Spherical harmonic analysis of a harmonic function given on a spheroid

A new analytical method for the computation of a truncated series of solid spherical harmonic coefficients (HCs) from data on a spheroid (i.e. an oblate ellipsoid of revolution) is derived, using a transformation between surface and solid spherical HCs. A two-step procedure is derived to extend this...

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Main Author: Claessens, Sten
Format: Journal Article
Published: Blackwell Publishing Ltd 2016
Online Access:http://hdl.handle.net/20.500.11937/30661
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author Claessens, Sten
author_facet Claessens, Sten
author_sort Claessens, Sten
building Curtin Institutional Repository
collection Online Access
description A new analytical method for the computation of a truncated series of solid spherical harmonic coefficients (HCs) from data on a spheroid (i.e. an oblate ellipsoid of revolution) is derived, using a transformation between surface and solid spherical HCs. A two-step procedure is derived to extend this transformation beyond degree and order (d/o) 520. The method is compared to the Hotine-Jekeli transformation in a numerical study based on the EGM2008 global gravity model. Both methods are shown to achieve submicrometre precision in terms of height anomalies for a model to d/o 2239. However, both methods result in spherical harmonic models that are different by up to 7.6 mm in height anomalies and 2.5 mGal in gravity disturbances due to the different coordinate system used. While the Hotine-Jekeli transformation requires the use of an ellipsoidal coordinate system, the new method uses only spherical polar coordinates. The Hotine-Jekeli transformation is numerically more efficient, but the new method can more easily be extended to cases where (a linear combination of) normal derivatives of the function under consideration are given on the surface of the spheroid. It therefore provides a solution to many types of ellipsoidal boundary-value problems in the spectral domain.
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spelling curtin-20.500.11937-306612017-09-13T15:08:55Z Spherical harmonic analysis of a harmonic function given on a spheroid Claessens, Sten A new analytical method for the computation of a truncated series of solid spherical harmonic coefficients (HCs) from data on a spheroid (i.e. an oblate ellipsoid of revolution) is derived, using a transformation between surface and solid spherical HCs. A two-step procedure is derived to extend this transformation beyond degree and order (d/o) 520. The method is compared to the Hotine-Jekeli transformation in a numerical study based on the EGM2008 global gravity model. Both methods are shown to achieve submicrometre precision in terms of height anomalies for a model to d/o 2239. However, both methods result in spherical harmonic models that are different by up to 7.6 mm in height anomalies and 2.5 mGal in gravity disturbances due to the different coordinate system used. While the Hotine-Jekeli transformation requires the use of an ellipsoidal coordinate system, the new method uses only spherical polar coordinates. The Hotine-Jekeli transformation is numerically more efficient, but the new method can more easily be extended to cases where (a linear combination of) normal derivatives of the function under consideration are given on the surface of the spheroid. It therefore provides a solution to many types of ellipsoidal boundary-value problems in the spectral domain. 2016 Journal Article http://hdl.handle.net/20.500.11937/30661 10.1093/gji/ggw126 Blackwell Publishing Ltd fulltext
spellingShingle Claessens, Sten
Spherical harmonic analysis of a harmonic function given on a spheroid
title Spherical harmonic analysis of a harmonic function given on a spheroid
title_full Spherical harmonic analysis of a harmonic function given on a spheroid
title_fullStr Spherical harmonic analysis of a harmonic function given on a spheroid
title_full_unstemmed Spherical harmonic analysis of a harmonic function given on a spheroid
title_short Spherical harmonic analysis of a harmonic function given on a spheroid
title_sort spherical harmonic analysis of a harmonic function given on a spheroid
url http://hdl.handle.net/20.500.11937/30661