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  • 1
    Call number: 6/S 02.0237(20) / 1. Ex. ; 6/S 02.0237(20) / 2. Ex. ; 15/S 02.0237(20) / 3. Ex. ; 15/S 02.0237(20) / 4. Ex.
    In: Geotechnologien science report
    Description / Table of Contents: Significant advances in the scientific use of space based data were achieved in three joint interdisciplinary projects based on data of the satellite missions CHAMP, GRACE and GOCE within the R&D program GEOTECHNOLOGIEN. It was possible to explore and monitor changes related to the Earth's surface, the boundary layer between atmosphere and solid earth, and the oceans and ice shields. This boundary layer is our habitat and therefore is in the focus of our interests. The Earth's surface is subject to anthropogenetic changes, to changes driven by the Sun, Moon and planets, and by changes caused by processes in the Earth system. The state parameters and their changes are best monitored from space. The theme Observation of the System Earth from Space offers comprehensive insights into a broad range of research topics relevant to society including geodesy, oceanography, atmospheric science (from meteorology to climatology), hydrology and glaciology.
    Type of Medium: Series available for loan
    Pages: xv, 230 S. : farb. graph. Darst, , 70 schw.-w. Ill., 10 farb. Ill. , 235 mm x 155 mm
    ISBN: 9783642321344
    Series Statement: Geotechnologien science report 20
    Classification:
    Geodesy
    Location: Reading room
    Location: Reading room
    Location: Reading room
    Location: Reading room
    Branch Library: GFZ Library
    Branch Library: GFZ Library
    Branch Library: GFZ Library
    Branch Library: GFZ Library
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  • 2
    Call number: SR 90.0092(49)
    In: Mitteilungen der geodätischen Institute der Technischen Universität Graz
    Type of Medium: Series available for loan
    Pages: 104 S.
    Series Statement: Mitteilungen der Geodätischen Institute der Technischen Universität Graz 49
    Language: German
    Location: Lower compact magazine
    Branch Library: GFZ Library
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  • 3
    Series available for loan
    Series available for loan
    Graz
    Associated volumes
    Call number: S 90.0092(77)
    In: Mitteilungen der geodätischen Institute der Technischen Universität Graz
    Type of Medium: Series available for loan
    Pages: XIV, 149 S.
    Series Statement: Mitteilungen der Geodätischen Institute der Technischen Universität Graz 77
    Classification:
    Geodetic Theory and Modeling
    Language: German
    Location: Lower compact magazine
    Branch Library: GFZ Library
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  • 4
    Call number: SR 90.0092(81)
    In: Mitteilungen der geodätischen Institute der Technischen Universität Graz
    Type of Medium: Series available for loan
    Pages: X, 156 S.
    Series Statement: Mitteilungen der geodätischen Institute der Technischen Universität Graz 81
    Classification:
    Gravity Field
    Language: English
    Location: Lower compact magazine
    Branch Library: GFZ Library
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  • 5
    Publication Date: 2023-08-25
    Description: After it was found that the gravity gradients observed by the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite could be significantly improved by an advanced calibration, a reprocessing project for the entire mission data set was initiated by ESA and performed by the GOCE High-level processing facility (GOCE HPF). One part of the activity was delivering the gravity field solutions, where the improved level 1b and level 2 data serve as an input for global gravity field recovery. One well-established approach for the analysis of GOCE observations is the so-called time-wise approach. Basic characteristics of the GOCE time-wise solutions is that only GOCE observations are included to remain independent of any other gravity field observables and that emphasis is put on the stochastic modeling of the observations’ uncertainties. As a consequence, the time-wise solutions provide a GOCE-only model and a realistic uncertainty description of the model in terms of the full covariance matrix of the model coefficients. Within this contribution, we review the GOCE time-wise approach and discuss the impact of the improved data and modeling applied in the computation of the new GO_CONS_EGM_TIM_RL06 solution. The model reflects the Earth’s static gravity field as observed by the GOCE satellite during its operation. As nearly all global gravity field models, it is represented as a spherical harmonic expansion, with maximum degree 300. The characteristics of the model and the contributing data are presented, and the internal consistency is demonstrated. The updated solution nicely meets the official GOCE mission requirements with a global mean accuracy of about 2 cm in terms of geoid height and 0.6 mGal in terms of gravity anomalies at ESA’s target spatial resolution of 100 km. Compared to its RL05 predecessor, three kinds of improvements are shown, i.e., (1) the mean global accuracy increases by 10–25%, (2) a more realistic uncertainty description and (3) a local reduction of systematic errors in the order of centimeters.
