ITRF2014: A new release of the International Terrestrial Reference Frame modeling non-linear station motions
Zuheir Altamimi, Paul Rebischung, Laurent Métivier, Xavier Collilieux
For the first time in the International Terrestrial Reference Frame (ITRF) history, the ITRF2014 is generated with an enhanced modeling of non-linear station motions, including seasonal (annual and semi-annual) signals of station positions and post-seismic deformation for sites that were subject to major earthquakes. Using the full observation history of the four space geodetic techniques (VLBI, SLR, GNSS, DORIS), the corresponding international services provided reprocessed time series (weekly from SLR and DORIS, daily from GNSS and 24-hour session-wise from VLBI) of station positions and daily Earth Orientation Parameters (EOPs). ITRF2014 is demonstrated to be superior to past ITRF releases, as it precisely models the actual station trajectories leading to a more robust secular frame and site velocities. The ITRF2014 long-term origin coincides with the Earth system center of mass as sensed by SLR observations collected on the two LAGEOS satellites over the time-span between 1993.0 and 2015.0. The estimated accuracy of the ITRF2014 origin, as reflected by the level of agreement with the ITRF2008 (both origins are defined by SLR) is at the level of less than 3 mm at epoch 2010.0 and less than 0.2 mm/yr in time evolution. The ITRF2014 scale is defined by the arithmetic average of the implicit scales of SLR and VLBI solutions as obtained by the stacking of their respective time series. The resulting scale and scale rate differences between the two solutions are 1.37 (± 0.10) ppb at epoch 2010.0 and 0.02 (± 0.02) ppb/yr. While the post-seismic deformation models were estimated using GNSS/GPS data, the resulting parametric models at earthquake co-location sites were applied to the station position time series of the three other techniques, showing a very high level of consistency which enforces more the link between techniques within the ITRF2014 frame. The users should be aware that the post-seismic deformation models are part of the ITRF2014 products, unlike the annual and semi-annual signals, which were estimated internally with the only purpose of enhancing the velocity field estimation of the secular frame.
http://onlinelibrary.wiley.com/doi/10.1 ... 8/abstract