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document
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
document
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
document
Tangdamrongsub, N. (author), Ditmar, P.G. (author), Steele-Dunne, S.C. (author), Gunter, B.C. (author), Sutanudjaja, E. H. (author)
In this study, satellite observations including gravity (GRACE), terrestrial reflectance (MODIS), and global precipitation (TRMM) data, along with the output from the PCR-GLOBWB hydrological model, are used to generate monthly and sub-monthly terrestrial water storage (TWS) estimates and quantify flood events over the Tonlé Sap basin between...
journal article 2016
document
Ran, J. (author), Ditmar, P.G. (author), Klees, R. (author), Farahani, H. (author)
We present an improved mascon approach to transform monthly spherical harmonic solutions based on GRACE satellite data into mass anomaly estimates in Greenland. The GRACE-based spherical harmonic coefficients are used to synthesize gravity anomalies at satellite altitude, which are then inverted into mass anomalies per mascon. The limited...
journal article 2017
document
Ditmar, P.G. (author), Tangdamrongsub, N. (author), Ran, J. (author), Klees, R. (author)
We propose a technique to regularize a GRACE-based mass-anomaly time-series in order to (i) quantify the Standard Deviation (SD) of random noise in the data, and (ii) reduce the level of that noise. The proposed regularization functional minimizes the Month-to-month Year-to-year Double Differences (MYDD) of mass anomalies. As such, it does...
journal article 2018
document
Ditmar, P.G. (author)
Time-varying Stokes coefficients estimated from GRACE satellite data are routinely converted into mass anomalies at the Earth’s surface with the expression proposed for that purpose by Wahr et al. (J Geophys Res 103(B12):30,205–30,229, 1998). However, the results obtained with it represent mass transport at the spherical surface of 6378 km...
journal article 2018
document
Sun, Y. (author), Riva, R.E.M. (author), Ditmar, P.G. (author), Rietbroek, Roelof (author)
We present a new approach to estimate time variations in J2. Those variations are represented as the sum of contributions from individual sources. This approach uses solely Gravity Recovery And Climate Experiment (GRACE) data and the geoid fingerprints of mass redistributions that take place both at the surface and in the interior of the solid...
journal article 2019
document
Groh, Andreas (author), Horwath, Martin (author), Horvath, Alexander (author), Meister, Rakia (author), Wouters, B. (author), Ditmar, P.G. (author), Ran, J. (author), Klees, R. (author), Schrama, E.J.O. (author)
Satellite gravimetry data acquired by the Gravity Recovery and Climate Experiment (GRACE) allows to derive the temporal evolution in ice mass for both the Antarctic Ice Sheet (AIS) and the Greenland Ice Sheet (GIS). Various algorithms have been used in a wide range of studies to generate Gravimetric Mass Balance (GMB) products. Results from...
journal article 2019
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