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The IAG (International Association of Geodesy) Sub-Commission for the European referenceframe (EUREF) passed a resolution recommending application of the ETRF2000 frame asnational realizations of the ETRS89 reference system during the XXth EUREF Symposium inGävle (Sweden) in 2010. The PL-ETRF2000 system is comprised of EPN (EUREFPermanent Network) sites. Their coordinates and their temporal changes (velocities) wereaccurately determined on the basis of long-term GNSS observations. The transfer of the PLETRF2000system onto the territory of Poland is realized by the ASG-EUPOS (ActiveGeodetic Network – European Position Determination System) permanent sites network. TheASG-EUPOS tasks include also system maintenance by continuous or periodical control ofthe coordinates and velocities constancy. According to the current Regulation of the Ministry of Administration and Digitizationconcerning geodesic, gravimetric and magnetic warps, the accuracy of sites of thefundamental warp (EPN sites belonging to ASG-EUPOS) may not be worse than 0.01 m forhorizontal position and 0.02 m for geodesic height. It results in the necessity to monitor theperformance of the reference sites for proper maintenance of the reference system. A new team for modeling deformations in Europe was established within the EUREFWorking Group (The EUREF Working Group on Deformation Models) during the EUREF2012 Symposium in Paris. One of its tasks is taking geo-kinematic models into considerationfor national realizations of the ETRS89 and maximum usage of knowledge concerning thevelocity field. The paper deals with the problem of temporal validity of the catalogue coordinates andthe necessity of periodical updating them on the basis of velocities derived from long-termobservations. Although Poland is located in a tectonically calm area and the intraplatevelocities are small, some of the EPN and ASG-EUPOS sites have significant velocities andare subject to vertical movements. Lack of periodical updating of the coordinates realizing thereference system will cause lack of fulfillment of the assumed accuracy criterion. Analysis of horizontal and vertical velocities of sites belonging to the fundamentalwarp lead to assumption that two sites will exceed horizontal criterion in a period of timeshorter than 10 years counting from the reference epoch (i.e. from 2011.0): KATO horizontalcoordinates should be updated in 2014 and GWWL in 2021. Mores sites will exceed vertical criterion: BOGI (2021), GWWL (2015), KATO (2019), SWKI (2019) and ZYWI (2021). Thevertical component updating will require of course changes of the horizontal component(coordinates are determined in the Cartesian orthogonal XYZ coordinate system and thenrecalculated for the ellipsoidal coordinates). Besides periodical coordinates updating it isrecommended to conduct repeated processing for the entire network according to the EUREFstandards for taking the current GNSS observations into consideration.

The problem of temporal validity of reference coordinates in the context of reliability of the ETRS89 system realization in Poland