Regional tidal modeling on the European coast using tide gauges and satellite altimetry

The study investigates sea-level measurements along the coastal area of Europe for the 60-year (1961–2020) time span. Linear and quadratic modeling of tide gauge measurements showed an almost positive rate of trend of sea-level rise (0.09 to 3.6 mm/yr) and low acceleration (−0.05 to 0.40 mm/yr2). A least-squares harmonic estimation tidal modeling was carried out to estimate frequency (cycles per day) for a certain period. The smaller and higher tidal frequencies of these stations indicate their stability in terms of their surface variation. We used the 1993–2020 satellite altimetry data from the nearest grid points of the tide gauge station. The correlation coefficient between observed and satellite altimetry (lowest 0.53 and highest 0.93) varies at each station. This happens because of many factors that can affect the large difference in the sea-level trend between the satellite-derived and tide gauge results. Finally, to implement a global reference system for physical heights, the offshore topographic slope direction and slope range with contour spacing from the sea to the associated coastline were analyzed using bathymetry data. The abrupt change in slope from the coastline toward the sea can be seen toward the east, west, and southeast on the European coast. This is also an important factor that affects the variation of sea level

EDM-GNSS distance comparison at the EURO5000 calibration baseline: preliminary results

[EN] At the Pieniny Klippen Belt in Poland, the novel primary reference baseline EURO5000 is required as part of the European Research project GeoMetre to both validate refractivity-compensated EDM prototypes and investigate the metrological traceability of GNSS-based distances. Since the aimed uncertainty is 1 mm at 5 km (k = 2), the design, construction, and validation must be carefully prepared to fulfil the high standards of the GeoMetre field campaigns which are planned to be carried out in May 2022. This contribution describes the main features of the EURO5000 and presents the results of the preliminary validation which includes a first comparison between the results obtained by using precise currently available EDMs as well as GNSS techniques following the standard GNSS geodetic processing algorithms, on the one hand, and the improved GNSS-Based Distance Meter (GBDM+) approach developed at UPV, on the other hand. The preliminary validation presented in this contribution also permits (1) to detect potential problems in the use of the baseline such as potential geodynamic problems, atmospheric refraction or multipath limitations, (2) to produce a set of reliable results, and (3) to pave the way for the final field comparisons between the novel EDMs and the GBDM+ approach. The result of this metrological experiment may significantly contribute to overcome the limitations of current high-precision deformation monitoring applications that require their scale to be consistent with the SI-metre within 0.1 ppm in several km.The project 18SIB01 GeoMetre hasreceived funding from the EMPIR programme co-financedby the Participating States and from the European Union's Horizon 2020 research and innovation programme, funderID: 10.13039/100014132. Raquel Lujan acknowledges the funding from the Programa de Ayudas de Investigaciony Desarrollo (PAID-01-20) de la Universitat Politecnica deValencia.Wezka, K.; García-Asenjo Villamayor, L.; Próchniewicz, D.; Baselga Moreno, S.; Szpunar, R.; Garrigues Talens, P.; Walo, J.... (2023). EDM-GNSS distance comparison at the EURO5000 calibration baseline: preliminary results. Journal of Applied Geodesy. 17(2):101-108. https://doi.org/10.1515/jag-2022-004910110817

Performance comparison of ionospheric models used for GNSS positioning

An evaluation of applicability of ionospheric corrections derived from the two global total electron content (TEC) maps, Neustrelitz DLR/GIM and Center for Orbit Determination in Europe CODE/GIM, for mitigation of ionospheric threads in precise GNSS positioning, has been done. Investigations on the both models have been performed in the following empirical approach. Investigation in the domain of coordinates: Processing of selected static GPS data in relative pseudo-kinematic mode, taking ionospheric corrections from the two selected models, to solve for position at every observational epoch. Comparison of the obtained results (time series of coordinates) with precise reference coordinates of the station calculated over a long time period. Investigation in the domain of TEC corrections: Preparation of two time series of interpolated TEC values for the all observation epochs using the CODE- and DLR maps, and calculation of TEC time series from the recorded GPS observations. Comparison and analysis of the all three sets of TEC values. Calculation of the Rate of TEC (ROT) and of scintillation index S4 as indicators of ionospheric irregularities. Analysis of the time series of TEC, ROT, S4 and the pseudo-kinematic station coordinates to detect and identify origin of anomalous signals. Experimental GPS data from the continuously operated station at Kiruna (Sweden) located at the polar region, and Wettzell (Germany)located at mid latitude, have been processed. The paper presents first results of investigations on GPS data recorded during a quiet period and under the presence of ionospheric irregularities. Further investigations are in progress

