The ESEAS Coordinate Time Series Analysis Strategy: Strategy Outline and Initial Results
Norman Teferle(1), Simon D. P. Williams(2), Halfdan P. Kierulf(3), Richard M. Bingley(1) and Hans-Peter Plag(3,4)
(1) Institute of Engineering Surveying and Space Geodesy, University
of Nottingham, Nottingham, UK
(2) Proudman Oceanographic Laboratory, Bidston Observatory
Birkenhead CH437RA, UK
(3) Norwegian Mapping Authority
3507 Honefoss, Norway
(4) Nevada Bureau of Mines and Geology and Seismological Laboratory
University of Nevada, Reno, Mailstop 178, Reno, NV 89557, USA
This presentation summarizes the work of ESEAS Partners P1 (NMA), P3 (NERC-POL) and P4 (UNOTT), within Work Package2 Tasks 2.2 and 2.5: "Define, implement and validate a strategy for the analysis of CGPS time series, which will enable the determination of vertical station velocities in a consistent reference frame with an uncertainty of less than 0.5\,mm/yr" and "Carry out a coherent analysis of the time series from CGPS stations co-located with ESEAS observing sites, based on the strategy developed in Task 2.2", respectively.
The ESEAS CGPS coordinate time series analysis strategy was developed in order to obtain highly accurate vertical station velocities by separation of real geophysical signals from the underlying noise. Coordinate time series pre-processing first identifies outliers and discontinuities in the time series. Parameterisation then includes a mean value, a constant rate, periodic terms with annual and semi-annual frequencies, and offset magnitudes for the identified discontinuities. Maximum Likelihood Estimation (MLE) determines all parameters plus the magnitudes of different stochastic noise. Empirical Orthogonal Function (EOF) analysis allows the discrimination between local, station-specific, deterministic processes and inter-station, correlated transient signals, i.e. common mode errors. Using the common mode errors from the EOF analysis, the coordinate time series can then be filtered and improved.
After outlining the ESEAS CGPS coordinate time series analysis strategy this presentation gives the initial results from the analysis of coordinate time series produced by several ESEAS Analysis Centers.