Improved determination of heights using a conversion surface by combining gravimetric quasi-geoid/geoid and GPS-levelling height differences

Nahavandchi, Hossein; Soltanpour, A.

doi:10.1007/s11200-006-0010-3

Cited by 21 publications

(9 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…where (z, y) is the SRBF, N i and β i,k are the number and unknown coefficient of the SRBF at level i, respectively, and y i,n is the position of the SRBF at this level. The reference GGM and RTM corrections are removed from the original data to decrease the signal correlation length and smooth the data (Omang and Forsberg, 2000). Then, only the residual disturbing potential T res (z) is parameterized by the SRBF using the MRR approach.…”

Section: Multilayer Approachmentioning

confidence: 99%

A multilayer approach and its application to model a local gravimetric quasi-geoid model over the North Sea: QGNSea V1.0

Luo

Zhong

et al. 2018

Geosci. Model Dev.

View full text Add to dashboard Cite

Abstract. A multilayer approach is set up for local gravity field recovery within the framework of multi-resolution representation, where the gravity field is parameterized as the superposition of multiple layers of Poisson wavelets located at different depths beneath the Earth's surface. The layers are designed to recover gravity signals at different scales, where the shallow and deep layers mainly capture the short- and long-wavelength signals, respectively. The depths of these layers are linked to the locations of different anomaly sources beneath the Earth's surface, which are estimated by wavelet decomposition and power spectrum analysis. For testing the performance of this approach, a gravimetric quasi-geoid model over the North Sea, QGNSea V1.0, is modeled and validated against independent control data. The results show that the multilayer approach fits the gravity data better than the traditional single-layer approach, particularly in regions with topographical variation. An Akaike information criterion (AIC) test shows that the multilayer model obtains a smaller AIC value and achieves a better balance between the goodness of fit of data and the simplicity of the model. Further, an evaluation using independent GPS/leveling data tests the ability of regional models computed from different approaches towards realistic extrapolation, which shows that the accuracies of the QGNSea V1.0 derived from the multilayer approach are better by 0.4, 0.9, and 1.1 cm in the Netherlands, Belgium, and parts of Germany, respectively, than that using the single-layer approach. Further validation with existing models shows that QGNSea V1.0 is superior with respect to performance and may be beneficial for studying ocean circulation between the North Sea and its neighboring waters.

show abstract

Section: Multilayer Approachmentioning

confidence: 99%

A multilayer approach and its application to model a local gravimetric quasi-geoid model over the North Sea: QGNSea V1.0

Luo

Zhong

et al. 2018

Geosci. Model Dev.

View full text Add to dashboard Cite

show abstract

“…Originally, corrector surfaces were used to facilitate the transformation of ellipsoidal heights into levelling-based heights (e.g. Featherstone 1998;Grebenitcharsky et al 2005;Nahavandchi and Soltanpour 2006). However, they are also being used as a simple tool to obtain improved quasi-geoid models from a combination of gravity anomalies and GNSS-levelling data (e.g.…”

Section: Comparison With the Corrector-surface Approachmentioning

confidence: 99%

The combination of GNSS-levelling data and gravimetric (quasi-) geoid heights in the presence of noise