Assessing the High-Accuracy Service at High Latitudes

The Galileo High-Accuracy Service (HAS) was declared operational (initial service) in January 2023 after an intense testing phase aimed at assessing its service performance through the transmission of live HAS corrections. The HAS performance at high latitudes is evaluated by analyzing data collected at the Polish Polar Station located in Hornsund, in the Norwegian Svalbard archipelago. At such a location, the reception conditions can be affected by poor satellite geometries and ionospheric scintillation may degrade the signal quality. In this respect, data affected by scintillation events were identified and used for the performance analysis. The assessment is carried out by comparing the HAS corrections with the International GNSS Service (IGS) precise products. Moreover, the retrieved HAS corrections are used to assess the Precise Point Positioning (PPP) performance

EDM-GNSS distance comparison at the EURO5000 calibration baseline: preliminary results

[EN] At the Pieniny Kippen Belt in Poland, the novel primary reference baseline EURO5000 is required as part of the European Research project GeoMetre to both validate refractivity-compensated EDM prototypes and investigate the metrological traceability of GNSS-based distances. Since the aimed uncertainty is 1 mm at 5 km (k=2), the design, construction, and validation must be carefully prepared to fulfil the high standards of the GeoMetre field campaigns which are planned to be carried out in May 2022. This contribution describes the main features of the EURO5000 and presents the results of the preliminary validation which includes a first comparison between the results obtained by using precise currently available EDMs as well as GNSS techniques following the standard GNSS geodetic processing algorithms, on the one hand, and the improved GNSS-Based Distance Meter (GBDM+) approach developed at UPV, on the other hand. The preliminary validation presented in this contribution also permits (1) to detect potential problems in the use of the baseline such as potential geodynamic problems, atmospheric refraction or multipath limitations, (2) to produce a set of reliable results, and (3) to pave the way for the final field comparisons between the novel EDMs and the GBDM+ approach. The result of this metrological experiment may significantly contribute to overcome the limitations of current high-precision deformation monitoring applications that require their scale to be consistent with the SI-metre within 0.1 ppm in several km.The project 18SIB01 GeoMetre has received funding from the EMPIR programme co-financed by the Participating States and from the European Union’s Horizon 2020 research and innovation programme, funder ID: 10.13039/100014132. Raquel Luján acknowledges the funding from the Programa de Ayudas de Investigación y Desarrollo (PAID-01-20) de la Universitat Politècnica de València.Wezka, K.; García-Asenjo, L.; Próchniewicz, D.; Baselga, S.; Szpunar, R.; Garrigues, P.; Walo, J.... (2023). EDM-GNSS distance comparison at the EURO5000 calibration baseline: preliminary results. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/19211

Large-Scale Dimensional Metrology for Geodesy : First Results from the European GeoMetre Project

In a joint effort, experts from measurement science and space-geodesy develop instrumentation and methods to further strengthen traceability to the SI definition of the metre for geodetic reference frames (GRF). GRFs are based on space-geodetic observations. Local-tie surveys at co-location sites play an important role for their computation. Novel tools are hence developed for reference point monitoring, but also for local tie vector determination and ground truth provision. This contribution reports on the instrumental approaches and achievements after 24 months project duration and discusses the remaining work in the project

The European GeoMetre project : developing enhanced large-scale dimensional metrology for geodesy

We provide a survey on the joint European research project “GeoMetre”, which explores novel technologies and their inclusion to existing surveying strategies to improve the traceability of geodetic reference frames to the SI definition of the metre. This work includes the development of novel distance meters with a range of up to 5 km, the realisation of optical multilateration systems for large structure monitoring at an operation distance of 50 m and beyond, and a novel strategy for GNSS-based distance determination. Different methods for refractivity compensation, based on classical sensors, on dispersion, on spectroscopic thermometry, and on the speed of sound to reduce the meteorological uncertainties in precise distance measurements, are developed further and characterised. These systems are validated at and applied to the novel European standard baseline EURO5000 at the Pieniny Kippen Belt, Poland, which was completely refurbished and intensely studied in this project. We use our novel instruments for a reduced uncertainty of the scale in the surveillance networks solutions for local tie measurements at space-geodetic co-location stations. We also investigate novel approaches like close-range photogrammetry to reference point determination of space-geodetic telescopes. Finally, we also investigate the inclusion of the local gravity field to consider the deviations of the vertical in the data analysis and to reduce the uncertainty of coordinate transformations in this complex problem