Acta Geodynamica et Geomaterialia

Title: INVESTIGATION OF TIME_CHANGEABLE SEASONAL COMPONENTS IN THE GPS HEIGHT TIME SERIES: A CASE STUDY FOR CENTRAL EUROPE
Authors: Gruszczynska Marta, Klos Anna, Grusycynski Maciej and Bogusz Janusz
DOI: 10.13168/AGG.2016.0010
Journal: Acta Geodynamica et Geomaterialia, Vol. 13, No. 3 (183), Prague 2016
Full Text: PDF file (1.2 MB)
Keywords: GPS height time series, seasonal variations, Singular Spectrum Analysis, Least-Squares Estimation
Abstract: Nowadays, beyond the dispute we should take into account the time-varying parameters of seasonals in the GPS-derived position time series. Either real geophysical effects or system-specified artifacts can introduce non-sinusoidal changes. For this study, we used 18 daily position time series from Central European stations provided by the Jet Propulsion Laboratory (JPL) processed in the GIPSY-OASIS software in a Precise Point Positioning (PPP) mode. We tested two different approaches to subtract the seasonal signal: Least-Squares Estimation (LSE) and Singular Spectrum Analysis (SSA). The SSA approach is suitable for all (stationary and non-stationary) time series, without prior knowledge about the data characteristics, which is an undisputable advantage. We extracted periodicities from GPS signals, and demonstrated the usefulness of the SSA approach on the example of the vertical component. We showed, that the reassembled signal, containing only the first four Reconstructed Components, has a larger correlation coefficient than LSE-extracted signals, with respect to the original time series. Moreover, using the Akaike Information Criterion and Fisher-Snedecor test we tested optimum length of the sliding window and significance of the obtained RCs, respectively.