Contribution of DGFI to ITRF2014
Abstract:A new realization of the International Terrestrial Reference System (ITRS) is in preparation and will be finished in 2015. The ITRS realization is based on the combination of the observation data of the four geodetic space techniques VLBI, SLR, GNSS and DORIS, which include all observations from the individual beginning of the techniques until end of 2014. The final solution is planned to be finished in October 2015. As the previous solution, ITRF2008, the new realization ITRF2014 will contain station positions and velocities as well as consistently estimated Earth Orientation Parameters (EOP). Additionally, for the first time sine-cosine fits of the station positions annual signals will be provided. The ITRF2014 will be more accurate and stable than ITRF2008 as six more years of observation data of the four space geodetic techniques, new observing stations and improved models are available and in ITRF2014 for the first time non-linear station motions will be considered.
Three ITRS Combination Centres of the IERS (DGFI, IGN and JPL) are each in charge with the computation of this new realization. While the combination strategies of IGN and JPL are based on the combination of parameters, DGFI’s strategy uses the combination of normal equation systems. A further difference between the ITRS realization strategies is that DGFI considers non-linear station motions by applying non-tidal loading signals of atmosphere, hydrology and ocean, while the other CC set up sine-cosine functions to do this. This paper presents the DGFI realization DTRF2014. It demonstrates shortly the combination strategy and its characteristics. It discusses the results of the analysis of the datum parameters, station coordinates and EOP. Finally, it presents the DTRF2014 solution as well as the validation results.