A high-resolution gravimetric quasigeoid model for Vietnam

Vũ, Đình Toàn; Bruinsma, Sean; Bonvalot, Sylvain

doi:10.1186/s40623-019-1045-3

Cited by 15 publications

(23 citation statements)

References 27 publications

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“…A gravimetric-only quasigeoid model (GEOID_LSC) was determined for Vietnam and its surrounding areas based on new gravity data [3]. A set of 29,121 land gravity measurements has been used in combination with fill-in data where no gravity data existed.…”

Section: Gravimetric Quasigeoid Model (Geoid_lsc)mentioning

confidence: 99%

“…A set of 29,121 land gravity measurements has been used in combination with fill-in data where no gravity data existed. A mixed model ('GOCE DIR5 plus EGM2008', [3]) up to degree/order 2159, plus Residual Terrain Model (RTM) effects and gravity field derived from altimetry satellites were used to provide the fill-in information over land and marine areas, respectively. The mixed model up to degree/order 719 was used for the removal of the long and medium wavelengths and the calculation of the quasigeoid restore effects.…”

Section: Gravimetric Quasigeoid Model (Geoid_lsc)mentioning

confidence: 99%

“…For GNSS levelling applications since the late 1990s in Vietnam, Global Gravity field Models (GGM) have been used: EGM96 [1] at first, and currently EGM2008 [2]. However, EGM2008 has a standard deviation (STD) of 29.1 cm when compared with GNSS/levelling points in Vietnam [3], and its accuracy is insufficient to meet fourth-order levelling network specifications (a misclosure of 25 √ k mm over a distance of k km). A high-resolution gravimetric-only quasigeoid model (GEOID_LSC) was recently determined for Vietnam [3].…”

Section: Introductionmentioning

confidence: 99%

“…However, EGM2008 has a standard deviation (STD) of 29.1 cm when compared with GNSS/levelling points in Vietnam [3], and its accuracy is insufficient to meet fourth-order levelling network specifications (a misclosure of 25 √ k mm over a distance of k km). A high-resolution gravimetric-only quasigeoid model (GEOID_LSC) was recently determined for Vietnam [3]. This model has a mean bias of 50 cm, STD of 9.7 cm and differences ranging from 13.6 to 81.6 cm when compared with a set of 812 GNSS/levelling points.…”

Section: Introductionmentioning

confidence: 99%

“…Even at the national scale, the Vietnam LVD is only valid for the continental territory but not for the islands and territorial waters of Vietnam. Thanks to the high-resolution GEOID_LSC model [3], we were able to determine the height for the whole islands towards unifying the height references for Vietnam. Moreover, this model is also used in combination with high-quality GNSS/levelling data (referring to the VLVD) for estimating the gravity potential value of the VLVD to connect the height system of Vietnam with the neighboring countries.…”

Section: Introductionmentioning

confidence: 99%

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A Quasigeoid-Derived Transformation Model Accounting for Land Subsidence in the Mekong Delta towards Height System Unification in Vietnam

et al. 2020

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A vertical offset model for Vietnam and its surrounding areas was determined based on the differences between height anomalies derived from 779 Global Navigation Satellite System (GNSS)/levelling points and those derived from a dedicated high-resolution gravimetric-only quasigeoid model called GEOID_LSC. First, the deterministic transformation model to effectively fit the differences between the quasigeoid and GNSS/levelling heights was based on a third-order polynomial model. Second, the residual height anomalies have been interpolated to a grid employing Least-Squares Collocation. Finally, the distortions were restored to the residual grid. This model can be used for combination with a gravimetric quasigeoid model in GNSS levelling. The quality of GNSS/levelling data in Vietnam was analyzed and evaluated in this study. The annual subsidence rate from ALOS-1 was also used to analyze the effects of subsidence on the quality of GNSS/levelling data in the Mekong Delta. From this we made corrections to improve the accuracy of GNSS/levelling data in this region. The offset model was evaluated using cross-validation technique by comparing with GNSS/levelling data. Results indicate that the offset model has a standard deviation of 5.9 cm in the absolute sense. Based on this offset model, GNSS levelling can be carried out in most of Vietnam’s territory complying third-order levelling requirements, while the accuracy requirements for fourth-order levelling networks is met for the entire country. This model in combination with the developed gravimetric quasigeoid model should also contribute to the modernization of Vietnam’s height system. We also used high-quality GNSS/levelling data and the determined quasigeoid model to determine the geopotential value W0 for the Vietnam Local Vertical Datum. The gravity potential of the Vietnam Local Vertical Datum is estimated equal to W 0 LVD = 62,636,846.81 ± 0.70 m2s−2 with the global equipotential surface realized by the conventional value W0 = 62,636,853.4 m2s−2.

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Section: Gravimetric Quasigeoid Model (Geoid_lsc)mentioning

confidence: 99%

Section: Gravimetric Quasigeoid Model (Geoid_lsc)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Quasigeoid-Derived Transformation Model Accounting for Land Subsidence in the Mekong Delta towards Height System Unification in Vietnam

et al. 2020

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Potential of cold-atom airborne gravimetry to improve coastal gravity field and quasigeoid modelling

Vu,

Bonvalot,

Seoane

et al. 2024

J Geod

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We investigate using the GIRAFE cold-atom gravimeter during an airborne gravity survey for improving gravity field and quasigeoid modelling. The study is conducted over the Bay of Biscay, France. Geoid/quasigeoid determination is usually a major challenge over such coastal areas due to scarce and inconsistent gravity data. In a first step, the GIRAFE dataset is analysed and compared with available surface gravity data as well as with global altimetry models from UCSD and DTU. The comparisons indicate that the DTU model is better than the UCSD model within around 10 km from the coastline. Furthermore, recent satellite altimeter missions significantly improve the altimetry models in coastal areas. A significant bias (− 4.00 mGal) in shipborne data is also found from this comparison. In a second step, eight quasigeoid solutions are calculated to evaluate the contribution of GIRAFE data. This contribution reaches 3 cm in terms of height anomaly for DTU21 while being much larger for UCSDv31 and shipborne data. Finally, the quasigeoid solutions are validated using GNSS-levelling data. The results indicate that using GIRAFE data improves by approximately 50% the quality of quasigeoid models over land near the coast. The highest accuracy, around 1 cm, is achieved when GIRAFE data are merged with refined gravity data. Importantly, the standard deviation is just 1.2 cm when compared with GNSS-levelling points if using only GIRAFE data over marine areas, which is very close to the 1 cm goal of geoid/quasigeoid model determination in modern geodesy. This study thus confirms the benefits of performing airborne gravity survey using quantum sensors.

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Refinement of gravimetric geoid model by incorporating terrestrial, marine, and airborne gravity using KTH method

Pa’suya

Din

Yusoff³

et al. 2021

Arab J Geosci

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A high-resolution gravimetric quasigeoid model for Vietnam

Cited by 15 publications

References 27 publications

A Quasigeoid-Derived Transformation Model Accounting for Land Subsidence in the Mekong Delta towards Height System Unification in Vietnam

A Quasigeoid-Derived Transformation Model Accounting for Land Subsidence in the Mekong Delta towards Height System Unification in Vietnam

Potential of cold-atom airborne gravimetry to improve coastal gravity field and quasigeoid modelling

Refinement of gravimetric geoid model by incorporating terrestrial, marine, and airborne gravity using KTH method

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