Global Terrestrial Reference Frames (TRF) are fundamental for monitoring the Earth's rotation in space, and to many Earth science applications that need absolute positioning and precise orbit determination of near-Earth satellites. Accurate and stable TRFs are especially needed for the quantification of global change phenomena such as sea level rise, current ice melting, tectonic, and seismic deformations. This session generally welcomes contributions on the computation, the evaluation and the use of TRFs.

The computation of TRFs relies on space geodetic observations acquired by ground networks of stations. Nowadays, measurement biases and imperfect background models in space geodetic data analysis are the main factors limiting the accuracy of TRFs. This session therefore welcomes contributions that develop strategies to overcome systematics in space geodetic observing systems such as range biases in SLR observations, gravitational deformation of VLBI antennas, GNSS antenna phase patterns, etc. The understanding of the discrepancies between the terrestrial scale observed by the different space geodetic techniques, and the improvement of geocentre motion determination are of particular interest.

Another key ingredient to the construction of TRFs are geometric ties between instruments of the different space geodetic techniques, be they co-located on ground (“local ties”) or onboard satellite missions (“space ties”). Contributions are therefore strongly encouraged on the determination of new local ties at co-location sites, on new methods for local tie determination, as well as on the handling and impact of space ties in TRF determination, with the perspective of exploiting ESA’s dedicated GENESIS mission. Papers that explore new TRF construction strategies, e.g., combination of the different techniques at the observation level, or any type of development that could improve future TRF solutions, are also highly welcome.

Besides reviewing improvements in TRF determination, another objective of this session is to bring together contributions from individual technique services, space geodetic data analysts, ITRS combination centers and TRF users to discuss the TRF solutions produced by different groups, with a special focus on their comparison and evaluation. Papers on the exploitation of different TRF solutions for various geodetic and geophysical applications are therefore also solicited.