Towards an Integrated Global Reference System: Geodesy as a Utility
The global reference system provides a framework that allows users to determine geocentric coordinates with a precision of 1 cm or better. The overall accuracy of the system is probably ~5 mm in long-term position and about 1 to 2 mm/yr in rates. This is similar to the 1-day precision of the best measurement systems, an indication that systematic errors dominate over random observational noise in the long term. Nonetheless, the current system satisfies the requirements of all but the most demanding users and it continues to improve. This achievement, combined with the relatively easy and cost-effective access provided by GPS, is transforming the global reference system from a research tool into a geodetic utility. The trend is likely to continue and perhaps accelerate. The IAG is uniquely suited to promote and guide this development in such a way as to ensure the highest standards of user service are met while protecting the interests of scientific researchers. However, doing so will require new organizational structures to link the observing techniques and to provide improved user interfaces and services.
KeywordsVery Long Baseline Interferometry Synthetic Aperture Radar Satellite Laser Range Earth Orientation Parameter Terrestrial Reference Frame
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