Analysis of the Coordinate Differences caused by Different Methods to align the Combined EUREF Solution to the ITRf

摘要

The station coordinates in the weekly combined EUREF SINEX solution are the main product of the EUREF Permanent Network (EPN). However, these weekly solutions are not consistent in time because the underlying reference frame has changed several times throughout the years. When re-aligning each of the EUREF SINEX solutions to the ITRF2000 using the minimum constraint approach, the vertical component of the station coordinates changes at the cm-level. This coordinate change finds its origin in a bug in a subroutine correcting the Earth tides in the Bernese GPS software. This bug affected the vertical component of the weekly EUREF solution with an annual periodicity reaching peak-to-peak 2.8 cm for a typical EPN station like Brussels. While this annual period is clearly seen in the coordinates of the combined EUREF solution, it fades in the minimally constrained solution because it is absorbed by the underlying Helmert transformation.