The Effect and Correction of Non-Tectonic Crustal Deformation on Continuous GPS Position Time Series

Abstract

GPS observed crustal deformation usually includes both tectonic and non‐tectonic deformation signals, and it is vitally important to remove the non‐tectonic deformation signals in the data in order to effectively use GPS observations for tectonic deformation studies. Using the Earth satellite data and geophysical models, we calculate non‐tectonic crustal deformation caused by the ocean tide loading, atmospheric mass loading, snow and soil moisture mass loading, and non‐tidal ocean mass loading. Based on the quantitative analyses, the effects due to non‐tectonic crustal deformation on the position time series of GPS fiducial stations from the Crustal Movement Observation Network of China are studied and corrected. Our study shows that these effects on the vertical components of station positions are remarkable, especially the effects resulting from the atmospheric mass loading and snow and soil moisture mass loading. Using these models to correct for the non‐tectonic deformation, we have reduced the RMS of the station vertical position by about 1mm, which is about 11% of the total RMS. The amplitudes of annual vertical position variations are also reduced by about 37%. Moreover, we find that the position time series corrected using geophysical models followed by an empirical fitting of annual and semi‐annual variations are smoother than that corrected using the empirical fitting of annual and semi‐annual variations alone, indicating that the geophysical model corrections can not be substituted by pure empirical fitting in removing the non‐tectonic deformation effects.

Noise analysis for environmental loading effect on GPS time series

“…the Up component of DLFT (Delft, the Netherlands station) is greater than one centimeter, which is consistent with the study results From the above analysis, we can see that even though the loading effect is close to zero average for long time series, the instantaneous impact on GPS time series is non-trivial, especially for high-precision geophysical studies. Besides, the results indicate that the loading effect behaves with regional difference in spatial scale, and this explains why there is significant disagreement on the effect of environmental loading on GPS position time series from various authors (Dong et al, 2002;Wang et al, 2005;Yuan et al, 2008;Yan et al, 2009;Rietboek et al, 2011;Jiang et al, 2013).…”

“…Dong et al (2002) assumed that less than half of the observed GPS seasonal variation could be explained by redistributions of environmental surface mass loads. Wang et al (2005) quantified the effects of ocean tides, atmospheric pressure, snow depth and soil moisture, non-tide ocean loading (NTOL) on the position time series of GPS stations. They demonstrated that these environmental loads could reduce the RMS of the station vertical position by about 1 mm or about 11 % of the total RMS (root mean square).…”

Spatiotemporal analysis of GPS time series in vertical direction using independent component analysis

“…The GPS time series in the horizontal direction are featured with the linear velocity caused by plate movement, and in the vertical direction with more cyclical variation caused by geophysical phenomena such as non-tectonic deformation. Some researches show that the mass loading can explain most seasonal variations estimated in vertical GPS time series Wang et al 2005;Zhang et al 2002).…”

Effect of the span of Australian GPS coordinate time series in establishing an optimal noise model

“…With accumulated continuous GPS (CGPS) observation data, it is now possible to comprehensively analyze the effect of the time series span on the establishment of the inferred noise model and thus on the likely velocities and their uncertainties (Langbein and Johnson, 1997;Zhu et al, 2003;Wang et al, 2005Wang et al, , 2008Cheng et al, 2008;Yang et al, 2008;Tian and Shen, 2009;Jiang and Liu, 2010;Yuan et al, 2010;Chen et al, 2012;Wang et al, 2013).…”