Formulation and validation of a global laterally varying topographical density model

Sheng, Michael; Shaw, Cliff S. J.; Vaníček, Petr; Kingdon, Robert; Santos, Marcelo C.; Foroughi, Ismael

doi:10.1016/j.tecto.2019.04.005

Cited by 35 publications

(20 citation statements)

References 14 publications

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“…In future work, we plan to introduce a higher-resolution laterally varying global topographic density model (e.g., UNB_ TopoDens) and to forward model the topographic gravity field up to a higher degree using the approach presented in this paper. With this we expect to receive a more realistic topographic gravity field together with uncertainty estimation derived from UNB_TopoDens (Sheng et al 2019) which then will be used to augment EIGEN-6C4 and further develop the EIGEN-X series. Moreover, the methodology presented in this paper allows us to introduce different density values for different shells positioned at different depths.…”

Section: Discussionmentioning

confidence: 99%

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Forward Gravity Modelling to Augment High-Resolution Combined Gravity Field Models

et al. 2020

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During the last few years, the determination of high-resolution global gravity field has gained momentum due to high-accuracy satellite-derived observations and development of forward gravity modelling. Forward modelling computes the global gravitational field from mass distribution sources instead of actual gravity measurements and helps improving and complementing the medium to high-frequency components of the global gravity field models. In this study, we approximate the global gravity potential of the Earth's upper crust based on ellipsoidal approximation and a mass layer concept. Such an approach has an advantage of spectral methods and also avoids possible instabilities due to the use of a sequence of thin ellipsoidal shells. Lateral density within these volumetric shells bounded by confocal lower and upper shell ellipsoids is used in the computation of the ellipsoidal harmonic coefficients which are then transformed into spherical harmonic coefficients on the Earth's surface in the final step. The main outcome of this research is a spectral representation of the gravitatioal potential of the Earth's upper crust, computed up to degree and order 3660 in terms of spherical harmonic coefficients (ROLI_EllApprox_SphN_3660). We evaluate our methodology by comparing this model with other similar forward models in the literature which show sub-cm agreement in terms of geoid undulations. Finally, EIGEN-6C4 is augmented by ROLI_EllApprox_SphN_3660 and the gravity field functionals computed from the expanded model which has about 5 km half-wavelength spatial resolution are compared w.r.t. ground-truth data in different regions worldwide. Our investigations show that the contribution of the topographic model increases the agreement up to ~ 20% in the gravity value comparisons.

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Section: Discussionmentioning

confidence: 99%

“…bin). It is worth noting that there are other density models (Gladkikh and Tenzer 2011;Sheng et al 2019) which can be used in the modelling as well. In this study, Earth2014 (Hirt and Rexer 2015) is used and the grid files can be downloaded from the Curtin University's website http://ddfe.curti n.edu.au/gravi tymod els/Earth 2014/data_1min/.…”

Section: Datamentioning

confidence: 99%

Forward Gravity Modelling to Augment High-Resolution Combined Gravity Field Models

et al. 2020

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“…A better knowledge of the distribution of these densities in the topography would make it possible to improve the modeling of the residual terrain effects (Hirt, 2010). So, for futures studies of RTM effects on the study area, we should integrate a topographical density model in our computations (Sheng et al, 2019).…”

Section: Methodsmentioning

confidence: 99%

Refinement of Bouguer anomalies derived from the EGM2008 model, impact on gravimetric signatures in mountainous region: Case of Cameroon Volcanic Line, Central Africa

Kamto

Adiang

Nguiya

et al. 2020

Earth and Planetary Physics

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“…The introduction of a laterally variable topographic density model will also be of importance. Recently, Sheng et al (2019) developed a two-dimensional global topographic density model at a 30 × 30 arcsecond resolution. Considering such a heterogeneous density distribution would enhance the accuracy of the terrain gravity correction, the indirect effect, and the RTM.…”

Section: Future Prospectsmentioning

confidence: 99%

Refinement of a gravimetric geoid model for Japan using GOCE and an updated regional gravity field model

Matsuo

Kuroishi

2020

Earth Planets Space

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We developed a refined gravimetric geoid model for Japan on a 1 × 1.5 arc-minute (2 km) grid from a GOCE-based satellite-only global geopotential model and a regional gravity field model updated in this study. First, we have constructed a regional gravity field model for Japan using updated gravity datasets together with a residual terrain model: 323,431 land gravity data, 77,389 shipborne marine gravity data, and Sandwell's v28.1 altimetry-derived global marine gravity model. Then, the geoid was determined with the gravity field model. The methodology for gravimetric geoid determination was based on the remove-compute-restore technique with Helmert's second method of condensation of topography (Stokes-Helmert scheme). Here, the hybrid Meissl-Molodensky modified spheroidal Stokes kernel was employed to minimize the truncation error under an appropriate combination of different kinds of gravity data. In addition, a high-resolution GSI-DEM on a 0.4 × 0.4 arc-second (10 m) grid, together with the SRTM-DEM on a 7.5 × 11.25 arc-second (250 m) grid, was utilized for precisely applying terrain correction to the regional gravity field model. Consequently, we created a gravimetric geoid model for Japan, consistent with 971 GNSS/leveling geoid heights distributed over the four main islands of Japan with a standard deviation of 5.7 cm, showing a considerable improvement by 2.3 cm over the previous model (JGEOID2008). However, there remain some areas with large discrepancies between the computed and GNSS/leveling geoid heights in northern Japan (Hokkaido), mountainous areas in central Japan, and some coastal regions. Since terrestrial gravity data are especially sparse in these areas, we speculated that the largeness of the geoid discrepancies there could be partly attributed to the insufficient coverage and accuracy of gravity data. The Geospatial Information Authority of Japan has started airborne gravity surveys to be covered over the Japanese Islands, and in future, we plan to develop a geoid model for Japan further accurately by incorporating airborne gravity data to come.

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Formulation and validation of a global laterally varying topographical density model

Cited by 35 publications

References 14 publications

Forward Gravity Modelling to Augment High-Resolution Combined Gravity Field Models

Forward Gravity Modelling to Augment High-Resolution Combined Gravity Field Models

Refinement of Bouguer anomalies derived from the EGM2008 model, impact on gravimetric signatures in mountainous region: Case of Cameroon Volcanic Line, Central Africa

Refinement of a gravimetric geoid model for Japan using GOCE and an updated regional gravity field model

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