Ambrus Kenyeres

Noise and Periodic Terms in the EPN Time Series

The EUREF Permanent Network (EPN) has been installed in 1996 with some 30 stations and now includes more than 190 permanent GNSS sites (see Fig. 1). The network is operated according to the standards of the International GNSS Service (IGS) and it is considered as a regional densification of the ITRF (International Terrestrial Reference Frame). The EPN is primarily a geodetic reference network, but its results are also widely used for geophysical studies. In order to better serve the user needs, the EUREF Time Series Analysis special project monitors the weekly combined SINEX solutions, cleans the individual station coordinate series, and maintains and publishes the database of the detected coordinate offsets and outliers. Using this info, cleaned cumulative solutions are then computed with the CATREF software (Altamimi et al 2004). The estimated coordinates and velocities, together with the outlier and offset database are regularly updated and published on the EPN CB website (www.epncb.oma.be ).

Realization of the Hungarian geodynamic GPS reference network

Abstract The Pannonian Basin, which includes Hungary, tectonically belongs to the Eurasian Plate and is considered to be relatively quiet. Detailed geological studies revealed four main tectonic units in this area—the Tisza, Pelso, Austro-Alpine and Vepor units. All of these can be genetically related to tectonic processes in the Mediterranean and Alpine-Adria region. In 1989 the Satellite Geodetic Observatory (SGO) in cooperation with several institutions has initiated the establishment of a geodynamic global positioning system (GPS) Reference Network (HGRN) for three-dimensional deformation studies in Hungary. The HGRN consists of 13 primary sites which were selected according to geological and geophysical considerations and satisfied international standards for tectonic studies with the GPS technique. Particular care was devoted to the point marks concerning mechanical stability and the repeatability of antenna set-ups at the HGRN sites, therefore a point mark and a mechanical adapter to mount the GPS antenna had been developed at the SGO for this purpose. This point mark has been used at all HGRN sites. A GPS Datum Point was also established for Hungary in 1990 at the Satellite Geodetic Observatory; here quasi continuous observations are foreseen. The Penc station has been accepted as a fiducial station of the International GPS Geodynamic Service (IGS). The zero epoch measurements were completed in fall 1991 and monitoring is planned every second year at least for the next 10 years. Preliminary processing of the data has been carried out in the SGO, Penc and at the Lustbuhel Observatory at Graz, using the TRIMVEC PLUS and BERNESE V3.2 programs respectively

EUREF’s Contribution to National, European and Global Geodetic Infrastructures

The EUREF key infrastructures are the EUREF Permanent GNSS Network (EPN) and the Unified European Levelling Network (UELN). The EPN runs almost 250 Global Navigation Satellite System (GNSS) stations in a well organized environment and serves as the backbone of the realization of and access to the European Terrestrial Reference System (ETRS89) and as contribution to the densification of the International Terrestrial Reference Frame (ITRF2008). The upcoming European navigation system Galileo will be a big challenge for the EPN in sense of upgrading the station network.

The European Reference Frame: Maintenance and Products

EUREF, the IAG (International Association of Geodesy) Reference Frame Sub-commission for Europe, deals with the definition, realization and maintenance of the European Reference Frame. EUREF works in close cooperation with the pertinent IAG components and EuroGeographics, the consortium of the NMCA (National Mapping and Cadastre Agencies) in Europe.

A Regional ITRF Densification by Blending Permanent and Campaign Data - The CEGRN campaigns and the Central European Velocity Field

The CERGOP Project of the Central European Countries initiated six GPS observation campaigns from 1994 to 2001. By the high standards set within this project for site selection, observation and analysis a consistent set of epoch solutions with a precision in the 3–5 mm range was created. The network contains about 19 permanent and 38 epoch stations. In this paper a first combination solution over the seven years with a velocity field in the ITRF2000 is presented. It is based on the IGS and EUREF permanent sites and is analyzed in view of its consistency with ITRF2000 for common sites, with respect to time series for the individual stations and for the difficulties stemming from eccentricities required at some sites. Estimated velocities are at or below the 1 mm/yr accuracy level for the main sites and are consistent with the EUREF Permanent Network results. The final velocity field is to be published at the end of this year and will be used for the densification of the ITRF in Central Europe and for the analysis of geokinematics in that area.

