SC 1.2 - Global Reference Frames

WG 1.2.2 - Global Geodetic Observatories

Chair:  Perguido Sarti (Italy)

An effective integration of space geodetic instruments at the observing sites is a crucial issue for the computation of the terrestrial reference frame. In fact, the computation of the global terrestrial frame depends, on the one hand, on the number, distribution and quality of the co-located sites and, on the other hand, on the accuracy of the tie vectors that express the relative position of the co-located instruments.

The ITRF is a geodetic product that serves Earth and space sciences. Although, its significance and exploitation goes beyond scientific research: societal application, natural hazards mitigation and Earth observations go beyond purely scientific uses and have an impact on the whole society.

Geophysical research requires a wider concept of integration where co-locations are realized not only with space and terrestrial geodetic instruments but also with other geophysical sensors like seismometers, weather stations, lidars, radio-sondes, gravimeters, tide gauges, radiometers, etc…

In this perspective, the integration of geodetic and geophysical sensors must be realized at the highest level of accuracy providing the relative positions into a consistent frame at local and global scales.

The task force will examine and revise the state of the art in local tie surveying and tie vector estimation, spotlighting the current deficiencies and promoting cooperation on the relevant research topics. The definition of reference points for each instrument as well as the related calibration issues will also be considered, in close cooperation with individual technique services (IGS, IVS, ILRS, IDS, PSMSL, IGFS...). The most recent and highest standards achieved in the integration of geodetic instruments will be transposed to the problem of co-locating, operating and managing a wider class of geophysical instruments with the purpose of defining the guidelines for their effective co-location and integration towards the creation of multipurpose geophysical observatories.

Other types of considerations will be also investigated, such as operational issues, international governance, labelization, standardization and certification.


  • Revise the needs related to the co-location of geophysical sensors.
  • Revise existing tie vector estimation processes methods and accuracies.
  • Transpose the state of the art of tie vector estimation to non-geodetic instruments.
  • Liaise with IERS, IAG and GGOS.
  • Set guidelines on geophysical co-location surveying and management.
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