Searched for: subject%3A%22gravity%255C%2Bfield%22
(1 - 20 of 34)

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Schreiter, Lucas (author), Montenbruck, Oliver (author), Zangerl, Franz (author), Siemes, C. (author), Arnold, Daniel (author), Jäggi, Adrian (author)
Gravity fields derived from GPS tracking of the three Swarm satellites have shown artifacts near the geomagnetic equator, where the carrier phase tracking on the L2 frequency is unable to follow rapid ionospheric path delay changes due to a limited tracking loop bandwidth of only 0.25 Hz in the early years of the mission. Based on the...
journal article 2021
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Haagmans, Roger (author), Siemes, C. (author), Massotti, Luca (author), Carraz, Olivier (author), Silvestrin, Pierluigi (author)
The paper addresses the preparatory studies of future ESA mission concepts devoted to improve our understanding of the Earth’s mass change phenomena causing temporal variations in the gravity field, at different temporal and spatial scales, due to ice mass changes of ice sheets and glaciers, continental water cycles, ocean masses dynamics and...
review 2020
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Guo, Xiang (author), Ditmar, P.G. (author), Zhao, Qile (author), Xiao, Yun (author)
To monitor temporal variations of the Earth’s gravity field and mass transport in the Earth’s system, data from gravity recovery and climate experiment (GRACE) satellite mission and its successor GRACE Follow-On (GFO) are used. To fill in the temporal gap between these missions, other satellites’ kinematic orbits derived from GPS-based high...
journal article 2020
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Visser, T. (author), March, G. (author), Doornbos, E.N. (author), de Visser, C.C. (author), Visser, P (author)
Thermospheric wind measurements obtained from linear non-gravitational accelerations of the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite show discrepancies when compared to ground-based measurements. In this paper the cross-wind is derived from both the linear and the angular accelerations using a newly developed...
journal article 2019
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Visser, T. (author), March, G. (author), Doornbos, E.N. (author), de Visser, C.C. (author), Visser, P.N.A.M. (author)
Recently, the horizontal and vertical cross wind at 225- to 295-km altitude were derived from linear acceleration measurements of the Gravity field and steady-state Ocean Circulation Explorer satellite. The vertical component of these wind data is compared to wind data derived from the mass spectrometers of the Atmosphere Explorer C and E and...
journal article 2019
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Klees, R. (author), Slobbe, D.C. (author), Farahani, H. (author)
The posed question arises for instance in regional gravity field modelling using weighted least-squares techniques if the gravity field functionals are synthesised from the spherical harmonic coefficients of a satellite-only global gravity model (GGM), and are used as one of the noisy datasets. The associated noise covariance matrix, appeared...
journal article 2018
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Klees, R. (author), Slobbe, D.C. (author), Farahani, H. (author)
The paper is about a methodology to combine a noisy satellite-only global gravity field model (GGM) with other noisy datasets to estimate a local quasi-geoid model using weighted least-squares techniques. In this way, we attempt to improve the quality of the estimated quasi-geoid model and to complement it with a full noise covariance matrix...
journal article 2018
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Sun, Y. (author)
Geocenter motion and changes in the Earth’s dynamic oblateness (J2) are of great importance in many applications. Among others, they are critical indicators of largescale mass redistributions, which is invaluable to understand ongoing global climate change. The revolutionary Gravity Recovery and Climate Experiment (GRACE) satellite mission...
doctoral thesis 2017
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Nardi, Alex (author)
This research aims at modeling the trajectory followed by the Galileo spacecraft during a variety of flybys about the Galilean moons. The chosen flybys have good Earth’s elevation angles and either low or high closest-approach altitudes, so that the comparison of the two can give relevant insight into the accuracy of the corresponding...
master thesis 2017
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Guo, X. (author), Ditmar, P.G. (author), Zhao, Q (author), Klees, R. (author), Farahani, H. (author)
GPS data collected by satellite gravity missions can be used for extracting the long-wavelength part of the Earth’s gravity field. We propose a new data processing method which makes use of the ‘average acceleration’ approach to gravity field modelling. In this method, satellite accelerations are directly derived from GPS carrier phase...
