Next Article in Journal
A Methodology to Detect and Update Active Deformation Areas Based on Sentinel-1 SAR Images
Next Article in Special Issue
A New Online Service for the Validation of Multi-GNSS Orbits Using SLR
Previous Article in Journal
Polarimetric ALOS PALSAR Time Series in Mapping Biomass of Boreal Forests
Previous Article in Special Issue
Inter-System Differencing between GPS and BDS for Medium-Baseline RTK Positioning
Open AccessArticle

Global Surface Mass Variations from Continuous GPS Observations and Satellite Altimetry Data

1
National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, China
2
Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China
*
Authors to whom correspondence should be addressed.
Remote Sens. 2017, 9(10), 1000; https://doi.org/10.3390/rs9101000
Received: 7 August 2017 / Revised: 8 September 2017 / Accepted: 22 September 2017 / Published: 27 September 2017
The Gravity Recovery and Climate Experiment (GRACE) mission is able to observe the global large-scale mass and water cycle for the first time with unprecedented spatial and temporal resolution. However, no other time-varying gravity fields validate GRACE. Furthermore, the C20 of GRACE is poor, and no GRACE data are available before 2002 and there will likely be a gap between the GRACE and GRACE-FOLLOW-ON mission. To compensate for GRACE’s shortcomings, in this paper, we provide an alternative way to invert Earth’s time-varying gravity field, using a priori degree variance as a constraint on amplitudes of Stoke’s coefficients up to degree and order 60, by combining continuous GPS coordinate time series and satellite altimetry (SA) mean sea level anomaly data from January 2003 to December 2012. Analysis results show that our estimated zonal low-degree gravity coefficients agree well with those of GRACE, and large-scale mass distributions are also investigated and assessed. It was clear that our method effectively detected global large-scale mass changes, which is consistent with GRACE observations and the GLDAS model, revealing the minimums of annual water cycle in the Amazon in September and October. The global mean mass uncertainty of our solution is about two times larger than that of GRACE after applying a Gaussian spatial filter with a half wavelength at 500 km. The sensitivity analysis further shows that ground GPS observations dominate the lower-degree coefficients but fail to contribute to the higher-degree coefficients, while SA plays a complementary role at higher-degree coefficients. Consequently, a comparison in both the spherical harmonic and geographic domain confirms our global inversion for the time-varying gravity field from GPS and Satellite Altimetry. View Full-Text
Keywords: GNSS; satellite altimetry; time-varying gravity field; mass redistribution GNSS; satellite altimetry; time-varying gravity field; mass redistribution
Show Figures

Graphical abstract

MDPI and ACS Style

Zhang, X.; Jin, S.; Lu, X. Global Surface Mass Variations from Continuous GPS Observations and Satellite Altimetry Data. Remote Sens. 2017, 9, 1000.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop