DGFI-TUM Analysis and Scale Investigations of the Latest Terrestrial Reference Frame Realizations

Abstract

Solutions for the most recent realization of the International Terrestrial Reference System (ITRS) were computed by the three ITRS Combination Centers (CCs) of the International Earth Rotation and Reference Systems Service (IERS), namely the IGN in Paris (France), the JPL in Pasadena (USA), and the DGFI-TUM in Munich (Germany). Thereby, the solutions of IGN and DGFI-TUM comprise conventional parameters of the ITRS (station coordinates and velocities) at a reference epoch as defined in the IERS Conventions 2010. Although the two solutions are based on identical input data, there exist systematic differences between them. Within all ITRS realizations, the scale is realized as a mean scale between SLR (satellite laser ranging) and VLBI (very long baseline interferometry). If the combined scale is compared to the scale realized by both techniques itself, the IGN solution reveals significant differences between SLR and VLBI whereas the DGFI-TUM solution shows much smaller differences. When the combined solutions of IGN and DGFI-TUM as well as the single-technique solutions of both institutions are investigated and compared, a significant scale difference between SLR and VLBI is only visible in the IGN analysis but not in the results of the two other ITRS CCs. It is also found that the scale analysis via Helmert parameter is very difficult since the results are quite sensitive w.r.t. particular station networks. In addition, scale comparisons of the IVS and ILRS CCs also do not confirm a systematic scale offset.