Reference Frame Working Group Progress on recommendations made at the 2016 IGS workshop in Sydney, Australia Presented to the IGS Governing Board and Associate Members on 11 December 2016

The group recommends: Prepare, implement, test and adopt the IGS14/igs14.atx framework Revisit the consistency of repro2 station position time series with loading models Paul Rebischung Reference Frame Splinter Session Summary Recommendations Splinter session discussions were mostly focused on the new ITRF2014 realization and on the post-seismic deformation models coming along with it. The procedure for the preparation and implementation of its IGS realization have been defined. IGS14 is planned to be adopted in the second half of 2016, together with the updated ANTEX file igs14.atx.

Progress since Sydney: IGS14/igs14.atx Preliminary IGS14/igs14.atx made available to ACs in July Some parallel IGS14-based AC solutions received since September Test SINEX combinations performed; no unexpected results Impact of the switch to IGS14/igs14.atx studied by re-combining the AC repro2 SINEX solutions in the new framework Poster G41A-0998, Thursday, 15 Dec, 10:20–12:20 Waiting for IERS DB and IGS GB / ACs approval to: Set the date of the official switch (GPS week 1934 – 29 Jan 2017?) Announce the switch via IGS-MAIL (this week?)

Progress since Sydney: repro2 vs. loading Li et al., EGU 2016: “A comparison of three environmental load combinations with repro2 residuals” Similar results as obtained by Ray et al. (2011) using repro1 series Loading corrections reduce WRMS and annual amplitude for most stations, but most variability remains (esp. in horizontal) No significant improvement in loading models, nor in IGS position time series Median WRMS reduction Median annual amp. reduction East North Up Ray et al. (2011) 1.6 % 3.8 % 15.2 % 8 % 22 % 48 % Li et al. (2016) 2.8 % 5.0 % 11.5 % 13% 14% 44%

Future Work IGS14: Long-term objective: Official adoption Prepare new IGS cumulative solution based on repro2 solutions and improved discontinuity list Long-term objective: Study, understand and mitigate errors in IGS station position time series

Contact: Paul Rebischung - paul.rebischung@ign.fr Thank You Contact: Paul Rebischung - paul.rebischung@ign.fr