Benchmark forward gravity schemes: the gravity field of a realistic lithosphere model WINTERC-G
<p>Several alternative gravity forward modelling methodologies and associated numerical codes with their own advantages and limitations are available for the solid Earth community. With upcoming state-of-the-art lithosphere density models and accurate global gravity field data sets, it is vita...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2022-05-01
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| Series: | Solid Earth |
| Online Access: | https://se.copernicus.org/articles/13/849/2022/se-13-849-2022.pdf |
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| author | B. C. Root B. C. Root J. Sebera J. Sebera W. Szwillus C. Thieulot Z. Martinec J. Fullea J. Fullea |
| author_facet | B. C. Root B. C. Root J. Sebera J. Sebera W. Szwillus C. Thieulot Z. Martinec J. Fullea J. Fullea |
| author_sort | B. C. Root |
| collection | DOAJ |
| description | <p>Several alternative gravity forward modelling methodologies and associated numerical codes with their own advantages and limitations are available for the solid Earth community. With upcoming state-of-the-art lithosphere density models and accurate global gravity field data sets, it is vital to understand the opportunities and limitations of the various approaches. In this paper, we discuss the four widely used techniques: global spherical harmonics (GSH), tesseroid integration (TESS), triangle integration (TRI), and hexahedral integration (HEX). A constant density shell benchmark shows that all four codes can produce similar precise gravitational potential fields. Two additional shell tests were conducted with more complicated density structures: laterally varying density structures and a crust–mantle interface density. The differences between the four codes were all below 1.5 % of the modelled gravity signal suitable for reproducing satellite-acquired gravity data. TESS and GSH produced the most similar potential fields (<span class="inline-formula"><0.3</span> %).</p>
<p>To examine the usability of the forward modelling codes for realistic geological structures, we use the global lithosphere model WINTERC-G that was constrained, among other data, by satellite gravity field data computed using a spectral forward modelling approach. This spectral code was benchmarked against the GSH, and it was confirmed that both approaches produce a similar gravity solution with negligible differences between them. In the comparison of the different WINTERC-G-based gravity solutions, again GSH and TESS performed best. Only short-wavelength noise is present between the spectral and tesseroid forward modelling approaches, likely related to the different way in which the spherical harmonic analysis of the varying boundaries of the mass layer is performed. The spherical harmonic basis functions produce small differences compared to the tesseroid elements, especially at sharp interfaces, which introduces mostly short-wavelength differences. Nevertheless, both approaches (GSH and TESS) result in accurate solutions of the potential field with reasonable computational resources. Differences below 0.5 % are obtained, resulting in residuals of 0.076 mGal standard deviation at 250 km height.</p>
<p>The biggest issue for TRI is the characteristic pattern in the residuals that is related to the grid layout. Increasing the resolution and filtering allow for the removal of most of this erroneous pattern, but at the expense of higher computational loads with respect to the other codes. The other spatial forward modelling scheme, HEX, has more difficulty in reproducing similar gravity field solutions compared to GSH and TESS. These particular approaches need to go to higher resolutions, resulting in enormous computation efforts. The hexahedron-based code performs less than optimal in the forward modelling of the gravity signature, especially with a laterally varying density interface. Care must be taken with any forward modelling software as the approximation of the geometry of the WINTERC-G model may deteriorate the gravity field solution.</p> |
| first_indexed | 2024-12-12T01:02:04Z |
| format | Article |
| id | doaj.art-b64f4699baf340b0aad996d14f52c0de |
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| issn | 1869-9510 1869-9529 |
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| last_indexed | 2024-12-12T01:02:04Z |
| publishDate | 2022-05-01 |
| publisher | Copernicus Publications |
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| series | Solid Earth |