Klees

Prutkin

2010

J Geod

View full text Add to dashboard Cite

We propose a methodology for the combination of a gravimetric (quasi-) geoid with GNSS-levelling data in the presence of noise with correlations and/or spatially varying noise variances. It comprises two steps: first, a gravimetric (quasi-) geoid is computed using the available gravity data, which, in a second step, is improved using ellipsoidal heights at benchmarks provided by GNSS once they have become available. The methodology is an alternative to the integrated processing of all available data using least-squares techniques or least-squares collocation. Unlike the correctorsurface approach, the pursued approach guarantees that the corrections applied to the gravimetric (quasi-) geoid are consistent with the gravity anomaly data set. The methodology is applied to a data set comprising 109 gravimetric quasi-geoid heights, ellipsoidal heights and normal heights at benchmarks in Switzerland. Each data set is complemented by a full noise covariance matrix. We show that when neglecting noise correlations and/or spatially varying noise variances, errors up to 10% of the differences between geometric and gravimetric quasi-geoid heights are introduced. This suggests that if highquality ellipsoidal heights at benchmarks are available and are used to compute an improved (quasi-) geoid, noise covariance matrices referring to the same datum should be used in the data processing whenever they are available. We compare the methodology with the corrector-surface approach using various corrector surface models. We show that the commonly used corrector surfaces fail to model the more complicated spatial patterns of differences between geometric and gravimetric quasi-geoid heights present in the data set. More flexible parametric models such as radial basis R. Klees (B) · I. Prutkin Delft Institute of Earth Observation and Space Systems (DEOS), Delft University of Technology, Kluyverweg 1, 2629 HS Delft, The Netherlands e-mail: r.klees@tudelft.nl function approximations or minimum-curvature harmonic splines perform better. We also compare the proposed method with generalized least-squares collocation, which comprises a deterministic trend model, a random signal component and a random correlated noise component. Trend model parameters and signal covariance function parameters are estimated iteratively from the data using non-linear least-squares techniques. We show that the performance of generalized least-squares collocation is better than the performance of corrector surfaces, but the differences with respect to the proposed method are still significant.

show abstract

“…Typically given in the form of a spherical harmonic series (SHS) expansion for the external gravitational potential [10], [25], these models provide valuable tools for several geodetic and surveying applications. From a geodetic positioning perspective, for example, modern geopotential models play a key role for the unification of national height systems and the support of vertical datum modernization efforts based on precise GPS positioning [1], [4], [6], [21], [22], [30]. In view of the recent progress and upcoming improvements in gravity field mapping (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…), they often can lead to a reliable assessment of the GGM accuracy level over different areas. Furthermore, the statistical agreement between absolute and/or relative GPS-based and GGM-based geoid undulations, as well as the spatial pattern of their differences, provide useful information for the performance of GGM/GPS-aided levelling and the feasibility of fitting auxiliary parametric models to improve the consistency among ellipsoidal heights, local orthometric heights and GGM geoid undulations within specific geographical regions [3], [4], [ 6], [13], [21].…”

Section: Introductionmentioning

confidence: 99%

Quality Analysis of Global Geopotential Models at 1542 GPS/levelling Benchmarks Over the Hellenic Mainland

Kotsakis

Katsambalos

2010

Survey Review

View full text Add to dashboard Cite

The aim of this study is to present the results of several 'external' quality tests for the most recent (at the time of writing this paper) global geopotential models (GGMs) using precise GPS and leveled orthometric heights over the area of Greece. The tested GGMs include the GRACE-based combined model GGM03C, the latest EIGEN-type combined models EIGEN-GL04C and EIGEN-GL05C, the ultra-high resolution model EGM08 that was released last year by the US National GeospatialIntelligence Agency, and also the older NASA/NIMA/OSU's EGM96 model. The evaluation tests are based on comparisons of absolute and relative geoid undulations that are computed from the selected GGMs and the external GPS/levelling data. The test network covers the entire part of the Hellenic mainland and it consists of more than 1500 benchmarks which belong to the Hellenic national triangulation network, with direct levelling ties to the Hellenic vertical reference frame. The spatial positions of these benchmarks have been recently re-determined at cm-level accuracy (with respect to ITRF00) through a nation-wide GPS campaign that was organized in the frame of the HEPOS project. Our results show that the EGM08 model offers a remarkable improvement for the agreement among geoidal, ellipsoidal and orthometric heights in the mainland part of Greece, compared to the performance of other combined GGMs over the same area. Finally, our study gives a preliminary (yet realistic) accuracy assessment for GGM/GPS-aided orthometric height determination, over different baseline lengths, throughout the Hellenic mainland.

show abstract

Improved determination of heights using a conversion surface by combining gravimetric quasi-geoid/geoid and GPS-levelling height differences

Cited by 21 publications

References 18 publications

A multilayer approach and its application to model a local gravimetric quasi-geoid model over the North Sea: QGNSea V1.0

A multilayer approach and its application to model a local gravimetric quasi-geoid model over the North Sea: QGNSea V1.0

The combination of GNSS-levelling data and gravimetric (quasi-) geoid heights in the presence of noise

Quality Analysis of Global Geopotential Models at 1542 GPS/levelling Benchmarks Over the Hellenic Mainland

Contact Info

Product

Resources

About