ITRS Combination Centre at DGFI-TUM
DGFI-TUM has been acting as one of the ITRS Combination Centres within the International Earth Rotation and Reference Systems Service (IERS) since 2001. The related activities are embedded into DGFI-TUM's research on the realization of Global Terrestrial Reference Frames within the research area Reference Systems.
Realizations of the ITRS are based on the combination of space geodetic observations of the four techniques VLBI, SLR, GNSS, and DORIS at globally distributed geodetic observatories. Respective input data is provided by the corresponding technique services (IVS, ILRS, IGS, IDS).
DGFI-TUM's latest realization of the ITRS is the DTRF2014. It comprises coordinates and linear velocities of 1712 stations. Additionally, for the first time, non-tidal atmospheric and hydrological loading is considered in the solution. DTRF2014 data is available for download here.
The computation of the DTRF2014 was completed in August 2016. The DTRF2014 is an independent realization of the ITRS. It is based on the same input data as the realizations ITRF2014 (computed by the IITS Combination Centre at IGN, Paris) and JTRF (computed by the ITRS Combination Centre at JPL, Pasadena), but the three realizations DTRF2014, ITRF2014 and JTRF2014 result from different combination strategies: While the ITRF2014 is based on the combination of solutions, the DTRF2014 is computed by the combination of normal equations. JTRF2014 is based on time series of station positions instead of station positions and velocities as provided in DTRF2014 and ITRF2014.
The reference epoch for station positions is 2005-01-01, 0:00 UTC. The Earth Orientation Parameters (EOP), i.e., coordinates of the terrestrial and the celestial pole, UT1-UTC and the Length of Day (LOD), were simultaneously estimated with the station coordinates. The EOP time series cover the period from 1979.7 to 2015.0.