The EUREF reference frame solution is the most accurate and up-to-date (updated each 15 weeks) positions and velocities of the EPN GNSS stations.

The EUREF reference frame solution is designed for maintaining the ETRS89 and it provides the positions and velocities of the EPN reference stations to be used to tie of a GNSS network into the ETRS89 or ITRS. The Tool for Reference Station Selection based on the station classification of the EPN stations is available to help the users select the most suitable EPN reference stations for their specific project.

Since the release C1950, the EUREF reference frame solution is maintained by the EPN Reference Frame Coordinator (Juliette Legrand, Royal Observatory of Belgium).

The EUREF reference frame solutions is a multi-year position and velocity solution computed with the CATREF software (Altamimi et al., 2007). The positions and velocities are aligned to the IGb14 reference solution under minimal constraints using 14 transformations parameters (translations, rotations, scale and their rates) on a selection of IGb14 reference stations.

Discontinuities
During the stacking, position and velocity discontinuities (discontinuity file) are introduced to account for sudden position change or velocity change in the position time series. A new station position and velocity is estimated after each discontinuity and the velocities are usually constrained to be equal before and after a discontinuity.
Post seismic deformations
In addition, this solution incorporates the ITRF2014 post-seismic deformation models for 5 stations: ANKR00TUR, BUCU00ROU, ISTA00TUR, REYK00ISL, TUBI00TUR.
Collocated stations
Also, except in cases of significant disagreements, the velocities of collocated sites are constrained to be the same.
Input Files
The EPN multi-year solution, is computed using the EPN daily combined SINEX files:
  • from 001/1996 (GPS week 834) up to 363/2013 (GPS week 1772), the daily SINEX are resulting from the EPN-repro2,
  • after GPS week 1772, the routine daily EPN combined SINEX files are used.

In January 2017 (GPS week 1934), the IGS (International GNSS Service) released the IGS14 together with the isg_14.atx. The epn_14.atx calibration file, used within the EPN since GPS week 1934, consists of the individual antenna calibrations of the EPN stations plus the igs_14.atx.

The EPN positions estimated prior to 028/2017 (GPS week 1934) were computed using epn_08.atx (indiv. calib. + igs_08.atx). In order to ensure the consistency of the daily EPN solutions before GPS Week 1934 with the IGS14/epn_14.atx, their positions were corrected for the position changes caused by the switch from epn_08.atx to epn_14.atx. To maximize the consistency with IGS, when available, the position offsets computed by the IGS for IGS station/antenna pairs were used. If not available, the latitude-dependent models (IGSMAIL-7399) of the expected position offsets were applied.

The most recent EUREF reference frame solution is available from: https://epncb.oma.be/ftp/product/referenceframe/latest/.
See below for the naming of the products.

Previous reference frame solutions have been archived at: https://epncb.oma.be/ftp/product/referenceframe/.

The EUREF reference frame product consists in:

Positions & Velocities of EPN stations with more than 3 years

The positions and velocities of the EPN stations with more than 3 years of observations and without modelled post-seismic deformations are provided in the SNX and SSC format and are expressed in 3 different reference frames IGb14, ETRF2000, ETRF2014.

SINEX Format SSC Format
ITRS (IGb14 realization) EPN_IGb14.SNX.Z ➔ EPN_IGb14_C2190.SNX.Z EPN_IGb14.SSC ➔ EPN_IGb14_C2190.SSC
ETRS89 (ETRF2000 realization) EPN_ETRF2000.SNX.Z ➔ EPN_ETRF2000_C2190.SNX.Z EPN_ETRF2000.SSC ➔ EPN_ETRF2000_C2190.SSC
ETRS89 (ETRF2014 realization) EPN_ETRF2014.SNX.Z ➔ EPN_ETRF2014_C2190.SNX.Z EPN_ETRF2014.SSC ➔ EPN_ETRF2014_C2190.SSC

They are also available through ETRS89/ITRS Positions & Velocities web pages (e.g. for ACOR00ESP station).

Under test: For Bernese users, a CRD (EPN_IGb14_C2190_R.CRD) and a VEL (EPN_IGb14_C2190_R.VEL) file are available for all the stations observed within the last 270 days. For each station, the position and the velocity of the last available solution number is given.

Positions of other EPN stations

The positions of the stations with less than 3 years of observations and of the 5 stations with modeled post-seismic deformations (ANKR00TUR, BUCU00ROU, ISTA00TUR, REYK00ISL, TUBI00TUR) are only provided in the SSC format and expressed in 3 different reference frames: IGb14, ETRF2000, ETRF2014.

SSC Format
ITRS (IGb14 realization) EPN_IGb14_short.SSC ➔ EPN_IGb14_C2190_short.SSC
ETRS89 (ETRF2000 realization) EPN_ETRF2000_short.SSC ➔ EPN_ETRF2000_C2190_short.SSC
ETRS89 (ETRF2014 realization) EPN_ETRF2014_short.SSC ➔ EPN_ETRF2014_C2190_short.SSC

The station positions and velocities are also available through web pages (e.g. for BAUT00DEU station).

Position Time Series of EPN Stations
Extended Position Time Series of EPN Stations

Each day, the EPN CB extends the multi-year EPN time series with recent EPN solutions to enable a quick monitoring of the EPN station positions. In practice, currently, the multi-year EPN solution from GPS week 834 till 2190 has been extended in time using the operational daily combined EPN solutions from GPS week 2191 till 2208 and the rapid daily combined solutions from GPS week 2209 till 2216.

Dynamic plots of the extended position (in IGb14 and ETRF2014) and residual position time series in IGb14 and ETRF2014 are available online.

EPN discontinuities
EPN_discontinuities.snx contains a catalogue of all discontinuities observed in the EPN multi-year solution. It defines the solution numbers (soln) used in the solution. The list has been as much as possible harmonized to agree with the IGS/ITRF discontinuity table. Unfortunately, some stations still disagree due to different period of observations.
Outliers
EPN_outliers.lst contains the list of positions removed from EPN daily combined SINEXs before the multi-year combination.
Station classification and tool for selecting the reference stations
Station classification and tool for selecting the reference stations
Miscellanous plots

Please cite the EPN Multi-year Position and Velocity Solutions as:
Legrand J. (2022): EPN multi-year position and velocity solution CWWWW, Available from Royal Observatory of Belgium, https://doi.org/10.24414/ROB-EUREF-CWWWW.

A DOI is also available for each solution since solution C2085. Please cite the current multi-year solution as:
Legrand J. (2022): EPN multi-year position and velocity solution C2190, Available from Royal Observatory of Belgium, https://doi.org/10.24414/ROB-EUREF-C2190.