Abstract
Vertical deformations caused by non-tidal mass variations still remain in global navigation satellite system (GNSS) height time series, and can be computed from both Gravity Recovery and Climate Experiment (GRACE) and geophysical models. In this study, we provide a thorough evaluation of the relationships between these different techniques in the global scale by comparing non-tidal vertical deformations from IGS second reprocessing campaign (IG2), GRACE and Global Geophysical Fluid Center (GGFC) solutions, and investigate the noise properties of the GNSS corrected by GRACE solutions and GNSS corrected by GGFC solutions for global stations using optimal noise models. Our results demonstrate that the consistency between seasonal vertical deformations derived from GNSS, GRACE and GGFC is high. When correcting GNSS deformations with GRACE and GGFC solutions, 81% and 73% of the 186 stations have the weight root mean square (WRMS) reduction, respectively. The WRMS variations averaged over all stations are −12.3% and −5.6%, respectively for GNSS corrected by GRACE and GNSS corrected by GGFC solutions. The obvious difference occurs in the GNSS corrected by GGFC solutions WRMS increase, with the mean increase value up to 29%, mainly happening to stations located on islands or small peninsulas. In addition, noise properties of the GNSS corrected by GRACE solutions and GNSS corrected by GGFC solutions for global stations are investigated using optimal noise models. After correcting non-tidal loading effects, the solutions of GNSS corrected by GRACE solutions have the lowest noise level, and can occupy 5% of the noise behavior presenting in global stations, while the solutions of GNSS corrected by GGFC solutions can bring more than 5% of the noise into global stations, implying that GRACE correction solutions can present more favorable results when interpreting GNSS non-tidal loading deformations.
Highlights
Global navigation satellite system (GNSS) coordinate time series have been widely used in varieties of studies, including global/regional reference frame establishment [1], tectonic deformation monitoring [2], and conducting strain accumulation on sea-level variations [3], glacial isostatic adjustment (GIA), subsidence studies [4]
The results indicate that for both types of optimal noise model, after subtracting the loading effects, GNSS corrected by Gravity Recovery and Climate Experiment (GRACE) solutions have the lowest noise level, demonstrating that the GNSS corrected by GRACE solutions present more favorable results than that of GNSS corrected by Global Geophysical Fluid Center (GGFC) solutions
We provide a thorough evaluation of the potential of two totally independent solutions to observe the non-tidal loading signal in GNSS, and attempt to explain the remaining GNSS–GRACE/geophysical models (GMs) residuals
Summary
Global navigation satellite system (GNSS) coordinate time series have been widely used in varieties of studies, including global/regional reference frame establishment [1], tectonic deformation monitoring [2], and conducting strain accumulation on sea-level variations [3], glacial isostatic adjustment (GIA), subsidence studies [4]. In terms of the comparisons between GNSS and GMs. The research of [28] comprehensively compared three different environmental loading methods to estimate surface deformations and correct the nonlinear variations in a set of GNSS weekly height time series. The research of [28] comprehensively compared three different environmental loading methods to estimate surface deformations and correct the nonlinear variations in a set of GNSS weekly height time series They demonstrated that there are differences remaining in different GMs, and pointed out that for different GMs, the consistency of the VD signals showed discrepancies. Our main objective is to investigate the consistency of the non-tidal seasonal VD obtained by GNSS, GRACE and GMs in the global scale, and we attempt to provide new noise solutions to identify the sources of the comparison differences. We try to perform comparisons with the previous research and detail the thermal expansion effects and leakage errors analysis
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