Extracting Geophysical Signals from GRACE Using a Data-Adaptive Spatio-Temporal Filter
Abstract
Earth's gravity field solutions from the Gravity Recovery and Climate Experiment (GRACE) mission exhibit systematic and random errors, with potential specific spatial and temporal patterns. In order to extract geophysical signals from the GRACE data polluted by systematic and random errors, several methods have been proposed. Previous attempts based on filtering techniques required a priori assumptions on the spatio-temporal structure of the errors. Here we explore an alternative approach, using an objective spatio-temporal filter. We rely on the Multichannel Singular Spectrum Analysis (MSSA), a data-adaptive, multivariate, and non-parametric method that simultaneously exploits the spatial and temporal correlations of geophysical fields to extract common modes of variability. We perform a MSSA on 13 years of GRACE spherical harmonics solutions from 5 different processing centers simultaneously. We show that the method allows for the extraction of common modes of variability between solutions, and removal of the solution-specific spatio-temporal errors arising from each processing strategies. In particular, the method filters out efficiently the spurious North-South stripes, most likely caused by aliasing of the imperfect geophysical correction models. Then, we compare our GRACE solution - based on extracting common signals in space and time from 5 existing spherical harmonics solutions - to independent mass concentration (MASCON) solutions using a priori information on the spatio-temporal pattern on expected geophysical signals.Finally, we use our filtered GRACE solution to predict surface displacements at continuous GNSS (cGNSS) stations located in South America. Comparing common modes of variability between GNSS observations and GRACE derived model, we discuss the frequency-dependent rheological model of Earth required to explain surface displacements induced by annual to pluri-annual hydrological loading.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.G13C0531P
- Keywords:
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- 1217 Time variable gravity;
- GEODESY AND GRAVITYDE: 1218 Mass balance;
- GEODESY AND GRAVITYDE: 1223 Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions;
- GEODESY AND GRAVITYDE: 1240 Satellite geodesy: results;
- GEODESY AND GRAVITY