journal article 2017
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Hashemi Farahani, H. (author), Ditmar, P.G. (author), Miragaia Gomes Inacio, P. (author), Engels, Olga (author), Gunter, B.C. (author), Klees, R. (author), Guo, X. (author), Guo, Jing (author), Sun, Y. (author), Liu, Xianglin (author), Zhao, Qile (author), Riva, R.E.M. (author)
We present a high resolution model of the linear trend in the Earth’s mass variations based on DMT-2 (Delft Mass Transport model, release 2). DMT-2 was produced primarily from K-Band Ranging (KBR) data of the Gravity Recovery And Climate Experiment (GRACE). It comprises a time series of monthly solutions complete to spherical harmonic degree 120...
journal article 2017
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de Teixeira da Encarnacao, J.G. (author), Arnold, Daniel (author), Bezděk, Aleš (author), Dahle, Christoph (author), Doornbos, E.N. (author), van den IJssel, J.A.A. (author), Jäggi, Adrian (author), Mayer-Gürr, Torsten (author), Sebera, Josef (author), Visser, P.N.A.M. (author), Zehentner, Norbert (author)
It is of great interest to numerous geophysical studies that the time series of global gravity field models derived from Gravity Recovery and Climate Experiment (GRACE) data remains uninterrupted after the end of this mission. With this in mind, some institutes have been spending efforts to estimate gravity field models from alternative...
journal article 2016
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Teixeira Encarnação, J. (author)
The main objective of the thesis is to identify the optimal set-up for future satellite gravimetry missions aimed at monitoring mass transport in the Earth’s system.The recent variability of climatic patterns, the spread of arid regions and associ- ated changes in the hydrological cycle, and vigorous modifications in the ice coverage at polar...
doctoral thesis 2015
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Sun, Y. (author), Ditmar, P. (author), Riva, R. (author)
A new methodology is proposed to estimate changes in the Earth’s dynamic oblateness (?J2 or equivalently, ?5??C20) on a monthly basis. The algorithm uses monthly Gravity Recovery and Climate Experiment (GRACE) gravity solutions, an ocean bottom pressure model and a glacial isostatic adjustment (GIA) model. The resulting time series agree...
journal article 2015
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Wakker, K.F. (author)
This book deals with the motion of the center of mass of a spacecraft; this discipline is generally called astrodynamics. The book focuses on an analytical treatment of the motion of spacecraft and provides insight into the fundamentals of spacecraft orbit dynamics. A large number of topics are treated in a uniform and consistent way. The text...
book 2015
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Hamayun, H. (author)
Currently, a tremendous improvement is observed in the accuracy and spatial resolution of global Earth’s gravity field models. This improvement is achieved due to using various new data, including those from satellite gravimetry missions (CHAMP, GRACE, and GOCE); terrestrial and airborne gravity data, as well as altimetry data. The new gravity...
doctoral thesis 2014
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Ditmar, P. (author), Teixeira da Encarnacao, J. (author), Hashemi Farahani, H. (author)
Spectral analysis of data noise is performed in the context of gravity field recovery from inter-satellite ranging measurements acquired by the satellite gravimetry mission GRACE. The motivation of the study is two-fold: (i) to promote a further improvement of GRACE data processing techniques and (ii) to assist designing GRACE follow-on missions...
journal article 2012
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Tenzer, R. (author), Novák, P. (author), Vajda, P. (author), Gladkikh, V. (author), Hamayun, K. (author)
We developed and applied a novel numerical scheme for a gravimetric forward modelling of the Earth’s crustal density structures based entirely on methods for a spherical analysis and synthesis of the gravitational field. This numerical scheme utilises expressions for the gravitational potentials and their radial derivatives generated by the...
journal article 2011
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Gruber, T. (author), Visser, P.N.A.M. (author), Ackermann, C. (author), Hosse, M. (author)
Three GOCE-based gravity field solutions have been computed by ESA’s high-level processing facility and were released to the user community. All models are accompanied by variance-covariance information resulting either from the least squares procedure or a Monte-Carlo approach. In order to obtain independent external quality parameters and to...
journal article 2011
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Klees, R. (author), Prutkin, I. (author)
We propose a methodology for the combination of a gravimetric (quasi-) geoid with GNSS-levelling data in the presence of noise with correlations and/or spatially varying noise variances. It comprises two steps: first, a gravimetric (quasi-) geoid is computed using the available gravity data, which, in a second step, is improved using ellipsoidal...
journal article 2010
Searched for: subject%3A%22gravity%255C%2Bfield%22
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