    Description: European Space Agency http://dx.doi.org/10.13039/501100000844
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Gauss Centre for Supercomputing e.V./John von Neumann Institute for Computing
    Description: Projekt DEAL
    Description: https://goce-ds.eo.esa.int/oads/access/
    Keywords: ddc:526 ; GOCE ; Spherical harmonics ; Gravity gradients ; Time-wise approach ; Global gravity field model ; Uncertainty description ; Stochastic modeling
    Language: English
    Type: doc-type:article
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  • 6
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    PANGAEA
    In:  Supplement to: Becker, Silvia; Losch, Martin; Brockmann, Jan Martin; Freiwald, Grit; Schuh, Wolf-Dieter (2014): A tailored computation of the mean dynamic topography for a consistent integration into ocean circulation models. Surveys in Geophysics, 35(6), 1507-1525, https://doi.org/10.1007/s10712-013-9272-9
    Publication Date: 2023-05-12
    Description: Geostrophic surface velocities can be derived from the gradients of the mean dynamic topography-the difference between the mean sea surface and the geoid. Therefore, independently observed mean dynamic topography data are valuable input parameters and constraints for ocean circulation models. For a successful fit to observational dynamic topography data, not only the mean dynamic topography on the particular ocean model grid is required, but also information about its inverse covariance matrix. The calculation of the mean dynamic topography from satellite-based gravity field models and altimetric sea surface height measurements, however, is not straightforward. For this purpose, we previously developed an integrated approach to combining these two different observation groups in a consistent way without using the common filter approaches (Becker et al. in J Geodyn 59(60):99-110, 2012, doi:10.1016/j.jog.2011.07.006; Becker in Konsistente Kombination von Schwerefeld, Altimetrie und hydrographischen Daten zur Modellierung der dynamischen Ozeantopographie, 2012, http://nbn-resolving.de/nbn:de:hbz:5n-29199). Within this combination method, the full spectral range of the observations is considered. Further, it allows the direct determination of the normal equations (i.e., the inverse of the error covariance matrix) of the mean dynamic topography on arbitrary grids, which is one of the requirements for ocean data assimilation. In this paper, we report progress through selection and improved processing of altimetric data sets. We focus on the preprocessing steps of along-track altimetry data from Jason-1 and Envisat to obtain a mean sea surface profile. During this procedure, a rigorous variance propagation is accomplished, so that, for the first time, the full covariance matrix of the mean sea surface is available. The combination of the mean profile and a combined GRACE/GOCE gravity field model yields a mean dynamic topography model for the North Atlantic Ocean that is characterized by a defined set of assumptions. We show that including the geodetically derived mean dynamic topography with the full error structure in a 3D stationary inverse ocean model improves modeled oceanographic features over previous estimates.
    Type: Dataset
    Format: application/x-netcdf, 392.8 MBytes
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  • 7
    Publication Date: 2020-05-06
    Description: One of the most critical steps in a multitemporal D-InSAR analysis is the resolution of the phase ambiguities in the context of phase unwrapping. The Extended Minimum Cost Flow approach is one of the potential phase unwrapping algorithms used in the Small Baseline Subset analysis. In a first step, each phase gradient is unwrapped in time using a linear motion model and, in a second step, the spatial phase unwrapping is individually performed for each interferogram. Exploiting the temporal and spatial information is a proven method, but the two-step procedure is not optimal. In this paper, a method is presented which solves both the temporal and spatial phase unwrapping in one single step. This requires some modifications regarding the estimation of the motion model and the choice of the weights. Furthermore, the problem of temporal inconsistency of the data, which occurs with spatially filtered interferograms, must be considered. For this purpose, so called slack variables are inserted. To verify the method, both simulated and real data are used. The test region is the Lower-Rhine-Embayment in the southwest of North Rhine-Westphalia, a very rural region with noisy data. The studies show that the new approach leads to more consistent results, so that the deformation time series of the analyzed pixels can be improved.
    Electronic ISSN: 2072-4292
    Topics: Architecture, Civil Engineering, Surveying , Geography
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  • 8
    Publication Date: 2020-04-15
    Description: Covariance function modeling is an essential part of stochastic methodology. Many processes in geodetic applications have rather complex, often oscillating covariance functions, where it is difficult to find corresponding analytical functions for modeling. This paper aims to give the methodological foundations for an advanced covariance modeling and elaborates a set of generic base functions which can be used for flexible covariance modeling. In particular, we provide a straightforward procedure and guidelines for a generic approach to the fitting of oscillating covariance functions to an empirical sequence of covariances. The underlying methodology is developed based on the well known properties of autoregressive processes in time series. The surprising simplicity of the proposed covariance model is that it corresponds to a finite sum of covariance functions of second-order Gauss–Markov (SOGM) processes. Furthermore, the great benefit is that the method is automated to a great extent and directly results in the appropriate model. A manual decision for a set of components is not required. Notably, the numerical method can be easily extended to ARMA-processes, which results in the same linear system of equations. Although the underlying mathematical methodology is extensively complex, the results can be obtained from a simple and straightforward numerical method.
    Electronic ISSN: 2227-7390
    Topics: Mathematics
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  • 9
    Publication Date: 2019-10-01
    Description: This paper analyses the critical phase unwrapping step in a differential interferometric phase (D-InSAR) stack where both the solving of conventional methods and alternative approaches are discussed. It can be shown that including the temporal relationship between interferograms in the phase unwrapping step improves the results. This leads to the three-dimensional extended minimum cost flow algorithm. To unwrap the phase in a multitemporal way a motion model has to be considered. The estimation of these parameters is an important step. By default, the parameters are estimated in an iterative search process, where in each step, a linear program has to be solved. The best parameters are defined by the minimal costs. Often the choice of this search space is not straightforward. Furthermore, with this discrete optimization function, the solution is often not unique. This paper presents an alternative way to estimate the motion model parameters by maximizing a continuous function, the ensemble phase coherence. With the help of a closed-loop simulation and real data, both methods, the standard and the alternative way, are numerically compared and analyzed. Consequently, it is shown that maximizing the ensemble phase coherence is a good alternative to the established iterative procedure. It offers the advantage that the run time can be reduced considerably and is thus well suited in the processing of large data sets.
    Electronic ISSN: 2072-4292
    Topics: Architecture, Civil Engineering, Surveying , Geography
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  • 10
    Publication Date: 2014-11-25
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
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