To assign more realistic uncertainties on the GPS velocities, the noise content in the position time series was examined by the maximum likelihood estimation (MLE) technique using CATS software (Williams, 2008). Time series were detrended at the CATREF stage. Details on the GPS velocity uncertainty assessment are given in the reference below.

- Vertical velocities table

The ULR6a_Vertical-Velocities_Table provides the vertical GPS velocities and uncertainties for the 497 stations fulfilling the criteria of 3 years of minimum length without discontinuities and with data gaps not exceeding 30%.

- Daily residual time series

The file contains individual station data files of daily residual position time series in ITRF2008 with respect to the linear long-term combined solution at the reference epoch. These residuals (detrended) are expressed in meters in the local frame (North, East, and Up). The reference position and the 3D velocity in the local coordinate system (East, North, Up) are provided in the header of each file.

- Position discontinuities

The ULR6a_discontinuities_Table.txt file provides the position offsets that were estimated.

- Solution file

The long-term solution ULR6a in SINEX format (567 Mo) can be downloaded too. However, we recommend its use only to those familiar with SINEX files, and having a good geodetic background and experience.