HR: 10:40h
AN: G32A-02 INVITED     [Abstracts]
TI: The Effect of Discontinuities, Noise and Geophysical Signals on the Maintenance of a Terrestrial Reference Frame.
AU: * Williams, S D
EM: sdwil@pol.ac.uk
AF: Proudman Oceanographic Laboratory, Joseph Proudman Building 6 Brownlow Street, Liverpool, L3 5DA United Kingdom
AU: Lavallée, D A
EM: d.a.lavallee@ncl.ac.uk
AF: School of Civil Engineering and Geosciences, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU United Kingdom
AU: Penna, N
EM: Nigel.Penna@newcastle.ac.uk
AF: School of Civil Engineering and Geosciences, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU United Kingdom
AB: A terrestrial reference frame (TRF) is defined as a set of physical points with precisely determined coordinates in a specific coordinate system. This framework of points are assumed to be attached to a solid Earth surface and move only due to linear tectonic motions, well-defined geophysical effects (primarily periodic) and, possibly, known discontinuities (offsets). The maintenance of an accurate and reliable terrestrial reference frame therefore depends upon the quality of the data (and information) at these points. Any remaining effects such as unknown discontinuities, long period geophysical signals, unmodeled periodic signals and noise will degrade the stability of the reference frame. In this paper we aim to discuss the contribution these effects have on the reference frame in terms of their importance and the limitations to the precision and accuracy they imply. It is almost inevitable that geodetic time series become contaminated by offsets, either artificial or real. Analysis of current GPS datasets suggests that one offset occurs between once every 9 years to possibly once every 2 years. We will discuss the implications of offsets in geodetic time series, the effects they induce if they are not detected and the effects if they are detected and estimated. We aim to provide an overview of the different types of noise currently seen in GPS (and other) time series and the impact of these and unmodeled periodic systematic errors on the reference frame. Overall the TRF process is about a practical solution to the problem so we hope to provide some clear practical recommendations to help minimize the above effects.
DE: 1229 Reference systems
DE: 1241 Satellite geodesy: technical issues (6994, 7969)
DE: 3265 Stochastic processes (3235, 4468, 4475, 7857)
DE: 3270 Time series analysis (1872, 4277, 4475)
SC: Geodesy [G]
MN: Fall Meeting 2005