References of "Keller, W"
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See detailBoundary elements for modelling gravitational signals observed by inter-satellite ranging
Antoni, M.; Weigelt, Matthias UL; Keller, W. et al

Poster (2013, September)

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See detailTime variability from high-low SST - filling the gap between GRACE and GFO
Weigelt, Matthias UL; Jäggi, A.; Prange, L. et al

Scientific Conference (2012, October)

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See detailLarge scale time variability from high-low SST - filling the gap between GRACE and GFO
Weigelt, Matthias UL; van Dam, Tonie UL; Jäggi, A. et al

Scientific Conference (2012, September)

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See detailOn the Comparison of Radial Base Functions and Single Layer Density Representations in Local Gravity Field Modelling from Simulated Satellite Observations
Weigelt, Matthias UL; Keller, W.; Antoni, M.

in Sneeuw, Nico; Novák, Pavel; Crespi, Mattia (Eds.) et al VII Hotine-Marussi Symposium on Mathematical Geodesy (2012, January)

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See detailTowards the time-variable gravity field from CHAMP
Weigelt, Matthias UL; Jäggi, A.; Prange, L. et al

Scientific Conference (2011, July)

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See detailGRACE Gravity Field Solutions Using the Differential Gravimetry Approach
Weigelt, Matthias UL; Keller, W.

Scientific Conference (2011, July)

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See detailEvaluation of the EGM2008 by Comparison with Global and Local Gravity Solutions from CHAMP
Weigelt, Matthias UL; Sneeuw, N.; Keller, W.

in Mertikas, S. P. (Ed.) Gravity, Geoid and Earth Observation (2010, June)

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See detailRegional gravity field recovery from GRACE using position optimized radial base functions
Weigelt, Matthias UL; Antoni, M.; Keller, W.

in Mertikas, Stelios P. (Ed.) Gravity, Geoid and Earth Observation (2010, January)

Global gravity solutions are generally influenced by degenerating effects such as insufficient spatial sampling and background models among others. Local irregularities in data supply can only be overcome ... [more ▼]

Global gravity solutions are generally influenced by degenerating effects such as insufficient spatial sampling and background models among others. Local irregularities in data supply can only be overcome by splitting the solution in a global reference and a local residual part. This research aims at the creation of a framework for the derivation of a local and regional gravity field solution utilizing the so-called line-of-sight gradiometry in a GRACE-scenario connected to a set of rapidly decaying base functions. In the usual approach, the latter are centered on a regular grid and only the scale parameter is estimated. The resulting poor condition of the normal matrix is counteracted by regularization. By contrast, here the positions as well as the shape of the base functions are additionally subject to the estimation process. As a consequence, the number of base functions can be minimized. The analysis of the residual observations by local base functions enables the resolution of details in the gravity field which are not contained in the global spherical harmonic solution. The methodology is tested using simulated as well as real GRACE data. [less ▲]

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See detailA Closed Solution of the Variational Equations for Short-Arc SST
Keller, W.; Antoni, M.; Weigelt, Matthias UL

Scientific Conference (2009, September)

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See detailLokale Schwerefeldbestimmung mit Hilfe der Randelementemethode und radialer Basisfunktionen
Weigelt, Matthias UL; Keller, W.; Antoni, M.

Scientific Conference (2009, September)

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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 detailLine-of-sight Gradiometrie und ihre praktische Umsetzung im Falle von GRACE
Weigelt, Matthias UL; Keller, W.

Poster (2008, October)

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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 ▲]

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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)

Detailed reference viewed: 25 (0 UL)