On the estimation of a multi-resolution representation of the gravity field based on spherical harmonics and wavelets

et al. 2018

Geosci. Model Dev.

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.

“…According to Schmidt et al (2006Schmidt et al ( , 2007, the MRR of the Earth's disturbing potential T (z) at position z is expressed as…”

Section: Multilayer Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Luo

et al. 2018

Geosci. Model Dev.

“…Freeden et al (2009) demonstrated that the multi-scale approach using spherical wavelets provided local fine-structured features such as those caused by plumes, which allowed a scale-and space-dependent characterization of this geophysical phenomenon. Schmidt et al (2005Schmidt et al ( , 2006Schmidt et al ( , 2007 developed a multi-representation method for static and spatiotemporal gravity field modeling through SRBFs, where 15 the input gravity signals were decomposed into a certain number of frequency-dependent detail signals, and concluded that this approach could improve the spanning fixed time intervals with respect to the usual time-variable gravity fields. Chambodut et al (2005) set up a multi-scale method for magnetic and gravity field recovery using Poisson wavelets, and created a set of hierarchical meshes associated with the wavelets at different scales, where a level of subdivision corresponded to a given wavelet scale.…”

Section: Freeden and 10mentioning

confidence: 99%

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

Luo

et al. 2018

Preprint

Abstract:A multilayer approach is set up for local gravity field modeling based on the idea of multi-resolution representation merging heterogeneous gravity data. Different layers of Poisson wavelets' grids are formed to recover the signals at various levels, where the shallow and deep layers mainly capture the short-and long-wavelength signals, respectively. The depths of these layers beneath the topography are linked to the locations that the anomaly sources locate, estimated by the wavelet decomposition and power spectrum analysis. For testing the performance of this 15 approach, a gravimetric quasi-geoid over the North Sea in Europe called QGNSea V1.0 is computed and compared with other existing models. The results show that the multilayer approach outperforms the traditionally used single-layer one in high-frequency bands, and the former fit the gravity data better, especially in regions with a tendency toward topographical variation. The evaluation with GPS/leveling data show the accuracies of QGNSea V1.0 modeled from the multilayer approach are improved by 0.3 cm, 0.6 cm and 0.8 cm in the Netherlands, Belgium and 20 parts of Germany, respectively, compared to the original solution computed from the single-layer approach. Further validation with existing models show QGNSea V1.0 has the best quality, which may be beneficial for studying the ocean circulation between the North Sea and neighbouring waters.

“…We parameterize the regional gravity field with the extensively used SRBFs, which are radially symmetric basis functions that have localizing properties in both the spatial and frequency domains [ Holschneider et al ., ; Schmidt et al ., ; Tenzer and Klees , ]. The rest of the paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

Regional gravity field recovery using the GOCE gravity gradient tensor and heterogeneous gravimetry and altimetry data

Zhou

et al. 2017

JGR Solid Earth

A regional approach using Poisson wavelets is applied for gravity field recovery using the GOCE (Gravity Field and Steady‐State Ocean Circulation Explorer) gravity gradient tensor, heterogeneous gravimetry data, and altimetry measurements. The added value to the regional model introduced by GOCE data is validated and quantified. The performances of the solutions modeled with different diagonal components of GOCE data and their combinations are investigated. Numerical experiments in a region in Europe show that the effects introduced by GOCE data demonstrate long‐wavelength patterns on the centimeter scale in terms of quasi‐geoid heights, which may allow reducing the remaining long‐wavelength errors in ground‐based data, and improve the regional model. The accuracy of the gravimetric quasi‐geoid computed with a combination of three diagonal components is improved by 0.6 cm (0.5 cm) in the Netherlands (Belgium) compared to that derived from gravimetry and altimetry data alone, when GOCO05s is used as the reference model. Moreover, the added value from GOCE data reduces the mean values of the misfit between the gravimetric solution and GPS/leveling data. Performances of different components and their combinations are not identical, and the solution with vertical gradients is best when a single component is used. The incorporation of multiple components shows further improvements, and the combination of three components best fits the local GPS/leveling data. Further comparison shows that our solution is the highest quality and may be substituted for existing models for engineering purposes and geophysical investigations over the target area.