth’s surface defoRmations and Seismic risk” will be held on December 4th-5th, 2019 at Wrocław University of Environmental and Life Sciences (UPWr).

The main purpose of this project is to enlarge the number of research-intensive sections in the field of geospatial sciences at Wrocław University of Environmental and Life Sciences, represented by the Institute of Geodesy and Geoinformatics – IGiG. Aiming to foster development of leaders to form Lead Research Working Groups in InSAR, LiDAR and GNSS seismology and to finally establish strong networks with the best Universities in Europe to generate competitive research applications in H2020. The main partners of the project are TU Delft (NL), TU Wien (AT) and Sapienza University of Rome (IT).

The main objective of the project will be achieved by strengthening the IGiG team with a cohort of young motivated MSc and PhD students who will work with leading experts in Europe in the fields of InSAR (TU Delft), LiDAR (TU Wien) and GNSS seismology (Sapienza UR) including scientific visits in the GATHERS partners’ headquarters for one to three months per year. Within the three-years realisation of the project we will organise three summer schools and two hackathons, three workshops and four meetings with businesses.
UPWr’s IGiG ambition is to become one of the leading centres of excellence in geospatial science in Central and Eastern Europe within the next years.

New radiometers at the Institute of Geodesy and Geoinformatics

Within the EPOS-PL project (POIR.04.02.00-14-A003/16) two microwave radiometers RPG-HATPRO-G5, supplied by Radiometer Physics GmbH, were purchased. The instruments were installed on the building of the Faculty of Environmental Engineering and Geodesy of the Wrocław University of Environmental and Life Sciences and in the  Geodetic-Geophysical Observatory Borowa Góra. RPG-HATPRO series develops microwave radiometers designed for continuous measurement of temperature and humidity profiles in the troposphere, parallely in several selected frequency channels. Radiometers enable continuous monitoring of troposphere condition with one-second frequency of recording parameters. The use of infrared radiometer, which is a module of the instrument, allows to detect clouds and to measure the height of the base of clouds. Radiometers are also equipped with Vaisala meteorological stations (WXT530) that allow to conduct surface measurement of pressure, temperature, relative humidity, wind speed, wind direction and rainfall. In addition to the temperature and humidity profiles, the instruments measure integrated quantities such as the Integrated Water Vapour (IWV) and the Liquid Water Path (LWP). In the context of research conducted in the Institute of Geodesy and Geoinformatics, one of the most important functions of the acquired equipment is detection of microwave signal delays in the troposphere in the zenith direction. Moreover, one of the purchased radiometers (located in Wrocław) has been equipped with an azimuthal positioner with a controller that enable to scan the sky for given vertical angles. The combination of these modules will allow to determine the microwave signal delay due to the presence of water vapour in the troposphere for all GNSS satellites visible above the horizon, on the direction to the satellite. The data from the instrument will serve as a reference data source for the NRT system for the determination of zenith tropospheric delays developed within the EPOS-PL project. Moreover, the measurements of slant tropospheric delay will expand the set of observations of the tomographic model TOMO2 developed at the Institute. The instrument software provides access to data at all levels: raw measurement data, calibrated brightness temperatures and atmospheric products, which in the future will supply the resources of national scientific consortia, such as the Aerosol Research Network Poland-AOD.

Fig. 1. Microwave radiometer RPG-HATPRO-G5 in the Geodetic-Geophysical Observatory Borowa Góra.

 

Fig. 2. Profiles of absolute humidity, temperature and liquid water path registered by the microwave radiometer RPG-HATPRO-G5 in the Institute of Geodesy and Geoinformatics at the Wrocław University of Environmental and Life Sciences.

 

Conference presentations – GNSS Meteorology Workshop 2019

We are pleased to announce that the presentations from the GNSS Meteorology Workshop 2019 are now available to download. The presentations have been split into two thematic sessions: Session 1 “Innovative GNSS processing” and Session 2 “RO missions and applications“. Also, the presentation from the invited talk given by Prof. Guergana Guerova from Sofia University, entitled “GNSS Meteorology: state-of-the-art and challenges” is available. All the links can be found below.

 

Invited talk on the GNSS meteorology

Guergana Guerova
Faculty of Physics, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
GNSS Meteorology: state-of-the-art and challenges

 

Session 1 Innovative GNSS processing

Andrea Gatti
Geomatics Research & Development s.r.l. (GReD), Lomazzo, Italy
goGPS for GNSS CORS stations data processing: an insight on its capabilities for meteorological studies

Tomasz Hadaś
Institute of Geodesy and Geoinformatics, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
Low-cost receivers for GNSS meteorology

Kamil Kaźmierski
Institute of Geodesy and Geoinformatics, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
A service for the validation of the real-time GNSS orbit and clock quality

Damian Tondaś
Institute of Geodesy and Geoinformatics, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
Near-Real Time estimation of Zenith Troposphere Delay

Estera Trzcina
Institute of Geodesy and Geoinformatics, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
Irregular parametrisation for GNSS tomography

