Cause Analysis of the Non‐Linear Variations of the IGS Reference Station Coordinate Time Series in China

Abstract

GPS position time series exhibit dramatic seasonal variations. It is generally considered that atmospheric pressure loading, nontidal ocean loading snow depth and soil moisture loading account for these seasonal changes. Focusing on the 11 IGS reference stations in China, this paper calculates station displacements caused by the above four kinds of surface mass loadings to correct the coordinate time series of these 11 stations during period of 1995–2010 under ITRF2005. We establish a preliminary numerical link among certain geophysical phenomena, seasonal variations and noise characteristics, finding that the calculated four kinds of surface mass loadings could produce variations in station's noise features, mainly exhibiting characteristics of band pass noise and random walk noise, and could reduce the annual amplitude of station's Up component. However, it could not well interpret station's semi‐annual and horizontal annual movement. We investigate the possible factors that could cause non‐linear variations of IGS stations, taking emphasis on the contributions of diurnal (S1) and semi‐diurnal (S2) atmospheric tides to the annual amplitude of the 11 stations, and propose that the S1–S2 atmospheric tides could be one of the main factors for annual motion of IGS stations in China, especially for the vertical annual motion of stations in central and southern regions.

Adaptive vertical-deformation field estimation and current tectonic deformation significance analysis in Shanxi rift valley

“…3) The annual motion amplitude of the GPS vertical time series can reach up to 5-10 mm owing to nontectonic factors such as atmospheric pressure, nontidal ocean loads, and hydrological loads (snow cover and soil water) (Mangiarotti et al, 2001;Dong et al, 2002;Dong et al, 2006;Wang, 2009;Jiang, 2013).The observation period of the campaign sites is small and the observation time is not fixed each year, it is significantly affected by the unestimated parameters when determining the vertical motion rate (Blewitt and Lavallée, 2002;Dong et al, 2002;Bos et al, 2010;Zhan et al, 2016). Considering that GPS vertical annual motion bears regional correlation (Wdowinski et al, 1997;Jiang, 2013;Sheng et al, 2014), this paper used the method of Liang (2014) to correct the vertical nonstructural load deformation of the GPS campaign station. First, 64 GPS continuous stations with long observational timespan were selected in the study area, and the annual term amplitude and initial equality parameters of the continuous station time series were fitted through the chord function.…”

Extraction of periodic signals in GNSS vertical coordinate time series using adaptive Ensemble Empirical Modal Decomposition method

“…direction (Davis et al, 2012;Jiang et al, 2013;Wang et al, 2018). Therefore, accurately extracting periodic signals from GNSS coordinate time series holds significant importance (Van Dam et al, 2001;Sorin et al, 2021).…”