Local geoid computation from gravity using the fast fourier transform technique

Nagy, D.; Fury, Rudolf J.

doi:10.1007/bf02519181

Cited by 6 publications

(3 citation statements)

References 6 publications

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“…In fact, most of the procedures in the geoid computation mentioned above, such as applying the remove‐restore technique and the terrain reduction, are well‐known to the geodetic society (Meissl 1971; Omang and Fosberg 2000). Furthermore, the computational issues, namely the selection of the Fourier transformation or the least‐squares collocation have been studied in many papers (International Geoid Service 1997) and showed that nearly all comparable results can be obtained by both methods (Denker 1988; Forsberg and Solheim 1988; Nagy and Fury 1990; Schwarz, Sideris and Forsberg 1990). In practice, however, the determination of a geoid is not such a straightforward procedure.…”

Section: Background and Strategymentioning

confidence: 99%

Update of the precision geoid determination in Korea

Bae

Lee

Kwon

et al. 2011

Geophysical Prospecting

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From the late 1990s, many studies on local geoid construction have been made in South Korea. However, the precision of the previous geoid has remained about 15 cm due to distribution and quality problems of gravity and GPS/levelling data. Since 2007, new land gravity data and GPS/levelling data have been obtained through many projects such as the Korean Land Spatilaization, Unified Control Point and Gravity survey on the Benchmark. The newly obtained data are regularly distributed to a certain degree and show much better improvement in their quality. In addition, an airborne gravity survey was conducted in 2008 to cover the Korean peninsula (South Korea only). Therefore, it is expected that the precision of the geoid could be improved. In this study, the new South Korean gravimetric geoid and hybrid geoid are presented based on land, airborne, ship‐borne, altimeter gravity data, geopotential model and topographic data. As for the methodology, the general remove‐restore approach was applied with the best chosen parameters in order to produce a precise local geoid. The global geopotential model EGM08 was used to remove the low‐frequency components using degree and order up to 360 and the short wavelength part of the gravity signal was dealt with by using the Shuttle Radar Topography Mission data. The parameters determined empirically in this study include for Stokes’ integral 0.5° and for Wong‐Gore kernel 110–120°, respectively and 10 km for both the Bjerhammar sphere depth and attenuation factor. The final gravimetric geoid in South Korea ranges from 20–31 m with a precision of 5.45 cm overall compared to 1096 GPS/levelling data. In addition, the South Korean hybrid geoid produces 3.46 cm and 3.92 cm for degrees of fitness and precision, respectively and a better statistic of 2.37 cm for plain and urban areas was achieved. The gravimetric and hybrid geoids are expected to improve further when the refined land gravity data are included in the near future.

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Section: Background and Strategymentioning

confidence: 99%

Update of the precision geoid determination in Korea

Bae

Lee

Kwon

et al. 2011

Geophysical Prospecting

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“…These models will contribute, in a significant way, to the realization of a Tunisian geoid of high accuracy. Indeed, it would be necessary to integrate various methods to reach the required precision (gravimetric collocation) [44] [45].…”

Section: Discussionmentioning

confidence: 99%

Computing Local Geoid Model Using DTM and GPS Geodetic Points. Case Study: Mejez El Bab-Tunisia

Rebai¹,

Zenned²,

Trabelsi³

2018

IJG

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Different methods have been deployed to compute the geoid, the altimetry reference for surveying applications. One of their main goals is to allow the use of GPS (Global Positioning System) or GNSS heights, which are related to an ellipsoid and therefore must be corrected. Some of these methods are accurate but quite heavy as developed by [1], but one of them is easy to use while giving very good results in a local system: some mm for a 10 × 10 km 2 area developed by [2] [3]. In our study, we have used software called "Géoide Program", previously used at the CERN in Switzerland and set up by [4], which they complete this software allowing a parameterization of general data to provide results in a general system. Then, tests have shown the way to optimize computations without any loss of accuracy. For our computations we use gridded of geodetic heights, from Lambert or WGS 84 datum's, DTM (Digital Terrain Model) and leveled GPS points. To obtain these results, components of the vertical deflection are computed for every point on the grid, deduced from the attraction exerted by the mass Model. Then, geodetic heights are computed by an incremental way from an arbitrary reference. Once the calculation is performed, the geodetic height of any point located in the modelled area can be interpolated. The variations of parameters (mainly size and increments of the DTM and of the modeled area, and ground density) have shown that they do not play a significant role although DTM must be large enough to take into account an important area around a selected zone. However, the choice of the levelled GPS points is primordial. We have performed tests with real data concerning Mejez El Bab zone, in north of Tunisia. Nevertheless, for a few hundreds of square kilometers area, and just by using a DTM and a few levelled GPS points, this method provides results that look

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“…Closed formulas for the gravity anomaly and potential have been derived by Nagy (1966) and Nagy and Fury (1990). The gradient formulas can be found in Forsberg (1984).…”

Section: Prism Mass Modelmentioning

confidence: 99%

Euler deconvolution of gravity tensor gradient data

et al. 2000

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Tensor Euler deconvolution has been developed to help interpret gravity tensor gradient data in terms of 3-D subsurface geological structure. Two forms of Euler deconvolution have been used in this study: conventional Euler deconvolution using three gradients of the vertical component of the gravity vector and tensor Euler deconvolution using all tensor gradients. These methods have been tested on point, prism, and cylindrical mass models using line and gridded data forms. The methods were then applied to measured gravity tensor gradient data for the Eugene Island area of the Gulf of Mexico using gridded and ungridded data forms. The results from the model and measured data show significantly improved performance of the tensor Euler deconvolution method, which exploits all measured tensor gradients and hence provides additional constraints on the Euler solutions.

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Local geoid computation from gravity using the fast fourier transform technique

Cited by 6 publications

References 6 publications

Update of the precision geoid determination in Korea

Update of the precision geoid determination in Korea

Computing Local Geoid Model Using DTM and GPS Geodetic Points. Case Study: Mejez El Bab-Tunisia

Euler deconvolution of gravity tensor gradient data

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