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Information - G1 Reference system stability, accuracy, and the presence of secular or seasonal signals (co-listed in CR & HS)
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Event Information |
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As geodetic applications in the Earth sciences advance in their capabilities and accuracy goals, the demands placed on the International Terrestrial Reference Frame (ITRF) increase also since this is the fundamental platform from which most large-scale measurements are made. The basic ITRF requirements concern: accuracy in terms of origin and scale; precision in terms of relative internal consistency of station positions and velocities; long-term stability of origin, scale, and orientation; universal and easy user access.
ITRF is formed by a combination of different space geodetic techniques. Since no one technique possesses all the needed strengths, a major challenge is to detect and mitigate systematic errors from the individual techniques optimally. Stability is particularly important for such problems as reliable detection of e.g. sea-level change, which requires scale rate uncertainties <0.1 ppb/yr. It is difficult to objectively assess whether this level is actually being attained or not because there is minimal internal redundancy, especially for origin and scale.
The presence of non-linear (non-tidal) variations in station motions complicates ITRF maintenance. On the one hand, these can provide valuable geophysical insights, for example into large-scale fluid mass movements or aspects of global change or post-seismic deformation. Full geophysical utilization requires separating complicating effects such as highly localized motions like subsidence, or effects caused by long wavelength GPS orbit errors, propagation correction errors, antenna model limitations, multipath and other environmental effects etc.
This session will focus on updating user requirements for the ITRF and examining its current capabilities and limitations. Any inputs that might aid in improving the next ITRF realization and studies of the ITRF accuracy or stability using independent methods are welcome.
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Preliminary List of Solicited Speakers |
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