| spelling | doaj.art-b64f4699baf340b0aad996d14f52c0de2022-12-22T00:43:41ZengCopernicus PublicationsSolid Earth1869-95101869-95292022-05-011384987310.5194/se-13-849-2022Benchmark forward gravity schemes: the gravity field of a realistic lithosphere model WINTERC-GB. C. Root0B. C. Root1J. Sebera2J. Sebera3W. Szwillus4C. Thieulot5Z. Martinec6J. Fullea7J. Fullea8Delft University of Technology, Faculty of Aerospace Engineering, Department of Space Engineering, Delft, the NetherlandsDublin Institute for Advanced Studies, School of Cosmic Physics, Geophysics Section, Dublin, IrelandAstronomical Institute of the Czech Academy of Sciences, Department of Galaxies and Planetary Systems, Prague, Czech RepublicChristian Albrechts University, Department of Geosciences, Kiel, GermanyChristian Albrechts University, Department of Geosciences, Kiel, GermanyUtrecht University, Faculty of Geosciences, Department of Earth Sciences, Utrecht, the NetherlandsDublin Institute for Advanced Studies, School of Cosmic Physics, Geophysics Section, Dublin, IrelandDublin Institute for Advanced Studies, School of Cosmic Physics, Geophysics Section, Dublin, IrelandUniversidad Complutense de Madrid (UCM), Physics of the Earth and Astrophysics department, Madrid, Spain<p>Several alternative gravity forward modelling methodologies and associated numerical codes with their own advantages and limitations are available for the solid Earth community. With upcoming state-of-the-art lithosphere density models and accurate global gravity field data sets, it is vital to understand the opportunities and limitations of the various approaches. In this paper, we discuss the four widely used techniques: global spherical harmonics (GSH), tesseroid integration (TESS), triangle integration (TRI), and hexahedral integration (HEX). A constant density shell benchmark shows that all four codes can produce similar precise gravitational potential fields. Two additional shell tests were conducted with more complicated density structures: laterally varying density structures and a crust–mantle interface density. The differences between the four codes were all below 1.5 % of the modelled gravity signal suitable for reproducing satellite-acquired gravity data. TESS and GSH produced the most similar potential fields (<span class="inline-formula"><0.3</span> %).</p> <p>To examine the usability of the forward modelling codes for realistic geological structures, we use the global lithosphere model WINTERC-G that was constrained, among other data, by satellite gravity field data computed using a spectral forward modelling approach. This spectral code was benchmarked against the GSH, and it was confirmed that both approaches produce a similar gravity solution with negligible differences between them. In the comparison of the different WINTERC-G-based gravity solutions, again GSH and TESS performed best. Only short-wavelength noise is present between the spectral and tesseroid forward modelling approaches, likely related to the different way in which the spherical harmonic analysis of the varying boundaries of the mass layer is performed. The spherical harmonic basis functions produce small differences compared to the tesseroid elements, especially at sharp interfaces, which introduces mostly short-wavelength differences. Nevertheless, both approaches (GSH and TESS) result in accurate solutions of the potential field with reasonable computational resources. Differences below 0.5 % are obtained, resulting in residuals of 0.076 mGal standard deviation at 250 km height.</p> <p>The biggest issue for TRI is the characteristic pattern in the residuals that is related to the grid layout. Increasing the resolution and filtering allow for the removal of most of this erroneous pattern, but at the expense of higher computational loads with respect to the other codes. The other spatial forward modelling scheme, HEX, has more difficulty in reproducing similar gravity field solutions compared to GSH and TESS. These particular approaches need to go to higher resolutions, resulting in enormous computation efforts. The hexahedron-based code performs less than optimal in the forward modelling of the gravity signature, especially with a laterally varying density interface. Care must be taken with any forward modelling software as the approximation of the geometry of the WINTERC-G model may deteriorate the gravity field solution.</p>https://se.copernicus.org/articles/13/849/2022/se-13-849-2022.pdf |
| spellingShingle | B. C. Root B. C. Root J. Sebera J. Sebera W. Szwillus C. Thieulot Z. Martinec J. Fullea J. Fullea Benchmark forward gravity schemes: the gravity field of a realistic lithosphere model WINTERC-G Solid Earth |
| title | Benchmark forward gravity schemes: the gravity field of a realistic lithosphere model WINTERC-G |
| title_full | Benchmark forward gravity schemes: the gravity field of a realistic lithosphere model WINTERC-G |
| title_fullStr | Benchmark forward gravity schemes: the gravity field of a realistic lithosphere model WINTERC-G |
| title_full_unstemmed | Benchmark forward gravity schemes: the gravity field of a realistic lithosphere model WINTERC-G |
| title_short | Benchmark forward gravity schemes: the gravity field of a realistic lithosphere model WINTERC-G |
| title_sort | benchmark forward gravity schemes the gravity field of a realistic lithosphere model winterc g |
| url | https://se.copernicus.org/articles/13/849/2022/se-13-849-2022.pdf |
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