Properties and Applications of EOF-Based Filtering of GRACE Solutions
Several filter strategies have been proposed in the past to deal with noise in the GRACE gravity field solutions, particularly with the North-South stripes. These strategies have led to several families of filters, roughly characterized by the properties stochastic vs. deterministic and isotropic vs. anisotropic. One type of filter that has been shown to be very effective is based on Empirical Orthogonal Functions (EOF) analysis in combination with white-noise testing of the resulting time series in the spectral domain (Wouters and Schrama: Geophys. Res. Lett. 34, 2007 doi: 10.1029/2007GL032098). In this paper, we recast the EOF procedure into a filter equation, i.e. the filter transfer is described explicitly. This allows us to emphasize the characteristics of the EOF-based filter. Moreover, our formulation provides an easy means to propagate the GRACE fields into degree variances and spatial covariance functions.
KeywordsEOF filtering GRACE Gravity field
- Chen JL, Wilson CR, Famiglietti JS, Rodell M (2007) Attenuation effect on seasonal basin-scale water storage changes from GRACE time-variable gravity J Geod 81:237–245, doi: 10.1007/s00190-006-0104-2Google Scholar
- Iran Pour S, Bentel K, Sneeuw N (2009) EOF-based filtering of GRACE gravity field solutions: A comparison between spectral and spatial approaches Geophysical Research Abstracts, Vol. 11, EGU2009-2853-1, Vienna, Austria 2009Google Scholar
- Preisendorfer RW (1988) Principal component analysis in meteorology and oceanography, Elsevier, AmsterdamGoogle Scholar
- Swenson S, Wahr J (2006) Post-processing removal of correlated errors in GRACE data Geophys Res Lett 33, doi: 10.1029/2005GL025285Google Scholar
- Wouters B, Schrama EJO (2007) Improved accuracy of GRACE gravity solutions through empirical orthogonal function filtering of spherical harmonics Geophys Res Lett 34, doi: 10.1029/2007GL032098Google Scholar