Influences of Environmental Loading Corrections on the Nonlinear Variations and Velocity Uncertainties for the Reprocessed Global Positioning System Height Time Series of the Crustal Movement Observation Network of China

Peng Yuan,Wu Chen,Zhao Li,Yifang Ma,Nico Sneeuw,Weiping Jiang

doi:10.3390/rs10060958

Abstract

Mass redistribution of the atmosphere, oceans, and terrestrial water storage generates crustal displacements which can be predicted by environmental loading models and observed by the Global Positioning System (GPS). In this paper, daily height time series of 235 GPS stations derived from a homogeneously reprocessed Crustal Movement Observation Network of China (CMONOC) and corresponding loading displacements predicted by the Deutsche GeoForschungsZentrum (GFZ) are compared to assess the effects of loading corrections on the nonlinear variations of GPS time series. Results show that the average root mean square (RMS) of vertical displacements due to atmospheric, nontidal oceanic, hydrological, and their combined effects are 3.2, 0.6, 2.7, and 4.0 mm, respectively. Vertical annual signals of loading and GPS are consistent in amplitude but different in phase systematically. The average correlation coefficient between loading and GPS height time series is 0.6. RMS of the GPS height time series are reduced by 20% on average. Moreover, an investigation of 208 CMONOC stations with observing time spans of ~4.6 years shows that environmental loading corrections lead to an overestimation of the GPS velocity uncertainty by about 1.4 times on average. Nevertheless, by using a common mode component filter through principal component analysis, the dilution of velocity precision due to environmental loading corrections can be compensated.

Highlights

Global Positioning System (GPS) height time series record complex nonlinear variations, which have been demonstrated to be caused by GPS errors, environmental loading, and other effects [1]
The average root mean square (RMS) of atmospheric loading (ATML), nontidal oceanic loading (NTOL), hydrological loading (HYDL), and SumL for the 235 stations are 3.2, 0.6, 2.7, and 4.0 mm, respectively, indicating that ATML contributes the largest share of the environmental loading at these stations on average
For 34 coastal stations located within 100 km distance of the coast, most of their RMS of ATML are lower than 3.5 mm, apparently lower than those of their neighboring inland regions due to the inverted barometer (IB) effect

Summary

Introduction

Global Positioning System (GPS) height time series record complex nonlinear variations, which have been demonstrated to be caused by GPS errors, environmental loading, and other effects [1]. With regard to atmospheric loading (ATML), van Dam et al [18] estimated its influences on GPS height time series. With regard to hydrological loading (HYDL), van Dam et al [25] investigated the height time series of 147 GPS stations and found significant reductions of scatter at 92 stations after HYDL correction. Dong et al [1] found the vertical annual amplitudes of GPS height time series can be partially explained by environmental loading for 90 out of 128 globally distributed GPS stations. Yan et al [29] estimated the thermal expansion of 86 globally distributed GPS stations and found that thermal expansion can cause GPS height changes with a few millimeters

Results

Discussion

Conclusion