Print Email Facebook Twitter Signal and noise in Gravity Recovery and Climate Experiment (GRACE) observed surface mass variations Title Signal and noise in Gravity Recovery and Climate Experiment (GRACE) observed surface mass variations Author Schrama, E.J.O. Wouters, B. Lavallée, D.A. Faculty Aerospace Engineering Department Space Engineering Date 2007-08-04 Abstract The Gravity Recovery and Climate Experiment (GRACE) product used for this study consists of 43 monthly potential coefficient sets released by the GRACE science team which are used to generate surface mass thickness grids expressed as equivalent water heights (EQWHs). We optimized both the smoothing radius and the level of approximation by empirical orthogonal functions (EOFs) and found that 6.25° and three modes are able to describe more than 73.5% of the variance. The EQWHs obtained by the EOF method describe all known variations in the continental hydrology, present?day ice sheet melting, and global isostatic adjustment. To assess the quality of the estimated grids, we constructed degree error spectra of EQWHs. We conclude that a significant part of the errors in GRACE can be explained by a scaling factor of 0.85 relative to degree error estimates provided by the GGM02C gravity model but that the present?day errors in the GRACE data are a factor 2 to 5 larger than forecasted by tide model differences and atmospheric pressure differences. Comparison to a network of 59 International GNSS Service (IGS) stations confined the filter parameter settings to three EOF modes and 5° or 6.25° smoothing radius. Residuals that remain after the EOF method do exhibit S2 aliasing errors and a semiannual continental hydrology signal contained in the Global Land Data Assimilation Systems (GLDAS) model. Further analysis of the residual EOF signal revealed alternating track correlation patterns that are partially explained by the GRACE covariance matrix and the handling of nuisance parameters in the GRACE data processing. Subject GRACEtemporary gravityspherical harmonicserror analysisempirical orthogonal functionsGPS To reference this document use: http://resolver.tudelft.nl/uuid:96f4f149-de9f-451f-9a69-b9d66e4704a2 DOI https://doi.org/10.1029/2006JB004882 Publisher American Geophysical Union ISSN 0148-0227 Source http://europa.agu.org/?view=article&uri=/journals/jb/jb0708/2006JB004882/2006JB004882.xml Source Journal of Geophysical Research, 112, 2007 Part of collection Institutional Repository Document type journal article Rights (c) 2007 The Author(s); American Geophysical Union Files PDF Schrama_2007.pdf 958.45 KB Close viewer /islandora/object/uuid:96f4f149-de9f-451f-9a69-b9d66e4704a2/datastream/OBJ/view