Global Assessment of Time-Varying Periodic Signals in GNSS Vertical Displacements Using SSA Versus Parameterized Models Considering Environmental Loading Effects

Abstract Environmental loading affects the periodic variation of Global Navigation Satellite System (GNSS) vertical coordinate time series. This study extracts periodic signals from the global GNSS vertical coordinate time series using Singular Spectrum Analysis (SSA) and parameterization methods. Then, the accuracy of the GNSS time-varying periodic signal obtained by the SSA method compared to the GNSS periodic signal fitted by the parameterization method was statistically analyzed. The results show that the stations with positive RMS reduction ratio account for 97.46% of the total 630 stations worldwide. Subsequently, this article conducted a comparative study on the correlation between time-varying periodic signals obtained by SSA method, periodic signals fitted by the parameterization method, and the GNSS original coordinate time series with environmental loading displacement. The results indicate that the correlation between the time-varying periodic signal obtained by the SSA method and the environmental loading is highly consistent with the correlation between the original GNSS coordinate time series and the environmental loading. Finally, the time-varying periodic sequence obtained using the SSA method is used to analyze the impact of environmental loading corrections (ELCs) on the global GNSS vertical coordinate time series periodic signal. Research has shown that 79.52% of global stations have reduced time-varying periodic signals and weakened the nonlinear amplitude of GNSS coordinate time series after ELCs.