Zohreh Adavi
Faculty of Geodesy and Geomatics Engineering, Khaje Nasir Toosi University of Technology, Tehran, Iran
Assessment of constraints and parameterization methods in GNSS Tropospheric Tomography

Natalia Hanna
Department of Geodesy and Geoinformation, TU Wien, Vienna, Austria
TOMOREF operator as a new tool in the wet refractivity fields assimilation

Martin Schneider
The Institute for Ubiquitous Meteorology (UBIMET), Vienna, Austria
UBIMET Forecasting System

 

Session 2 RO missions and applications

Tzvetan Simeonov
Meteorological Observatory Lindenberg, Deutscher Wetterdienst, Offenbach, Germany
Monitoring soil moisture and snow height using GNSS reflected signals

Hwa Chien
Graduate Institute of Hydrological and Oceanic Sciences, National Central University, Taoyuan City, Taiwan
Recent progress of Triton – the GNSS-R in Taiwan

Chian-Yi Liu
Center of Space and Remote Sensing Research, National Central University, Taoyuan City, Taiwan
Improving RO sounding by synergistic use of IR/MW radiances and its impact in NWP model

Lung-Chih Tsai
GPS Science and Application Research Center (GPSARC), National Central University, Taoyuan City, Taiwan
Ionospheric electron density tomography based on the GPS radio occultation and NNSS-like beacon data

Pierre-Yves Touringand
Department of Geosciences, University of Padova, Padova, Italy
Volcanic ash plume monitoring using GNSS radio occultation techniques

Martin Slavchev
Faculty of Physics, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
Raytracing of the Hail storm on 8 July 2014 in Sofia, Bulgaria

Elżbieta Lasota
Institute of Geodesy and Geoinformatics, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
A Comparison Between Raytraced GFS/WRF/ERA and GNSS Slant Path Delays in Tropical Cyclone Meranti

Rafał Marciniak
Institute of Geodesy and Geoinformatics, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
Comparison of tropospheric correction techniques for two-pass DInSAR application in local scale regions

 

 

ESA Awards

The 7th International Colloquium on Scientific and Fundamental Aspects of GNSS organized by the European Space Agency (ESA) wah held on September 4-6, 2019 at ETH Zürich in Switzerland. During the plenary session crowning the Colloquium, ESA awarded the best papers presenting groundbreaking research using satellite systems, with particular emphasis on the European Galileo system. As many as three awards went to current and former PhD students and employees from GNSS&Meteo WG:
• MSc. Grzegorz Bury  received an award for the best presentation in the field of Precise Orbit Determination for a paper on developing an analytical “Box-Wing” model of Galileo satellites enabling significant improvement of satellite positioning by elimination of perturbing forces: “Challenges in the modeling of perturbing forces acting on Galileo orbits”,
• Dr Karina Wilgan received an award in the field of Remote Sensing: Troposphere and Weather for a paper on troposphere research using unmanned aerial vehicles – drones recording satellite signals: “Quality assessment of tropospheric estimates from GNSS and meteorological observations on a UAV”,
• Dr Krzysztof Sośnica received an award in the field of Fundamental Physics for a paper on measurements of space-time curvature resulting from general relativity using Galileo satellites: “Measurements of the Galileo orbit geometry deformations caused by the general relativity”.
More information on the conference can be found on the Colloquium pages:
https://atpi.eventsair.com/QuickEventWebsitePortal/19a07—7th-gnss-colloquium/7th-international-colloquium
Congratulations!

GNSS Meteorology Workshop 2019

We kindly invite everyone who is interested in novel applications of GNSS in meteorology to take a part in the workshop “GNSS Meteorology Workshop 2019”.

The seminar will take place on 19-20 September, 2019, Faculty of Environmental Engineering and Geodesy, Lecture Room II M (Thursday) and II G (Friday), hours 9:30-17:15 on Thursday and 10:00-14:30 on Friday.

Please find here here more information about Workshop, including invited speakers, seminar programme and other details.

We are looking forward to meet you at the seminar venue.

The eighth edition of the CLGE Students’ Contest

The eighth edition of the CLGE Students’ Contest, organised by the Council of European Geodetic Surveyors (CLGE) in partnership with the European GNSS Agency (GSA), is now open for submissions. The deadline for applications is 23:00 on 29 July 2019.

For the eighth consecutive year, the CLGE Students’ Contest is inviting students of topography, GIS, geodesy, mapping and related studies to submit their innovative ideas. Each winner or winning team stands to win a prize of EUR 1000.

There are five categories in the competition:

• Geodesy, topography,

• Galileo, EGNOS, Copernicus,

• GIS, mapping,

• Cadastre and property surveying,

• Student and youngster engagement.

The first four are open to all Bachelor and Masters students in the surveying sector or a related field from all European countries. PhD students are not currently allowed to participate with their PhD thesis, but this may change in the future. However, they can participate with their Bachelor or Master’s thesis, if it meets other requirements. The fifth category is open to surveyors under the age of 35 or those who have been registered as surveyors for less than 10 years.

More information: https://www.gsa.europa.eu/newsroom/news/2019-clge-students%E2%80%99-contest-scouting-ideas