Are there detectable common aperiodic displacements at ITRF co-location sites?

de La Serve, Maylis; Rebischung, Paul; Collilieux, Xavier; Altamimi, Zuheir; Métivier, Laurent

The time evolution of station positions has historically been described by piece-wise linear models in the International Terrestrial Reference Frame (ITRF). Although those models were extended with exponential and logarithmic functions in the ITRF2014 and with annual and semiannual sine waves in the ITRF2020, part of the Earth’s surface deformation is still not captured by such deterministic functions. Taking into account additional aperiodic ground deformation in the reference frame could in principle provide a better description of the shape of the Earth. This would, however, require the aperiodic displacements of the different space geodetic techniques to be tied into a common frame by means of co-motion constraints. The relevance of applying co-motion constraints to the measured aperiodic displacements raises questions because of the presence of technique-specific errors in the station position time series. In this article, we investigate whether common aperiodic displacements, other than post-seismic deformation, can be detected at ITRF co-location sites. We use for that purpose station position time series extracted from the solutions provided by the four technique services for ITRF2014 and carefully aligned to a common reference frame in order to minimize differential network effect. The time series are then cleaned from linear, post-seismic and periodic signals (including seasonal deformation and technique systematic errors). The residual time series are finally compared within ITRF co-location sites. Modest correlations are observed between Global Navigation Satellite Systems residual time series and the other space geodetic techniques, mostly in the vertical component, pointing to a domination of technique errors over common aperiodic displacements. The pertinence of applying co-motion constraints to measured aperiodic displacements is finally discussed in light of these results.

Journal of Geodesy, 2023, Vol 97, Issue 8, p1

0949-7714

Academic Journal

10.1007/s00190-023-01769-3