A Dense Global Velocity Field Based on GNSS Observations: Preliminary Results

In a collaborative effort with the regional sub-commissions within IAG sub-commission 1.3 “Regional Reference Frames”, the IAG Working Group (WG) on “Regional Dense Velocity Fields” (see http://epncb.oma.be/IAG) has made a first attempt to create a dense global velocity field. GNSS-based velocity solutions for more than 6,000 continuous and episodic GNSS tracking stations, were proposed to the WG in reply to the first call for participation issued in November 2008. The combination of a part of these solutions was done in a two-step approach: first at the regional level, and secondly at the global level. Comparisons between different velocity solutions show an RMS agreement between 0.3 and 0.5 mm/year resp. for the horizontal and vertical velocities. In some cases, significant disagreements between the velocities of some of the networks are seen, but these are primarily caused by the inconsistent handling of discontinuity epochs and solution numbers. In the future, the WG will re-visit the procedures in order to develop a combination process that is efficient, automated, transparent, and not more complex than it needs to be.

Unified European Gravity Reference Network 2002 (UEGN02) — Status 2004

The last previous realisation of the Unified European Gravity Reference Network was completed in 1994 (UEGN94) covering 11 West European countries. Since that time significant work has been done e.g. in the frame of the UNIGRACE project that focused on the establishment of absolute gravity stations in Central and East European countries.

Implementation of the ETRS89 in Europe: Current Status and Challenges

The EUREF (Reference Frame Sub-Commission for Europe) Permanent GNSS Network (EPN) serves as the backbone for the realization of, and access to, the European Terrestrial Reference System (ETRS89). The cumulative site positions and velocities for the EPN stations are used for national ETRS89 densifications and geo-information applications. EUREF has developed specific guidelines through which European countries ask validation of their national ETRS89 densification campaigns. Today, the majority of the European countries has passed this process and a large part of European National Mapping and Cartographic Agencies have officially adopted ETRS89. In addition, ETRS89 plays a fundamental role in INSPIRE (Infrastructure for Spatial Information in the European Community).

Future and Development of the European Combined Geodetic Network ECGN

The European Combined Geodetic Network ECGN aims at the unification of time series of spatial/geometric observations obtained from GNSS, physical quantities from gravity field related observations, and other parameters including precise levelling, tide gauge records, and Earth and ocean tides. The objective of ECGN is to contribute to the maintenance of a stable terrestrial reference system for Europe, including 3D geometric parameters together with the gravity related height component. We discuss future, need and structure of the ECGN and a pilot project initiated for practical demonstration of the ECGN.

IAG WG SC1.3 on Regional Dense Velocity Fields: First Results and Steps Ahead

The Working Group on “Regional Dense Velocity Fields” (see http://epncb.oma.be/IAG) of the International Association of Geodesy (IAG) aims at densifying the International Terrestrial Reference Frame and creating a dense velocity field based on regional and global GNSS networks. With the goal to generate a high-quality solution for a core network, several newly reprocessed global and regional cumulative position and velocity solutions were submitted to the Working Group. In order to find a consensus on discontinuity epochs for stations common to several networks (an issue which was problematic in previous submissions), the new submissions were restricted to contain only the core networks over which the analyst has full control so that ITRF2008 discontinuities could be applied. The 3D-RMS of the agreement of the new solutions with the ITRF2008 (after outlier rejection) varies between 0.6 and 1.1mm/year; it is extremely good for some solutions, while others still require more iteration to reach the required level of agreement. A part of these disagreements has been identified and often originates in the use of different data time spans within the ITRF2008 and submitted solution.