References of "Weigelt, Matthias 50003312"
     in
Bookmark and Share    
Full Text
Peer Reviewed
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

Detailed reference viewed: 14 (1 UL)
Full Text
See detailLine-of-sight Gradiometrie und ihre praktische Umsetzung im Falle von GRACE
Weigelt, Matthias UL; Keller, W.

Poster (2008, October)

Detailed reference viewed: 32 (0 UL)
Full Text
Peer Reviewed
See detailRegionale Schwerefeldmodellierung durch Slepian- und radiale Basisunktionen
Antoni, M.; Keller, W.; Weigelt, Matthias UL

in Zeitschrift für Vermessungswesen (2008), 133(2), 120--129

Zur Erfassung des statischen und des zeitvariablen Gravitati- onsfeldes der Erde sind seit 2000 bzw. seit 2002 die beiden Satellitenmissionen CHAMP und GRACE im Orbit. Üblicher- weise wird das aus den ... [more ▼]

Zur Erfassung des statischen und des zeitvariablen Gravitati- onsfeldes der Erde sind seit 2000 bzw. seit 2002 die beiden Satellitenmissionen CHAMP und GRACE im Orbit. Üblicher- weise wird das aus den Missionsdaten abgeleitete Gravita- tionsfeld als Summe von Kugelfunktionen dargestellt. Es zeigt sich aber, dass diese global definierten Basisfunktionen nicht in der Lage sind, alle in den Daten enthaltenen lokalen De- tails zu repräsentieren. Der Beitrag stellt zwei Methoden dar, das verbleibende Restsignal durch lokale Basisfunktionen auf- zulösen. Zum einen werden die radialen Basisfunktionen ver- wendet, zum anderen die Slepianfunktionen, die durch Or- thogonalisierung der Kugelflächenfunktionen auf einem vor- gegebenen Teil der Kugeloberfläche entstehen. Werden alle Parameter der radialen Basisfunktionen geschätzt, so erfor- dert das nichtlineare Problem neben den Startwerten auch eine Strahlminimierung, die die Konvergenz der Lösung ver- bessert, und ein Penalty-Verfahren, damit die geschätzten Parameter in einem sinnvollen Intervall fixiert werden. In ei- ner Simulationsstudie werden die erreichbaren Genauigkeiten und der numerische Aufwand beider Funktionensysteme mit- einander verglichen. [less ▲]

Detailed reference viewed: 23 (1 UL)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 61 (1 UL)
Full Text
See detailGravity field recovery in high latitude areas
Weigelt, Matthias UL; Keller, W.; Sneeuw, N.

Scientific Conference (2007, September)

Detailed reference viewed: 28 (0 UL)
Full Text
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)

Detailed reference viewed: 25 (0 UL)
Full Text
See detailGlobal and Local Gravity Field Recovery from Satellite-to-Satellite Tracking
Weigelt, Matthias UL

Doctoral thesis (2007)

The main objective of this thesis is the gravity field recovery using satellite-to-satellite tracking methods. Based on new technologies like the global positioning system and accelerometers satellite-to ... [more ▼]

The main objective of this thesis is the gravity field recovery using satellite-to-satellite tracking methods. Based on new technologies like the global positioning system and accelerometers satellite-to-satellite tracking yields a dramatic improvement in the de- termination of the Earth gravity field. Two dedicated satellite missions, namely the CHAllenging Minisatellite Payload (CHAMP) and the Gravity Recovery And Climate Experiment (GRACE) are underway. This work describes the processing of the satel- lite data from CHAMP and GRACE based on the energy balance approach. The first part discusses the global gravity field recovery from CHAMP. Specifically, it aims at a reprocessing of kinematic position data and at a refinement of the data processing strategies. Although the energy balance approach is theoretically simple, its imple- mentation proved to be quite challenging. By refining the processing techniques an improvement of up to 30\% is reached for the low degree spherical harmonic coefficients. Nevertheless, the solutions still depend strongly on the variability of the groundtrack. The quality of the monthly solutions can vary up to one order of magnitude. To ad- dress this challenge, an in-depth analysis gives new insight into the phenomenon, and a new and unique combination method with GRACE data is presented, which yields a more homogeneous set of solutions and reaches the edge of the recoverability of a time-variable gravity signal from high-low satellite-to-satellite tracking missions. In the second part the energy balance approach is applied to the GRACE mission. Pre- vious attempts of expressing the kinetic energy in terms of the K-band measurement make use of an approximation. In this work, an exact representation is introduced and is validated by simulations. In the third part, the aim is to make optimal usage of the data distribution in the high latitude area. For this, interpolation and downward continuation techniques are investigated and an improvement, compared to the global solutions, is achieved. Overall, the analysis provides new and valuable insight into the data processing of satellite-to-satellite tracking data using the energy balance approach. [less ▲]

Detailed reference viewed: 110 (5 UL)
Full Text
See detailCombination of CHAMP and GRACE data for Gravity Field Analysis
Weigelt, Matthias UL; Sideris, M. G.; Sneeuw, N.

Poster (2006, August)

Detailed reference viewed: 25 (0 UL)
Full Text
See detailCombination of CHAMP and GRACE satellite data for Earth monitoring
Weigelt, Matthias UL; Sideris, M. G.; Sneeuw, N.

Poster (2006, June)

Detailed reference viewed: 17 (1 UL)
Full Text
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)

Detailed reference viewed: 15 (0 UL)
Full Text
See detailOn the accelerometer calibration onboard GRACE
Raizner, C.; Weigelt, Matthias UL; Sideris, M. G.

Scientific Conference (2006, April)

Detailed reference viewed: 52 (0 UL)
Full Text
See detailGravity Field Recovery from satellite-to-satellite tracking missions
Weigelt, Matthias UL; Sideris, M. G.; Sneeuw, N.

Scientific Conference (2006, April)

Detailed reference viewed: 34 (0 UL)
Full Text
See detailHigh-latitude local gravity field recovery from CHAMP with least-squares collocation
Weigelt, Matthias UL; Sideris, M. G.; Sneeuw, N.

Poster (2006, April)

Detailed reference viewed: 42 (0 UL)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 78 (0 UL)
Full Text
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)

Detailed reference viewed: 21 (0 UL)
Full Text
See detailA note about covariance function and their propagation
Weigelt, Matthias UL

Diverse speeches and writings (2005)

Detailed reference viewed: 20 (2 UL)
Full Text
See detailNew CHAMP gravity results using the energy balance approach
Weigelt, Matthias UL; Sneeuw, N.

Scientific Conference (2003, May)

Detailed reference viewed: 33 (0 UL)
See detailRichtungsmessung zu Satelliten
Weigelt, Matthias UL

Bachelor/master dissertation (2002)

Detailed reference viewed: 33 (0 UL)