References of "Sneeuw, N"
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See detailEvaluation of PGM2007A by comparison with globally and locally estimated gravity solutions from CHAMP
Weigelt, Matthias UL; Sneeuw, N.; Keller, W.

in Newton's Bulletin (2009), 4

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See detailSpaceborne gravimetry and gravity field recovery
Xu, C.; Weigelt, Matthias UL; Sideris, M. G. et al

in Canadian Aeronautics and Space Journal (2008), 53(3/4), 65--75

As an integrated signal of mass transition and distribution, the Earth's gravity senses the inner and outer mass balance of the Earth. However gravity cannot be measured directly in space but can be ... [more ▼]

As an integrated signal of mass transition and distribution, the Earth's gravity senses the inner and outer mass balance of the Earth. However gravity cannot be measured directly in space but can be derived from other measurements obtained by space vehicles. The dedicated gravity field satellite missions CHAMP, GRACE, and GOCE serve as spaceborne gravimeters by utilizing satellite-to-satellite tracking (SST) and satellite gravity gradiometry (SGG) techniques. In this decade of the geopotentials, these missions will serve different purposes with particular spatial and spectral resolutions. This paper introduces the usefulness of these missions, their impacts on the geosciences the measurement principles, and their implementations. These space sensors will provide a significant number of observations during their mission lifespans. Therefore, global gravity field recovery is a computationally demanding task. Several approaches aimed at this goal are discussed, namely the brute-force approach, the space-wise approach, the time-wise approach, and the proposed torus-based semi-analytical approach. The paper addresses the characteristics of each approach and focuses mainly on the torus-based semi-analytical approach, which can be used to derive the gravity field from any geopotential functional. In this approach, the structure of the normal matrix becomes block-diagonal which leads to a powerful and efficient recovery tool through the use of the fast Fourier transform (FFT). Important issues such as downward continuation, interpolation methods, and regularization approaches are also discussed. To demonstrate the feasibility and efficiency of the torus-based semi-analytical approach of gravity field determination in spaceborne gravimetry, disturbing potential data from CHAMP and GRACE and simulated GOCE gravity gradient tensor data are processed. [less ▲]

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See detailGravity field recovery in high latitude areas
Weigelt, Matthias UL; Keller, W.; Sneeuw, N.

Scientific Conference (2007, September)

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See detailTime variable gravity field recovery in local areas by means of Slepian functions
Weigelt, Matthias UL; van der Wal, W.; Sneeuw, N. et al

Poster (2007, July)

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See detailCombination of CHAMP and GRACE data for Gravity Field Analysis
Weigelt, Matthias UL; Sideris, M. G.; Sneeuw, N.

Poster (2006, August)

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See detailCombination of CHAMP and GRACE satellite data for Earth monitoring
Weigelt, Matthias UL; Sideris, M. G.; Sneeuw, N.

Poster (2006, June)

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See detailComparison and combination of CHAMP and GRACE data for gravity field analysis
Weigelt, Matthias UL; El-Habiby, M. M.; Sideris, M. G. et al

Scientific Conference (2006, May)

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See detailGravity Field Recovery from satellite-to-satellite tracking missions
Weigelt, Matthias UL; Sideris, M. G.; Sneeuw, N.

Scientific Conference (2006, April)

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See detailHigh-latitude local gravity field recovery from CHAMP with least-squares collocation
Weigelt, Matthias UL; Sideris, M. G.; Sneeuw, N.

Poster (2006, April)

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See detailNumerical Velocity determination and Calibration Methods for CHAMP Using the Energy Balance Approach
Weigelt, Matthias UL; Sneeuw, N.

in Jekeli, Christopher; Bastos, Luisa; Fernandes, Joana (Eds.) Gravity, Geoid and Space Missions (2005, June)

More than two years of data of the champ satellite mission is available and the usage of the energy balance approach for global gravity field recovery has been successfully implemented by several groups ... [more ▼]

More than two years of data of the champ satellite mission is available and the usage of the energy balance approach for global gravity field recovery has been successfully implemented by several groups around the world. This paper addresses two important aspects of the data processing. First, high-quality gravity recovery requires numerical differentiation of kinematic positions. Two methods are investigated using simulated and real dynamic data. It is shown that a third order Taylor differentiator is sufficient to reach good results. Second drift due to the accelerometer bias has to be corrected. Two possible approaches are discussed: cross-over calibration on the one hand calibration w.r.t. a reference model on the other hand. Currently the crossover calibration fails due to the insufficient accuracy of the crossover determination whereas the calibration w.r.t. a reference model gives good results. [less ▲]

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See detailHigh-latitude gravity field recovery from CHAMP and its contribution to Earth monitoring
Weigelt, Matthias UL; Sideris, M. G.; Sneeuw, N. et al

Scientific Conference (2005, May)

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See detailNew CHAMP gravity results using the energy balance approach
Weigelt, Matthias UL; Sneeuw, N.

Scientific Conference (2003, May)

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See detailOn time-variable seasonal signals: comparison of SSA and Kalman filtering based approaches
Chen, Q.; Weigelt, Matthias UL; Sneeuw, N. et al

Scientific Conference (n.d.)

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