Searched for: author%3A%22Ditmar%2C+P.%22
(1 - 9 of 9)
document
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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Siemes, C. (author), Ditmar, P. (author), Riva, E.M. (author), Slobbe, D.C. (author), Liu, X.L. (author), Farahani, H. (author)
The Gravity Recovery and Climate Experiment (GRACE) satellite mission measures the Earth’s gravity field since March 2002. We propose a new filtering procedure for post-processing GRACE-based monthly gravity field solutions provided in the form of spherical harmonic coefficients. The procedure is tuned for the optimal estimation of linear trends...
journal article 2012
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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
document
Gunter, B.C. (author), Wittwer, T. (author), Stolk, W. (author), Klees, R. (author), Ditmar, P. (author)
In this study we address the question of whether regional gravity field modeling techniques of GRACE data can offer improved resolution over traditional global spherical harmonic solutions. Earlier studies into large, equatorial river basins such as the Amazon, Zambezi and others showed no obvious distinction between regional and global...
conference paper 2009
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Klees, R. (author), Liu, X. (author), Wittwe, T. (author), Gunter, B.C. (author), Revtova, E.A. (author), Tenzer, R. (author), Ditmar, P. (author), Winsemius, H.C. (author), Savenije, H.H.G. (author)
When using GRACE as a tool for hydrology, many different gravity field model products are now available to the end user. The traditional spherical harmonics solutions produced from GRACE are typically obtained through an optimization of the gravity field data at the global scale, and are generated by a number of processing centers around the...
journal article 2008
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Han, S.C. (author), Ditmar, P. (author)
A spatiospectral localization method is discussed for processing the global geopotential coefficients from satellite mission data to investigate time-variable gravity. The time-variable mass variation signal usually appears associated with a particular geographical area yielding inherently regional structure, while the dependence of the...
journal article 2007
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Ditmar, P. (author), Klees, R. (author), Liu, X. (author)
journal article 2007
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Ditmar, P. (author), Visser, P. (author), Klees, R. (author)
journal article 2003
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Klees, R. (author), Ditmar, P. (author), Broersen, P. (author)
An approach to handling colored observation noise in large least-squares (LS) problems is presented. The handling of colored noise is reduced to the problem of solving a Toeplitz system of linear equations. The colored noise is represented as an auto regressive moving-average (ARMA) process. Stability and invertability of the ARMA model allows...
journal article 2003
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