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IC-SG1.1 : Theory, implementation and quality assessment of geodetic reference frames


Chair: Athanasios Dermanis (Greece) [Joint with ICCT, IERS]


Terms of Reference


The realization of a reference system by means of a reference frame, in the form of coordinate time series or coordinate functions for a global set of control stations is a complicated procedure. It involves input data from various space techniques each one based on its own advanced modelling and observation analysis techniques, as well as, criteria for the optimal selection of the time evolution of the reference frame among all data compatible possibilities. The relevant “observed” coordinate time series demonstrate significant signals of periodic, non- periodic variations and discontinuities, which pose the challenge of departing from the current ITRF model of linear time evolution, realized by reference epoch coordinates and constant velocities. The final product needs proper quality measures, which take also into account the possible modelling discrepancies, systematic errors and noise level of each particular space technique. The connection with a celestial frame by means of earth orientation parameters (EOPs) and current geophysical plate motion hypotheses necessitate the study of the compatibility of the geodetically established reference system with reference systems introduced in theoretical studies of the earth rotation and in theoretical geophysics. The working group is primarily aiming in problem identification, outlining of possible solution directions and motivation of relevant scientific research.


Objectives

  • Study of models for time-continuous definitions of reference systems for discrete networks with a non-permanent set of points and their realization through discrete time series of station coordinate functions and related earth rotation parameters.
  • Understanding the relation between such systems and reference systems implicitly introduced in theories of earth rotation and deformation.
  • Extension of ITRF establishment procedures beyond the current linear (constant velocity) model, treatment of periodic and discontinuous station coordinate time series, understanding of their geophysical origins and related models.
  • Understanding the models used for data treatment within each particular technique, identification of possible biases and systematic effects and study of their influence on the combined ITRF solution. Study and improvement of current procedures for the merging of data from various space techniques.
  • Statistical aspects of reference frames, introduction and assessment of appropriate quality measures.

Program of activities


  • Launching of a web-page for dissemination of information, presentation, communication, outreach purposes, and providing a bibliography.
  • Working meetings at international symposia and presentation of research results in appropriate sessions.
  • Organization of workshops dedicated mainly to problem identification and motivation of relevant scientific research.
  • A special issue of the Journal of Geodesy on reference frames with papers from working group workshops and invited review papers.

Membership (provisional)


  • Athanasios Dermanis, Chair (Greece)
  • Zuheir Altamimi (France)
  • Claude Boucher (France)
  • Hermann Drewes (Germany)
  • Fernando Sansò (Italy)
  • Gerard Petit (France)
  • Xavier Collilieux (France)
  • Axel Nothnagel (Germany)
  • Erricos Pavlis (USA)
  • Jim Ray (USA)
  • Frank Lemoine (USA)
  • Geoff Blewitt (USA)

IC-SG1.1 : Theory, implementation and quality assessment of geodetic reference frames


Chair: Athanasios Dermanis (Greece) [Joint with ICCT, IERS]


Web site of the Inter-Commission : http://der.topo.auth.gr/sgrf

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