scholarly journals The Impact of Noise in a GRACE/GOCE Global Gravity Model on a Local Quasi‐Geoid

2019 ◽  
Vol 124 (3) ◽  
pp. 3219-3237 ◽  
Author(s):  
Cornelis Slobbe ◽  
Roland Klees ◽  
Hassan H. Farahani ◽  
Lennard Huisman ◽  
Bas Alberts ◽  
...  
Keyword(s):  
Gravity Model ◽  
Global Gravity ◽  
The Impact ◽  
Global Gravity Model

scholarly journals Generalized geoidal estimators for deterministic modifications of spherical Stokes' function

2010 ◽  
Vol 40 (1) ◽  
pp. 45-64 ◽  
Author(s):  
Michal Šprlák
Keyword(s):  
Gravity Model ◽  
Spherical Harmonic ◽  
Gravity Data ◽  
Surface Integral ◽  
Terrestrial Gravity ◽  
Global Gravity ◽  
Higher Derivatives ◽  
Stokes Integral ◽  
Global Gravity Model ◽  
Local Geoid

Generalized geoidal estimators for deterministic modifications of spherical Stokes' function Stokes' integral, representing a surface integral from the product of terrestrial gravity data and spherical Stokes' function, is the theoretical basis for the modelling of the local geoid. For the practical determination of the local geoid, due to restricted knowledge and availability of terrestrial gravity data, this has to be combined with the global gravity model. In addition, the maximum degree and order of spherical harmonic coefficients in the global gravity model is finite. Therefore, modifications of spherical Stokes' function are used to obtain faster convergence of the spherical harmonic expansion. Decomposition of Stokes' integral and modifications of Stokes' function have been studied by many geodesists. In this paper, the proposed deterministic modifications of spherical Stokes' function are generalized. Moreover, generalized geoidal estimators, when the Stokes' integral is decomposed in to spectral and frequency domains, are introduced. Higher derivatives of spherical Stokes' function and their numerical stability are discussed. Filtering and convergence properties for deterministic modifications of the spherical Stokes' function in the form of a remainder of the Taylor polynomial are studied as well.

Joint estimation of gravity anomalies using second and third order potential derivatives

2019 ◽  
Author(s):  
Mohsen Romeshkani ◽  
Mohammad A Sharifi ◽  
Dimitrios Tsoulis
Keyword(s):  
Gravity Field ◽  
Gravity Model ◽  
Variance Component ◽  
Gravity Anomalies ◽  
Variance Component Estimation ◽  
Third Order ◽  
Global Gravity ◽  
Isostatic Gravity ◽  
Component Estimation ◽  
Global Gravity Model

Abstract Satellite gradiometry data provide the framework for estimating and validating Earth's gravity field from second and third order derivatives of the Earth's gravitational potential. Such procedures are especially useful when applied locally, as they relate to local and regional characteristics of the real gravity field. In the present study a joint inversion procedure is proposed for the estimation of gravity anomalies at sea surface level from second and third order potential derivatives, based on a standard Gauss-Markov estimation model. The estimation procedure is applied for a test area stretching over Iran involving simulated grids from GOCE-only model GGM_TIM_R05 at GOCE altitude and gravity anomalies recovered at sea level. In order to validate the proposed estimation three different reductions have been considered independently, namely the removal of the long-wavelength part of the observed field through a global gravity model, the removal of the high-frequency part of the field through the incorporation of a topographic/isostatic gravity model and the application of variance component estimation. The application of a global gravity model leads to an improvement in the individual component estimation of the order of magnitude 3 per cent to 73 per cent, with a significant reduction in bias to 4 mGal. Smoother gradient components can come out according to removing the topography and taking into account for isostasy that improved up results of recovery to 25 per cent for the radial second order derivative. Finally, the implementation of variance component estimation leads to no significant improvement in results of recovered gravity anomalies.

scholarly journals Comparison and testing of GOCE global gravity models in Central Europe

2011 ◽  
Vol 1 (4) ◽  
pp. 333-347 ◽  
Author(s):  
Juraj Janák ◽  
Martin Pitoňák
Keyword(s):  
Reference Frame ◽  
Gravity Model ◽  
Central Europe ◽  
Terrestrial Reference Frame ◽  
Gravity Models ◽  
Direct Solution ◽  
Model Solutions ◽  
Global Gravity ◽  
Global Gravity Models ◽  
Global Gravity Model

Comparison and testing of GOCE global gravity models in Central EuropeThree different global gravity model solutions have been released by the European GOCE Gravity Consortium: a direct solution, a time-wise solution and a space-wise solution. To date, two releases of each solution have been issued. Each of these solutions has specific positives and weaknesses. This paper shows and analyzes the differences between each solution in Central Europe by means of comparison with respect to the EGM2008 and GOCO02S global gravity models. In order to make an independent comparison, the global GOCE models are tested by the SKTRF (Slovak Terrestrial Reference Frame) network in Slovakia.

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