Analysis of the Discrepancies Between the Brazilian Vertical Reference Frame and GOCE-Based Geopotential Model

Ferreira, Vagner G.; Freitas, Sílvio Rogério Correia de; Heck, Bernhard

doi:10.1007/1345_2015_20

Cited by 5 publications

(7 citation statements)

References 20 publications

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“…For the computation of the zero-degree term, we use 62,636,856.00 m 2 ·s −2 and 62,636,851.7146 m 2 s −2 as the potentials on the geoid W 0 and WGS 84 ellipsoid U 0 [1,22]. We validate these geoid models by first comparing them with 11 GPS/trigonometric data in what is known as absolute validation, where the geoid heights from the gravimetric geoid are compared with geometric geoid heights from GPS/trigonometric data (N GPS = h P − H P ).…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

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%

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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“…In Brazil, with the old RAAP normal orthometric heights, Ferreira, De Freitas and Heck (2016) analyzed the use of the approach based on parametric modeling for the entire national territory. Specifically for the São Paulo state, in the context of the new RAAP normal heights, Delgado and Rodrigues (2022) have investigated the use of the geopotential-based approach with an adaptation.…”

Section: Palavras-chave: Altitudes Normais Brasileiras; Modelo Global...mentioning

confidence: 99%

“…However, an essential factor to be analyzed with the use of the approaches based on the mean of discrepancies between height anomalies, the GBPV solution, and the use of the zero-level geopotential value are the approximation and measurement errors in the input data set for the estimation of the transformation parameters (Kotsakis, Katsambalos & Ampatzidis 2012;Ferreira, De Freitas & Heck 2016). According to Grombein, Seitz and Heck (2017), these errors cause biases in the height datum offset, which will vary regionally.…”

Section: Palavras-chave: Altitudes Normais Brasileiras; Modelo Global...mentioning

confidence: 99%

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Linkage of Normal Heights Obtained from GNSS and Refined XGM2019 GGM to Brazilian Vertical Data Using Different Approaches

Delgado

Rodrigues

2023

Anu. Inst. Geociênc.

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This work aimed to analyze the use of different approaches to link normal heights obtained via Global Navigation Satellite System (GNSS)/Global Geopotential Model (GGM) refined by the RTM technique to the Brazilian Vertical Data (Imbituba Brazilian Vertical Datum – IBVD and Santana Brazilian Vertical Datum – SBVD). Specifically, it analyzed approaches based on the weighted mean of discrepancies between height anomalies, the zero- level geopotential value, the Geodetic Boundary Value Problem (GBVP) solution, and the use of parametric modeling of a plane with a scale factor. For the numerical tests, two different study regions have been used, the first with heights referenced to IBVD and the second to SBVD. Using the first three approaches, the local modeling idea has been investigated in both regions. In this context, spatial cluster analysis of the outliers of differences between local and global height anomalies defined the sub-regions. In the fourth approach, the treatment of local modeling was initially considered. In the accuracy analysis of linkages, it has been verified that approaches based on the mean of the discrepancies between height anomalies and using zero- level geopotential value propose practically the same results. On the other hand, there were improvements at the centimeter level with the use of the GBPV solution-based approach compared to the first two, except for two worsening cases. With the approach based on parametric modeling, the accuracy results were mainly worse considering the approaches with local modeling. The most significant differences reached the decimeter level.

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“…Comparisons with other recent combined models, such as EIGEN-6C4 (Förste et al 2014), and a local geoid/quasigeoid based on new gravity datasets show that the proposed combination, weighting the different input contributions not only on a global basis but also according to some local error information, can perform even better than other more sophisticated combinations in areas where the input global error description is not reliable enough. Solution 4 is more performant than the solution given by De Freitas et al (2016) because the referred local error was not used in the enhancement of combined model in that solution as described in Ferreira, De Freitas and Heck (2015).…”

Section: The Corrected Normal Heightmentioning

confidence: 99%

Physical Connection Between BVRF Segments Based on Leveling Associated With Gravimetry

2019

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Considering the efforts to establish Global Reference Systems linked to the geopotential space, new alternatives are sought to address the problems found in the classic national vertical networks. The Brazilian Vertical Reference Frame (BVRF) was materialized in two different segments with independent datums (Imbituba and Santana tide gauges) due to the terrain difficulties for conventional leveling. The 2018 BVRF realization, in the geopotential space, still remains without interoperability between its segments. We analyze alternatives for physical connection based on the new precepts of the International Association of Geodesy (IAG) involving the geopotential space. Some proposed solutions for physical connection based on GPS leveling associated with gravimetry are presented. These solutions were developed with the aim of evidencing the discrepancy between the two BVRF segments, now carried out in terms of geopotential numbers and normal heights. The results indicate differences ranging from about 45 cm to 140 cm between the two segments depending on the strategy employed. Comparisons with previous determinations based on indirect strategies and involving previous BVRF realizations are made.

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Analysis of the Discrepancies Between the Brazilian Vertical Reference Frame and GOCE-Based Geopotential Model

Cited by 5 publications

References 20 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

Linkage of Normal Heights Obtained from GNSS and Refined XGM2019 GGM to Brazilian Vertical Data Using Different Approaches

Physical Connection Between BVRF Segments Based on Leveling Associated With Gravimetry

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