Mutual evaluation of global gravity models (EGM2008 and GOCE) and terrestrial data in Amazon Basin, Brazil

Bomfim, Everton Pereira; Braitenberg, Carla; Molina, Eder Cassola

doi:10.1093/gji/ggt283

Cited by 35 publications

(21 citation statements)

References 12 publications

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“…We have compared averaged free-air gravity anomalies with gravity anomalies computed from DIR-R5, EGM2008, GECO and TIM-R5 at d/o 90, 150, 200, 222, 234, and 250 (see Figure 3). Recall that the direct comparison of terrestrial and satellite gravity data (see panels (c) and (d) of Figure 2) does not take into consideration the varying frequencies, or as it were, assumes that the terrestrial data and satellite data have the same We have decided to select the coordinates of the smoothed gravity anomalies to coincide with the coordinates of the original data points as opposed to grid knots, as used in reference [5]. This decision was partly influenced by the likelihood of errors arising from resampling the original data into a grid.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

“…Because GGMs are generally known to be very accurate in the low frequencies, LP filters have been used as a way of assessing systematic errors in ground-based gravity data [4,5] by filtering the terrestrial gravity data so that they can be compared with GGMs. Following Huang et al [4], an LP filter is generally given by the equation: ∆g…”

Section: The Gaussian Averaging Filtermentioning

confidence: 99%

“…To this end, the main contribution of this paper is the extension of the Gaussian averaging function from the traditional smoothing of the Earth's gravity field [3] and determination of systematic errors in terrestrial gravity data [4,5] to the selection of an optimal GGM and d/o for geoid computation. This is the first attempt at an informed selection of both GGM and d/o using a low pass filter and is especially useful for regions with limited financial capital and low-resolution gravity data, albeit this approach may be used even in regions with comparatively high-resolution gravity data.…”

Section: Introductionmentioning

confidence: 99%

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Towards the Selection of an Optimal Global Geopotential Model for the Computation of the Long-Wavelength Contribution: A Case Study of Ghana

2017

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Abstract:The selection of a global geopotential model (GGM) for modeling the long-wavelength for geoid computation is imperative not only because of the plethora of GGMs available but more importantly because it influences the accuracy of a geoid model. In this study, we propose using the Gaussian averaging function for selecting an optimal GGM and degree and order (d/o) for the remove-compute-restore technique as a replacement for the direct comparison of terrestrial gravity anomalies and GGM anomalies, because ground data and GGM have different frequencies. Overall, EGM2008 performed better than all the tested GGMs and at an optimal d/o of 222. We verified the results by computing geoid models using Heck and Grüninger's modification and validated them against GPS/trigonometric data. The results of the validation were consistent with those of the averaging process with EGM2008 giving the smallest standard deviation of 0.457 m at d/o 222, resulting in an 8% improvement over the previous geoid model. In addition, this geoid model, the Ghanaian Gravimetric Geoid 2017 (GGG 2017) may be used to replace second-order class II leveling, with an expected error of 6.8 mm/km for baselines ranging from 20 to 225 km.

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Section: Numerical Results and Discussionmentioning

confidence: 99%

Section: The Gaussian Averaging Filtermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Towards the Selection of an Optimal Global Geopotential Model for the Computation of the Long-Wavelength Contribution: A Case Study of Ghana

2017

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“…All reductions were made considering this 4,000 m height. As mentioned above, the formal error at the full resolution of the GOCE spherical harmonic expansion (N D 250) is estimated to be globally 5.1 mGal (Bomfim et al 2013). The GOCE derived gravity field presents an improvement with respect to existing gravity data, as has been shown in studies aimed at the evaluation of the GOCE field (Hirt et al 2011).…”

Section: The Reductions Of the Goce Gravity Fieldmentioning

confidence: 92%

“…After downward continuation of the observations to ground level the precision at 80 km wavelength is comparable to that of an aero gravimetric campaign (measurements accuracy near to 4 mGal), with the great bonus of having a global access to the observations (Braitenberg et al 2010). In fact the gravity anomaly error up to degrees 180, 200, and 250 derived from the cumulative error curves of the third generation GOCE only model TIM (Pail et al 2011) spherical harmonic expansion is 0.8 mGal, 1.5 mGal and 5.1 mGal respectively (Bomfim et al 2013). This does not imply that the aerogravimetric campaign cannot have greater spatial resolution, but it shows that at the long-wavelength end of the aero-gravimetric measurements the two observations are of similar precision.…”

Section: Introductionmentioning

confidence: 95%

A Grip on Geological Units with GOCE

Braitenberg

2014

Gravity, Geoid and Height Systems

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The scope of this work is to show the observations of satellite GOCE in mapping geological units in a key area for mineral exploration, which is also a key location for understanding the formation of the America and Africa continents from the former western Gondwana. The observations of the satellite GOCE have allowed to achieve a qualitative leap ahead in today's global gravity. The new global field has an improved resolution of 80 km with precision of 5 mGal; this resolution is sufficient to study crustal thickness variations and the upper crustal structure. Geological macrostructures generating density variations are mapped for the first time by a global satellite derived field in continental areas, which opens a new series of applications in geophysical exploration. The study area is located in and around the Congo craton, which is a part of Africa poorly covered in ground gravity surveys, so that GOCE data are essential there. The GOCE gravity field is reduced by the effect of topography, of the isostatic crustal thickness and by sediments, obtaining the field representative of the geologic lineaments. The foldbelts surrounding the Congo craton are identified well through the field, generating signals near to 50 mGal. Compared to the existing geologic map, along the Kibalien belt, a narrow belt with increased density is distinguished, about 125 km wide, and 800 km long, that must be representative of a major compressive or magmatic geologic event that generated these rocks. The distinction of separate geologic units characterized by density variation is useful for identifying the areas where focused future geophysical and geologic mapping will be effective in the exploration of new mineral resources.

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Analysis of the Illapel Mw = 8.3 Thrust Earthquake Rupture Zone Using GOCE-Derived Gradients

Álvarez¹,

Pesce²,

Giménez³

et al. 2017

The Chile-2015 (Illapel) Earthquake and Tsunami

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Mutual evaluation of global gravity models (EGM2008 and GOCE) and terrestrial data in Amazon Basin, Brazil

Cited by 35 publications

References 12 publications

Towards the Selection of an Optimal Global Geopotential Model for the Computation of the Long-Wavelength Contribution: A Case Study of Ghana

Towards the Selection of an Optimal Global Geopotential Model for the Computation of the Long-Wavelength Contribution: A Case Study of Ghana

A Grip on Geological Units with GOCE

Analysis of the Illapel Mw = 8.3 Thrust Earthquake Rupture Zone Using GOCE-Derived Gradients

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